ABSTRACT
Seeking a second opinion (SO) is a patient's right that is essential to appropriate decision‐making for their care and treatment. In Japan, however, no previous studies have provided objective data on the nationwide practice of SO among cancer patients. In this study, we investigated SO referrals, including delays in initiating care, using data from nationwide hospital‐based cancer registries and 2018–2020 the Diagnosis Procedure Combination (DPC) survey. Among the more than 2.6 million patients diagnosed with cancer, 1.6% received SO referral letters as reimbursement. The referral rates varied based on sex, age, and geographic regions. A total of 52.1% of SO were sought before active treatment of the tumor. Approximately 60% of the patients who sought SO prior to the initial treatment returned to their original provider for treatment. The average period from diagnosis to the start of treatment among those who sought SO was 18 days and 22 days longer for non‐small lung cancer and breast cancer, respectively, than among those who did not seek SO. In the future, the risk–benefit of SO referral should be examined, considering both the prognostic impact of treatment delay due to SO and the psychological benefits for the patient gained from SO.
Keywords: cancer, patient care, referral and consultation, second opinion, treatment delay
We investigated SO referrals, including delays in initiating care, using data from nationwide hospital‐based cancer registries and 2018–2020 Diagnosis Procedure Combination (DPC) survey in Japan. We identified differences in the mean time from diagnosis to treatment initiation between patients who sought SO and those who did not.
Abbreviations
- DPC
Diagnosis Procedure Combination
- SO
second opinion
1. Introduction
Seeking a second opinion (SO) is considered one of the fundamental rights of patients and was included in the 1995 revision of the Lisbon Declaration as “the right to freedom of choice (of the patient)” [1]. In Japan, insurance coverage for providing referral letters designated for SO started in 2006, and was handled separately from regular referral letters. Although SO is not limited to any particular disease in Japan, previous studies of the general public have shown that patients consider SO to be more vital in the diagnosis of cancer than for other diseases [2]. Additionally, previous systematic reviews have indicated that the common motivation of patients for seeking SO is to confirm the diagnosis of cancer and to seek treatment for unresolved symptoms [3, 4]. Only a few studies have indicated SO for non‐cancer surgeries and general medical concerns.
Japan's SO policy supports the idea that patients are guaranteed the opportunity to receive a second opinion when undergoing cancer treatment. In addition to the insurance coverage described above, the Standard Requirements for Designated Cancer Care Hospitals also added “a systematic structure to inform patients about the option of seeking second opinions” as a requirement for designated cancer care hospitals. However, patient experience surveys, conducted to monitor the progress of cancer control plans, revealed that only 40.3% and 34.9% of patients in the 2014 and 2018 surveys, respectively, were informed about SOs before the start of treatment [5, 6]. These findings indicate that the percentage of doctors explaining the use of SOs to patients was not high.
Prior studies on the frequency of SO were self‐reported. The percentage of patients receiving SO was 22% (N = 5487) among Dutch patients with common cancer diagnoses, 19% (N = 1984) among US patients with breast cancer (stages 0 to II), and 24.7% (N = 150) among parents of pediatric patients with blood cancer in Israel [7, 8, 9]. In Japan, 19.5% of patients with cancer who participated in the 2018 “Patient Experience Survey” responded that they received a second opinion [6]; however, no previous studies have revealed the use of objective data to indicate the nationwide status of SO.
Theoretically, seeking an SO may result in a delay in treatment initiation because it involves additional processes between diagnosis and treatment. If the delay is substantial, it may affect survival. A previous single‐center U.S. study compared the time from biopsy to surgery for patients with breast cancer who were treated at a hospital while seeking SO elsewhere and those who were treated at a hospital from initial diagnosis to treatment. The findings revealed that although the time from biopsy to making an appointment for surgery was longer in the SO group than in the non‐SO group, the time from biopsy to surgery was not statistically different [10]. This may be attributed to making efforts to compensate for the delay between the biopsy and surgery appointment, or a few tests being performed at a different institution at the time of the SO. In addition, a study of elderly patients with breast cancer in the U.S. suggested that seeing more than one healthcare provider in a short period between diagnosis and surgery is associated with good outcomes [11]. However, the actual situation regarding SO and delays in treatment initiation in Japan remains unclear.
