Global burden of female breast cancer: new estimates in 2022, temporal trend and future projections up to 2050 based on the latest release from GLOBOCAN

Abstract

Background

Breast cancer (BC) incidence and mortality vary significantly across countries, highlighting the need to update the global burden of female BC, including current trends and future projections.

Methods

Data were sourced from GLOBOCAN 2022, including estimated new cases and deaths from BC across 21 United Nation (UN) regions and 185 countries, the age-standardized incidence rate (ASIR) and mortality rate (ASMR), the estimated annual percentage changes (EAPC), and demographic projections through 2050. The region-specific and country-specific BC burden for women of all ages and for young women (< 40 years old) was reorganized and re-plotted to highlight subgroup differences. Linear regression was used to explore the link between ASIR/ASMR and the human development index (HDI). Transitioning countries referred to those with low or medium HDI, while transitioned countries were those with high or very high HDI.

Results

In 2022, an estimated 2.3 million new BC cases and 666,000 BC-related deaths occurred globally, accounting for 23.8 % and 15.4 % of all cancer cases and deaths in women, respectively. Regionally, Eastern Asia reported the highest number of cases (480,019, ASIR: 37.54/100,000), while South-Central Asia had the highest number of deaths (135,348, ASMR: 13.41/100,000). At the country level, China had the highest number of cases due to its large population, whereas India reported the highest number of deaths. ASIR for both overall and early-onset BC increased with HDI, while ASMR for early-onset BC decreased with HDI (P < 0.05). Overall BC showed an increasing trend in ASIR during 2003–2015 (EAPC: 0.92 %) and a decreasing trend in ASMR during 2006–2016 (EAPC:-1.06 %). Early-onset BC showed a more significant rise in ASIR (EAPCs: 1.4 %) and a slight increase in ASMR (EAPCs: 0.16 %). If national rates remain stable, BC cases and deaths will increase by 54.7 % and 70.9 %, respectively, by 2050. Notably, increased early-onset BC cases are only observed in transitioning countries, while decreased cases are seen in transitioned countries.

Conclusions

Breast cancer remains the leading cancer burden in women, particularly in transitioning countries. Addressing this growing burden requires urgent integration of primary prevention, early detection and high-quality treatment through multi-sectoral collaboration.

1. Introduction

Female breast cancer (BC) has been the leading cause of cancer morbidity and mortality among women in the majority of countries for decades. In 2020, there were an estimated 2.3 million new cases and 685,000 deaths from female BC worldwide, which accounted for one in four cancer cases and one in six cancer deaths among women.¹ According to the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021, BC is the leading cancer in terms of disability adjusted life years (DALYs) for women of all ages, with BC death burden ranking second only to lung cancer. The forecasted BC DALYs increased from 238.6 (223.2–254.2) per 100,000 in 2022 to 239.5 (186.9–300.6) per 100,000 in 2050.² Globally, about 30 % of BC cases are attributable to modifiable risk factors, such as excess body weight, physical inactivity, and alcohol consumption, thus may be preventable.3, 4, 5 Elevated incidence supported that female-specific factors related to reproductive characteristics, including early age at menarche, later age at menopause, advanced age at first birth, fewer number of children, less breastfeeding, hormonal menopausal therapy, oral contraceptive, and breast density, also collectively contributed a large proportion of BC cases.^1,6, 7, 8, 9 High-quality randomized trials further suggested that mammography screening for BC can reduce nearly 20 % of BC mortality.⁹ Alongside the benefits of effective prevention and mammography screening, advances in treatment can further prevent death and substantially reduce BC mortality. Given the marked difference in exposure to modifiable risk factors and female reproductive characteristics, coverage of mammography screening and levels of effective treatment across different countries, it is vitally important to update the global landscape of BC burden, including the current status, temporal trend and future projections, according to the latest global estimates of female BC.

