Postdiagnosis Weight Change and Survival Following a Diagnosis of Early-Stage Breast Cancer

BACKGROUND: Achieving healthy weight is recommended for all breast cancer survivors. Previous research on post-diagnosis weight change and mortality had conflicting results. MATERIALS AND METHODS: We examined whether change in bodyweight in the 18mo following diagnosis is associated with overall and breast cancer-specific mortality in a cohort of n=12,590 stage I-III breast cancer patients at Kaiser Permanente using multivariable-adjusted Cox regression models. Follow-up was from 18mo post-diagnosis weight until death or June, 2015 (median follow-up [range]: 3 [0–9] years). We divided follow-up into earlier (18–54mo) and later (>54mo) post-diagnosis periods. RESULTS: Mean (SD) age-at-diagnosis was 59 (11) yrs. 980 women died, 503 from breast cancer. Most women maintained weight within 5% of diagnosis bodyweight; weight loss and gain were equally common at 19% each. Compared to weight maintenance, large losses (≥10%) were associated with worse survival, with hazard ratios (HR) and 95% confidence intervals (CI) for all-cause death of 2.63 (2.12, 3.26) earlier and 1.60 (1.14, 2.25) later in follow-up. Modest losses (>5–<10%) were associated with worse survival earlier (1.39 [1.11, 1.74]), but not later in follow-up (0.77 [0.54, 1.11]). Weight gain was not related to survival. Results were similar for breast cancer-specific death. CONCLUSION: Large post-diagnosis weight loss is associated with worse survival in both earlier and later post-diagnosis periods, independent of treatment and prognostic factors. IMPACT: Weight loss and gain are equally common after breast cancer, and weight loss is a consistent marker of mortality risk