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. 2014 May 1;9(5):e96088. doi: 10.1371/journal.pone.0096088

Cancer Incidence and Survival among Adolescents and Young Adults in Korea

Eun-Kyeong Moon 1, Hyeon Jin Park 2, Chang-Mo Oh 1, Kyu-Won Jung 1, Hee Young Shin 3, Byung Kiu Park 2, Young-Joo Won 1,*
Editor: Bart O Williams4
PMCID: PMC4006908  PMID: 24789075

Abstract

Background

In Korea, cancer is the third leading cause of death among adolescents and young adults (AYAs). However, cancer incidence and survival trends among AYAs (15–29 years) have never been studied in Korea. Therefore, this study aimed to investigate the incidence and relative survival rates and their trends among AYAs in Korea.

Materials and Methods

Cancer incidence data from 1999–2010 were obtained from the Korea Central Cancer Registry (KCCR). Each cancer was classified into subgroups according to the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) AYA site recode. Percent distributions, age-specific incidence rates, age-standardized incidence rates per million, and annual percent changes (APCs) were calculated for AYAs according to sex. Five-year relative survival rates were estimated for cases diagnosed between 1993 and 2010 and followed up to 2011.

Results

The age-standardized incidence rates of all cancers combined were 196.4 and 367.8 per million for males and females, respectively (male-to-female (M/F) ratio: 0.5). The age-standardized incidence rates increased from 208.7 per million in 1999 to 396.4 per million in 2010, and the APC was 6.3% (P<0.001). The five most common cancers among AYAs were thyroid carcinoma, non-Hodgkin lymphoma, stomach carcinoma, breast carcinoma, and acute myeloid leukemia. In males, the 5-year relative survival rate improved, from 46.5% in 1993–1995 to 75.9% in 2006–2010. In females, the 5-year relative survival rate also improved, from 66.7% in 1993–1995 to 89.1% in 2006–2010.

Conclusions

Our study showed increases in cancer incidence and improvements in the 5-year relative survival rate among Korean AYAs. This study also provides additional data regarding temporal and geographic trends in cancer that may enhance future efforts to identify factors affecting cancer incidence and responses to treatment among AYAs.

Introduction

Cancers in adolescents and young adults (AYAs; 15–29 years) have distinctive characteristics compared with cancers in children and older cohorts.

The incidence pattern of specific cancer types differ between AYAs and younger and older patients. In addition, the genetic and histologic patterns of cancers among AYAs differ from those of older patients [1]. Because cancer is uncommon among AYAs, this patient population has not drawn public attention compared with the pediatric and adult populations. However, an increase in cancer incidence among AYAs has been reported in Europe [2]–[4] and the United States [5].

Over 200,000 new cancer patients are diagnosed annually in Korea [6], and approximately 3,200 (1.6%) AYAs were diagnosed with cancer in Korea in 2010. According to the U.S. National Cancer Institute Surveillance Epidemiology and End Results (SEER), 2% of all invasive cancers are diagnosed in individuals aged 15–29 years [5]. Although only a small proportion of all malignancies are diagnosed in AYAs, high-grade and later-stage tumors of certain cancers are more likely to be diagnosed in this patient population [1]. Furthermore, cancer diagnosis in AYAs can greatly influence future quality of life and life expectancy [7]. In fact, in Korea, cancer is the leading cause of death among AYAs, after suicide and traffic accidents [8]. However, to the best of our knowledge, cancer incidence and survival among AYAs in Korea have never been studied. Therefore, this study aimed to investigate cancer incidence and survival among AYAs in Korea. We examined the trends in cancer incidence rates from 1999 to 2010 and the trends in relative survival rates from 1993 to 2010 among Korean AYAs.

Materials and Methods

Data Sources

In 1980, the Korean Ministry of Health and Welfare started the Korea Central Cancer Registry (KCCR), a nationwide, hospital-based cancer registry [9]. Until 1998, the registry collected cancer cases from more than 180 hospitals in Korea annually, and these data represent 80–90% of all cancer incidence in Korea [10]. Since 1999, the KCCR has covered the entire population under the population-based cancer registry program [6]. The Korea National Cancer Incidence Database (KNCIDB) KCCR data from 1999 to 2002 and from 2003 to 2007 have been published in Cancer Incidence in Five Continents, which reflects the completeness and validity of the incidence data [11].

Incidence data were collected for Korean AYAs aged 15–29 years who were newly diagnosed with cancer between 1999 and 2010. The incidence data were collected from the KNCIDB of the KCCR and included age, sex, diagnosis date, primary tumor site, morphology, the diagnostic method, and stage at diagnosis.

Survival data for individuals aged 15–29 years who were newly diagnosed with cancer from 1993–2010 were obtained from the KNCIDB, and the patients’ vital status was followed until December 31, 2011. The survival analysis was based on the KNCIDB data and mortality data obtained from Statistics Korea.

Case Definition

In accordance with the guidelines of the National Cancer Institute SEER Program [5] and the Canadian Cancer Society [12] in this study, AYAs were defined as adolescents and young adults aged 15–29 years.

Cancer sites were coded by primary site and morphology using the International Classification of Diseases for Oncology (third edition) [13]. Cancers were classified according to the SEER AYA scheme, which is based on a modified version of the International Classification of Childhood Cancer [5]. In particular, the SEER AYA scheme is based on an updated classification proposed by Barr et al. and is composed of ten major groups and second- and third-level subgroups according to the site of origin [14].

Incidence

Age-specific incidence rates per million were analyzed in each diagnostic subgroup according to the age at diagnosis (15–19 years, 20–24 years, and 25–29 years), and age-standardized rates (ASRs) according to sex were calculated using the world standard population defined by the World Health Organization [15]. Trends in annual ASRs were calculated using the annual percent change (APC), which was estimated using the following formula: 100×(eβ-1), where β is the slope calculated from a linear regression of log age-standardized incidence rates in a calendar year [16]. The male-to-female (M/F) ratio was the ratio of the ASR among males to the ASR among females. Comparisons of age-standardized incidence rates in males and females were calculated by the direct method [17].

Survival

Relative survival rates were estimated according to the time period: 1993–1995, 1996–2000, 2001–2005 and 2006–2010. Relative survival rates according to the diagnostic group were calculated by dividing observed survival by expected survival among comparable groups in the general population [18] using the Ederer II method [19]. These survival rates were estimated using “complete analysis”, which included “right-censored” patients. Due to this inclusion of the early survival experience of more recently recruited patients, the analysis provided more up-to-date and precise survival rates in long-term survival [20]. Trends in 5-year relative survival rates were also calculated. Additionally, the effects of sex, diagnostic group, and time period on survival were assessed using a relative excess risk model. All analyses were performed using SAS version 9.2.

Results

Incidence

From 1999 to 2010, 39,639 cancer cases (2.3% of all cancer patients) were newly diagnosed in AYAs. Of these cases, 14,016 (35.4%) and 25,623 (64.6%) cases were diagnosed in males and females, respectively. According to the age at diagnosis, 6,396 (16.1%) cases were diagnosed at 15–19 years of age, 10,433 (26.3%) cases were diagnosed at 20–24 years, and 22,810 (26.3%) cases were diagnosed at 25–29 years.

The number of cases per age group (15–19 years, 20–24 years and 25–29 years) by sex, age-specific incidence rates, and age-standardized incidence rates among both males and females and M/F ratios according to the diagnostic group are shown in Table 1.

Table 1. Number of cases, age-specific incidence rates, and age-standardized incidence rates from 1999 to 2010 according to sex and age.