Moreover, despite a series of measures that have been taken in several countries (especially in transitioned countries) based on the above effective interventions, regional and country-specific studies suggested that both incidence and mortality of BC would continue to increase in the future decades worldwide,¹⁰ especially regarding the burden of early-onset BC, diagnosed at or before the age of 40.11, 12, 13, 14 The excessive BC cases would largely reflect the dramatic changes in female reproductive characteristics associated with socioeconomic development, the rapid increase in aging and growth of the population, as well as the delayed introduction of effective BC screening programs in the vast majority of transitioning countries.^8,15,16 Extensive research has been conducted in the past using GLOBOCAN 2020 or earlier data to investigate the global burden of breast cancer. However, there are currently few analyses based on the latest GLOBOCAN 2022 data to assess the most recent disease burden. Furthermore, there is limited research exploring the global distribution patterns of early-onset breast cancer, trends over the past decades, and its associations with national socioeconomic development levels.

Therefore, based on the latest data from GLOBOCAN 2022 released by the International Agency for Research on Cancer (IARC), this study aimed to provide a description of the global incidence and mortality of overall and early-onset female BC, as well as to assess the geographic difference. Specifically, we used the burden of BC in representative countries as examples to support decision-making for global BC prevention and control strategies. Then we tried to describe the temporal trend of overall and early-onset female BC burden over the available data and end with a description of future female BC burden up to 2050 based on global demographic projections.

2. Materials and methods

2.1. Data sources

All data were obtained from the GLOBOCAN 2022 database (https://gco.iarc.fr/), including estimated new cases and deaths, the age-standardized incidence rate (ASIR) and mortality rate (ASMR), the estimated annual percentage changes (EAPC), and demographic projections up to 2050. In brief, country-specific raw data on cancer burden released by countries around the world are aggregated and combined by the IARC under the World Health Organization (WHO) according to uniform standards to form the GLOBOCAN database. Until 2022, the GLOBOCAN database has covered the estimated burden of 36 cancer diseases across 185 countries and 21 regions worldwide, including the current, past, and future incidence, mortality and prevalence of cancer by site and sex. Particularly, the Cancer Today database was extracted to present the current estimated cases and deaths from BC in 2022.¹⁷ Cancer incidence refers to the number of new cancer cases diagnosed in a specific population during a defined period of time, while cancer mortality represents the number of deaths attributed to cancer within a specified population during a given period. Incidence data are regularly gathered by national or subnational population-based cancer registries, while cause-specific mortality data are routinely compiled by national vital registration systems. The Cancer Over Time database was used to present temporal trends in cancer-specific incidence and mortality rates over the available period based on the Cancer Incidence in Five Continents (CI5 plus) database and the WHO mortality.¹⁸ The Cancer Tomorrow database provided the estimated new cancer cases and deaths up to 2050 based on the estimates in 2022.¹⁹

2.2. Selected regions and the human development index (HDI)

In this study, both incidence and mortality of BC were majorly presented according to 21 aggregated regions defined by the United Nations Population Division. Based on the United Nation (UN) Development Program's Human Development Report 2021–22,²⁰ the HDI was used to present the difference in BC burden across countries with different levels of socioeconomic development, and it was calculated based on life expectancy, education level and gross domestic income per capita. All countries were reclassified into four levels on the basis of HDI: low HDI (< 0.55), medium HDI (0.55–0.70), high HDI (0.70–0.79) and very high HDI (≥ 0.80).^10,21 According to the UN Development Program report, a transitioning HDI country, which included countries with low or medium HDI, typically refers to a nation undergoing significant changes in its HDI ranking over recent years, including improvements or declines in any of the HDI components mentioned above. A transitioned HDI country, namely those with high or very high HDI, refers to nations that have moved from one category of the HDI to another over a period of time, after experienced significant changes in their HDI rankings due to improvements or declines in factors such as life expectancy, education attainment, and income per capita.

