Overweight and obesity at different times in life as risk factors for non-Hodgkin's lymphoma: the multiethnic cohort.

Obesity may increase the risk for non-Hodgkin's lymphoma (NHL) through an inflammatory pathway. We explored the relation of NHL with body size at different times in life within the Multiethnic Cohort that includes African Americans, Caucasians, Japanese, Latinos, and Native Hawaiians. Participants were 45 to 75 years old at recruitment in 1993 to 1996. This analysis included 87,079 men and 105,972 women with 461 male and 378 female NHL cases. We used Cox regression to model NHL risk with age as the time metric while adjusting for age at baseline, ethnicity, education, alcohol intake, and age at first live birth. Body weight and body mass index at age 21 were stronger predictors of NHL risk than anthropometric characteristics at baseline. For men, being in the highest quartile of body mass index and body weight at age 21 conferred a nonsignificant 86% and 41% higher NHL risk, respectively, whereas there was no association at baseline. For women, the risk associated with the highest quartile of weight at age 21 was 1.6 (P(trend) = 0.04), whereas women in the highest quartile at baseline had a nonsignificant risk of 27%. Height was positively related to NHL in men and women. Despite the small numbers, there was some consistency for risk estimates across ethnic groups and weak evidence for an association with NHL subtypes. These findings indicate that weight at age 21 may represent lifetime adiposity better than body weight at cohort entry. Alternatively, weight at age 21 may be more relevant for the etiology of NHL.