Diagnostic group (SEER) Males Females Total M/F
15–19 years 20–24 years 25–29 years 15–29 years 15–19 years 20–24 years 25–29 years 15–29 years Ratio*
Cases CR Cases CR Cases CR Cases ASR Cases CR Cases CR Cases CR Cases s ASR ASR
All Cancers 3,249 150.9 3,891 170.7 6,876 273.4 14,016 196.4 3,147 160.4 6,542 305.6 15,934 663.3 25,623 367.8 279.9 0.5 †
All Cancers (excluding thyroid carcinoma) ‡ 3,065 142.3 3,445 151.1 5,665 225.2 12,175 171.7 2,275 115.9 3,660 171.0 8,793 366.0 14,728 213.6 192.2 0.8 †
1. Leukemias 737 17.1 600 13.2 694 13.8 2,031 14.8 482 12.3 430 10.0 549 11.4 1,461 11.3 13.1 1.3 †
1.1 Acute lymphoid leukemia 307 7.1 177 3.9 130 2.6 614 4.6 170 4.3 110 2.6 95 2.0 375 3.0 3.9 1.5†
1.2 Acute myeloid leukemia 265 12.3 230 10.1 287 11.4 782 11.3 226 11.5 190 8.9 283 11.8 699 10.8 11.0 1.1†
1.3 Chronic myeloid leukemia 96 4.5 131 5.7 187 7.4 414 5.8 37 1.9 75 3.5 92 3.8 204 3.0 4.5 1.9†
1.4 Other and unspecified leukemia 69 3.2 62 2.7 90 3.6 221 3.2 49 2.5 55 2.6 79 3.3 183 2.8 3.0 1.1†
2. Lymphomas 516 24.0 533 23.4 612 24.3 1,661 23.9 269 13.7 414 19.3 568 23.6 1,251 18.7 21.4 1.3 †
2.1 Non-Hodgkin lymphoma 406 18.9 437 19.2 524 20.8 1,367 19.6 199 10.1 314 14.7 461 19.2 974 14.5 17.1 1.4†
2.2 Hodgkin lymphoma 110 5.1 96 4.2 88 3.5 294 4.3 70 3.6 100 4.7 107 4.5 277 4.2 4.3 1.0
3. CNS and Other Intracranial and Intraspinal Neoplasms 332 15.4 320 14.0 406 16.1 1,058 15.2 228 11.6 214 10.0 361 15.0 803 12.2 13.8 1.2 †
3.1 Astrocytoma 88 4.1 110 4.8 171 6.8 369 5.2 82 4.2 74 3.5 155 6.5 311 4.7 4.9 1.1†
3.2 Other glioma 44 2.0 50 2.2 101 4.0 195 2.7 42 2.1 33 1.5 88 3.7 163 2.4 2.6 1.1†
3.3 Ependymoma 23 1.1 24 1.1 33 1.3 80 1.1 15 0.8 21 1.0 22 0.9 58 0.9 1.0 1.3†
3.4. Medulloblastoma and other PNET 66 3.1 35 1.5 24 1.0 125 1.9 47 2.4 30 1.4 24 1.0 101 1.6 1.8 1.2†
3.5 Other specified intracranial and intraspinal neoplasms 11 0.5 9 0.4 10 0.4 30 0.4 3 0.2 7 0.3 11 0.5 21 0.3 0.4 1.4†
3.6 Unspecified intracranial and intraspinal neoplasms 100 4.6 92 4.0 67 2.7 259 3.8 39 2.0 49 2.3 61 2.5 149 2.3 3.1 1.7†
4. Osseous and Chondromatous Neoplasms 379 17.6 219 9.6 146 5.8 744 11.3 189 9.6 124 5.8 120 5.0 433 6.9 9.2 1.6 †
4.1 Osteosarcoma 257 11.9 104 4.6 53 2.1 414 6.4 126 6.4 49 2.3 47 2.0 222 3.7 5.1 1.8†
4.2 Chondrosarcoma 28 1.3 39 1.7 45 1.8 112 1.6 10 0.5 33 1.5 34 1.4 77 1.1 1.4 1.4†
4.3 Ewing tumor 53 2.5 44 1.9 18 0.7 115 1.7 30 1.5 14 0.7 21 0.9 65 1.0 1.4 1.7†
4.4 Other specified and unspecified bone tumors 41 1.9 32 1.4 30 1.2 103 1.5 23 1.2 28 1.3 18 0.7 69 1.1 1.3 1.4†
5. Soft Tissue Sarcomas 220 10.2 248 10.9 345 13.7 813 11.5 174 8.9 223 10.4 302 12.6 699 10.5 11.1 1.1 †
5.1 Fibromatous neoplasms 44 2.0 63 2.8 92 3.7 199 2.8 35 1.8 59 2.8 88 3.7 182 2.7 2.7 1.0
5.2 Rhabdomyosarcoma 58 2.7 26 1.1 25 1.0 109 1.7 36 1.8 16 0.7 19 0.8 71 1.2 1.4 1.4†
5.3 Other soft tissue sarcoma 118 5.5 159 7.0 228 9.1 505 7.1 103 5.2 148 6.9 195 8.1 446 6.7 6.9 1.1†
6. Germ Cell and Trophoblastic Neoplasms 340 15.8 417 18.3 473 18.8 1,230 17.6 341 17.4 300 14.0 295 12.3 936 14.7 16.1 1.2 †
6.1 Germ cell and trophoblastic neoplasms of gonads 84 3.9 231 10.1 364 14.5 679 9.3 283 14.4 243 11.4 195 8.1 721 11.4 10.3 0.8†
6.2 Germ cell and trophoblastic neoplasms of nongonadal sites 256 11.9 186 8.2 109 4.3 551 8.3 58 3.0 57 2.7 100 4.2 215 3.2 5.9 2.5†
7. Melanoma and Skin Carcinomas 21 1.0 40 1.8 107 4.3 168 2.3 19 1.0 42 2.0 98 4.1 159 2.3 2.3 1.0
7.1 Melanoma 12 0.6 20 0.9 50 2.0 82 1.1 11 0.6 26 1.2 46 1.9 83 1.2 1.2 0.9
7.2 Skin carcinomas 9 0.4 20 0.9 57 2.3 86 1.2 8 0.4 16 0.7 52 2.2 76 1.1 1.1 1.1
8. Carcinomas 516 24.0 1,272 55.8 3,653 145.2 5,441 73.0 1,257 64.1 4,451 207.9 12,959 539.4 18,667 262.2 165.0 0.3 †
8.1 Thyroid carcinoma 184 8.5 446 19.6 1,211 48.1 1,841 24.7 872 44.4 2,882 134.6 7,141 297.3 10,895 154.2 87.7 0.2†
8.2 Other carcinoma of head and neck 81 3.8 133 5.8 213 8.5 427 5.9 72 3.7 133 6.2 199 8.3 404 6.0 5.9 1.0
8.2.1 Nasopharyngeal carcinoma 40 1.9 43 1.9 47 1.9 130 1.9 17 0.9 19 0.9 28 1.2 64 1.0 1.4 1.9†
8.2.2 Other sites in lip, oral cavity, and pharynx 36 1.7 81 3.6 143 5.7 260 3.6 47 2.4 104 4.9 152 6.3 303 4.4 4.0 0.8
8.2.3 Nasal cavity, middle ear, sinuses, larynx, and other ill-defined sites in head/neck 5 0.2 9 0.4 23 0.9 37 0.5 8 0.4 10 0.5 19 0.8 37 0.5 0.5 1.0
8.3 Carcinoma of trachea, bronchus, and lung 25 1.2 50 2.2 104 4.1 179 2.4 16 0.8 52 2.4 121 5.0 189 2.7 2.6 0.9†
8.4 Carcinoma of breast 2 0.1 3 0.1 5 0.1 15 0.8 265 12.4 1,672 69.6 1,952 26.5 13.0 0.003†
8.5 Carcinoma of genitourinary tract 30 1.4 93 4.1 290 11.5 413 5.5 154 7.8 524 24.5 1,986 82.7 2,664 37.1 20.9 0.1†
8.5.1 Carcinoma of kidney 17 0.8 52 2.3 173 6.9 242 3.2 18 0.9 34 1.6 108 4.5 160 2.3 2.8 1.4†
8.5.2 Carcinoma of bladder 12 0.6 30 1.3 103 4.1 145 1.9 2 0.1 16 0.7 31 1.3 49 0.7 1.3 2.8†
8.5.3 Carcinoma of gonads - - 3 0.1 2 0.1 5 0.1 123 6.3 242 11.3 420 17.5 785 11.5 5.6 0.01†
8.5.4 Carcinoma of cervix and uterus - - - - - - - - 8 0.4 229 10.7 1,399 58.2 1,636 22.2 10.8 -
8.5.5 Carcinoma of other and ill-defined sites in genitourinary tract 1 0.0 8 0.4 12 0.5 21 0.3 3 0.2 3 0.1 28 1.2 34 0.5 0.4 0.6†
8.6 Carcinoma of gastrointestinal tract 161 7.5 500 21.9 1,715 68.2 2,376 31.5 113 5.8 553 25.8 1,740 72.4 2,406 33.5 32.5 0.9†
8.6.1 Carcinoma of colon and rectum 67 3.1 176 7.7 530 21.1 773 10.3 46 2.3 165 7.7 402 16.7 613 8.7 9.5 1.2†
8.6.2 Carcinoma of stomach 41 1.9 179 7.9 764 30.4 984 12.9 33 1.7 298 13.9 1,116 46.5 1,447 19.9 16.3 0.6†
8.6.3 Carcinoma of liver and intrahepatic bile ducts 51 2.4 121 5.3 373 14.8 545 7.3 18 0.9 66 3.1 151 6.3 235 3.3 5.4 2.2†
8.6.4 Carcinoma of pancreas 1 0.0 16 0.7 21 0.8 38 0.5 12 0.6 14 0.7 32 1.3 58 0.9 0.7 0.6†
8.6.5 Carcinoma of other and ill-defined sites in gastrointestinal tract 1 0.0 8 0.4 27 1.1 36 0.5 4 0.2 10 0.5 39 1.6 53 0.7 0.6 0.6†
8.7 Carcinoma of other and ill-defined sites 35 1.6 48 2.1 117 4.7 200 2.7 15 0.8 42 2.0 100 4.2 157 2.2 2.5 1.2†
8.7.1 Adrenocortical carcinoma 1 0.0 5 0.2 6 0.2 12 0.2 3 0.2 7 0.3 8 0.3 18 0.3 0.2 0.6†
8.7.2 Carcinoma of other and ill-defined sites, NOS 34 1.6 43 1.9 111 4.4 188 2.6 12 0.6 35 1.6 92 3.8 139 2.0 2.3 1.3†
9. Miscellaneous Specified Neoplasms, NOS 120 5.6 117 5.1 181 7.2 418 6.0 100 5.1 141 6.6 254 10.6 495 7.3 6.6 0.8 †
9.1 Other pediatric and embryonal tumors, NOS 30 1.4 20 0.9 24 1.0 74 1.1 20 1.0 17 0.8 22 0.9 59 0.9 1.0 1.2†
9.2 Other specified and embryonal tumors, NOS 90 4.2 97 4.3 157 6.2 344 4.9 80 4.1 124 5.8 232 9.7 436 6.4 5.6 0.8†
10. Unspecified Malignant Neoplasms 67 3.1 125 5.5 259 10.3 451 6.2 88 4.5 203 9.5 428 17.8 719 10.4 8.2 0.6 †
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*M/F Ratio  =  Male ASR/Female ASR.