2.3. Statistical analysis

The region-specific and country-specific BC burden for women of all ages and for young women (< 40 years old) was reorganized and re-plotted to highlight subgroup differences. Specifically, the statistical descriptive analysis method was mainly used to present the UN regional and country-specific incidence and mortality of overall and early-onset BC in this study. The ASIR and mortality rate ASMR of BC were calculated based on the population originally proposed by Segi (1960) and later modified by Doll et al (1966).²² The early-onset BC was defined as patients who were diagnosed as BC before 40 years old. The linear regression model was used to characterize the relationship between ASIR or ASMR and HDI, and log-transformed correlation coefficient (r) was used to measure the magnitude of the correlation. The estimated annual percentage change (EAPC) was calculated using a generalized linear model used to characterize the temporal trend in ASIR and ASMR over the time period selected with a Gaussian distribution considered.¹⁸ The projections for BC incidence and mortality in 2050 presented in the analysis were sourced from the Cancer Tomorrow website. Demographic projections of BC cases and deaths were predicted to 2050 after assuming that the national projected changes in population growth and aging would not change in the forecast period between 2022 and 2050.¹⁹ The change percentage in the future estimated burden of BC was calculated as the predicted estimates in 2050 minus the corresponding estimates in 2022 and then divided by the estimates in 2022. The change percentages were further grouped by HDI.

All statistical analyses were performed with R software (version 4.2.3), Microsoft Excel (version 4.2.3) and the Global Cancer Observatory online, and P < 0.05 was considered statistically significant.

3. Results

3.1. Global and regional breast cancer burden in 2022

In 2022, an estimated 2,296,840 new cases of female BC were reported globally, with an ASIR of 46.8 per 100,000. BC accounted for approximately 23.8 % of all cancer cases in women worldwide (Supplementary Fig. 1). Regionally, Eastern Asia had the highest number of incident cases (480,019 cases, ASIR: 37.54/100,000), followed by Northern America (306,307 cases, ASIR: 95.12/100,000). At the country level, China reported the most BC cases due to its large population (16 % of global cases), followed by the United States (12 %) and India (8 %) (Fig. 1). South Central Asia had the highest number of early-onset BC cases across different regions (44,266), with China (13 %), India (11 %), the USA (7 %) leading in this category across different countries (Fig. 1). Australia-New Zealand had the highest ASIR for overall BC (100.28/100,000) (Table 1), while South Central Asia recorded the lowest (26.70/100,000) (Table 1). For early-onset BC, Southern Europe had the highest ASIR (15.82/100,000), while Micronesia had the lowest (4.45/100,000) (Table 1).

Fig. 1.

Country-level proportion of estimated cases and deaths from female breast cancer worldwide in 2022. (A, B) Proportion of overall (A) and early-onset (B) breast cancer cases. (C, D) Proportion overall (C) and early-onset (D) breast cancer deaths.

Table 1.

The estimated burden of breast cancer for different regions in 2022.

