Studies Examine Breast Cancer Risk, Disparities, and Outcomes Across Diverse Populations

Large international cohort data suggest plant-forward eating patterns and certain micronutrients may be linked to lower breast cancer risk and improved survival, while separate research highlights significant disparities in breast cancer care and outcomes across different populations.

In a study published in the journal Frontiers in Nutrition, researchers examined whether adherence to healthful plant-based diets and intake of specific micronutrients were associated with the risk of breast cancer and mortality among breast cancer patients. The analysis used data from two prospective cohorts, the UK Biobank and the Chinese Longitudinal Healthy Longevity Survey (CLHLS). The UK Biobank sample included 67,045 individuals who did not have breast cancer and 3,397 women with breast cancer at baseline.

Among UK Biobank participants, higher adherence to the Healthful Plant-Based Diet Index (HPDI) was correlated with reduced breast cancer incidence and improved survival. Women in the highest HPDI tertile were 11% less likely to develop breast cancer compared to those in the lowest tertile. Each standard deviation increase in HPDI corresponded to a 4% reduction in risk. Among women with breast cancer, those in the highest HPDI tertile experienced a 28% lower risk of all-cause mortality, and each standard deviation increase in HPDI was associated with an 11% reduction in mortality risk.

Greater intake of calcium, vitamins B2 and C, magnesium, and phosphorus was associated with a lower risk of mortality, whereas higher sodium intake increased the risk of mortality. These associations were observational and do not establish causation. Plant-based diets are rich in antioxidants, fiber, and bioactive compounds that may exert anti-inflammatory and anticancer effects, though these biological mechanisms remain plausible hypotheses rather than proven causal pathways in this study.

Dietary intake in the UK Biobank was assessed using a validated 24-hour recall, whereas CLHLS used a food frequency questionnaire. The cohorts differed substantially in age structure, ethnicity, and dietary assessment approaches, which may affect comparability. The HPDI incorporated 17 food groups, assigning positive scores to healthy plant foods and negative scores to animal foods and less healthy plant foods.

Separate research from the University of Calgary examined disparities in breast cancer care for Black women in Canada. National Canadian research shows Black women are 45% more likely than White women to be diagnosed with breast cancer before the age of 50, outside of the age range targeted by routine screening. Data shows other disparities persist for Black women. They face up to 70% higher breast cancer mortality rates. About 26% of Black women are diagnosed at Stage 3 or 4, compared with 17% of White women.

Breast cancer is the most commonly diagnosed cancer among Canadian women, with about one in eight expected to develop it in their lifetime. Much of the evidence used to shape breast cancer screening guidelines, risk-assessment tools and treatment protocols is drawn from clinical trials and cancer registries in which Black women are underrepresented or where race-based data is not consistently collected.

Researchers at the University of Calgary conducted focus groups with over 100 Black women and community stakeholders across Alberta. The research, funded by the Canadian Cancer Society in partnership with the African Cancer Support Group, explored the obstacles women face when accessing breast cancer screening. Participants described mistrust of health-care providers, discrimination and a lack of culturally relevant information about breast cancer. Unconscious assumptions about knowledge, pain tolerance, age and health literacy also shaped interactions with providers.

Alberta Health Services recommends screening mammograms every two years for women ages 45 to 74 with no symptoms. But studies show Black women are more likely to be diagnosed with breast cancer at a younger age, often outside standard screening time frames.

A multicenter retrospective cohort study from Uruguay examined clinical characteristics and long-term outcomes of young women with breast cancer. The study included women aged 18-40 years diagnosed with invasive breast cancer between 2006 and 2024 at two public referral centers. A total of 267 patients were included, with a mean age at diagnosis of 34.8 years.

Invasive ductal carcinoma was the predominant histology (85.8%), with a high proportion of grade III tumors (39.3%). The most common biological subtype was luminal (48.8%), followed by HER2-positive (27.7%) and triple-negative disease (17.2%). Stage II disease was most frequent (40.4%), while 28.7% of patients presented with stage III disease. Modified radical mastectomy was the most commonly performed surgical procedure (38.2%).

With a median follow-up of 52.3 months, estimated overall survival was 84.8% at 5 years and 80.9% at 10 years. Survival outcomes differed significantly according to clinical stage but not biological subtype. The findings underscore the importance of early detection strategies and equitable access to guideline-based care in middle-income countries.

Globally, breast cancer in young women accounts for approximately 10-15% of all cases, although this proportion varies according to geographic region and population age structure. Population-based studies and systematic reviews have reported that 20-27% of breast cancer cases in Latin America are diagnosed in women younger than 45 years, nearly twice the proportion observed in high-income countries. National cancer registries from countries such as Brazil, Colombia, Costa Rica, and Ecuador confirm this pattern and describe a progressive increase in both incidence and mortality among young women.

Breast cancer in young women is associated with more aggressive features, including a higher prevalence of triple-negative and HER2-positive subtypes, higher histologic grade, increased tumor proliferation, and a greater proportion of advanced-stage disease at diagnosis. Women younger than 40 years have worse overall survival and disease-free survival compared with older patients, even within the same molecular subtypes, with a particularly increased risk of recurrence in hormone receptor-positive tumors. This group shows a higher prevalence of germline mutations in cancer predisposition genes, such as BRCA1 and BRCA2, underscoring the importance of genetic testing and risk-reduction strategies for both patients and their families.