BODY WEIGHT AND PROGNOSTIC INDICATORS IN BREAST CANCER

Abstract

The relations of body weight, height, and Quetelet index to axillary node involvement at diagnosis, estrogen receptor status, and histologic features of the primary tumor were examined in 656 patients with a newly diagnosed infiltrating breast carcinoma first treated in Québec City from July 1982 to December 1984. Node involvement increased with body weight and Quetelet index. This association was more regular and much stronger among patients with estrogen receptor-positive tumors than among those with estrogen receptor-negative breast cancers. Among patients with estrogen receptor-positive tumors, the percentage with involved nodes at diagnosis increased regularly from 32.9% among lean patients (Quetelet index less than 21 kg/m2) to 65.6% among obese women (Quetelet index greater than 27 kg/m2). This trend was seen even after adjustment for age and tumor size. In contrast, among patients with estrogen receptor-negative breast cancers, the association of weight and Quetelet index with node involvement were weak and irregular. The modifying effect of estrogen receptor status on the relation of obesity to node involvement was apparent in pre- and post-menopausal women. Body weight and Quetelet index were not related to estrogen receptor status or to any of the measured histologic features of breast tumors including nuclear grade, histologic grade, tubule formation, mitotic activity, and size of nucleus of cancer cells. These findings suggest that the observed deleterious effect of obesity on breast cancer prognosis is unlikely to be an artifact of delayed diagnosis in overweight patients. It may be due to hormonal changes associated with increases in body weight.