LAUSR

e15772 Background: Pancreatic cancer (PC) is the third leading cause of cancer mortality in the United States, with an overall relative 5-year survival rate of 8.2%. We conducted a comprehensive evaluation of survival trends after PC diagnosis overall and by stage and histologic sub-type. Methods: We conducted a retrospective, population-based study of 91,234 PC cases using nationally representative data from the SEER program to evaluate 5-year survival trends by histologic sub-type from 2000 to 2015. Our model incorporated sub-type-specific random intercepts to effectively stabilize survival estimates by borrowing information across all sub-types. The estimation was performed in a fully Bayesian setting in R. Results: Adenocarcinoma, not otherwise specified (NOS) and ductal adenocarcinomas comprised 81% of PC. Cancer stage and histologic sub-type were both important factors in explaining variability in 5-year survival. We observed a consistent ordering of cancer stages within each histologic sub-type from highest to lowest survival for local, regional, and metastatic disease, respectively. Adenocarcinoma not otherwise specified, ductal adenocarcinoma, ductal specified as mucinous, and poorly specified type had the lowest 5-year survival with fitted ranges of 25-35% for localized, 5-19% for regional and < 4% for metastatic disease. Ductal arising from intraductal papillary mucinous neoplasm, ductal specified as cystic, acinar cell, other adenocarcinoma, and non-carcinomas had intermediate 5-year survival of 54-75%; while endocrine non-secretory or neuroendocrine, endocrine secretory, carcinoid, and solid pseudopapillary cancers had the best survival (87-98%). On average, across histologic sub-types, PC survival improved by 0.5% (90% credible interval 0.01%, 1.0%) per year, or 5.1% (0.1%, 10.0%) per decade. Some improvement in fitted survival occurred across all stages and histologic sub-types. Conclusions: Overall survival for patients with PC has improved by around 5% per decade from 2000 to 2015, with significant heterogeneity by histologic sub-type.