Obesity May Raise Breast Cancer Risk, More So in Women with Heart Disease: Meta Analysis

A new study published in Cancer by researchers from the International Agency for Research on Cancer (IARC) and partner institutions reinforces the link between obesity and an increased risk of breast cancer in postmenopausal women. Importantly, the study reveals that this risk is significantly heightened in women with a history of cardiovascular disease (CVD), highlighting a critical intersection between two major health concerns.

The findings come from a large meta-analysis combining individual participant data from two of Europe’s most comprehensive cohort studies the European Prospective Investigation into Cancer and Nutrition (EPIC) and the UK Biobank. The analysis included 168,547 postmenopausal women who were cancer-free and had not been diagnosed with type 2 diabetes or cardiovascular disease at the time of their enrollment. These women were followed for approximately 10 years to assess long-term health outcomes.

The researchers found that among women without cardiovascular disease, each 4.5 kg/m² increase in body mass index (BMI) was associated with a 13% higher risk of developing breast cancer. However, among women with a history of cardiovascular disease, the same increase in BMI corresponded to a 31% rise in breast cancer risk. This sharp difference underscores how underlying cardiovascular conditions may amplify the cancer risks associated with excess weight.

In contrast, the relationship between BMI and breast cancer risk was not significantly different between women with and without type 2 diabetes.

These findings suggest that preventing obesity among postmenopausal women with CVD may lead to greater reductions in breast cancer incidence compared with the general population. Furthermore, the results could support the development of risk-stratified breast cancer prevention and screening strategies, particularly targeting women with CVD.

Reference: Fontvieille 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. 2025;e35911. doi:10.1002/cncr.35911