Global burden and trends of breast cancer: GLOBOCAN 2022 estimates of incidence and mortality in 185 countries

Abstract

Background:

Breast cancer is the most common malignancy among women, posing major health, social, and economic challenges worldwide. This study analyzed global breast cancer incidence and mortality in 2022 using Global Cancer Observatory (GLOBOCAN) 2022 data and projected the disease burden to 2050.

Methods:

Breast cancer incidence and mortality were categorized by region and age. Correlations between age-standardized rates (ASRs) and the Human Development Index (HDI) were assessed using Spearman’s rank correlation coefficient (ρ). Future burden estimates for 2050 were projected based on current trends.

Results:

In 2022, approximately 2.30 million new breast cancer cases and 666,103 deaths were reported globally. Age-specific patterns of breast cancer incidence and mortality differed across development HDI levels with incidence peaking at ages 45–69 years and mortality at ages 50–≥85 years across HDI levels. The proportion of cases and deaths among women aged ≥50 years relative to those aged ≤49 years increased with HDI, ranging from 79% vs. 21% for incidence and 90% vs. 10% for deaths in very high HDI countries to 51% vs. 49% and 59% vs. 41% in low HDI countries. HDI showed strong positive correlations with age-standardized incidence rates (ρ = 0.773), period incidence rates (ρ = 0.958), and period mortality rates (ρ = 0.907), and a negative correlation with mortality-to-incidence ratios (ρ = –0.817). Projections indicate that by 2050, breast cancer cases may rise to 3.55 million and deaths to 1.14 million if current patterns continue.

Conclusions:

Breast cancer remains a major global health concern. Strengthening prevention, early detection, and therapeutic strategies is essential to reduce incidence, improve survival, and alleviate its global burden.

Introduction

In 2022, breast cancer emerged as the second most frequently diagnosed malignant cancer worldwide and the fourth leading cause of cancer mortality across all genders.^[1] Notably, it holds the highest rank for both incidence and mortality among women. The disease claimed the lives of 666,103 individuals, accounting for 6.8% of all cancer-related deaths and 15.4% of deaths among female patients with cancer.^[1] This statistic demonstrates that approximately three out of every 20 women with cancer succumbed to breast cancer, highlighting its profound impact on female oncology.^[2] This has imposed a significant burden on healthcare systems globally. Numerous lifestyle and reproductive factors have been identified as risk factors for breast cancer. Among these, modifiable risk factors are as follows: Obesity, alcohol intake, tobacco use, a high-protein diet, and a short duration of breastfeeding, whereas an early age at menarche is classified as a non-modifiable risk factor.^[3–8] However, a further minor proportion of breast cancer incidence and progression can be attributed to genetic mutations, such as the BRCA1 and BRCA2 genes.^[9] There is a correlation between the prevalence and fatality rates of breast cancer and the level of Human Development Index (HDI) in the respective countries. Nations characterized by a low to medium HDI tend to exhibit elevated rates of both incidence and mortality in relation to breast cancer.^[10]

The World Health Organization (WHO) has introduced the Global Breast Cancer Initiative (GBCI), established in 2021, to address the increasing prevalence of breast tumors. The primary objective of this initiative is to decrease mortality rates, particularly in transitioning countries, by ensuring widespread availability of early detection services.^[11] It would be advantageous to comprehend the present worldwide burden of breast cancer to facilitate the advancement and execution of this initiative. To enhance comprehension of breast cancer prevalence on a global, national, and regional scale, we have conducted an analysis of data sourced from the Global Cancer Observatory (GLOBOCAN) 2022. This study examines the incidence and mortality rates of breast cancer in 185 countries and regions worldwide in 2022, explores the correlation between incidence and mortality rates and the economic development status of these areas, and projects the future trends of breast cancer incidence and mortality up to 2050 based on the global population projections. The primary objective of this research is to provide valuable insights for governments and policymakers to formulate evidence-based strategies for breast cancer prevention and management.

Methods

Ethics approval

This study does not involve any animal or human experimental models. Hence, ethical approval is not required.

Data sources

Data on new cases and deaths from breast cancer (International Classification of Diseases, tenth revision [ICD-10] code C50) were sourced from the GLOBOCAN 2022 database, managed by the International Agency for Research on Cancer (IARC). GLOBOCAN provides comprehensive estimates for 36 types of cancers, including incidence, mortality, and prevalence (1-, 3-, and 5-years) across 185 countries or territories, segmented by sex and 18 distinct age groups (0–4, 5–9, …, 80–84, 85 years and over). In our analysis, we aggregated the age data into two broad categories: 0–49 and ≥50–85 years, aligning these groups with premenopausal and postmenopausal stages, respectively. This stratification facilitates targeted insights into breast cancer dynamics across different life stages. In addition, demographic data for 2022 were accessed through the United Nations (UN) website. The methodologies and hierarchical processes for compiling these cancer estimates have been extensively detailed in earlier publications.^[12–14] The data of breast cancer obtained from GLOBOCAN were estimated; however, the validity of this estimate depended on the degree of representativeness and quality of the source in the national cancer registries. Thus, 95% uncertainty intervals (UIs) for the number of incidences and mortality were provided. The results of this article are presented in a variety of formats, disaggregated by 185 countries and 21 subregions (defined by the UN).