†

P-values <0.05.

‡

Thyroid carcinoma was excluded from the calculation of the incidence rate of all cancers combined because of its unusually high incidence rate.

CR, crude incidence rate; CNS, central nervous system; PNET, primitive neuroectodermal tumor; NOS, not otherwise specified.

Between 1999 and 2010, the overall age-standardized incidence rate of cancers among AYAs in Korea was 279.9 per million. Cancer incidence was higher in females (367.8 per million) than in males (196.4 per million), and for all cancers combined, the male/female ratio was 0.5 (P<0.05). The higher rate among females was largely due to a much higher incidence rate of thyroid carcinomas (24.7 per million among males vs. 154.2 per million among females). Because the incidence rate of thyroid carcinoma was unusually high, the age-standardized incidence rates of all cancers combined were recalculated, excluding thyroid carcinoma (group 8.1). Removing thyroid carcinomas, the overall ASR of cancers was 192.2 per million (171.7 per million for males and 213.6 per million for females) (Table 1).

The incidence increased with age, from 150.9 in males and 160.4 in females per million at 15–19 years of age to 170.7 in males and 305.6 in females per million, respectively, at 20–24 years of age. The incidence further increased at 25–59 years of age, to 273.4 in males and 663.3 in females per million, respectively (Table 1). The incidence rates were correlated with age group for most subtypes, with the notable exceptions of leukemia and osseous/chondromatous neoplasms, which were more common among younger AYAs (Table 1).

Table 2 shows the secular trends in cancer incidence among AYAs from 1999 to 2010 according to the diagnostic group. The incidence rate of all cancers among AYAs significantly increased, from 208.7 per million in 1999 to 396.4 per million in 2010 (APC = 6.3%; P<0.05). Over the studied time period, there was also a steady increase in the incidence of cancer among AYAs for both males (APC = 3.9%) and females (APC = 7.8%) (Figure 1).

Table 2. Trends in age-standardized incidence rates among Korean AYAs and estimated annual percent changes (APCs).

