Inflammatory breast cancer survival: The role of obesity and menopausal status at diagnosis

No previous studies have evaluated the effect of body size and menopausal status at diagnosis on survival from inflammatory breast cancer (IBC). We evaluated whether obesity and menopausal status had an impact on IBC survival in a cohort of 177 female IBC patients seen from 1974 to 1993 at The University of Texas MD Anderson Cancer Center. Survival time was defined as time from diagnosis until death or censorship at last date of contact. We categorized women by body size by using the National Institutes of Health/National Heart, Lung, and Blood Institute's definitions of obesity as body mass index ((BMI) = weight in kg/(height in m)²) ≥ 30, overweight as 25 ≤ BMI < 30 kg/m², and normal/lean as BMI <25 kg/m². Cox proportional hazards analysis, adjusting for axillary lymph node involvement and chemotherapy protocol, revealed a modifying effect of menopausal status at diagnosis on the association between obesity and IBC survival (P = 0.02). Relative to postmenopausal women, premenopausal women had significantly worse survival (hazard ratio (HR) = 1.51, 95% confidence interval (CI) = 1.03-2.22). After stratifying by menopausal status, premenopausal obese women had non-significantly better survival than their leaner premenopausal counterparts (HR = 0.63, 95% CI = 0.34-1.15) while postmenopausal obese women had significantly worse survival than their leaner counterparts (HR = 1.86, 95% CI = 1.02-3.40). These findings suggest that factors associated with larger body size at diagnosis may contribute to shorter IBC survival among postmenopausal women but not premenopausal women, who were found to have poorer survival regardless of body size.