HDI, established by the UN Development Programme, serves as a comprehensive metric for assessing national development. This composite index integrates indicators such as life expectancy, mean years of schooling, expected years of schooling, and gross national income per capita.^[15] HDI was stratified into four tiers ranging from a minimum of 0 to a maximum of 1: Low HDI (<0.550), medium HDI (0.550–<0.700), high HDI (0.700–≤0.800), and very high HDI (>0.800). For clarity, we used “transitioning”, “emerging”, and “lower HDI” to denote countries with low or medium HDI, whereas “transitioned” and “higher HDI” referred to countries with high or very high HDI.

Our analyses employed tabular data and graphical visualizations to represent new cases and mortality rates, alongside age-standardized incidence rates (ASIRs) and age-standardized mortality rates (ASMRs) per 100,000 individuals. The world standard population used for these calculations followed the Segi population standard, with modifications from Doll and Cook.^[16] Age-standardization was applied to adjust for differences in age distribution across populations, facilitating accurate comparisons of morbidity and mortality rates globally.^[16,17]

Menopausal status was inferred based on age at diagnosis using established thresholds: Women aged <50 years were classified as premenopausal, and those aged ≥50 years as postmenopausal. This approach aligns with the GLOBOCAN age groupings for breast cancer epidemiology, where premenopausal incidence and mortality are defined in women aged under 50 years, and postmenopausal in those aged 50 years and above. The classification accounts for the global average age of natural menopause (45–55 years) and addresses the lack of direct menopausal status documentation in cancer registries.^[12]

The 5-year breast cancer survival rate was estimated using the country-level mortality-to-incidence ratio (MIR), defined as the ratio of the total number of breast cancer deaths to the total number of incident cases across all ages.^[18] The period incidence ratio (PIR) was defined as the ratio of the 5-year prevalence of breast cancer to the number of new cases across all ages, whereas the period mortality ratio (PMR) was defined as the ratio of the 5-year prevalence to the total number of deaths across all ages. These epidemiological metrics such as PIR, PMR, and MIR offer insights into the efficacy of health systems and the quality of oncological care across different countries.^[19]

Statistical analysis

For the countries or territories with available HDI data, we analyzed the relationships between age-standardized rates (ASRs), MIR, PIR, and PMR for breast cancer and the HDI using Spearman’s rank correlation coefficient (Spearman’s ρ). This approach assesses the strength of association by utilizing the ranks of variables, thereby avoiding reliance on linearity assumptions. It is appropriate for examining monotonic relationships and demonstrates robustness against the influence of outliers. All correlation analyses were conducted as two-tailed tests, with the significance threshold established at P <0.05. The magnitude of the Spearman’s rank correlation coefficient was employed to determine the association strength, categorized into five levels: no correlation (0–<0.20), weak correlation (0.20–<0.40), moderate correlation (0.40–<0.60), strong correlation (0.60–0.79), and very strong correlation (0.80–1.00). Identical interpretive thresholds were applied to both positive and negative coefficients. Using demographic projections, we examined the anticipated number of new breast cancer cases and deaths from 2022 to 2050. By using 2022 as the baseline year, we analyzed potential increases or decreases in case and death rates to visually illustrate the impact of various interventions on future epidemiological trends in breast cancer.

Results

Breast cancer incidence, mortality, and ASR in 2022 worldwide

The GLOBOCAN 2022 estimates reveal that breast cancer will account for approximately 2.30 million new cases and 666,103 deaths globally, representing 11.5% of all new malignancies and 6.8% of cancer-related deaths across all genders [Table 1]. Among women, these proportions are predominantly higher, with breast cancer constituting 23.8% (2,296,840/9,664,889) of new cases and 15.4% (666,103/4,313,548) of deaths. Out of the 185 countries and territories assessed, breast cancer ranks as the most prevalent malignant tumor in 82 of these locations for all sexes, and its prominence increased to 158 countries and territories when considering only females. In addition, it is the leading cause of cancer mortality in 28 countries and territories across all sexes and in 111 countries and territories specifically among women. These statistics elucidate the widespread impact of breast cancer globally, highlighting its significant burden on both incidence and mortality.

Table 1.

Breast cancer incidence and mortality in 2022 by UN region and HDI level.

