Abstract BACKGROUND Increased body weight at the time patients are diagnosed with breast carcinoma has been associated with an increased risk of recurrence and reduced survival. Weight gain also is common after diagnosis. Increasing physical activity (PA) after diagnosis may minimize these adverse outcomes. In this population‐based study, the authors investigated whether PA levels after diagnosis declined from prediagnosis levels and whether any changes in PA varied by disease stage, adjuvant treatment, patient age, or body mass index (BMI) in 812 patients with incident breast carcinoma (from in situ to Stage IIIa). METHODS Types of sports and household activities and their frequency and duration for the year prior to diagnosis and for the month prior to the interview (i.e., 4–12 months postdiagnosis) were assessed during a baseline interview. RESULTS Patients decreased their total PA by an estimated 2.0 hours per week from prediagnosis to postdiagnosis, an 11% decrease ( P < 0.05). Greater decreases in sports PA were observed among women who were treated with radiation and chemotherapy (50% decrease) compared with women who underwent surgery only (24% decrease) or who were treated with radiation only (23%; ( P < 0.05). Greater decreases in sports PA were observed among obese patients (41% decrease) compared with patients of normal weight (24% decrease; P < 0.05). CONCLUSIONS PA levels were reduced significantly after patients were diagnosed with breast carcinoma. Greater decreases in PA observed among heavier patients implied a potential for greater weight gain among women who already were overweight. Randomized, controlled trials are needed to evaluate how PA may improve the prognosis for patients with breast carcinoma. Cancer 2003;97:1746–57. © 2003 American Cancer Society. DOI 10.1002/cncr.11227
Irwin et al. (2003) studied this question.