World regions	Incidence				Mortality
	All ages		< 40 years old		All ages		< 40 years old
	Numbers	ASR (per 100,000)	Numbers	ASR (per 100,000)	Numbers	ASR (per 100,000)	Numbers	ASR (per 100,000)
World	2,296,840	46.80	246,060	8.10	666,103	12.70	48,700	1.60
Region
Northern America	306,307	95.12	18,096	13.14	49,744	12.32	1391	1.00
Eastern Asia	480,019	37.54	42,048	6.81	97,389	6.52	3935	0.62
Eastern Africa	47,300	31.94	11,747	7.12	25,330	17.58	5342	3.25
Middle Africa	16,856	29.97	4456	7.24	9142	16.82	2043	3.33
Northern Africa	64,977	53.17	13,703	13.69	23,186	19.00	3562	3.52
Southern Africa	15,815	46.16	1912	6.12	5693	16.57	548	1.74
Western Africa	53,605	41.63	11,350	8.19	27,901	22.25	5085	3.68
Caribbean	14,862	49.57	1768	10.55	5953	18.17	410	2.39
Central America	39,835	38.28	6010	7.96	10,670	10.05	830	1.08
South-Eastern Asia	168,536	41.73	23,109	8.39	61,228	14.85	4693	1.68
South Central Asia	273,902	26.70	44,266	5.27	135,348	13.41	12,063	1.43
Western Asia	63,360	45.40	10,958	9.56	21,344	15.11	2514	2.16
Eastern Europe	163,474	58.30	11,911	10.19	49,973	14.44	1419	1.15
Northern Europe	89,324	90.80	4675	12.03	18,629	13.70	409	1.04
Southern Europe	124,621	81.76	7543	15.82	31,450	13.81	503	1.00
Western Europe	180,113	89.81	10,067	15.27	44,387	15.37	805	1.19
Australia-New Zealand	25,786	100.28	1601	13.31	4152	12.81	109	0.88
Melanesia	2294	49.21	446	10.55	1179	26.77	180	4.26
South America	165,427	57.16	20,354	11.30	43,253	13.80	2853	1.54
Micronesia	133	43.88	9	4.45	53	16.74	0	0
Polynesia	294	76.89	31	12.43	99	25.26	6	2.34
HDI
Very HDI country	1,092,663	75.63	74,665	12.54	245,043	13.21	7025	1.15
High HDI country	737,959	38.79	87,293	7.88	195,347	9.50	13,420	1.18
Medium HDI country	331,089	29.71	51,744	5.67	153,835	13.96	15,259	1.67
Low HDI country	134,122	34.10	32,255	7.75	71,458	18.99	12,965	3.12

Abbreviations: ASIR, age-standardized incidence rate; ASMR, age-standardized mortality rate; HDI, human development index.

In 2022, there were an estimated 666,103 BC-related deaths globally (ASMR of 12.70/100,000), accounting for approximately 15.4 % of all cancer deaths in women (Supplementary Fig. 1). Regionally, South-Central Asia recorded the highest number of deaths (135,348, ASMR: 13.41/100,000), followed by Eastern Asia (97,389, ASMR: 6.52/100,000). At the country level, India reported the highest number of BC-related deaths (15 % of global deaths), followed by China (11 %), the USA (6 %), Indonesia (3 %), Brazil (3 %), Russia (3 %), Germany (3 %) and Japan (3 %) (Fig. 1). South-Central Asia also had the highest number of early-onset BC deaths (12,063, ASMR: 1.43/100,000), with India (16 %), China (7 %), Ethiopia (5 %), and Nigeria (5 %) leading in the category across different countries (Fig. 1). Melanesia has the highest ASMR for overall BC (26.77/100,000) (Table 1), while Eastern Asia had the lowest (6.52/100,000) (Table 1). For early-onset BC, Melanesia again had the highest ASMR (4.26/100,000), followed by Western Africa (3.68/100,000) (Table 1).

3.2. Link between HDI and BC incidence and mortality

Countries with very high HDI reported the highest number of female BC cases (1,092,663, ASIR: 75.63/100,000), much higher than those with high HDI (737,959, ASIR: 38.79/100,000), medium HDI (331,089, ASIR: 29.71/100,000), and low HDI (134,122, ASIR: 34.10/100,000). The same pattern was observed for early-onset BC, with countries of very high HDI having the highest ASIR (12.54 /100,000), and medium HDI countries having the lowest (5.67/100,000, Table 1). In contrast, countries with low HDI had the highest ASMR for both overall (18.99/100,000) and early-onset BC (3.12/100,000). High HDI countries had the lowest ASMR for overall BC (9.50/100,000), while very high HDI countries had the lowest ASMR for early-onset BC (1.15/100,000, Table 1).