Items	Incidence			Mortality			Prevalence		MIR	PIR	PMR
	Number of cases	95% CI	ASIR (per 100,000)	Number of cases	95% CI	ASMR (per 100,000)	Number of cases	Rate (per 100,000)
Region
Northern America	306,307	305,083−307,536	95.1	49,744	49,238−50,255	12.3	1,332,343	706.7	0.16	4.35	26.78
Eastern Asia	480,019	478,036−482,010	37.5	97,389	96,409−98,379	6.5	1,678,042	210.9	0.20	3.50	17.23
Eastern Africa	47,300	45,975−48,663	31.9	25,330	24,234−26,475	17.6	105,252	44.6	0.54	2.23	4.16
Middle Africa	16,856	16,257−17,477	30.0	9142	887−9621	16.8	37,839	39.7	0.54	2.24	4.14
Northern Africa	64,977	63,758−66,220	53.2	23,186	22,402−23,998	19.0	193,595	152.6	0.36	2.98	8.35
Southern Africa	15,815	15,495−16,142	46.2	5693	5508−5885	16.6	46,730	132.9	0.36	2.95	8.21
Western Africa	53,605	52,646−54,581	41.6	27,901	27,118−28,707	22.3	124,243	59.1	0.52	2.32	4.45
Caribbean	14,862	14,142−15,618	49.6	5953	5554−6380	18.2	46,468	208.5	0.40	3.13	7.81
Central America	39,835	39,140−40,543	38.3	10,670	10,384−10,963	10.1	129,245	138.0	0.27	3.24	12.11
Southeastern Asia	168,536	166,442−170,656	41.7	61,228	59,848−62,639	14.9	535,043	156.8	0.36	3.17	8.74
South Central Asia	273,902	272,153−275,662	26.7	135,348	133,994−136,715	13.4	758,630	75.9	0.49	2.77	5.61
Western Asia	63,360	61,976−64,775	45.4	21,344	20,466−22,260	15.1	225,328	164.0	0.34	3.56	10.56
Eastern Europe	163,474	161,691−165,276	58.3	49,973	49,075−50,888	14.4	635,747	411.4	0.31	3.89	12.72
Northern Europe	89,324	88,381−90,277	90.8	18,629	18,206−19,062	13.7	386,051	712.7	0.21	4.32	20.72
Southern Europe	124,621	121,054−128,293	81.8	31,450	30,706−32,212	13.8	512,758	661.6	0.25	4.11	16.30
Western Europe	180,113	176,593−183,704	89.8	44,387	43,608−45,180	15.4	761,939	761.3	0.25	4.23	17.17
Australia–New Zealand	25,786	25,403−26,174	100.3	4152	3997−4313	12.8	112,904	724.7	0.16	4.38	27.19
Melanesia	2294	2135−2465	49.2	1179	1069−1300	26.8	6051	107.0	0.51	2.64	5.13
South America	165,427	163,505−167,372	57.2	43,253	42,429−44,093	13.8	549,304	247.1	0.26	3.32	12.70
Micronesia	133	92−192	43.9	53	31−92	16.7	210	75.7	0.40	1.58	3.96
Polynesia	294	232−373	76.9	99	63−155	25.3	671	196.4	0.34	2.28	6.78
Total	2,296,840	NA	46.8	666,103	NA	12.7	8,178,393	209.0	0.29	3.56	12.28
HDI
Very high HDI	1,092,663	1,084,577–1,100,809	75.6	245,043	241,022–249,131	13.2	4,598,317	553.9	0.22	4.21	18.77
High HDI	737,959	733,993–741,946	38.8	195,347	193,005–197,718	9.5	2,369,445	173.0	0.26	3.21	12.13
Medium HDI	331,089	328,834–333,360	29.7	153,835	152,189–155,499	14.0	911,903	82.2	0.46	2.75	5.93
Low HDI	134,122	131,486–136,810	34.1	71,458	69,305–73,678	19.0	298,728	49.7	0.53	2.23	4.18
World	2,295,833	NA	46.8	665,683	NA	12.7	8,178,393	209.1	0.29	3.56	12.29

ASIR: Age-standardized incidence rate; ASMR: Age-standardized mortality rate; CI: Confidence interval; HDI: Human Development Index; Prevalence rate: 5-year prevalence rate (number of breast cancer patients per 100,000); MIR: Ratio of all-age death counts and all-age cases of breast cancer; NA: Not applicable; PIR: Ratio of all-age 5-year prevalence and all-age incidence in count; PMR: Ratio of 5-year prevalence and all-age death counts; UN: United Nations.

As shown in Table 1, Eastern Asia reports the highest incidence, with 480,019 (95% confidence interval [CI]: 478,036–482,010) cases, whereas Micronesia has the lowest incidence, recording just 133 (95% CI: 92–192) cases. Mortality rates followed a similar pattern, with South Central Asia experiencing the highest number of deaths at 135,348 (95% CI: 133,994–136,715), and Micronesia the lowest, with only 53 (95% CI: 31–92) deaths.