Therefore, we conducted a novel retrospective cohort study of cancer patients diagnosed between 2018 and 2020, collected by the National Cancer Center for the evaluation of equalization of cancer care, to capture the actual nationwide situation in Japan. Furthermore, we clarified the treatment delays caused by SO.
2. Materials and Methods
2.1. Data Sources
Among patients diagnosed with cancer at facilities implementing hospital‐based cancer registries, including designated cancer care hospitals, we used patient data collected by linking health service utilization data generated in the Diagnosis Procedure Combination (DPC) survey between 2018 and 2020. The Hospital‐based Cancer Registry is a requirement for a facility to be labeled as a ‘designated cancer care hospital’ designated by the Ministry of Health, Labour and Welfare. The Cancer Registry Act encourages hospitals specializing in cancer treatment to implement this system. Compared with the incidence statistics from the National Cancer Registry, which outputs complete statistics on all cancer types occurring in Japan, the coverage rate of hospital‐based cancer registries was 71.7% in 2017 and 72.5% in 2018 [12, 13]. The DPC survey is a nationwide survey on the utilization of health services. While the DPC itself is a category system used to determine the per‐day reimbursement to hospitals, the DPC survey collects health service data in an equivalent form to the fee schedule for the fee‐for‐service reimbursement [14]. Cases registered in the hospital‐based cancer registry are linked to DPC survey data within the respective facilities, and data are collected to monitor quality indicators of cancer care [15].
2.2. Variables
The concordance rate between the various cancer types in the DPC survey data and the Hospital‐based Cancer Registry varies depending on the type of cancer [16, 17]. Therefore, we utilized the data from the Hospital‐based Cancer Registry for the variables pertaining to cancer and patient attributes, and we employed the data from the DPC survey for the variables related to referral. The following items included in the hospital‐based cancer registry were used as patient characteristics: sex, age at diagnosis, type of cancer, stage of pre‐treatment, institution of diagnosis, whether the first treatment was provided at the hospital where the cancer registry was conducted, and date of the first treatment intended to reduce or remove registered tumors. For hospital classification, categories were created based on the categories of designated cancer care hospitals as of April 1, 2020. The following items included in the DPC data were used for the SO and other medical details. Existence of SO referral (medical fee points: medical information provision fee [II]) and SO referral implementation date (calculation date) were also collected. Only the SO referral with the earliest date was treated as an SO in this study because SO referrals can be calculated multiple times for the same patient.
2.3. Analyses
To describe the current status of SO among cancer patients in Japan, we analyzed the following four points: (1) percentage of SO referrals using claims among patients with cancer; (2) timing of SO referral (before and after initial treatment) in patients with SO referral; (3) percentage of treatment started at the same hospital after SO referral; and (4) time from diagnosis to start of treatment and SO referral. We analyzed all types of cancers included in Hospital‐based Cancer Registry. Patient characteristics, such as age, sex, cancer type, and geography, were analyzed. The geography was divided into eight distinct regions. These regions are: Hokkaido–northern island; Tohoku–northeastern region of the main island; Kanto [except Tokyo], which is a suburban metropolitan area of the main island; Tokyo area; Chubu–central region of the main island; Kinki–western region of the main island; Chugoku and Shikoku–more western region; and Kyushu/Okinawa–southwestern islands.
For the percentage of SO referrals, the denominator was 2,625,045 cases of all new cancers, for which DPC data and hospital‐based cancer registries were linked. The referrals were characterized by patient sex, age, cancer type, clinical stage, and hospital type. To analyze the timing of SO, we calculated the proportion of patients with SO who were referred before the first treatment (i.e., treatment intended to reduce or resect the tumor in question). To calculate treatment at the same facility, the denominator was 1,769,286 cases diagnosed at hospitals in the study. Additionally, the percentage of cases treated for the first time at registered hospitals was calculated. Treatment included both anti‐cancer treatment aimed at shrinkage or resection of the tumor in question and palliative treatment for analysis (3), whereas cases with palliative treatment were excluded from the analysis (4).
