Cancer risk in cystic fibrosis: A 20-year nationwide study from the United States

BackgroundMany patients with cystic fibrosis (CF) now reach adulthood, at which time the risk of cancer is increased. The aim of this study was to determine cancer risks in nontransplanted and transplanted CF patients.MethodsFrom 1990 to 2009, we followed 41,188 patients who received care at one of the 250 CF care center programs in the United States and compared the observed number of cancers in nontransplanted and transplanted patients with that expected in the general US population.ResultsIn 344,114 patient-years of observation of nontransplanted patients, the overall cancer risk was similar to the background risk (standardized incidence ratio [SIR] = 1.1, 95% confidence interval [CI] = 1.0 to 1.3). However, we observed an elevated risk of digestive tract cancer (SIR = 3.5, 95% CI = 2.6 to 4.7) involving the esophago-gastric junction, biliary tract, small bowel, and colon. There was also an increased risk of testicular cancer (SIR = 1.7, 95% CI = 1.02 to 2.7) and lymphoid leukemia (SIR = 2.0, 95% CI = 1.2 to 3.1) and a decreased risk of malignant melanoma (SIR = 0.4, 95% CI = 0.2 to 0.9). In 8235 patient-years of observation of transplanted patients, 26 tumors were observed compared with 9.6 expected (SIR = 2.7, 95% CI = 1.8 to 3.9). The increased risk was particularly high for digestive tract cancers (SIR = 17.3, 95% CI = 10.7 to 26.5), with most cases arising in the bowel.ConclusionsThe overall burden of cancer in CF patients remains low; however they have an increased risk of digestive tract cancer, particularly following transplantation. They also have increased risk of lymphoid leukemia and testicular cancer, and decreased risk of melanoma.