As shown in Fig. 2, ASIRs for overall, early-onset and post-40 BC consistently increased with HDI. The correlation between HDI and overall BC ASIR (r = 0.689, P < 0.001) was stronger than the correlation between HDI and early-onset BC ASIR (r = 0.307, P < 0.001) (Fig. 2A and B), and slightly weaker than the correlation for post-40 BC (r = 0.703, P < 0.001) (Fig. 2C). The correlation between HDI and ASMR for overall BC (r = −0.044, P = 0.559, Fig. 2D) and post-40 BC (r = 0.046, P = 0.548, Fig. 2F) were non-significant. However, the correlation between HDI and early-onset BC ASIR was significant (r = −0.629, P < 0.001, Fig. 2E).

Fig. 2.

Link between HDI and ASIR and ASMR of female breast cancer. (A-C) Link between HDI and ASIR of overall (A), early-onset (B) breast cancer and post-40 breast cancer (C). (D-F) Link between HDI and ASMR of overall (D), early-onset (E) breast cancer and post-40 breast cancer (F). ASIR, age-standardized incidence rate; ASMR, age-standardized mortality rate; HDI, human development index.

3.3. Temporal trends in breast cancer incidence and mortality

Based on continuous data from registries, the ASIR of overall BC showed an upward trend in most countries. Notable examples include the Republic of Korea (1999–2017, EAPC: 5.5893 %), Thailand (1993–2017, EAPC: 3.5683 %), Japan (1978–2015, EAPC: 3.4873 %), Qatar (2003–2017, 3.1281 %), Uganda (1993–2017, 2.6998 %), Kuwait (1998–2017, 2.6449 %), and France (Martinique) (1993–2017, 2.5390 %) (Fig. 3A). When analyzing data within the continuous monitoring period covered by all countries (2006–2015), the global average EAPC for overall BC ASIR was 1 % (Supplementary Fig. 2A). The Republic of Korea exhibited the highest country-specific EAPC (4.5721 %) (Supplementary Fig. 2A). Globally, the ASIR of early-onset BC in most countries also showed an increased trend, with an average EAPC of 1.6 % between 2006 and 2015 (Supplementary Fig. 2B), which was higher than the EAPC for overall ASIR. In China, the EAPC of early-onset BC ASIR (4.7014 %, 2002–2017, Fig. 3B) was higher than that for overall BC ASIR (2.0032 %, 2002–2017, Fig. 3A), and a similar trend was observed in the UK (Wales) and France (metropolitan). Conversely, countries like the Republic of Korea, Japan, and India showed an opposite trend, with a higher EAPC in overall BC than early-onset BC (Fig. 3B).

Fig. 3.

EAPC of ASIR and ASMR of breast cancer in different countries. (A, B) EAPC of overall (A) and early-onset (B) breast cancer ASIR. (C, D) EAPC of overall (C) and early-onset (D) breast cancer ASMR. ASIR, age-standardized incidence rate; ASMR, age-standardized mortality rate; EAPC, estimated annual percentage change.

The ASMR for overall BC declined in most countries, with the global EAPC for ASMR at ˗1.06 % during 2006–2016 (Fig. 3C). At the country level, Malaysia showed an upward trend in ASMR during 2000–2020 (EAPC: 3.9825 %, Fig. 3C), while countries such as the UK, USA, and Germany reported a downward trend (Fig. 3C). For early-onset BC, the ASMR showed a downward trend in most countries, but globally, the average EAPC for early-onset BC ASMR showed a slightly upward trend during 2006–2016 (0.16 %) (Fig. 3D).

