Recent research shows that obesity may increase the risk of estrogen-dependent breast cancer in postmenopausal women. The most recent study indicates that obesity may also increase the risk of triple-negative breast cancer; an aggressive form of the disease not triggered by estrogen and usually has a poor outcome.

Researchers analyzed data from 155,723 postmenopausal Females who participated in a large-scale study called the Women’s Health Initiative. The women answered questions about their physical activity, height and weight. The women were categorized into four different groups, depending on their body mass index also known as your BMI score. Subjects in the highest quarter had BMIs of at least 30, which implies that they were obese.

Using an average follow-up time of 7.9 years, over 2,600 women were diagnosed with estrogen receptor-positive breast cancer, and just over 300 were diagnosed with triple-negative breast cancer.

Authors of the study found that women with the highest body mass index were 35 percent more likely to develop triple-negative breast cancer and 39 percent more likely to develop other types of breast cancer than those with the lowest body mass index.

In addition, women who exercised more had a lower chance of developing both estrogen receptor-positive breast cancer or triple-negative breast cancer compared to those who did not exercise at all.

More research will be needed to validate these findings and to confirm how obesity may affect the risk of breast cancer.