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 APC
All cancers 208.7 204.7 230.3 226.4 256.3 266.2 275.6 290.8 315.8 355.6 370.4 396.4 6.3*
All cancers (excluding thyroid carcinoma) † 174.8 170.9 188.2 178.9 193.6 188.0 193.5 197.1 203.8 210.7 208.2 207.5 1.8*
1 Leukemias 23.4 24.1 27.8 26.0 24.5 24.5 25.6 26.6 28.2 29.6 28.9 26.5 1.5*
1.1 Acute lymphoid leukemia 7.0 7.6 7.4 7.2 6.7 6.9 7.7 8.0 8.4 8.3 8.9 8.8 2.2*
1.2 Acute myeloid leukemia 10.4 9.2 12.3 12.2 10.5 10.5 10.8 12.5 11.3 12.7 11.1 9.3 0.3
1.3 Chronic myeloid leukemia 3.5 4.3 4.7 3.7 4.7 4.4 4.5 3.6 4.9 5.0 5.3 5.5 2.9*
1.4 Other and unspecified leukemia 2.5 3.0 3.4 2.8 2.7 2.6 2.7 2.5 3.6 3.5 3.6 2.8 1.5
2 Lymphomas 16.6 15.0 17.7 17.2 21.8 23.1 21.5 23.9 23.9 26.7 26.3 26.0 5.3*
2.1 Non-Hodgkin lymphoma 14.5 12.5 14.4 13.6 17.2 18.2 17.7 19.6 18.6 20.7 20.8 19.9 4.5*
2.2 Hodgkin lymphoma 2.1 2.4 3.3 3.6 4.6 4.9 3.8 4.3 5.3 6.0 5.5 6.1 9.1*
3 CNS and Other Intracranial and Intraspinal Neoplasms (all behaviors) 12.7 12.9 12.0 13.4 15.0 14.5 12.9 14.6 14.5 15.7 14.1 13.3 1.2
3.1. Astrocytoma 4.8 3.8 4.7 4.5 4.7 5.4 4.6 5.0 6.3 5.6 4.8 5.3 2.3*
3.2 Other glioma 1.4 1.8 1.5 2.8 2.8 2.5 2.5 2.6 2.7 4.2 3.3 3.4 8.0*
3.3 Ependymoma 0.5 1.0 1.1 0.9 1.1 0.9 0.7 1.2 1.0 1.4 1.2 1.3 4.9*
3.4. Medulloblastoma and other PNET 1.6 1.5 1.6 2.0 2.3 2.3 1.2 2.4 1.3 2.0 2.0 1.1 -0.8
3.5 Other specified intracranial and intraspinal neoplasms 0.6 0.4 0.4 0.2 0.5 0.4 0.3 0.2 0.5 0.5 0.2 0.3 -3.9
3.6 Unspecified intracranial and intraspinal neoplasms 3.7 4.5 2.8 3.0 3.7 2.9 3.6 3.1 2.8 2.0 2.5 2.1 -5.0*
4 Osseous & Chondromatous Neoplasms 8.4 8.7 11.4 7.9 10.6 8.5 8.2 7.6 9.7 10.2 8.8 10.5 0.6
4.1 Osteosarcoma 5.0 4.9 6.8 4.9 5.6 5.3 4.9 3.8 4.4 6.1 4.4 5.2 -1.1
4.2 Chondrosarcoma 1.4 1.4 1.1 0.9 1.9 1.0 1.3 1.1 1.5 1.6 1.2 2.0 2.3
4.3 Ewing tumor 0.7 1.3 1.7 1.2 1.4 1.0 1.2 1.3 1.9 1.3 1.9 2.1 5.8*
4.4 Other specified and unspecified bone tumors 1.3 1.1 1.8 0.9 1.7 1.1 0.8 1.5 1.9 1.2 1.3 1.2 0.4
5 Soft Tissue Sarcomas 8.9 8.5 10.6 9.5 11.0 10.9 9.7 12.5 13.0 12.9 13.6 12.8 4.1*
5.1 Fibromatous neoplasms 1.4 1.8 1.7 2.0 3.2 2.7 2.5 3.3 3.2 4.5 3.1 4.2 9.6*
5.2 Rhabdomyosarcoma 1.2 1.6 1.2 1.6 0.6 2.5 1.3 2.4 1.5 0.7 1.0 1.3 -1.6
5.3 Other soft tissue sarcoma 6.3 5.0 7.7 5.9 7.2 5.7 5.9 6.8 8.3 7.7 9.4 7.3 3.2*
6 Germ Cell and Trophoblastic Neoplasms 13.5 14.0 14.8 14.3 14.5 14.7 17.0 16.4 19.1 17.8 18.3 20.2 3.6*
6.1 Germ cell and trophoblastic neoplasms of gonads 9.1 8.6 9.9 9.0 9.0 10.2 10.3 10.3 11.2 12.0 11.4 12.9 3.3*
6.2 Germ cell and trophoblastic neoplasms of nongonadalsites 4.4 5.5 4.9 5.3 5.6 4.4 6.7 6.1 8.0 5.9 7.0 7.3 4.2*
7 Melanoma and Skin Carcinomas 1.7 2.1 2.6 1.8 1.0 1.5 3.7 2.5 2.3 2.7 3.2 2.5 4.8
7.1 Melanoma 1.1 1.2 1.2 0.9 0.5 0.9 2.0 0.9 0.9 1.4 1.9 1.1 2.6
7.2 Skin carcinomas 0.6 0.8 1.5 0.9 0.6 0.5 1.7 1.6 1.4 1.3 1.4 1.5 7.2*
8 Carcinomas 105.3 102.0 116.4 123.2 141.5 155.2 163.7 173.1 191.8 225.1 244.4 270.7 9.4*
8.1 Thyroid carcinoma 33.9 33.8 42.1 47.4 62.6 78.2 82.1 93.6 112.0 144.9 162.2 188.9 17.9*
8.2 Other carcinoma of head and neck 4.9 5.1 5.0 5.9 6.7 5.9 6.1 5.3 6.8 6.7 8.1 5.2 2.5
8.2.1 Nasopharyngeal carcinoma 1.1 1.8 1.2 1.2 1.9 1.6 1.3 1.1 1.4 1.7 1.8 1.4 1.2
8.2.2 Other sites in lip, oral cavity and pharynx 3.2 3.0 3.3 4.2 3.9 3.8 4.4 3.9 5.0 4.4 5.5 3.6 3.4*
8.2.3 Nasal cav,mid ear,sinuses,larynx,oth ill-defhead/neck 0.6 0.4 0.4 0.5 0.9 0.6 0.4 0.3 0.5 0.7 0.7 0.3 -0.6
8.3 Carcinoma of trachea,bronchus, and lung 2.4 1.5 2.9 2.2 2.5 3.0 3.1 3.0 1.9 2.2 2.9 3.4 2.6
8.4 Carcinoma of breast 8.5 11.4 12.3 13.6 12.2 12.6 15.1 13.8 13.9 14.1 13.8 15.3 3.5*
8.5 Carcinoma of genitourinary tract 18.4 14.7 17.2 18.7 21.5 21.1 20.9 23.8 22.2 24.5 24.0 25.7 4.2*
8.5.1 Carcinoma of kidney 2.2 0.9 2.3 2.1 2.1 2.8 2.5 4.2 2.4 4.3 4.4 3.3 9.1*
8.5.2 Carcinoma of bladder 1.4 0.8 1.4 1.1 1.7 1.5 1.8 1.1 1.6 1.2 0.9 1.4 0.7
8.5.3 Carcinoma of gonads 5.9 5.9 4.9 5.5 6.8 5.2 5.8 5.2 6.4 4.9 4.4 6.1 -0.8
8.5.4 Carcinoma of cervix and uterus 8.6 6.7 8.4 9.5 10.3 11.1 10.3 13.0 11.3 13.9 13.7 14.6 6.2*
8.5.5 Carc of other and ill-def sites, geniourinary tract 0.2 0.3 0.2 0.5 0.5 0.4 0.5 0.3 0.5 0.2 0.5 0.3 2.8
8.6 Carcinoma of gastrointestinal tract 34.2 32.3 34.2 33.1 34.3 31.6 34.0 31.2 31.7 31.1 31.1 30.4 -1.0*
8.6.1 Carcinoma of colon and rectum 9.1 8.1 8.4 7.7 9.1 8.3 9.2 9.4 9.8 12.9 11.8 11.3 3.7*
8.6.2 Carcinoma of stomach 18.8 17.3 18.4 18.7 17.4 15.8 17.3 15.4 15.3 13.2 13.7 13.2 -3.3*
8.6.3 Carcinoma of liver and intrahepatic bile ducts 5.2 5.5 6.8 5.8 6.3 5.4 6.0 5.2 5.3 3.6 4.3 4.5 -3.2*
8.6.4 Carcinoma of pancreas 0.4 0.8 0.3 0.6 0.6 1.0 0.8 0.8 0.8 0.6 0.4 1.1 4.8
8.6.5 Carc other and ill-def sites, gastrointestinal tract 0.7 0.6 0.4 0.2 0.8 1.0 0.6 0.4 0.6 0.8 1.0 0.3 0.1
8.7 Carcinoma of other and ill-def sites 3.0 3.3 2.7 2.3 1.8 2.8 2.4 2.5 3.1 1.7 2.4 2.0 -3.0
8.7.1 Adrenocortical carcinoma 0.2 0.2 0.1 0.2 0.2 0.1 0.1 0.4 0.5 0.1 0.4 - 6.7
8.7.2 Carcinoma of other and ill-defined sites, NOS 2.8 3.0 2.6 2.1 1.6 2.7 2.3 2.1 2.6 1.6 1.9 2.0 -3.4*
9 Miscellaneous specified neoplasms, NOS 3.1 4.4 4.3 4.3 7.5 6.4 7.5 8.2 8.2 9.7 8.1 9.1 9.8*
9.1 Other pediatric and embryonal tumors, NOS 0.7 1.3 0.7 0.8 1.4 0.6 1.3 0.9 0.9 1.5 0.7 1.4 3.0
9.2 Other specified and embryonal tumors, NOS 2.5 3.1 3.6 3.5 6.0 5.8 6.3 7.4 7.3 8.3 7.4 7.7 11.3
10 Unspecified Malignant Neoplasms 15.1 13.1 12.7 8.8 8.8 7.1 5.6 5.3 5.0 5.1 4.6 4.7 -10.9*
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*P-values <0.05.

†

Thyroid carcinoma was excluded from the calculation of the incidence rate of all cancers combined because of its unusually high incidence rate.

AYAs, adolescents and young adults (aged 15–29 years); CNS, central nervous system; PNET, primitive neuroectodermal tumor; NOS, not otherwise specified.

Figure 1. Annual percent change (APC) from 1999–2010 according to the diagnostic group (SEER).