ASIRs were highest in the Australia–New Zealand region at 100.3 per 100,000 individuals, followed by Northern America (95.1/100,000) and Northern Europe (90.8/100,000). Conversely, South Central Asia had the lowest ASIR at 26.7 per 100,000 individuals, followed by Middle Africa (30.0/100,000) and Eastern Africa (31.9/100,000). The disparity between the highest and lowest ASIR regions was nearly fourfold. Notably, the ranking of ASIR across different HDI subgroups did not directly align with the HDI categories as very high, high, low, and medium.

ASMRs were the highest in Melanesia at 26.8 per 100,000 individuals, followed by Polynesia (25.3/100,000) and Western Africa (22.3/100,000), whereas Eastern Asia exhibited the lowest ASMR at 6.5 per 100,000 individuals, with Central America (10.1/100,000) and Northern America (12.3/100,000) also reporting low rates. The variation between the highest and lowest ASMR regions exceeded fourfold. The ASMR ranking did not align with the HDI ranking either as low, medium, very high, and high [Table 1].

MIR globally stood at 0.29, with the highest values recorded in Middle Africa and Eastern Africa, both at 0.54, and the lowest in Northern America and Australia–New Zealand at 0.16. The MIR ranking followed the HDI order, which was consistent from low to high HDI [Table 1].

Eastern Asia had the largest number of women living with breast cancer within 5 years, with approximately 1.68 million affected. In contrast, Western Europe, characterized by a very high HDI, exhibited the highest 5-year prevalence rate, at 761.3 per 100,000 individuals, whereas Middle Africa reported the lowest rate at 39.7 per 100,000 individuals [Table 1]. PIR across regions varied nearly threefold, with Australia–New Zealand having the highest and Micronesia the lowest values. PMR followed a similar pattern, with Australia–New Zealand showing the highest value and Micronesia the lowest, respectively, reflecting almost a sevenfold difference. The PIR and PMR rankings were consistent with HDI, maintaining the order from the highest to the lowest HDI.

Breast cancer incidence and mortality in 2022 by countries

Analysis of breast cancer incidence and mortality across 185 countries and territories revealed substantial regional disparities. The incidence rate varied nearly 23-fold, ranging from a peak of 105.4 per 100,000 in France (Western Europe) to a low of 4.6 per 100,000 in Bhutan (South Central Asia) [Figure 1A]. Mortality rates also showed significant variation, with a nearly 17-fold difference between the highest rate of 38.9 per 100,000 in Fiji (Melanesia) and the lowest of 2.3 per 100,000 in Bhutan [Figure 1B].

Figure 1.

Age-standardized rates for breast cancer by country within each UN region in 2022. The regions are consistently ordered across both incidence and mortality panels, with countries exhibiting the highest and lowest age-standardized rates clearly labeled for comparative analysis. (A) ASIRs of breast cancer (per 100,000 individuals); (B) ASMRs of breast cancer (per 100,000 individuals). ASIR: Age-standardized incidence rate; ASMR: Age-standardized mortality rate; UN: United Nations.

Age distribution of breast cancer incidence and mortality rates by HDI

Regarding age-specific breast cancer cases, the peak incidence for countries with high and medium HDI was observed in the age group of 50–54 years. In contrast, low and very high HDI countries reported the highest number of cases in the age groups of 45–49 and 60–69 years, respectively. Globally, the highest number of deaths located in the age group of 60–64 years. For specific HDI categories, very high HDI countries showed the highest mortality in the age group of ≥85 years, high HDI countries in the 50–59-year-old group, medium HDI in the 55–64-year-old group, and low HDI in the 50–54-year-old group. These variations describe the influence of economic development on breast cancer incidence and mortality [Figure 2].

Figure 2.

Distribution of breast cancer incidence and mortality across different age groups for the year 2022. (A) Age-specific incidence and mortality in very high HDI countries; (B) Age-specific incidence and mortality in high HDI countries; (C) Age-specific incidence and mortality in medium HDI countries; (D) Age-specific incidence and mortality in low HDI countries; (E) Global age-specific incidence and mortality across all levels of HDI. Values represent numbers of cases and are scaled by a factor of 10⁵. This figure illustrates the variation in breast cancer burden by age, highlighting how incidence and mortality rates differ between younger and older populations. HDI: Human Development Index.

The ratio of breast cancer incidence in individuals aged 50 years and above compared with those aged 49 years and below showed a pronounced disparity across HDI levels. For very high HDI countries, this ratio was 0.79/0.21, whereas for low HDI countries, it was 0.51/0.49. Death ratios similarly varied, with very high HDI countries showing a 0.90/0.10 ratio and low HDI countries a 0.59/0.41 ratio [Figure 3].

Figure 3.