For the analysis of the period from diagnosis to the initiation of treatment, we first examined 1,610,392 cases in which the first treatment (i.e., treatment intended to reduce or remove the tumor in question) was performed at a hospital with a hospital‐based cancer registry and in which the first treatment was confirmed to have been performed after the diagnosis date in the hospital‐based cancer registry. The SO and non‐SO groups were compared within the same cancer type and stage to exclude the influence of cancer type on diagnosis and treatment. The analysis of the period from diagnosis to the initiation of treatment was conducted for non‐small cell lung cancers and breast cancers because the dataset included more than 1000 SO referrals. The large number enabled us to compare with sufficient numbers across groups (e.g., stages). The mean time from diagnosis to the start of treatment was calculated and compared between the SO and non‐SO groups to make univariate comparisons. Histograms were drawn to confirm the shape of the distribution and mode of occurrence. Multivariate linear regression analysis was performed with the number of days from diagnosis to the start of treatment as the dependent variable and the presence or absence of the first pre‐treatment SO referral as the primary explanatory variable. The regression model was adjusted for patient sex, age at diagnosis, pre‐treatment stage, registered hospital classification, and region. A p‐value of < 0.05 was defined as significant for all analyses. All analyses were conducted using Stata version 17.0.
3. Results
Among the 2,625,045 cases for which DPC data and hospital‐based cancer registries were linked, 2,624,718 were analyzed (excluding 325 cases with latent stage lung cancer and two cases with unknown months of diagnosis).
3.1. Frequency and Timing of SO Referrals
Table 1 shows the percentage of patients who received SO referral letters. Overall, 1.6% of patients were provided with SO referral letters. Female patients, young patients, and patients with more advanced diseases (i.e., those with higher stages) were more likely to seek SO. Among the cancer types examined, uterine sarcoma (9.0%), intrahepatic cholangiocarcinoma (4.1%), pancreatic neuroendocrine tumors (4.0%), and pancreatic cancer (4.0%) comprised the majority of SO referrals. Geographically, Tokyo and Kanto (excluding Tokyo) had SO referral rates of 2.7% and 2.0%, respectively (p < 0.05). The percentage of SO referrals in other cancer types, the type of medical institutions, and other regions are indicated in Table S1 for reference.
TABLE 1.
Characteristics of patients who obtained second opinion (SO) referrals.
| Number of patients (denominator) | With SO % | |
|---|---|---|
| Overall | 2,624,718 | 1.6 |
| Sex (p < 0.001) | ||
| Male | 1,457,066 | 1.5 |
| Female | 1,167,652 | 1.7 |
| Age (p < 0.001) | ||
| Under 15 years | 7110 | 5.0 |
| 15–39 years | 96,879 | 3.2 |
| 40–64 years | 698,017 | 2.5 |
| 65–74 years | 828,061 | 1.5 |
| 75–84 years | 740,253 | 0.9 |
| ≥ 85 years | 254,398 | 0.5 |
| Stage (p < 0.001) | ||
| 0 | 206,786 | 0.8 |
| I | 843,451 | 1.1 |
| II | 327,617 | 1.5 |
| III | 285,926 | 2.2 |
| IV | 412,162 | 2.9 |
| Stage not applicable | 202,243 | 2.1 |
| Unknown | 346,533 | 0.9 |
Abbreviation: SO, second opinion.
3.2. Timing of SO Referral
Among the 41,233 SO referrals mentioned above, 21,465 (52.1%) were made before the start of initial treatment (Table 2). Pre‐treatment SO referral was prominent among older and early‐stage patients. The cancer types with high pre‐treatment SO referrals were thyroid cancer (81.2%), pancreatic neuroendocrine tumors (74.1%), kidney cancer (68.1%), and breast cancer (66.2%). The percentage of pre‐treatment SO referrals in other cancer types, the type of medical institutions, and regions are indicated in Table S2 for reference.
TABLE 2.
Number and percentage of pretreated SOs among total SOs.
| Number of patients with SO referrals (denominator) | SO referral before treatment % | |
|---|---|---|
| Overall | 41,233 | 52.1 |
| Sex (p = 0.499) | ||
| Male | 21,248 | 51.9 |
| Female | 19,985 | 52.2 |
| Age (p < 0.001) | ||
| Under 15 years | 357 | 29.1 |
| 15–39 years | 3137 | 44.3 |
| 40–64 years | 17,430 | 49.3 |
| 65–74 years | 12,288 | 52.1 |
| 75–84 years | 6798 | 59.7 |
| ≥ 85 years | 1223 | 76.1 |
| Stage (p < 0.001) | ||
| 0 | 1638 | 65.1 |
| I | 9321 | 59.4 |
| II | 4898 | 52.8 |
| III | 6319 | 45.6 |
| IV | 11,743 | 45.6 |
| Stage not applicable | 4150 | 49.9 |
| Unknown | 3164 | 62.5 |
3.3. Treatment Place After Referral
Among the 1,769,026 patients who were initially diagnosed with cancer at a hospital‐based cancer registry facility, 17,228 (0.97%) were referred for SO. Among these patients, 10,705 (62.1%) received their initial treatment at the original hospital (Table S3). The characteristics associated with low return rates, including no treatment after referral, were esophageal cancer (48.2%), cervical cancer (49.7%), and prostate cancer (51.4%). Geographically, Tokyo had the lowest return rate, with only 55.4% of patients receiving initial treatment at the original hospital.
