Weight, breast cancer and heart disease are often discussed separately, but a new study suggests they may be more interconnected than we thought.
In a large analysis of postmenopausal women in Europe and the UK, researchers found that excess weight was linked to a significantly higher risk of breast cancer in women who also had cardiovascular disease. The study, published in CANCER, the peer-reviewed journal of the American Cancer Society, points to the importance of considering heart health when assessing breast cancer risk.
Researchers analyzed data from more than 168,000 postmenopausal women who were initially free of type 2 diabetes and cardiovascular disease. The team followed the participants for over a decade as part of two long-running health studies: the European Prospective Investigation into Cancer and Nutrition (EPIC) and UK Biobank.
Over that time, 6,793 women developed breast cancer. When researchers looked at how BMI affected breast cancer risk, they found an important distinction. For every 5 kg/m² increase in BMI:
Breast cancer risk rose 31% in women who developed cardiovascular disease.
The increase was 13% in women without cardiovascular disease.
Interestingly, the presence or absence of type 2 diabetes did not appear to change the weight-associated breast cancer risk.
The researchers estimated that having both a BMI over 25 and cardiovascular disease led to 153 additional cases of breast cancer per 100,000 women per year compared to women without those conditions.
“The findings of this study could be used to inform risk-stratified breast cancer screening programs,” said lead author Dr. Heinz Freisling of 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.”
The research was supported by the World Cancer Research Fund (UK) through its international grant program.