Global estimates of breast cancer (A) incidence and (B) mortality categorized by two distinct age groups in 2022. This figure provides an overview of how breast cancer affects different age demographics on a global scale, emphasizing disparities in incidence and mortality rates between age groups. HDI: Human Development Index.

Correlation between breast cancer incidence, mortality, and ASR with HDI

Correlation analyses revealed a robust positive relationship between ASIR and HDI, with a Spearman’s rank correlation coefficient of 0.773 (P <0.001). Conversely, the correlation between ASMRs and HDI was weak and statistically insignificant (Spearman’s rank correlation coefficient = −0.077, P = 0.331). A strong negative correlation existed between MIR and HDI (Spearman’s rank correlation coefficient = −0.817, P <0.001), although PIR and PMR both showed strong positive correlations with HDI (Spearman’s rank correlation coefficient of 0.958 and 0.907, respectively, both P <0.001) [Figure 4].

Figure 4.

Correlation analysis of breast cancer indicators with the HDI. (A) Age-standardized incidence rate (ASIR); (B) Age-standardized mortality rate (ASMR); (C) Mortality-to-incidence ratio (MIR); (D) Prevalence-to-incidence ratio (PIR); (E) Prevalence-to-mortality ratio (PMR). Definitions: ASIR represents the number of breast cancer cases per 100,000 individuals; ASMR denotes the number of breast cancer deaths per 100,000 individuals; MIR indicates the ratio of mortality to incidence; PIR reflects the ratio of prevalence to incidence; and PMR shows the ratio of prevalence to mortality. This figure examines the relationship between these metrics and HDI to understand how development levels influence breast cancer outcomes. HDI: Human Development Index.

Projections of breast cancer burden by 2050

Assuming current trends persist and in the absence of effective interventions, the global number of new breast cancer cases is projected to increase from approximately 2.30 million in 2022 to 3.55 million by 2050 (1.55-fold increase), while deaths are expected to rise from approximately 0.66 million to 1.14 million (1.71-fold increase) [Figure 5]. The most significant rise is anticipated in low HDI countries, with an estimated increase of 327.28%, although very high HDI countries are projected to see a doubling of cases [Figure 6]. Low HDI countries will experience the most substantial increase in deaths, estimated at 335.17%. Countries with high and medium HDI levels are expected to reach similar absolute numbers of deaths by 2050 (0.539 vs. 0.542 million), with medium HDI countries experiencing a notable percentage rise of 252.60%. Maintaining current mortality levels would necessitate an approximate 2% annual decrease in mortality rates. The majority of future cases and deaths are projected to occur in very high HDI countries, with an increase from about 1.09 million cases and 245,043 deaths in 2022 to 2.28 million cases and 598,602 deaths in 2050 [Figure 6].

Figure 5.

Projected (A) number of cases and (B) deaths of breast cancer worldwide from 2022 to 2050, aged 0–85 years. The black solid line represents the baseline projection assuming current incidence and mortality trends continue unchanged. The colored solid lines illustrate alternative scenarios in which the annual percentage change (APC) in incidence or mortality rates is varied by ±1%, ±2%, or ±3%.

Figure 6.

Projected breast cancer (A) incidence and (B) mortality between 2022 and 2050 in women based on Human Development Index (HDI) category.

Discussion

According to the latest GLOBOCAN 2022 data analysis, the number of breast cancer deaths, ASIR, ASMR, and PIR indicators show significant regional disparities among countries and territories. The ordering of ASIR and ASMR exhibited considerable variation across regions, ranging from developed regions, including Australia–New Zealand, Northern America, and Northern Europe to developing regions, such as Western Africa, Middle Africa, and Eastern Africa. The three African regions referenced above are in the lowest quartile of ASIR’s regional rankings, but appear among the highest ASMR rankings. The considerable discrepancies observed in the rankings of Australia–New Zealand, Northern America and Northern Europe are due to the opposite pattern seen in these regions: They have high ASIR but low ASMR, in contrast to the three African regions. Although they rank within the top four regions in ASIR, they fall into the lowest group of regions for ASMR. It is notable that all these regions encompass countries and territories with very high HDI levels. The prevalence of Western dietary patterns and the ideology of late marriage and childbearing, which results in prolonged estrogenic hormone stimulation of the mammary glands, also contributes to the increase in morbidity. There is also a pronounced focus on postmenopausal quality of life, leading to widespread use of menopausal hormone replacement therapy (HRT) aimed at mitigating menopausal symptoms and reducing cardiovascular risk.^[20] The increased life expectancy resulting from higher levels of healthcare has also led to increased morbidity of malignant tumors. It has been demonstrated that the probability of developing cancer increases in conjunction with rising HDI levels.^[21] Individuals living in countries and territories with very high HDI have a greater life expectancy, which consequently elevates their risk of developing cancer.^[22] The majority of deaths among those individuals residing in low HDI countries are attributed to causes other than cancer, such as acute infectious diseases. The discrepancy between ASIR and ASMR observed in countries with very high HDI levels can be attributed to a number of factors, including the availability of advanced treatment options, early diagnosis across a wide range of age groups, enhanced cancer prognosis care, and the implementation of mammography screening programs.^[23]