Figure 1

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Most cancer sites showed a trend of increasing incidence, with the exception of unspecified malignant neoplasms (group 10) among AYAs (APC  =  −10.9%). For miscellaneous specified neoplasms, NOS (group 9), a rapid increase in the incidence rate was observed for both sexes (APC = 9.8%), but the number of cases was small. For carcinomas (group 10), a large increase in the incidence rate was also observed among AYAs (APC = 9.4%). In particular, among carcinomas, the incidence of thyroid carcinoma showed the most rapid increase (APC = 17.9%; P<0.05). The annual percent change in all cancer combined, excluding thyroid carcinoma, was 1.8% (P<0.05) among AYAs (Table 2), with 1.9% (P<0.05) for males and 1.8% (P<0.05) for females (data not shown). Although the incidence of kidney carcinoma also exhibited a notable increase (APC = 9.1%), the number of cases was small.

The incidence of lymphomas (group 2) exhibited a large increase among AYAs (APC = 5.3%, P<0.05). In particular, Hodgkin lymphoma rapidly increased in incidence (APC = 9.1%, P<0.05) (Table 2).

Cancer incidence trends within diagnostic groups were observed to differ by gender. Among males, the incidence of most cancer sites was increased. Miscellaneous specified neoplasms, NOS, showed the largest increase in incidence (APC = 12.9%, P<0.05), followed by germ cell and trophoblastic neoplasms (APC = 6.9%, P<0.05). Among females, the incidence of most cancer sites was also increased. Carcinomas (APC  = 10.7%, P<0.05) and miscellaneous specified neoplasms, NOS (APC = 7.6%, P<0.05), showed the greatest increases. However, osseous/chondromatous neoplasms (APC  =  −0.5%) and germ cell and trophoblastic neoplasms (APC  =  −0.4%) slightly decreased in incidence (Figure 1). Additionally, a notable increase in the incidence of carcinomas among females was observed in the cervix (APC = 6.2%, P<0.05) and breast (APC = 3.5%, P<0.05) (data not shown).

Survival

A total of 52,077 cancer cases diagnosed from 1993 to 2010 were used for the survival analysis. Table 3 shows the 5-year relative survival rates and numbers of cases in the four time periods (1993–1995, 1996–2000, 2001–2005 and 2006–2010). For all cancers combined, the 5-year relative survival rate of AYAs significantly improved, from 58.9% in 1993–1995 to 84.8% in 2006–2010 (P<0.05). AYAs with leukemia and lymphoma showed the most marked improvement in survival from 25.8% (95% CI: 22.9–28.7) and 55.4% (95% CI: 50.6–59.9) in 1993–1995 to 58.8% (95% CI: 55.5–61.8) and 83.6% (95% CI: 80.9–85.9) in 2006–2010, respectively. Conversely, decreases in survival were observed from 1993–1995 to 2006–2010 for other glioma (group 3.2), carcinoma of gonads (group 8.5.3), and carcinoma of pancreas (group 8.6.4) (Table 3).

Table 3. Five-year RSRs for Korean AYAs according to the time period of cancer diagnosis.

Diagnostic group (SEER) Both sexes Change† P
1993–1995 1996–2000 2001–2005 2006–2010
Cases RSR Cases RSR Cases RSR Cases RSR
All Cancers 6,387 58.9 12,453 66.4 14,310 76.5 18,927 84.8 25.9 *
All Cancers (excluding thyroid carcinoma) ‡ 5,525 52.6 10,474 60.2 10,555 68.2 10,884 74.4 21.8 *
1. Leukemias 866 25.8 1,440 35.9 1,397 47.7 1,435 58.8 33.0 *
1.1 Acute lymphoid leukemia 237 19.9 433 29 379 33.9 425 48.6 28.7 *
1.2 Acute myeloid leukemia 375 26.0 602 37.5 624 47.2 588 52.7 26.7 *
1.3 Chronic myeloid leukemia 141 41.4 251 51.2 252 76 262 90.5 49.1 *
1.4 Other and unspecified leukemia 113 17.8 154 24.1 142 36 160 58.8 41.0 *
2. Lymphomas 439 55.4 937 65 1,133 75.8 1,315 83.6 28.2 *
2.1 Non-Hodgkin lymphoma 372 51.3 790 60.6 906 72.5 1,037 82.0 30.7 *
2.2 Hodgkin lymphoma 67 78.0 147 88.8 227 88.8 278 89.4 11.4 *
3. CNS and Other Intracranial and Intraspinal Neoplasms 371 53.4 689 54.5 730 60 750 65.6 12.2 *
3.1. Astrocytoma 179 43.2 305 45.1 275 45.2 291 54.3 11.1 *
3.2 Other glioma 65 72.7 83 61.7 141 66.1 177 71.2 -1.5
3.3 Ependymoma 14 86.1 49 79.9 57 88.0 62 87.0 0.9
3.4 Medulloblastoma and other PNET 18 44.6 84 49 92 47.9 84 52.3 7.7
3.5 Other specified intracranial and intraspinal neoplasms 13 61.9 27 74.4 20 80.2 18 72.6 10.7
3.6 Unspecified intracranial and intraspinal neoplasms 82 55.2 141 61.2 145 76.1 118 80.6 25.4 *
4. Osseous and Chondromatous Neoplasms 262 48.3 516 66.1 479 68.7 447 74.8 26.5 *
4.1 Osteosarcoma 160 43.3 305 65.5 281 65.3 231 72.2 28.9 *
4.2 Chondrosarcoma 28 64.6 75 87.0 69 87.2 77 94.9 30.3 *
4.3 Ewing tumor 30 40.2 66 39.5 67 52.4 72 51.0 10.8
4.4 Other specified and unspecified bone tumors 44 61.7 70 71.7 62 80.9 67 85.5 23.8 *
5. Soft Tissue Sarcomas 243 58.7 481 58.8 554 67.5 617 73.4 14.7 *
5.1 Fibromatous neoplasms 51 78.8 103 78 135 93.6 193 95.1 16.3 *
5.2 Rhabdomyosarcoma 32 28.3 73 37.1 66 34.9 55 37.5 9.2
5.3 Other soft tissue sarcoma 160 58.4 305 57.6 353 63.6 369 67.8 9.4 *
6. Germ Cell and Trophoblastic Neoplasms 278 81.6 745 87 842 89.9 936 91.7 10.1 *
6.1 Germ cell and trophoblastic neoplasms of gonads 174 89.4 465 92.3 558 94.3 613 96.2 6.8 *
6.2 Germ cell and trophoblastic neoplasms of nongonadal sites 104 68.6 280 78.1 284 81.2 323 83.2 14.6
7. Melanoma and Skin Carcinomas 56 64.6 111 59.7 122 77.3 138 86.3 21.7 *
7.1 Melanoma 25 32.2 64 43.9 63 60.5 59 65.0 32.8 *
7.2 Skin carcinomas 31 90.8 47 81.2 59 95.2 79 99.0 8.2 *
8. Carcinomas 3,205 67.5 6,607 72.2 8,366 82.4 12,601 89.9 22.4 *
8.1 Thyroid carcinoma 862 99.3 1,979 99.6 3,755 99.9 8,043 99.9 0.6 *
8.2 Other carcinoma of head and neck 140 69.6 289 77.8 339 83.1 333 85.5 15.9 *
8.2.1 Nasopharyngeal carcinoma 40 70.4 104 65.7 79 80.0 75 85.1 14.7 *
8.2.2 Other sites in lip, oral cavity, and pharynx 73 79.8 159 87.7 233 85.6 235 88.6 8.8
8.2.3 Nasal cavity, middle ear, sinuses,larynx, and other ill-defined sites in head/neck 27 41.0 26 65.6 27 70.6 23 60.5 19.5
8.3 Carcinoma of trachea, bronchus, and lung 73 24.8 136 36.2 144 47.4 132 43.1 18.3 *
8.4 Carcinoma of breast 310 68.0 691 77.2 825 82.0 841 86.5 18.5 *
8.5 Carcinoma of genitourinary tract 602 85.3 1,191 85.5 1,194 88.9 1,371 86.5 1.2
8.5.1 Carcinoma of kidney 35 68.9 94 76.9 142 87.6 209 87.0 18.1 *
8.5.2 Carcinoma of bladder 39 85.1 77 94.0 90 93.6 73 95.9 10.8
8.5.3 Carcinoma of gonads 234 86.6 396 84.5 326 88.2 291 82.7 -3.9
8.5.4 Carcinoma of cervix and uterus 285 86.6 605 86.7 611 89.1 781 87.0 0.4
8.5.5 Carcinoma of other and ill-defined sites,genitourinary tract 9 78.3 19 79.2 25 84.2 17 88.1 9.8
8.6 Carcinoma of gastrointestinal tract 1,123 38.0 2,127 42.3 1,974 50.2 1,766 59.2 21.2 *
8.6.1 Carcinoma of colon and rectum 246 47.0 527 52.8 500 63.2 603 73.9 26.9 *
8.6.2 Carcinoma of stomach 723 36.3 1,239 41.4 1,091 49.0 831 58.2 21.9 *
8.6.3 Carcinoma of liver andintrahepatic bile ducts 90 23.5 277 23.6 308 33.6 256 31.6 8.1 *
8.6.4 Carcinoma of pancreas 30 56.9 35 57.3 39 59.1 42 43.8 -13.1
8.6.5 Carcinoma of other and ill-defined sites ingastrointestinal tract 34 29.6 49 45.1 36 39.0 34 59.1 29.5 *
8.7 Carcinoma of other and ill-defined sites 95 41.3 194 39.3 135 44.6 115 54.0 12.7 *
8.7.1 Adrenocortical carcinoma N/S
8.7.2 Carcinoma of other and ill-defined sites, NOS 88 40.0 181 39.4 128 46.2 99 56.2 16.2 *
9. Miscellaneous Specified Neoplasms, NOS 121 54.0 213 72.5 348 79.2 453 79.7 25.7 *
9.1 Other pediatric and embryonaltumors, NOS 33 30.5 43 46.7 51 57.0 51 63.1 32.6 *
9.2 Other specified and embryonal tumors, NOS 88 62.8 170 79.1 297 83.0 402 81.7 18.9 *
10. Unspecified Malignant Neoplasms 546 62.0 714 70.8 339 79.0 235 77.8 15.8 *
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*P-values <0.05 for trend.

