Body mass index change in adulthood and lung and upper aerodigestive tract cancers

Body mass index (BMI) has been inversely associated with lung and upper aerodigestive tract (UADT) cancers. However, only a few studies have assessed BMI change in adulthood in relation to cancer. To understand the relationship between BMI change and these cancers in both men and women, we analyzed data from a population-based casecontrol study conducted in Los Angeles County. Adulthood BMI change was measured as the proportional change in BMI between age 21 and 1 year before interview or diagnosis. Five categories of BMI change were included, and individuals with no more than a 5% loss or gain were defined as having a stable BMI (reference group). Adjusted odds ratios (ORs) and their 95% confidence intervals (CIs) were estimated using logistic regression models. Potential confounders included age, gender, ethnicity, education, tobacco smoking and energy intake. For UADT cancers, we also adjusted for alcohol drinking status and frequency. A BMI gain of 25% or higher in adulthood was inversely associated with lung cancer (OR 0.53, 95% CI 0.330.84) and UADT cancers (OR 0.44, 95% CI 0.270.71). In subgroup analyses, a BMI gain of =25% was inversely associated with lung and UADT cancers among current and former smokers, as well as among current and former alcohol drinkers. The inverse association persisted among moderate and heavy smokers (=20 pack-years). The observed inverse associations between adulthood BMI gain and lung and UADT cancers indicate a potential role for body weight-related biological pathways in the development of lung and UADT cancers.