3.4. Period (Days) From Diagnosis to Treatment
From a total of 2,624,718 cases, 2,097,750 cases in which the first treatment was performed at the same hospitals were extracted. Among these, 255,496 cases in which treatment consisted only of follow‐up observation or palliative treatment were excluded. Furthermore, 231,862 cases in which the date of the first treatment was the same as or before the date of diagnosis were excluded, resulting in 1,610,392 cases for analysis.
Figure 1A–C show the distribution of this time period in stage I, III, and IV non‐small‐cell lung cancers comparing the SO and non‐SO groups. For stage I cell lung cancer, the mean and mode (calculated daily) for the SO group were 68 and 42 days, respectively, compared with 47 and 27 days for the non‐SO group (Figure 1A). For stage III non‐small cell lung cancer, the mean and mode for the SO group were 44 and 27 days, respectively, compared to 30 and 21 days for the non‐SO group (Figure 1B). For stage IV non‐small cell lung cancer, the mean and mode for the SO group were 40 and 28 days, respectively, whereas the mean and mode for the non‐SO group were 24 and 21 days, respectively (Figure 1C). The results of multivariate regression analysis indicated that the SO group had a 17.6 day (95% CI: 15.6–19.6) longer period from the date of diagnosis to the date of first treatment than the non‐SO group. Other factors that affected the time from the date of diagnosis to the date of first treatment are indicated in Table S4.
FIGURE 1.
(A) Distribution of the periods from diagnosis to treatment for stage I non‐small‐cell lung cancers. (B) Distribution of the periods from diagnosis to treatment for stage III non‐small‐cell lung cancers. (C) Distribution of the periods from diagnosis to treatment for stage IV non‐small‐cell lung cancers.
Similarly, Figure 2A,B depict the distribution of the periods from diagnosis to treatment for stage I and stage II breast cancer. For stage 0 breast cancer, the mean and mode for the SO group were 77 and 71 days, respectively, compared with 49 and 36 days for the non‐SO group. For stage I, the mean and mode were 59 and 41 days for the SO group and 41 and 36 days for the non‐SO group, respectively (Figure 2A). For stage II breast cancer, the mean and mode for the SO group were 56 and 38 days, respectively, compared with 37 and 36 days for the non‐SO group (Figure 2B). The results of the multivariate regression analysis indicated that the SO group had an average of 21.7 days (95% CI: 20.0–23.5) longer from the date of diagnosis to the date of first treatment than the non‐SO group. Other factors affecting the time from the date of diagnosis to the date of first treatment are shown in Table S5.
FIGURE 2.
(A) Distribution of the periods from diagnosis to treatment for stage I breast cancers. (B) Distribution of the periods from diagnosis to treatment for stage II breast cancers.
4. Discussion
Our analysis using data from more than 2.6 million patients registered nationwide in hospital‐based cancer registries revealed the current status of SO practices in hospitals. First, we identified that only 1.6% of the patients had SO referrals. The presence of SO referrals varied by patient sex and age and was higher in younger men and women compared to their older counterparts. This may be indicative of a dearth of information for younger cancer patients and their parents or guardians [18]. Furthermore, these patients may need further investigation into various therapeutic modalities to mitigate the impact of future infertility [19]. A few rare cancers, such as uterine sarcoma and intrahepatic cholangiocarcinoma, had a higher percentage of SO referrals compared to other cancers, thus indicating a greater need for information regarding treatment options. Approximately half of the SO referrals were made before active treatment, and the remaining were made after treatment was initiated. Additionally, we found that approximately 60% of patients who sought SO before the initial treatment returned to their original provider for treatment. Furthermore, this study revealed regional variations. In the Tokyo and Kanto (excluding Tokyo) regions, not only was the percentage of SO referrals after treatment high, but the percentage of SO referrals before treatment was also high. This may be attributed to the fact that there are multiple facilities in the region where patients can visit for SO.