†

Change (%) in the 5-year RSR from 1993–1995 to 2006–2010.

‡

Thyroid carcinoma was excluded from the calculation of the incidence rate of all cancers combined because of its unusually high incidence rate.

N/S: not shown because <20 cases were reported in each period.

AYAs, adolescents and young adults (aged 15–29 years); CNS, central nervous system; PNET, primitive neuroectodermal tumor; NOS, not otherwise specified.

Survival rates for thyroid carcinoma (group 8.1) and skin carcinoma (group 7.2) were very high across all time periods. The five-year relative survival rate for thyroid carcinoma among males increased slightly, from 95.3% in 1993–1995 to 99.7% in 2006–2010, whereas the rate was unchanged among females from 1993–1995 (99.9%) to 2006–2010 (100.0%). The survival rates for germ cell and trophoblastic neoplasms (group 6), skin carcinoma (group 7.2), and carcinoma of the genitourinary tract (group 8.5) consistently exceeded 80–90% in all time periods. Conversely, the lowest survival rates were observed for rhabdomyosarcoma (group 5.2); carcinoma of the trachea, bronchus, and lung (group 8.3); and carcinoma of liver and intrahepatic bile ducts (group 8.6.3) (Table 3).

The survival rates for all cancers combined significantly increased from 1993 to 2010 in both males and females. In particular, the 5-year relative survival rate increased from 46.5% to 75.9% in males (P<0.05) and from 66.7% to 89.1% in females (P<0.05). However, the 5-year relative survival rate for all cancers combined was slightly lower in males than in females, regardless of whether thyroid carcinoma was excluded (Table 4).

Table 4. Five-year RSRs for Korean AYAs according to the time period of cancer diagnosis and sex.