In the United States, approximately 14% of women aged 18–39 years, who are considered at an average risk for breast cancer, participated in mammography screening programs between 2011 and 2015.^[24] In high-income Asian countries, such as Japan and South Korea, mammography screening is recommended to begin at age of 40 years. Countries with very high HDI levels are well-positioned to implement comprehensive precancer screening programs, which are instrumental in detecting tumors at an early, more manageable stage. This early detection is crucial as it significantly improves prognosis by reducing the incidence of advanced and metastatic breast cancers, leading to lower mortality rates and improved overall survival outcomes.

Advanced age is an established risk factor for cancer.^[25] Countries characterized by higher HDI levels typically exhibit more pronounced aging populations, which contributes to the elevated cancer incidence rates observed in these high HDI countries. An elevated level of education is associated with an increased probability of developing breast cancer.^[26] Nonetheless, education itself does not directly elevate breast cancer risk; instead, it affects intermediary variables that mediate this relationship. For instance, women with higher educational attainment often experience improved socioeconomic status but also greater social and occupational stress, which may contribute to increased alcohol consumption. In addition, highly educated women tend to delay childbirth and have prolonged menstrual cycles, contributing to a later onset of menopause. Furthermore, this demographic is more likely to use HRT during menopause. These factors collectively serve as mediators through which education indirectly influences breast cancer risk.^[26]

The strong positive correlations observed between PIR, PMR, and HDI describe the relationship between economic development and cancer care quality. High HDI countries are equipped with advanced healthcare infrastructure and resources, which enable more effective cancer treatment and management. This correlation reflects not only the availability of early detection technologies and treatments but also the ability of these regions to offer supportive care that contributes to higher survival rates. Consequently, countries with higher HDI levels have lower breast cancer mortality and improved patient outcomes, reflecting their ability to provide quality healthcare and early interventions.

For countries with low HDI, limited healthcare investment often leads to underdiagnosis and delayed treatment of breast cancer, resulting in low ASIRs but elevated ASMRs. On the contrary, it is related to cancer registries, and IARC elucidates that countries with low and medium HDI levels still have a lot of room to develop population-based cancer registries.^[27] Sudden or prolonged sociopolitical and economic instability may prevent the establishment or maintenance of high-quality cancer registries in these areas.^[28] Insufficient funding may also lead to relatively high levels of deaths from competing causes other than cancer, such as acute infectious diseases, that will kill people from noncancer diseases.^[21] All of these factors contribute to a relatively low ASIR. In addition, in these areas, the insufficient supply of treatment medications, inconvenient transportation to and from healthcare service centers, limited treatment options, inability to afford treatment costs, inadequate coverage of healthcare service centers, as well as local cultural, social, and religious customs, may all become barriers for female patients in accessing healthcare services.^[19,29] A summary of Centers for Disease Control and Prevention report on breast cancer screening indicates that women with low incomes and education levels are highly unlikely to elect to undergo a mammography screening program.^[30] According to previous reports, food insecurity also affects compliance with mammography. People affected by food insecurity are not only likely to experience anxiety, depression, and psychological stress, but they are also more likely to fill up on nutritionally poor foods, thereby increasing their risk factors for breast cancer. Such individuals do not prioritize screening as a preferred option.^[31] The lack of breast cancer screening means that patients seek medical attention only after experiencing significant clinical symptoms, by which time the disease is often at an advanced stage. Research shows that many women in Africa seek help from traditional healers after symptoms appear, and these traditional healers promise not to use painful surgery and drug during treatment, further delaying treatment and leading to a poor prognosis.^[18] Among the 10 regions with the highest breast cancer mortality rates, five are located in Africa. Empirical studies indicate that the average prevalence of triple-negative breast cancer (TNBC) in Africa is approximately 27%, with West Africa exhibiting an especially high proportion, reaching up to 45.7%, nearly half of all breast cancer cases in that area.^[32] TNBC is recognized as the most aggressive breast cancer subtype and is associated with the poorest prognosis among all pathological classifications. This subtype distribution provides a plausible explanation for the elevated mortality rates observed in these African regions. The various factors mentioned above can lead to a high ASMR in low HDI countries.

