Overweight and obese women with hormone receptor (HR)-positive operable breast cancer have an increased risk of disease recurrence and death despite optimal treatment with chemohormonal therapy, according to new study findings.

Although obesity has been associated with inferior outcomes in operable breast cancer, the relationship between body mass index (BMI) and outcomes by breast cancer subtype had not been evaluated until the recent investigation by Joseph A. Sparano, MD, of the Albert Einstein College of Medicine’s Montefiore Medical Center in Bronx, New York, and colleagues. The researchers examined the association between BMI and outcomes in three adjuvant trials coordinated by the Eastern Cooperative Oncology Group. The trials involved chemotherapy with doxorubicin and cyclophosphamide for women with stage I-III breast cancer. The women had no significant comorbidities.

In one trial, known as E1199, increasing BMI within the obese (30 or higher) and overweight (25 to 29.9) ranges was associated with inferior disease-free survival and inferior overall survival in HR-positive, human epidermal growth receptor 2 (HER2)-negative disease, but not in HER2-overexpressing or triple-negative disease.

 “We found that obesity at diagnosis of breast cancer is associated with about a 30% higher risk of recurrence and a nearly 50% higher risk of death despite optimal treatment,” noted Sparano in a statement announcing the study results, which were published by the journal Cancer. “Treatment strategies aimed at interfering with hormonal changes and inflammation caused by obesity may help reduce the risk of recurrence.”