The average delay in treatment due to the return to the original institution with SO results after an outpatient SO visit at another institution was 18 days for non‐small cell lung cancer and 22 days for breast cancer. Although the results varied according to cancer type and pre‐treatment stage, a certain degree of delay was expected. In a previous systematic study for multiple cancers [20], including non‐small cell lung cancer and breast cancer, it has been demonstrated that even a four‐week (28‐day) period between diagnosis and treatment can impact overall survival. In light of this evidence, it is plausible that the treatment delays identified in this study may have influenced overall survival. Moreover, prior research on non‐small cell lung cancer [21] and breast cancer [22] indicates that the earlier the stage of the cancer, the more significant the impact on overall survival due to the longer interval between diagnosis and treatment. However, the interval difference between the SO and non‐SO groups tended to decrease as the disease stage increased in this research. The reasons for this trend should be explored in future studies. One potential reason may be that advanced‐stage patients receive more attention and are prioritized by healthcare facilities. Additionally, it is necessary to clarify whether SO increases patients' acceptance of the received treatment and overall patient satisfaction from the viewpoint of guaranteeing patient rights, which is the original purpose of SO. The risk–benefit of SO should be examined in combination with these factors.
In the present study, the proportion of SO referrals was 1.6%, which was considerably different from the 19.5% obtained from a patient experience survey (based on patients' self‐reports) in a previous study [6]. Patient self‐reports may include informal secondary opinions from family physicians without conveying detailed medical information for SO referral from their original physicians. The gap between the perceptions of patients regarding SO and formal SO referrals using detailed letters should be explored.
4.1. Limitations of the Study
This study has some limitations that warrant mentioning. First, we considered the presence of claims for preparation of SO referral letters as the seeking of SO; however, no data was available on the actual provision of SO at hospitals that are not covered by insurance (i.e., do not appear in insurance claims) and are paid out‐of‐pocket. Therefore, we could not confirm whether patients actually visited the hospital where they were sent for SO. Additionally, we could not confirm whether patients visited other hospitals without requesting a letter of referral. Furthermore, in certain cases, patients were sent regular non‐SO referral letters for SO referrals. As the fee for regular referral letters is significantly lower than that for SO referral letters, hospitals can choose not to charge the full SO referral and only charge according to the non‐SO letter. The gap between formal reimbursements for SO referrals and patient self‐reports is an area that requires future exploration. Second, in the analysis of treatment delay, there may have been factors that could not be included in the analysis of the SO and non‐SO groups from the time of diagnosis to the start of treatment, such as comorbidities that made treatment challenging but were not expressed in the pre‐treatment stage due to privacy‐related wishes of patients or their families. Third, all participating hospitals were those that operated hospital‐based cancer registries and did not include small hospitals. The practices of small hospitals may differ. However, hospital‐based cancer registries cover more than 70% of national hospitals, and we believe that our study provided sufficient national profiles. Finally, recent studies have indicated a decline in the number of individuals diagnosed with cancer in Japan in 2020 [23], as well as a decrease in the number of patients seeking second opinions [24]. These declines can be attributed to the proliferation of SARS‐CoV‐2. However, this study did not incorporate this variable into its analysis. It is plausible the decision of the population to avoid medical care may also have affected the frequency with which they sought SO referrals.
5. Conclusion
In conclusion, even though national policies support the promotion of SO, the frequency of SO referrals in recent years is not high. Although there was a certain amount of delay in the initiation of treatment due to SO, potentially impacting the outcomes, the delay decreased as the disease stage increased, suggesting that hospitals can make efforts to prevent delays depending on the condition of the patient. In the future, we must examine the risk–benefit of SO referrals, taking into consideration the extent to which these treatment delays affect prognosis and the psychological benefit to the patient gained from the SO.
Author Contributions
Mieko Takasawa: formal analysis, visualization, writing – original draft. Norihiro Teramoto: writing – review and editing. Natsumi Yamashita: writing – review and editing. Takahiro Higashi: conceptualization, data curation, formal analysis, methodology, supervision, writing – review and editing.
Ethics Statement
Approval of the research protocol by an Institutional Reviewer Board: The study protocol was approved by the Institutional Review Board of the National Cancer Center, Japan (protocol number: 2023‐161), and conforms to the provisions of the Declaration of Helsinki.
