Body mass index and additional risk factors for cancer in adults with cystic fibrosis

Background Adults with cystic fibrosis (CF) have an increased risk of a variety of cancers, notably gastrointestinal cancers. In CF higher body mass index (BMI) is associated with improved long-term outcomes, yet in the general population high BMI is associated with increased cancer risk. We aimed to delineate associations between BMI and other factors with cancer risk in adults with CF. Methods This was a retrospective cohort study using CF Foundation Patient Registry data from 1992 to 2015. Data were collected on age, sex, CFTR mutation class, pancreatic insufficiency, and annualized data on BMI and FEV1. The primary analysis was the association between BMI and cancer, with secondary analyses focused on BMI trajectory. Multivariable logistic regression was performed, with analyses stratified by history of transplant. Results Of 26,199 adults with CF, 446 (1.7%) had cancer diagnosed by histology at a mean age of 40.0 years (SD 12.2), with a higher proportion of transplanted patients developing cancer (137 (3.8%) v 309(1.4%), p