Postdiagnosis change in bodyweight and survival after breast cancer diagnosis

Weight gain after diagnosis is common among women with breast cancer, yet results have been inconsistent among the few studies examining its effects on survival.

We examined the effects of weight gain on mortality among a cohort of 1436 women diagnosed with a first primary breast cancer in 1996-1997, on Long Island, NY. Subjects were interviewed soon after diagnosis and again after approximately 5 years. Weight was assessed at each decade of adult life; 1 year before, at, and 1 year after diagnosis; and at the time of follow-up. Mortality through the end of 2005 was assessed using the National Death Index. Proportional hazards regression was used while using a selection model to account for missing data.

Compared with women who maintained their prediagnosis weight (±5%), those who gained more than 10% after diagnosis had worse survival (hazard ratio [HR] = 2.67; [95% credible interval = 1.37-5.05]). The effect was more pronounced during the first 2 years after diagnosis (>5% gain: all-cause mortality in the first 2 years, HR = 5.87 [0.89-47.8] vs. after 2 years, 1.49 [0.85-2.57]); among women overweight before diagnosis (overweight women: all-cause HR = 1.91 [0.91-3.88] vs. ideal-weight women, 1.39 [0.62-3.01]); and for women who had gained at least 3 kg in adulthood before diagnosis (≥3-kg gain before diagnosis: 1.80 [0.99-3.26 vs. <3 kg gain before diagnosis: 1.07 [0.30-3.37].

These results highlight the importance of weight maintenance for women after breast cancer diagnosis.