3.4. Demographic projection of breast cancer cases and deaths up to 2050

Based on the stable population growth, aging, and estimates in 2022, the number of BC cases globally is expected to rise to 3,533,037 by 2050, with an overall increase of 54.7 %. Similarly, BC-related deaths are projected to reach 1,138,155, representing a 70.9 % increase. When grouped by HDI, the increase in BC cases is projected to range from 19.9 % in countries with very high HDI to 145.4 % in countries with low HDI (Fig. 4A). Similarly, the increase in BC-related deaths is projected to range from 40.3 % in high HDI countries to 150.0 % in low HDI countries (Fig. 4C). The predicted burden of early-onset BC differs significantly from the overall BC burden. Estimated early-onset BC cases are expected to increase in countries with low and medium HDI (by 108.2 % and 16.1 %, respectively), but decrease in countries with high and very high HDI (˗13.0 % and ˗9.9 %) (Fig. 4B). A similar trend is anticipated for early-onset BC-related deaths (Fig. 4D).

Fig. 4.

Estimated new cases and deaths from female breast cancer up to 2050 by HDI. (A, B) New cases of overall (A) and early-onset (B) breast cancer. (C, D) Deaths of overall (C) and early-onset (D) breast cancer. HDI, human development index.

Among the top 19 countries with the highest number of BC cases in 2022, most are expected to see an increase in BC cases by 2050, with Japan being the only country projected to experience a decrease in cases. Specifically, China is projected to have the highest total number of BC cases, while India is expected to see the largest increase in cases (Fig. 5A). India is also predicted to have the highest number of early-onset BC cases, while China is expected to experience a significant decrease in early-onset cases (Fig. 5B). Similar trends are projected for country-specific deaths from both overall (Fig. 5C) and early-onset BC (Fig. 5D).

Fig. 5.

Estimated new cases and deaths from female breast cancer up to 2050 in selected countries with top 19 numbers of cases in 2022. (A, B) New cases of overall (A) and early-onset (B) breast cancer. (C, D) Deaths of overall (C) and early-onset (D) breast cancer.

4. Discussion

This study not only provided a valuable global landscape of BC burden, including the current status, temporal trend and future projections, but also enabled comparisons of BC burden across different populations. Globally, BC remains the leading cause of cancer morbidity and mortality in women, irrespective of the HDI level. Both incidence and mortality of BC vary widely by region. Moreover, BC incidence showed an upward trend worldwide, while mortality showed a decreasing trend. Both of these two trends were more obvious for early-onset BC. Given the increased burden of BC faced by most countries, this situation not only presented a great challenge for health services in different countries, but also provided a series of potential opportunities for creating innovative health service models and breakthroughs in treatment.

Countries with high ASIR of BC are predominantly located in Western Europe, including France, Cyprus, Belgium, and The Netherlands. These countries are mainly developed countries with a relatively high prevalence of risk factors, such as high-fat diets, physical inactivity, delayed marriage and childbearing, limited breastfeeding history, and prolonged use of hormone replacement therapy.²³ Many of these countries have high-quality screening systems.²⁴ With the exception of the Russian Federation, Bulgaria, Greece, the Czech Republic, and Slovakia, nearly all European countries have population-based BC screening programs. These screening initiatives not only contribute to higher rates of early diagnosis but also play a crucial role in maintaining lower mortality rates.²⁵ On the other hand, countries with high ASMR, such as Fiji, Jamaica, and the Bahamas, are mostly middle- or low-income countries. These resource-limited countries bear a high percentage of advanced-stage BC, poor BC prognosis and short disease-free survival.^26,27 In addition to organized screening, the gap in treatment availability represents another significant factor in explaining the discrepancies between BC ASMR across countries.²⁸ Specifically, the inability to provide consistent and complete treatment is a major challenge in low- and middle-income countries. Additionally, the struggle of healthcare systems with inadequate resources and infrastructure is another key factor contributing to poor prognosis in these regions. Cultural beliefs and the stigma surrounding BC treatment would further discourage women from seeking timely medical care or participating in screenings.^29,30

