UC San Diego

OBJECTIVES: We hypothesized that intentional weight loss may be associated with development of lymphohematopoietic cancers, based on observations of immune suppression following weight loss in short-term studies. METHODS: At the baseline of the Women's Health Initiative Observational Study (1994-1998), participants reported information about intentional weight loss episodes in the past 20 years. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) among 81,219 women for associations between past intentional weight loss and risk of developing non-Hodgkin lymphoma (NHL), leukemia, and multiple myeloma during an average 9.9 years of follow-up. RESULTS: The risk of NHL was associated with having lost a large maximum amount of weight (> or =50 pounds, HR = 1.68, 95% CI 1.13-2.50). NHL risk also varied by the frequency of intentional weight loss; women had increased risk if they lost 50 pounds or more > or =3 times (HR = 1.97, 95% CI 0.93-4.16; p trend by frequency = 0.09) or 20-49 pounds > or =3 times (HR = 1.55, 95% CI 1.00-2.40; p trend = 0.05), but there was no risk associated with smaller amounts of weight loss (10-19 pounds > or =3 times, HR = 0.78, 95% CI 0.46-1.33). These associations persisted with adjustment for body mass index at different ages. We observed non-significant associations of similar magnitude for multiple myeloma, but past intentional weight loss episodes were not associated with leukemia. CONCLUSION: Further assessment of intentional weight loss as a possible risk factor for lymphomas may provide insight into the etiology of these cancers.