Objective: To determine whether obesity is an independent prognostic factor among women receiving adjuvant chemotherapy for lymph node-positive breast cancer and to determine how obesity relates to other commonly used prognostic indicators.
Design: Retrospective review of the clinical characteristics and clinical course of 735 patients with stages II and III primary breast cancer who were treated using three consecutive postoperative adjuvant chemotherapy protocols. Univariate and multivariate analyses were used to determine the prognostic implications of obesity defined by weight and height tables and body mass index. In addition, we analyzed the relation between obesity and other known prognostic indicators for patients with primary breast cancer.
Setting: A comprehensive cancer center.
Patients: 735 patients with lymph node-positive primary breast cancer who were treated using three consecutive fluorouracil-doxorubicin-cyclophosphamide-containing adjuvant chemotherapy protocols and for whom complete data on weight, height, standard prognostic factors, and outcome were available.
Main outcome measurements: Disease-free and overall survival for the entire group and obese and nonobese subgroups.
Results: 24 percent of patients were more than 20% overweight. With a median follow-up of 10.7 years, the estimated 10-year, disease-free rate for patients not more than 20% overweight was 54% (95% CI, 50% to 58%) compared with 40% (CI, 33% to 47%) for remaining patients classified as obese. Although obese patients tended to have somewhat less favorable prognoses based on standard prognostic criteria, a proportional-hazards regression model adjusting for other factors indicated that risk for disease recurrence among obese patients was 1.33 times that of the nonobese population (CI, 1.05 to 1.68).
Conclusions: Obesity is an indicator of poor prognosis for patients with primary breast cancer even after the administration of adjuvant chemotherapy. The effect of dietary interventions to reduce body weight on the outcome of breast cancer therapy must be investigated.