BC ASIR significantly increased with the HDI for both older and younger women, however, the link appear to be more pronounced in older women. The absence of obvious economic and regional differences in early-onset BC incidence suggests that the risk is likely closely associated with unmodifiable genetic risks across counties with varying economic levels. Approximately half of early-onset BC in young women under 30 carry germline mutations in BRCA1, BRCA2, or TP53.^31,32 In contrast, the stronger relationship between ASIR and HDI for older women is more likely attributed to higher rates of mammographic screening in high-income countries, as well as the influence of changes in hormone exposure or lifestyle factors linked to socioeconomic development.³³ With improvements in living standards and changes in lifestyles, the prevalence of overweight and obesity has generally increased in several countries,³⁴ potentially elevating the risk of BC in these regions. Declining fertility rates lead to fewer pregnancies and later childbearing, which increases exposure to estrogen.³⁵ Additionally, the broader adoption of screening programs has facilitated earlier detection of BC.³⁶ Therefore, the higher BC ASIR in transitioned countries compared to transitioning countries reflects not only a relatively higher prevalence of modifiable risk factors (such as excess body weight, physical inactivity, and alcohol consumption),^3,4 but also reflects a longstanding higher prevalence of reproductive and hormonal risk factors (such as early menarche, later menopause, older age at first birth, fewer children), as well as increased detection through organized or opportunistic screening.^7,35,37,38 Further studies have found that increasing BC incidence is confined to estrogen receptor (ER)-positive BC but not ER-negative cancers, which would be supported by the link between excess body weight and ER-positive cancer and present the preferential detection slow-growing ER-positive cancers by the mammographic screening.39, 40, 41, 42 Although efforts to decrease excess body weight and alcohol consumption and to encourage physical activity and breastfeeding are expected to lead to a reduction of BC incidence worldwide,⁴³ establishing primary prevention programs for BC remains challenging. A generally uniform upward trend in BC incidence during 1980–2000 has been followed by stable or downward trends during 2001–2010 in several transitioned countries and regions (such as Northern America, Oceania, and Europe).^44,45 This downward trend in BC incidence would largely link to the reduced use of menopausal hormone replacement therapy after the Women's Health Initiative in July 2002,^46,47 though it would also reflect a plateauing in screening participation.^44,45 Therefore, the focus of BC control has gradually shifted towards screening, improved treatment, and other effective prevention strategies.

The upward trends in BC ASIR in transitioning countries would further reflect changes in above risk determinants associated with socioeconomic development^48,49 (such as increasing prevalence of overweight,50, 51, 52 declining age at menarche,⁵³ postponement of childbearing and falling fertility rate,^35,54 increasing use of estrogen and progesterone,^47,55 decreasing breastfeeding),⁵⁶ aging and growth of the population,^15,16 as well as changes in increased detection through mammographic screening in these countries.³⁶ The mean age at menarche decreased by approximately two years between women born in 1930 and those born in 1974 in China.⁵³ Additionally, fertility rates have steadily fallen in all countries since 1950 and are projected to continue declining worldwide. By 2050, less than one-quarter of countries are expected to have fertility rates above replacement level, and by 2100, only six are projected to do so.⁵⁴ Alongside the falling fertility rates and longer life expectancy, the multifaceted impact of rapid aging on economic development and health services has been deeply perceived by China and will continue to present great challenges to public health.^15,16 Other populous countries, such as India, Nigeria, the USA, and Pakistan, will also suffer from the increasing demand for health services and social support associated with the increasing aging population.⁴⁹ Additionally, after the widespread use of mammography in the United States, the detection rate of ductal carcinoma in situ ascended from 10/100,000 (1975–1979) to 79/100,000 during 2008–2012,⁵⁷ and the age at diagnosis of BC shifted from an elder age to a younger age at the onset of the disease and reached a plateau.⁵⁸ This situation was also observed in countries that had implemented or planned to initiate organized mammography screening,^59,60 and it would be another explanation for the increased estimates of BC in these countries.⁶¹ How to turn the above challenges into cancer control opportunities would be a global hot topic in public health in the near future. These not only require support from local health policies, but also urgently need innovative healthcare models and treatment breakthroughs to respond to the soaring demand for health services.

