County-level Variation in Use of Surgery and Cancer-specific Survival for Stage I-II Pancreatic Adenocarcinoma

OBJECTIVE The aim of the study was to describe county-level variation in use of surgery for stage I-II pancreatic ductal adenocarcinoma (PDAC) and the association between county surgery rates and cancer-specific survival (CSS). BACKGROUND The degree of small geographic area variation in use of surgery for stage I-II PDAC and the association between area surgery rates and CSS remain incompletely defined. METHODS This is a retrospective cohort study of patients aged 18 to 80 years in the 2007 to 2015 Surveillance, Epidemiology, and End Results database with stage I-II PDAC without contraindications to surgery or refusal. Multilevel models were used to characterize county-level variation in use of surgery and CSS. County-specific risk- and reliability-adjusted surgery rates and CSS rates were calculated. RESULTS Of 18,100 patients living in 581 counties, 10,944 (60.5%) underwent surgery. Adjusted county-specific surgery rates varied 1.5-fold from 49.9% to 74.6%. Median CSS increased in a graded fashion from 13 months [interquartile range (IQR) 13-14] in counties with surgery rates of 49.9% to 56.9% to 18 months (IQR 17-19) in counties with surgery rates of 68.0% to 74.6%. Results were similar in multivariable analyses. Adjusted county 18-month CSS rates varied 1.6-fold from 32.7% to 53.7%. Adjusted county surgery and 18-month CSS rates were correlated (r = 0.54; P < 0.001) and county surgery rates explained approximately half of county-level variation in CSS. Only 18 (3.1%) counties had adjusted surgery rates of 68.0% to 74.6%, which was associated with the longest CSS. CONCLUSIONS County-specific rates of surgery varied substantially, and patients living in areas with higher surgery rates lived longer. These data suggest that increasing use of surgery in stage I-II PDAC could lead to improvements in survival.