Background: Although some familial cancer syndromes include biliary tract cancers (BTCs; cancers of the gallbladder, intrahepatic and extrahepatic bile ducts, and ampulla of Vater), the few studies that have examined the relationships between family history of cancer (FHC) and BTCs have reported inconclusive findings. The objective of this study was to investigate the associations of FHC with risk of BTC in the Biliary Tract Cancers Pooling Project (BiTCaPP). Methods: We used Cox proportional hazards regressions models to estimate HRs and 95% confidence intervals for associations between FHC (any, first-degree, in female relative, in male relative, relative with gastrointestinal cancer, and relative with hormonally related cancer) and BTC risk by anatomic site within the biliary tract, adjusting for sex and race/ethnicity. Sensitivity analyses were conducted that restricted to studies reporting cholecystectomy data and to people without a history of cholecystectomy. Results: Data on FHC were available from 12 prospective studies within BiTCaPP, which collectively contributed 2,246 cases (729 gallbladder, 345 intrahepatic and 615 extrahepatic bile duct, and 385 ampulla of Vater cancers) with 21,706,107 person-years of follow-up. A marginal, inverse association between FHC and gallbladder cancer was driven to the null when analysis was restricted to studies reporting cholecystectomy data and to people without a history of cholecystectomy. FHC was not associated with risk of BTC at the other anatomic sites. Conclusions: These findings do not support an association between FHC and BTCs. Impact: In a study of 1.5 million people, FHC is not a risk factor for BTCs.
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