The higher ASMR in transitioning countries compared to transitioned countries largely reflects the combined impacts of lack of high-quality screening, late-stage cancer diagnosis and unavailability of effective treatment due to limited health resources (including adjuvant chemotherapy and hormone therapy since the 1980s and targeted therapy since the 1990s).^10,48,62 Notably, due to better and more targeted treatments as well as early detection through screening, BC mortality had fallen by nearly 43 % during 1989–2020 in the United States.³⁵ Similar reductions in BC mortality were also reported in Europe and would continue to decline.63, 64, 65 The Chinese government has launched nationwide BC screening in high-risk areas since 2008.⁶⁶ Although no obvious decline in the mortality of female BC appeared in China, a slower increase in mortality versus incidence had been observed in the past decade, which would also partially be attributed to the current screening.⁶⁷ Due to the late introduction of screening, the proportion of BC diagnosed at stage I was 27.6 % in China, which was much lower than that of the USA (51.2 %).⁶⁸ Alongside the lower early-stage BC at diagnosis, the five-year survival rate of BC was 82.0 % in China during 2012–2015 and 66 % in 12 sub-Saharan African countries during 2008–2015,^69,70,71 which was sharply contrasted with 85 % to 90 % in transitioned countries during 2010–2014.^72,73 Educational and cultural barriers, including lack of awareness of BC, an incorrect belief that cancer is incurable or contagious, the stigma of having a mastectomy and fear of rejection by their partner or community, would also collectively contribute to the higher mortality of BC in transitioning countries.⁷⁴ Expanding screening coverage, raising awareness of breast health, and promoting high-quality and effective treatment will be keys to reversing the upward trend in BC mortality in transitioning countries. Notably, expanding screening does not mean screening at an earlier age, before 50 years old. As highlighted by the IARC's comprehensive analysis,⁷⁵ the evidence supports the efficacy of mammographic screening primarily for women aged 50–69, with limited or inadequate evidence for younger women.

The strengths of the study included its comprehensive global scope, the use of the most recent GLOBOCAN 2022 data, and the detailed regional and country-specific analysis of BC burden. However, there were certain limitations worth noting. First, although this study provided a valuable global landscape of BC burden, it's important to note that high quality local data remained sparse in many countries, especially for transitioning countries, which would unavoidably affect the robustness of the BC estimates presented in these countries. Second, the current country-level BC estimates are not intended as a substitute for the continuous monitoring data collected by high-quality, population-based cancer registries and vital registration systems, which would also bias the estimates in the temporal trend of BC burden. Given the critical importance of continuous monitoring of high-quality data for cancer prevention and control, expanding the coverage of the cancer registry and improving the quality of data will be the basic guarantee for local decisions making on cancer prevention and control. Thirdly, other limitations included lack of male data, inconsistencies between global values and summation of country data, and lack of confidence or uncertainty intervals in the GLOBOCAN database.

5. Conclusions

Based on the latest GLOBOCAN 2022 dataset, this study presents the current status, historical trends, and projected future burden of overall and early-onset BC globally. Additionally, this study also analyzes these trends and burdens of breast cancer in relation to the socioeconomic levels of different countries. In conclusion, BC remains the leading cause of cancer morbidity and mortality in women worldwide, and the global BC burden is expected to increase with socioeconomic development, especially for transitioning countries. To cope with the growing global burden of BC, WHO and international partners launched the Global Breast Cancer Initiative in early 2021, which included three key pillars as an operational approach to achieve final goals, including centering on health promotion and early detection, timely diagnosis, and comprehensive breast cancer management.⁷⁶ Based on this global initiative, the local government should efficiently integrate the resources of primary prevention, early detection and high-quality treatment for BC to promote collaboration between community stakeholders, advocacy organizations, and health systems, especially under the soaring demand for high-quality health services associated with the increasing aging population.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.