Informed Consent: N/A.
Registry and the Registration No. of the study/trial: N/A.
Animal Studies: N/A.
Conflicts of Interest
The authors declare no conflicts of interest.
Supporting information
Table S1. Number of cases analyzed and percentage of SO referrals calculated.
Table S2. Number of SO referrals and percentage of referrals that are pre‐treatment SOs.
Table S3. Number of pre‐treatment SO referrals and percentage of patients treated at the original institution.
Table S4. Factors and magnitude of effect on time from date of diagnosis to date of first treatment for lung cancer (non‐small cell carcinoma) (N = 164,098).
Table S5. Factors and magnitude of influence on the time from date of diagnosis to date of first treatment for breast cancer (N = 195,511).
Acknowledgments
The authors thank the faculty of the University of Tokyo School of Public Health for their useful comments regarding the analyses.
Funding: This study was supported by the National Cancer Center Research and Development Fund.
References
- 1. Association WM , “WMA Declaration of Lisbon on the Rights of the Patient 1995,” accessed January 4, 2025, https://www.wma.net/wp‐content/uploads/2005/09/Declaration‐of‐Lisbon‐1995.pdf.
- 2. Könsgen N., Prediger B., Schlimbach A., et al., “Attitude Toward Second Opinions in Germany – A Survey of the General Population,” BMC Health Services Research 22, no. 1 (2022): 76, 10.1186/s12913-021-07422-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3. Payne V. L., Singh H., Meyer A. N. D., Levy L., Harrison D., and Graber M. L., “Patient‐Initiated Second Opinions: Systematic Review of Characteristics and Impact on Diagnosis, Treatment, and Satisfaction,” Mayo Clinic Proceedings 89, no. 5 (2014): 687–696, 10.1016/j.mayocp.2014.02.015. [DOI] [PubMed] [Google Scholar]
- 4. Greenfield G., Shmueli L., Harvey A., et al., “Patient‐Initiated Second Medical Consultations—Patient Characteristics and Motivating Factors, Impact on Care and Satisfaction: A Systematic Review,” BMJ Open 11, no. 9 (2021): e044033, 10.1136/bmjopen-2020-044033. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5. National Cancer Center Institute for Cancer Control , “Patient Experience Survey 2014,” accessed December 30, 2024, https://www.ncc.go.jp/jp/icc/policy‐evaluation/project/010/2014/index.html.
- 6. Watanabe T., Ichinose Y., Matsuki M., et al., “Experiences of Patients With Cancer at Health Care Facilities in Japan: Results From a Nationwide Survey,” BMC Health Services Research 21, no. 1 (2021): 1180, 10.1186/s12913-021-07184-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7. de Heus E., Engelen V., Dingemans I., et al., “Differences in Health Care Experiences Between Rare Cancer and Common Cancer Patients: Results From a National Cross‐Sectional Survey,” Orphanet Journal of Rare Diseases 16, no. 1 (2021): 249, 10.1186/s13023-021-01886-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8. Morrow M., Jagsi R., Alderman A. K., et al., “Surgeon Recommendations and Receipt of Mastectomy for Treatment of Breast Cancer,” Journal of the American Medical Association 302, no. 14 (2009): 1551–1556, 10.1001/jama.2009.1450. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9. Mordechai O., Tamir S., and Weyl‐Ben‐Arush M., “Seeking a Second Opinion in Pediatric Oncology,” Pediatric Hematology and Oncology 32, no. 4 (2015): 284–289, 10.3109/08880018.2014.987938. [DOI] [PubMed] [Google Scholar]
- 10. Beer M., Allison H., Fisher C., and Fan B., “Second Opinions in Breast Cancer Surgery: What Have We Learned?,” Cureus 14, no. 10 (2022): e30180, 10.7759/cureus.30180. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11. Egleston B. L., Bleicher R. J., Fang C. Y., Galloway T. J., and Vucetic S., “Benefits Versus Drawbacks of Delaying Surgery due to Additional Consultations in Older Patients With Breast Cancer,” Cancer Reports 6, no. 5 (2023): e1805, 10.1002/cnr2.1805. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12. National Cancer Center Institute for Cancer Control , “Reference: 2017 Percentage of Cancers Registered in the In‐Hospital Cancer Registry,” cited December 30, 2024, https://ganjoho.jp/public/qa_links/report/hosp_c/pdf/2017_report_add.pdf.