Diagnostic group (SEER) Males Females
1993–1995 1996–2000 2001–2005 2006–2010 Change† P 1993–1995 1996–2000 2001–2005 2006–2010 Change† P
Cases RSR Cases RSR Cases RSR Cases RSR Cases RSR Cases RSR Cases RSR Cases RSR
All Cancers 2,478 46.5 4,801 55.1 5,166 65.8 6,149 75.9 29.4 * 3,909 66.7 7,652 73.6 9,144 82.6 12,778 89.1 22.4 *
All Cancers (excluding thyroid carcinoma) ‡ 2,366 44.2 4,516 52.4 4,696 62.3 4,924 70.5 26.3 * 3,159 58.9 5,958 66.0 5,859 72.9 5,960 77.6 18.7 *
1. Leukemias 492 25.4 791 33.0 826 46.2 841 57.9 32.5 * 374 26.3 649 39.4 571 49.8 594 60.0 33.7 *
1.1 Acute lymphoid leukemia 140 22.3 253 27.4 236 30.2 272 49.2 26.9 * 97 16.5 180 31.2 143 39.9 153 47.4 30.9 *
1.2 Acute myeloid leukemia 194 26.5 307 30.4 318 44.5 313 51.1 24.6 * 181 25.5 295 44.8 306 50.1 275 54.7 29.2 *
1.3 Chronic myeloid leukemia 87 40.5 152 51.6 183 74.0 173 89.1 48.6 * 54 42.7 99 50.6 69 81.3 89 93.2 50.5 *
1.4 Other and unspecified leukemia 71 9.9 79 25.5 89 37.2 83 51.4 41.5 * 42 31.0 75 22.7 53 34.0 77 67.3 36.3 *
2. Lymphomas 262 50.7 558 60.9 637 72.8 748 80.9 30.2 * 177 62.3 379 71.1 496 79.6 567 87.0 24.7 *
2.1 Non-Hodgkin lymphoma 230 47.3 480 56.7 522 70.2 601 79.2 31.9 * 142 57.9 310 66.6 384 75.7 436 85.9 28.0 *
2.2 Hodgkin lymphoma 32 75.5 78 86.3 115 84.6 147 87.3 11.8 * 35 80.2 69 91.5 112 93.0 131 91.3 11.1 *
3. CNS and Other Intracranial and Intraspinal Neoplasms 220 49.9 393 52.2 417 59.4 423 63.0 13.1 * 151 58.4 296 57.6 313 60.8 327 68.9 10.5 *
3.1. Astrocytoma 104 36.8 169 39.8 156 43.1 155 48.4 11.6 75 52.2 136 51.6 119 48.0 136 60.8 8.6
3.2 Other glioma 41 76.1 53 56.9 68 70.8 102 66.9 -9.2 24 66.9 30 70.2 73 61.8 75 77.0 10.1
3.3 Ependymoma 5 100.6 32 84.8 28 86.0 39 94.0 -6.6 9 78.0 17 70.7 29 89.8 23 74.6 -3.4
3.4 Medulloblastoma and other PNET 8 37.8 43 44.4 51 37.4 46 41.5 3.7 10 50.1 41 53.8 41 61.1 38 63.8 13.7
3.5 Other specified intracranial and intraspinal neoplasms N/S N/S -
3.6 Unspecified intracranial and intraspinal neoplasms 54 54.1 80 61.5 102 77.7 72 78.3 24.2 * 28 57.3 61 60.8 43 72.2 46 84.3 27.0 *
4. Osseous and Chondromatous Neoplasms 163 48.8 317 65.0 290 66.1 296 74.7 25.9 * 99 47.6 199 68.0 189 72.6 151 75.4 27.8 *
4.1 Osteosarcoma 106 42.7 195 64.4 174 60.5 160 71.4 28.7 * 54 44.6 110 67.4 107 73.0 71 74.6 30.0 *
4.2 Chondrosarcoma 17 71.1 43 86.5 44 93.5 44 93.5 22.4 11 54.7 32 87.7 25 76.2 33 96.4 41.7
4.3 Ewing tumor 15 47.0 43 37.4 38 44.9 46 49.7 2.7 15 33.4 23 43.6 29 62.2 26 53.3 19.9
4.4 Other specified and unspecified bone tumors 25 60.4 36 75.4 34 82.6 46 89.4 29.0 * 19 63.3 34 67.8 28 78.7 21 77.1 13.8
5. Soft Tissue Sarcomas 126 52.7 244 57.7 287 63.3 342 68.8 16.1 * 117 65.1 237 60.1 267 72.1 275 78.6 13.5 *
5.1 Fibromatous neoplasms 23 78.8 61 75.8 64 90.9 103 93.4 14.6 * 28 78.8 42 81.1 71 96.0 90 96.7 17.9 *
5.2 Rhabdomyosarcoma 20 25.2 43 35.0 41 34.2 35 34.1 8.9 12 33.4 30 40.1 25 36.1 20 44.9 11.5
5.3 Other soft tissue sarcoma 83 52.2 140 56.7 182 60.1 204 62.8 10.6 * 77 65.1 165 58.3 171 67.4 165 73.4 8.3
6. Germ Cell and Trophoblastic Neoplasms 98 72.9 323 79.3 457 85.8 574 88.8 15.9 * 180 86.4 422 92.9 385 94.7 362 96.3 9.9 *
6.1 Germ cell and trophoblastic neoplasms of gonads 47 90.0 157 85.8 255 90.5 331 95.4 5.4 * 127 89.2 308 95.7 303 97.5 282 97.0 7.8 *
6.2 Germ cell and trophoblastic neoplasms of nongonadal sites 51 57.2 166 73.2 202 79.9 243 79.9 22.7 53 79.5 114 85.3 82 84.3 80 93.6 14.1
7. Melanoma and Skin Carcinomas 24 71.3 66 57.9 66 73.0 67 83.9 12.6 * 32 59.6 45 62.4 56 82.3 71 89.1 29.5 *
7.1 Melanoma 11 45.8 38 45.0 33 51.7 26 45.0 -0.8 14 21.5 26 42.4 30 70.1 33 76.5 55.0 *
7.2 Skin carcinomas 13 93.0 28 75.4 33 94.3 41 97.9 4.9 18 89.2 19 89.7 26 96.4 38 100.2 11.0
8. Carcinomas 872 52.3 1,787 57.0 1,935 68.2 2,561 80.5 28.2 * 2,333 73.1 4,820 77.9 6,431 86.6 10,040 92.4 19.3 *
8.1 Thyroid carcinoma 112 95.3 285 97.3 470 100.2 1,225 99.7 4.4 * 750 99.9 1,694 99.9 3,285 99.8 6,818 100.0 0.1
8.2 Other carcinoma of head and neck 76 62.3 147 71.1 177 79.4 170 86.8 24.5 * 64 78.4 142 84.7 162 87.2 163 84.5 6.1
8.2.1 Nasopharyngeal carcinoma 28 71.9 70 60.3 56 80.6 48 91.6 19.7 * 12 66.9 34 76.7 23 78.4 27 77.6 10.7
8.2.2 Other sites in lip, oral cavity, and pharynx 32 72.4 65 86.6 108 79.9 112 86.6 14.2 41 85.6 94 88.5 125 90.5 123 90.3 4.7
8.2.3 Nasal cavity, middle ear, sinuses, larynx, and other ill-defined sites in head/neck N/S N/S
8.3 Carcinoma of trachea, bronchus, and lung 41 24.6 68 37.0 65 52.5 64 39.6 15.0 32 25.1 68 35.4 79 43.1 68 46.7 21.6 *
8.4 Carcinoma of breast N/S 309 67.9 686 77.3 822 81.9 838 86.6 18.7 *
8.5 Carcinoma of genitourinary tract 52 83.3 116 91.0 158 91.5 197 92.2 8.9 550 85.5 1,075 85.0 1,036 88.5 1,174 85.5 0
8.5.1 Carcinoma of kidney 14 79.2 43 86.5 85 89.8 129 91.9 12.7 21 62.1 51 68.8 57 84.4 80 78.8 16.7 *
8.5.2 Carcinoma of bladder 30 87.3 61 95.6 61 95.4 60 95.0 7.7 N/S
8.5.3 Carcinoma of gonads N/S 231 86.8 392 84.4 324 88.1 290 82.6 -4.2
8.5.4 Carcinoma of cervix and uterus N/S 285 86.6 605 86.7 611 89.1 781 87.0 0.4
8.5.5 Carcinoma of other and ill-defined sites in genitourinary tract N/S N/S
8.6 Carcinoma of gastrointestinal tract 536 43.1 1,064 43.0 984 49.4 842 56.5 13.4 * 587 33.3 1,063 41.5 990 51.0 924 61.7 28.4 *
8.6.1 Carcinoma of colon and rectum 140 51.1 299 50.1 287 62.6 330 73.6 22.5 * 106 41.6 228 56.3 213 64.0 273 74.6 33.0 *
8.6.2 Carcinoma of stomach 307 44.0 530 48.0 445 51.9 310 56.5 12.5 * 416 30.6 709 36.5 646 47.0 521 59.3 28.7 *
8.6.3 Carcinoma of liver and intrahepatic bile ducts 62 26.0 193 19.3 226 28.4 170 31.4 5.4 * 28 17.9 84 33.4 82 47.7 86 31.4 13.5
8.6.4 Carcinoma of pancreas N/S 21 66.9 18 83.5 24 71.0 28 69.3 2.4
8.6.5 Carcinoma other and ill-defined sites in gastrointestinal tract 18 28.0 25 44.3 11 45.6 18 45.3 17.3 16 31.3 24 46.0 25 36.1 16 75.2 43.9 *
8.7 Carcinoma of other and ill-defined sites 54 31.7 102 44.3 78 51.5 60 48.1 16.4 * 41 53.8 92 33.8 57 35.2 55 60.2 6.4
8.7.1 Adrenocortical carcinoma N/S N/S
8.7.2 Carcinoma of other and ill-defined sites, NOS 51 33.6 94 44.9 76 51.5 53 48.7 15.1 * 37 48.8 87 33.4 52 38.5 46 66.1 17.3
9. Miscellaneous Specified Neoplasms, NOS 51 49.4 80 52.8 154 71.0 221 81.0 31.6 * 70 57.3 133 84.4 194 85.7 232 78.6 21.3
9.1 Other pediatric and embryonal tumors, NOS 21 33.6 24 33.5 32 53.3 27 62.6 29.0 * 12 25.1 19 63.3 19 63.3 24 63.4 38.3
9.2 Other specified and embryonal tumors, NOS 30 60.4 56 61.0 122 75.6 194 83.4 23.0 * 58 64.0 114 87.9 175 88.2 208 80.3 16.3
10. Unspecified Malignant Neoplasms 170 40.9 242 56.1 97 64.2 76 70.7 29.4 * 376 71.5 472 78.4 242 84.9 159 81.3 9.8 *
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*P-values <0.05 for trend.

†

Change (%) in the 5-year RSRs from 1993–1995 to 2006–2010.

‡

Thyroid carcinoma was excluded from the incidence rate of all cancers combined because of its unusually high incidence rate.

N/S: not shown because <20 cases were reported in each period.

AYAs, adolescents and young adults (aged 15–29 years); CNS, central nervous system; PNET, primitive neuroectodermal tumor; NOS, not otherwise specified.

Leukemia (group 1) showed the greatest increase in survival in both males (32.5%) and females (33.7%). In particular, chronic myeloid leukemia had the largest and second-largest increases in survival in males (48.6%; from 40.5% to 89.1%) and females (50.5%; from 42.7% to 93.2%), respectively.

