Body mass index as a prognostic feature in operable breast cancer: the International Breast Cancer Study Group experience.

BACKGROUND

Current information on the prognostic importance of body mass index (BMI) for patients with early breast cancer is based on a variety of equivocal reports. Few have data on BMI in relationship to systemic treatment.

PATIENTS AND METHODS

Patients (6792) were randomized to International Breast Cancer Study Group trials from 1978 to 1993, studying chemotherapy and endocrine therapy. BMI was evaluated with eight other factors: menopausal status, nodal status, estrogen receptor status, progesterone receptor status, tumor size, vessel invasion, tumor grade and treatment. BMI was categorized as normal (< or =24.9), intermediate (25.0-29.9) or obese (> or =30.0).

RESULTS

Patients with normal BMI had significantly longer overall survival (OS) and disease-free survival (DFS) than patients with intermediate or obese BMI in pairwise comparisons adjusted for other factors. Subset analyses showed the same effect in pre- and perimenopausal patients and in those receiving chemotherapy alone. When assessed globally and adjusted for other factors, BMI significantly influenced OS (P = 0.03) but not DFS (P = 0.12).

CONCLUSIONS

BMI is an independent prognostic factor for OS in patients with breast cancer, especially among pre-/perimenopausal patients treated with chemotherapy without endocrine therapy.