Menopausal status constitutes a critical determinant in the therapeutic management of patients with breast cancer, significantly guiding the selection of endocrine therapies, chemotherapeutic regimens, and targeted agents.^[33] Treatment strategies should incorporate a comprehensive evaluation of menopausal status, comorbid conditions such as osteoporosis, and individual patient tolerance. In the context of endocrine therapy, tamoxifen (TAM) monotherapy remains the standard of care for premenopausal patients. However, for those classified as high risk, the combination of ovarian function suppression (OFS) with aromatase inhibitors is recommended, as this approach has demonstrated superior efficacy compared to OFS combined with TAM. Among postmenopausal patients, aromatase inhibitors are the preferred therapeutic option, particularly within high-risk cohorts. This preference is supported not only by the primary indication of aromatase inhibitors in this population, but also by evidence indicating a significant reduction in recurrence risk (from 14.4% to 12.6%) without an associated increase in endometrial cancer incidence. Nonetheless, vigilant monitoring of bone mineral density is imperative, alongside supplementation with calcium and vitamin D2 to mitigate potential adverse effects.^[34] Furthermore, in premenopausal patients, particular consideration should be afforded to the implementation of OFS, the preservation of fertility, and the adoption of intensified systemic treatment protocols for aggressive breast cancer subtypes, including those characterized by low hormone receptor (HR) expression (HR-low) or TNBC.^[33]

With economic development and changes in dietary patterns, such as the consumption of high-fat and high-sugar foods, the proportion of obese people has increased worldwide, with >15% of adults classified as obese in most countries.^[35] Obesity is already a recognized risk factor for the development and progression of breast cancer.^[36] Being overweight or obese has been confirmed to increase the likelihood of developing HR-positive and luminal A-like subtypes of breast cancer. Existing studies have shown that the luminal A-like subtype of breast cancer accounts for the vast majority of postmenopausal breast cancer cases.^[37] Postmenopausal women experience a decline in ovarian function, leading to a decrease in estrogen secretion, which can even reach zero. This results in a slowed metabolism, making it easier for fat to accumulate in the abdominal area. The increase in abdominal obesity and body mass index after menopause raises the risk of developing breast cancer.^[12] This explains from different perspective why the number of new breast cancer cases aged 50 years and above in countries with very high HDI, high HDI, and medium HDI is several times that of those aged 49 years and below.

In countries and territories with low HDI levels, the ratio of new breast cancer cases among individuals under 50 years old to those aged 50 years and above is approximately 1:1. This can be attributed to two factors. Firstly, the life expectancy in low HDI countries is shorter, resulting in a reduced population base for those aged 50 years and above. If breast cancer incidence rates remain stable, we would expect a decrease in the number of new breast cancer cases within specific age groups, resulting in a diminishing ratio of new cases relative to the overall incidence. This shift suggests a near-equal distribution of new cases across age categories.

Moreover, genetic predispositions play a significant role in breast cancer incidence. Research highlights that women of African descent in low HDI countries exhibit a genetic propensity to develop breast cancer at an earlier age compared with their counterparts in higher HDI countries. Similarly, African American women in the United States are diagnosed with breast cancer at younger ages compared with other American women, despite similar economic and healthcare access levels. These observations suggest that genetic factors, rather than solely socioeconomic or medical advancements, significantly influence the age of breast cancer onset. Thus, although improvements in healthcare and life expectancy contribute to lower cancer rates in developed regions, genetic predispositions remain a crucial determinant of breast cancer incidence across different populations.^[38]

There exist notable disparities in the distribution of breast cancer mortality across regions characterized by varying levels of the HDI. In countries with very high HDI, the highest mortality rates are observed among individuals aged 85 years and older. This phenomenon can be explained by two primary factors. First, demographic aging and the associated base effect result in a larger elderly population, thereby increasing the absolute number of deaths within this age cohort. Second, the widespread implementation of breast cancer screening programs has substantially reduced mortality rates among middle-aged and younger women, particularly those aged 50–69 years. Empirical evidence from the United States indicates that initiating screening within this age range and maintaining it for a decade prevents approximately 21.3 breast cancer deaths per 10,000 women screened (95% CI: 10.7–31.7), implying that screening roughly 469 women over 10 years averts one death.^[39] This screening efficacy has markedly enhanced survival outcomes in the middle-aged and younger populations. Despite these advancements, it is important to recognize that elderly patients, especially those aged 75 years and above, tend to experience poorer prognoses irrespective of breast cancer subtype (including hormone receptor–positive/negative, Human Epidermal Growth Factor Receptor 2 (HER2)-positive, and triple-negative) and stage at diagnosis.^[40] This trend further intensifies the mortality burden within the oldest age groups. In countries characterized by low to medium HDI, particularly those with low HDI, the highest mortality rates are observed notably earlier, predominantly within the age range of 50–69 years. This pattern can be primarily attributed to two factors. First, there is a substantial incidence of late-stage cancer diagnoses, largely due to inadequate screening programs that result in many patients being identified at advanced stages of the disease.^[41] Second, there is a deficiency in treatment resources, as the accessibility and availability of essential therapeutic modalities, including targeted pharmaceuticals and radiotherapy equipment, are limited, thereby adversely impacting treatment efficacy and patient outcomes.^[42]