Figure 2 depicts the 5-year relative survival rates of all cancer patients in each of the four time periods according to age (15–19 years, 20–24 years and 25–29 years) and sex. Both gender, the 5-year relative survival rates increased in all age groups. For males aged 15–19 years, the 5-year relative survival rates in 1993–1995, 1996–2000, 2001–2005, and 2006–2010 for all cancers combined were 45.3% (95.% CI: 41.2–49.2), 55.4% (95% CI: 52.5–58.1), 65.3% (95% CI: 62.5–67.9), and 72.2% (95% CI: 69.2–75.0), respectively. The survival rates of males aged 20–24 years were 43.9% (95% CI: 40.2–47.5), 55.0% (95% CI: 52.2–57.7), 65.0% (95% CI: 62.5–67.3), and 77.0% (95% CI: 74.3–79.5) in 1993–1995, 1996–2000, 2001–2005, and 2006–2010, respectively. The survival rates of males aged 25–29 years were 48.8% (95% CI: 45.9–51.7), 55.0% (95% CI: 52.9–57.0), 66.5% (95% CI: 64.6–68.3), and 77.2% (95% CI: 75.3–79.0) in 1993–1995, 1996–2000, 2001–2005, and 2006–2010, respectively. For females aged 15–19 years, the 5-year relative survival rates for all cancers combined were 62.0% (95% CI: 58.0–65.8), 72.0% (95% CI: 69.4–74.5), 78.8% (95% CI: 76.3–81.0), and 82.2% (95% CI: 79.7–84.5) in 1993–1995, 1996–2000, 2001–2005, and 2006–2010, respectively. The survival rates of females aged 20–24 years were 67.4% (95% CI: 64.6–70.1), 74.4% (95% CI: 72.4–76.3), 83.7% (95% CI: 82.2–85.1), and 88.9% (95% CI: 87.4–90.2) in 1993–1995, 1996–2000, 2001–2005, and 2006–2010, respectively. The survival rates of females aged 25–29 years were 67.7% (95% CI: 65.7–69.6), 73.6% (95% CI: 72.2–74.9), 82.9% (95% CI: 81.9–83.9), and 90.4% (95% CI: 89.5–91.2) in 1993–1995, 1996–2000, 2001–2005, and 2006–2010, respectively.

Figure 2. Trends in relative survival after cancer in Korea according to age and the time period.

Figure 2

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Discussion

This is the first study to investigate cancer incidence, survival and their trends among AYAs using the population-based national cancer registry in Korea. The major findings of this study were that cancer in AYAs showed a trend of increasing incidence, with an increase of 6.3% per year (P<0.05), from 1999 to 2010 and that age- and gender-related cancer incidence patterns differed according to the primary site. Moreover, five-year relative survival rates for most cancers improved from 1993–1995 (58.9%) to 2006–2010 (84.8%) among AYAs.

When comparing our study with studies from other countries, cancer incidence rates among AYAs in our study were lower than incidence rates in the U.S. [5], France [21], Portugal [22], and Netherlands [3] and among males in Canada [12], even though the time period and age group differs. In other studies, cancer incidence in AYA males was generally similar to or higher than cancer incidence in AYA females. Conversely, we reported much lower incidence rates in males than in females. The reason for this difference in the incidence rate by gender was that thyroid carcinoma has the highest incidence and rapidly increased in incidence among AYA females in Korea.

Consistent with other studies, we found a rising incidence of cancer among AYAs during the study period.

The data on AYAs in Korea reported here exhibited several important differences from site-specific cancer incidence rates among AYAs in other regions of the world. Since the 2000s, an annual increase in incidence of 0.6–2.0% has been reported in several countries [16], [23]–[25]. However, our results showed an annual increase in incidence of 6.3%, which is a more rapid increase than observed in other studies. The increased cancer incidence rate may be partially explained by changes in cancer classification, as exemplified by changes in the classification of hematologic malignancies in a study by Park et al. [26].

The increased incidence of carcinomas was primarily due to an increase in the incidence rates of thyroid carcinoma (APC = 17.9%). An increased incidence rate of thyroid carcinoma has also been noted among AYAs in Western countries [23], [27], [28]. However, the incidence of thyroid carcinoma among AYAs is more than three- to tenfold higher in Korea than in Canada [12], England [23], the United States [5], the Netherlands [3] and Portugal [22]. The reasons for the high incidence of thyroid carcinoma in Korean AYAs compared with other nationalities are unknown. Although the rapid increase and high incidence rate of thyroid cancer among older individuals worldwide might be attributable to the development of improved technologies for early detection [29], the exact cause of the increased incidence of most cancers in AYAs is unknown. Because of the difficulty in recommending thyroid cancer screening for AYAs solely based on incidence rates, further research to identify associated risk factors, such as family history, socioeconomic status, and environmental exposure, is needed.

In this study, a notable trend of increasing incidence was also observed for cervical carcinoma (APC = 6.2%) among female AYAs in Korea. Although the incidence of cervical carcinoma in Korean females of all ages is decreasing (APC  =  −4.3%) [6], the incidence of cervical carcinoma has been increasing among Korean females under 30 years of age [30]. A steady increase in cervical carcinoma in young women (20–29 years) has also been observed in England [31]. The increased incidence of cervical carcinoma among AYAs has been attributed to increases in human papillomavirus (HPV) infection [32], [33]. More specifically, an increase in sexual behavior among younger age groups has led to an increased rate of HPV infection [34], [35], and the prevalence rate of HPV has been reported to increase with decreasing age [32]. Therefore, since 2007, the Korean Society of Gynecologic Oncology and Colposcopy (KSGOC) has recommended the HPV vaccine for females aged 15–17 for the prevention of cervical carcinoma. In fact, certain recent studies have reported a decrease in the incidence of cervical carcinoma due to the use of the HPV vaccine at an earlier age [36], [37]. Therefore, the incidence of cervical carcinoma is expected to gradually decline among AYAs in Korea due to the HPV vaccine.

In terms of survival, our data are consistent with that reported for other geographic regions. Although the time period in our study differed, the overall cancer survival rate among AYAs in Korea was similar to the rate and significantly improvement reported in the U.S. and Germany. Improvements in relative survival rates among AYAs can be partially explained by advances in cancer detection, more intensive treatments, and increased expertise in adolescent oncology [38]. Additionally, access to effective protocols and the development of health infrastructures may have also contributed to improvements in survival rates [39].

However several important differences should be highlighted in lymphoma and leukemia. In the present study, the most significant improvements in survival were observed in leukemia and lymphoma patients, but the survival rates for leukemia and lymphoma were noticeably lower than in the U.S. and Germany [40], [41]. This reason for this difference in the survival rate by ethnic was that the incidence cases of subgroup of leukemia and lymphoma was different between U.S. AYAs [41] and Korea AYAs. More, ethnic disparities in tumor biology and clinical factors may influence cancer treatment and survival [42].

Compared with the survival of patients aged 1 to 10 years, overall survival and disease-specific survival are clinically significantly poorer among AYA patients with acute lymphoblastic leukemia [43]. The survival rates for leukemia among the Korean AYAs in our study have remained worse than among Korean children based on data from the KCCR [44].

Among AYAs, breast cancer accounts for approximately 7% and 4.9% of all cancers diagnosed in the United States [5] and Korea, respectively. In the United States, the 5-year survival rate for breast cancer is lower among AYAs (80.2%) than among patients in other age groups (30–39 years, 83.4%; 40–49 years, 88.9%), and particularly older patients [41]. Our study showed similar results. The relative survival rate for breast cancer among Korean females aged 15–29 years was 86.8% in 2006–2010, whereas the relative survival rate among Korean females aged ≥40 years was 91.0% based on a direct estimate from the KNCIDB.

One limitation of our study is that the follow-up period began relatively soon after the diagnosis of cancer, in contrast to the protocols in other studies [3]–[5]. Another limitation of this study is that we could not estimate the survival rates after adjusting for cancer stage and treatment because our registry database did not include information on cancer stage and treatment.

In conclusion, our study provides representative cancer statistics regarding temporal trends in the AYA population in Korea. In particular, the results showed an increasing trend in cancer incidence and an improving survival trend among AYAs in Korea. These results may support cancer control and prevention plans focusing on AYAs.

In the future, further research will help to identify factors affecting cancer incidence and responses to treatment among AYAs. In particular, research on the etiological factors related to the rapid increase in thyroid carcinoma in AYAs is needed.

Funding Statement

This work was supported by the National Cancer Center Grant (NCC-1310222). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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