A new study has reported that obesity increases the likelihood of cancer recurrence and death among early-stage breast cancer survivors. The study was designed to investigate the influence of obesity on prognosis, taking into account adjuvant treatment (primarily chemotherapy and anti-estrogens). The study included 18,967 Danish women selected based on the availability of body mass index (BMI) at time of diagnosis, as well as information regarding subsequent recurrences and death.

Obese women (with a BMI of at least 30 kg/m2) tended to be older and have more advanced disease at diagnosis than those with normal weight (BMI lower than 25 kg/m2). The risk of developing distant metastases after 10 years was found to be 46% higher among obese women after adjusting for disease characteristics. The risk of dying as a result of breast cancer after 30 years was also found to be 38% higher among obese women. On the other hand, BMI was not found to be related to the risk of locoregional recurrence (recurrence in the breast, chest wall, or lymph nodes). Both chemotherapy and hormonal therapy appeared to be less effective after 10 or more years for obese women. The authors conclude that obesity is an independent prognostic factor for developing distant metastases and for breast cancer-specific death. In addition, the effects of adjuvant treatments such as chemotherapy and aromatase inhibitors appear to be lost more rapidly in obese breast cancer patients.