Postmenopausal women with cardiovascular disease and a higher body mass index (BMI) face a significantly increased risk of developing breast cancer, according to a new study led by the World Health Organization (WHO).
The findings, published in the CANCER journal of the American Cancer Society, highlight the complex relationship between weight, chronic illnesses, and cancer. Researchers from WHO’s International Agency for Research on Cancer (IARC), led by Dr. Heinz Freisling, analysed data from two major sources: the European Prospective Investigation into Cancer and Nutrition (EPIC) and the UK Biobank. The study involved 168,547 postmenopausal women who were free of cardiovascular disease and type 2 diabetes at the time of enrollment.
Over a median follow-up period of approximately 11 years, 6,793 of these women developed breast cancer. The research showed that for every 5 kg/m² increase in BMI, the risk of developing breast cancer rose by 31% in women who developed cardiovascular disease during the follow-up period, compared to a 13% increase in risk among women without heart disease.
Interestingly, the presence of type 2 diabetes did not appear to significantly influence the relationship between BMI and breast cancer. Women with or without diabetes had similarly increased risks related to higher BMI.
“This research offers important insights that could support the development of tailored breast cancer screening strategies based on cardiovascular health and weight,” said Dr. Freisling.
The combination of being overweight (BMI over 25 kg/m²) and having cardiovascular disease was linked to an estimated 153 additional cases of breast cancer per 100,000 women annually—highlighting the urgent need for targeted prevention efforts.
The link between obesity and cancer is well documented. Excess body weight has already been identified as a risk factor for at least 12 types of cancer, including cancers of the liver, kidney, uterus, and colon. A separate study published recently in Nature Communications found that overweight and obese women are more likely to be diagnosed with larger tumors and more advanced stages of breast cancer.
Freisling emphasized the need for future clinical trials on weight loss interventions to specifically include women with existing cardiovascular conditions, as part of comprehensive breast cancer prevention strategies.