- 13. National Cancer Center Institute for Cancer Control , “Hospital‐Based Cancer Registries of Base Hospitals for Cancer Treatment, etc. 2018 National Aggregate Report Data Percentage of Hospital‐Based Cancer Registries (Coverage) and Number of Registrations by Secondary Medical Region,” accessed December 30, 2024, https://ganjoho.jp/public/qa_links/report/hosp_c/pdf/2017_report_add.pdf.
- 14. Yasunaga H., “Updated Information on the Diagnosis Procedure Combination Data,” Annals of Clinical Epidemiology 6, no. 4 (2024): 106–110, 10.37737/ace.24015. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15. Higashi T., Nakamura F., Saruki N., and Sobue T., “Establishing a Quality Measurement System for Cancer Care in Japan,” Japanese Journal of Clinical Oncology 43, no. 3 (2013): 225–232, 10.1093/jjco/hyt001. [DOI] [PubMed] [Google Scholar]
- 16. Okuyama A. and Higashi T., “Usability of Clinical Information in Discharge Summary Data in the Diagnosis Procedure Combination Survey for Cancer Patients,” International Journal of Environmental Research and Public Health 17, no. 2 (2020): 521, 10.3390/ijerph17020521. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17. Shigemi D., Morishima T., Yamana H., Yasunaga H., and Miyashiro I., “Validity of Initial Cancer Diagnoses in the Diagnosis Procedure Combination Data in Japan,” Cancer Epidemiology 74 (2021): 102016, 10.1016/j.canep.2021.102016. [DOI] [PubMed] [Google Scholar]
- 18. Kerras S., Hetherington K., Toofanian S., Manoharan N., Ziegler D. S., and Mateos M. K., “Second Opinion Seeking in Paediatric Oncology: Motivations and Predictors,” Psychooncology 33, no. 11 (2024): e70011, 10.1002/pon.70011. [DOI] [PubMed] [Google Scholar]
- 19. Burns K. C., Hoefgen H., Strine A., and Dasgupta R., “Fertility Preservation Options in Pediatric and Adolescent Patients With Cancer,” Cancer 124, no. 9 (2018): 1867–1876, 10.1002/cncr.31255. [DOI] [PubMed] [Google Scholar]
- 20. Hanna T. P., King W. D., Thibodeau S., et al., “Mortality due to Cancer Treatment Delay: Systematic Review and Meta‐Analysis,” British Medical Journal 371 (2020): m4087, 10.1136/bmj.m4087. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21. Hall H., Tocock A., Burdett S., et al., “Association Between Time‐To‐Treatment and Outcomes in Non‐Small Cell Lung Cancer: A Systematic Review,” Thorax 77, no. 8 (2022): 762–768, 10.1136/thoraxjnl-2021-216865. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22. Polverini A. C., Nelson R. A., Marcinkowski E., et al., “Time to Treatment: Measuring Quality Breast Cancer Care,” Annals of Surgical Oncology 23, no. 10 (2016): 3392–3402, 10.1245/s10434-016-5486-7. [DOI] [PubMed] [Google Scholar]
- 23. Okuyama A., Watabe M., Makoshi R., Takahashi H., Tsukada Y., and Higashi T., “Impact of the COVID‐19 Pandemic on the Diagnosis of Cancer in Japan: Analysis of Hospital‐Based Cancer Registries,” Japanese Journal of Clinical Oncology 52, no. 10 (2022): 1215–1224, 10.1093/jjco/hyac129. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24. Teramoto N., Yamashita N., and Ohira Y., “Trends in Patients' Behavior for Cancer Care and the Number of Registered Cancer Cases in Ehime Prefecture During the Coronavirus Disease Pandemic,” Japanese Journal of Clinical Oncology 53, no. 10 (2023): 922–927, 10.1093/jjco/hyad076. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Table S1. Number of cases analyzed and percentage of SO referrals calculated.
Table S2. Number of SO referrals and percentage of referrals that are pre‐treatment SOs.
Table S3. Number of pre‐treatment SO referrals and percentage of patients treated at the original institution.
Table S4. Factors and magnitude of effect on time from date of diagnosis to date of first treatment for lung cancer (non‐small cell carcinoma) (N = 164,098).
Table S5. Factors and magnitude of influence on the time from date of diagnosis to date of first treatment for breast cancer (N = 195,511).