Study Finds Higher BMI Increases Breast Cancer Risk in Women With Heart Conditions

A higher body mass index (BMI) in women with cardiovascular disease (CVD) is associated with an increased risk of breast cancer, according to researchers from the International Agency for Research on Cancer—a specialized cancer agency of the WHO. Their findings, published in Cancer, further inform risk factors for breast cancer in postmenopausal women with cardiometabolic diseases.¹

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As women age, their risk for developing breast cancer increases dramatically. Adiposity, measured by BMI, is a well-established risk factor for postmenopausal breast cancer. However, it remains unclear whether the relationship between BMI and breast cancer risk is influenced by the presence of CVD or type 2 diabetes (T2D).¹

To investigate this, researchers analyzed individual participant data from 168,547 postmenopausal women enrolled in the European Prospective Investigation into Cancer and Nutrition (EPIC) and the UK Biobank (UKB). All participants were free of cancer, T2D, and CVD at baseline. Incidence rates and rate differences per 1000 person-years were also calculated, and findings from the 2 cohorts were combined in a meta-analysis.¹

Over a median follow-up of 10.7 years in EPIC and 10.9 years in UKB, 6793 women developed breast cancer. The meta-analysis revealed that each 5 kg/m² increase in BMI was more strongly associated with breast cancer risk among women with CVD (HR, 1.31; 95% CI, 1.16–1.47) compared with those without (HR, 1.13; 95% CI, 1.11–1.16), with a statistically significant interaction (P = .02).¹

In contrast, T2D did not significantly modify the association between BMI and breast cancer risk (P = .33). Notably, the joint presence of overweight or obesity (BMI ≥25 kg/m²) and CVD was associated with 1.53 additional cases of breast cancer per 1000 person-years (95% CI, 0.35–2.71) beyond what would be expected from their individual effects. No similar joint effect was observed with T2D.¹

“The findings of this study could be used to inform risk-stratified breast cancer screening programs,” said Heinz Freisling, PhD, from the International Agency for Research on Cancer. “This study should also inspire future research to include women with a history of cardiovascular diseases in weight loss trials for breast cancer prevention.”²

Continued investigations are crucial to further elucidate breast cancer risk factors as women age, helping clinicians and pharmacists identify high-risk patients, tailor preventive strategies, and guide counseling on modifiable risk factors such as weight management and cardiovascular health.

REFERENCES

1. Fontvielle E, Jansana A, Peruchet-Noray L, et al. Body mass index and breast cancer risk among postmenopausal women with and without cardiometabolic diseases: Findings from two prospective cohort studies in Europe. Cancer. July 7, 2025. Doi:10.1002/cncr.35911

2. How does body mass index affect breast cancer risk in postmenopausal women with and without cardiovascular disease?. News Release. July 7, 2025. Accessed July 16, 2025. https://www.eurekalert.org/news-releases/1089601