A Population-Based Description of Familial Clustering of Pancreatic Cancer

BACKGROUND & AIMS: Several familial pancreatic cancer syndromes have been identified. However, the prevalence of familial pancreatic cancers in the general population has not been well defined. METHODS: We linked pancreatic cancer cases, identified through the Utah Cancer Registry, to the Utah Population Database, which contains genealogic data from Utah pioneers and their descendants. This database includes 1411 pancreatic adenocarcinoma cases with 3 or more generations of Utah pioneer genealogy. We examined the familial clustering of pancreatic cancer by evaluating the relative risk (RR) of pancreatic cancer among relatives of cases. We also used the genealogical index of familiality to test the hypothesis of no excess relatedness among pancreatic cancer cases. RESULTS: The risk of pancreatic cancer was significantly increased in first-degree (RR, 1.84; 95% confidence interval [CI], 1.47-2.29; P < .0001) and second-degree (RR, 1.59; 95% CI, 1.31-2.91; P < .0001) relatives of individuals with pancreatic cancer. Analysis of case relatedness indicated significant excess relatedness for pancreatic cancer. More than 300 high-risk pedigrees were identified, with from 3-14 cases observed among descendants of pedigree founders. CONCLUSIONS: This population-based study provides evidence for increased risk of pancreatic cancer among relatives of cases and for a significantly higher average relatedness among cases than expected. These observations support the role of genetic factors in pancreatic cancer.