Pre-diagnosis body mass index and survival after breast cancer in the After Breast Cancer Pooling Project

Abstract

Obese and underweight women who develop breast cancer may have poorer survival compared to normal-weight women. However, the optimal weight for best prognosis is still under study. We conducted a prospective investigation of pre-diagnosis body mass index (BMI) and mortality among 14,948 breast cancer patients in the After Breast Cancer Pooling Project. Breast cancer patients diagnosed from 1990-2006 with AJCC Stage I-III breast tumors were drawn from four prospective cohorts. Hazard ratios (HR) and 95% confidence intervals (CI) representing the associations of BMI categories (World Health Organization international classifications) with recurrence and mortality were estimated using delayed entry Cox proportional hazards models. Obese (30-<35 kg/m2), severely obese (35-<40 kg/m2), and morbidly obese (≥40 kg/m2) were examined. After a mean follow-up of 7.8 years, 2,140 deaths and 2,065 recurrences were documented. Both underweight (HR=1.59; 95% CI: 1.18, 2.13) and morbidly obese women (HR=1.81; 95% CI: 1.42, 2.32) had the greatest risk of overall mortality compared to normal-weight (18.5-24.9 kg/m2) women. Severe obesity (HR=1.09; 95% CI: 0.88, 1.36) and obesity (HR=1.11; 95% CI: 0.97, 1.27) were related to small, non-significant increased risks. Overweight (25.0-29.9 kg/m2) was not associated with any excess risk compared to normal weight. Similar associations were found for breast cancer death and non-breast cancer death but not recurrence. Women who were underweight and morbidly obese before breast cancer diagnosis were at the greatest risk of all-cause mortality. Morbidly obese women were also at increased risk of death from breast cancer. These results suggest that degree of obesity confers differential risk on survival.

Interaction between body mass index and hormone-receptor status as a prognostic factor in lymph-node-positive breast cancer

“…Several earlier studies have reported that not only obesity but also UW is a negative prognostic indicator in breast cancer [9,[14][15][16]. Some authors have recently demonstrated a relationship between UW and breast cancer subtype with respect to outcome.…”

Biopsychosocial Predictors of Psychological Functioning Among African American Breast Cancer Survivors

“…Our findings were similar to Berger, Hertzog, Geary, Fischer, and Farr (2012), who reported that BMI was predictive of psychological functioning among breast cancer survivors. A study by Kwan et al (2011) reported that for breast cancer survivors, the degree of obesity confers a greater risk for survival. In our sample, though the overall sample BMI was 30.06, caution should be taken with the measurement of BMI in some individuals of African ancestry.…”

Clinical implications of low skeletal muscle mass in early-stage breast and colorectal cancer

“…15 Obesity is a well-established risk factor for breast cancer incidence and survival, but as described previously, although studies have clearly shown worse mortality with obesity, the association between breast cancer survival and overweight (BMI 25–30) have been less consistent, with some studies showing no adverse effect. 33–35 Body mass index only incompletely captures the more relevant physiologic measures of skeletal muscle and adipose tissue.…”