In comparison with the Global Burden of Disease (GBD) 2021 study on breast cancer, the present analysis reveals a largely consistent global pattern in incidence and mortality across various age groups. Both investigations identify the highest incidence of new breast cancer cases within the 50–59 age cohort. However, a divergence emerges regarding the age group with the peak mortality: This study reports it as 60–64 years, whereas the GBD study indicates 55–59 years. It is pertinent to acknowledge that the two data sources emphasize different metrics; the current study prioritizes absolute case numbers, although the GBD study focuses predominantly on ASR. Despite these methodological differences, both studies demonstrate an upward trajectory in breast cancer incidence and mortality, underscoring the persistent global health challenge posed by this disease.^[43] Within the GBD database, breast cancer incidence rates tend to be higher in countries and regions characterized by a high sociodemographic index (SDI) relative to those with medium or low SDI levels, whereas mortality rates are comparatively lower. This pattern is consistent with findings from the GLOBOCAN for countries and regions with high or very high HDI scores. Such trends may be attributable to widespread implementation of early detection programs, enhanced access to therapeutic interventions, and overall improvements in healthcare quality. Certain discrepancies are observed in data from specific countries; for instance, some high-SDI nations exhibit marginally elevated mortality rates in GBD estimates compared with those reported by GLOBOCAN.^[44] These inconsistencies may stem from differences in modeling approaches, data sources, and disease classification methodologies.^[45]

Our projections reveal that the burden of breast cancer is expected to remain substantial, particularly in low HDI countries and among individuals aged 50 years and older. This elucidates the urgent need for implementing proactive and effective strategies to mitigate future impacts. In terms of modifiable risk factors, interventions remain relatively limited. Key components of primary prevention include maintaining a healthy weight, increasing physical activity, reducing tobacco and alcohol consumption, and promoting extended breastfeeding. Evidence supports these strategies, as they can significantly reduce breast cancer risk. For instance, studies have shown that weight management and regular exercise lower estrogen levels, which are associated with reduced breast cancer risk. In addition, extended breastfeeding has been linked to a decreased risk of breast cancer, likely due to hormonal changes during lactation.

A randomized controlled trial conducted in low- and middle-income countries has highlighted the effectiveness of clinical breast palpation for early detection. This method has been shown to enhance early diagnosis and reduce the stage at which breast cancer is detected, thereby improving prognosis and treatment outcomes. Early detection through clinical examination can lead to less aggressive treatments and better survival rates, demonstrating the importance of integrating accessible and cost-effective screening methods into public health strategies.^[46] In countries and territories with low HDI levels that cannot afford mammography screening program, clinical breast palpation should be promoted by healthcare professionals to local women as a simple and cost-effective procedure. This should be done to increase awareness of self-examination, educate them about the early symptoms and signs of breast cancer, and reduce stigma through public education and awareness-raising. The aim is to detect and diagnose patients at an early stage and provide early treatment, which should result in a better prognosis.^[47,48] A survey conducted in several high-income countries and one lower-middle-income country have shown that the incidence of estrogen receptor-positive breast cancer is increasing. If this trend could be identified on a global scale under expanded survey conditions, as this particular subtype of breast cancer has a more favourable prognosis, it would be highly beneficial in reducing the prognostic burden associated with breast cancer.^[12]

Our study is subject to several limitations. Our forecasts for the burden of breast cancer in 2050 do not account for potential shifts in incidence rates over time, including variations among different breast cancer subtypes. These predictions are based solely on population growth and aging trends from 2022 to 2050. Disparities in breast cancer diagnosis and detection programs across different countries and periods further complicate comparability, as variations in these practices can influence reported incidence and mortality rates.

In conclusion, this study highlights the geographical disparities in breast cancer incidence and mortality rates, categorized by age and HDI, and projects these incidence and mortality metrics for 2050. The significant variability in breast cancer burden across regions describes the necessity for region-specific cancer prevention programs. Tailoring these programs to address the unique economic contexts and epidemiological trends of each region will enhance their effectiveness.

Moreover, in an era of globalization, increasing awareness of socioeconomic and cultural factors that influence cancer risk is crucial. Healthcare systems must anticipate and adapt to rising breast cancer risks associated with these factors. Effective cancer control strategies should focus on comprehensive population education, risk factor management, promotion of screening programs, and ensuring both the accessibility and affordability of treatment. By implementing targeted interventions and adapting to local contexts, governments and healthcare providers can better address the evolving challenges of breast cancer.

Acknowledgements

The authors thank the International Agency for Research on Cancer and its collaborators for providing access to the GLOBOCAN database. We also thank the supporting staff of the cancer center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China, for their assistance in data interpretation and manuscript preparation.

Funding

This study was supported by the Henan Natural Science Foundation (No. 222300420534).

Conflicts of interest

None.