Impact of obesity and exercise on chemotherapy-related fatigue

Breast cancer patients undergoing adjuvant chemotherapy often develop fatigue from their treatment that may persist for months. While the positive effects of physical activity in cancer patients are increasingly recognized, the impact of obesity on chemotherapy-induced fatigue has not been well studied.

Female age 35-75 years with stage I-III breast cancer receiving adjuvant chemotherapy were enrolled in an IRB-approved study. Patient fatigue was self-reported using a 14-question fatigue symptom inventory. Patients were queried about fatigue and their level of exercise before, during, and after completion of chemotherapy. BMI was measured prior to their first cycle of chemotherapy.

Of the 47 evaluable patients, 37 reported performing exercise on a regular basis. Following chemotherapy, 53 % of the exercise group and 80 % of the non-exercise group displayed a worsening of their FS. In patients with a BMI < 25, the fatigue score (FS) after chemotherapy was 27.6 in the exercise group versus 40.5 in the non-exercise group. In patients with a BMI > 25, the FS after chemotherapy was 25.96 in the exercise group versus 32.6 in the non-exercise group.

Our study indicates a trend towards fatigue reduction with exercise even in patients who are overweight. Thus, an elevated BMI at diagnosis does not preclude a breast cancer patient from experiencing the same positive effects from exercise on chemotherapy-related fatigue as patients with normal BMIs. This indicates an important role of physicians in the primary care setting to encourage patients to initiate physical activity when offering cancer-screening services.