A dynamic analysis of empirical survival outcomes after pancreatectomy for pancreatic ductal adenocarcinoma.

Abstract

Survival outcomes after pancreatectomy for pancreatic ductal adenocarcinoma may be biased by right-censoring. We herein analyzed a large dataset with no censored events for up to 5 years and dynamically investigated the impact of known prognostic factors, accounting for unobserved tumor characteristics. Consecutive patients undergoing pancreatectomy from 2000 to July 2015 were included. The 1- to 5-year empirical survival rates were calculated, and factors associated with long-term survival (≥5 years) were analyzed using multivariable models. Dynamic analyses of survival and recurrence were conducted through landmarking, and the contribution of unobserved heterogeneity was estimated using frailty models. The study population included 1,048 patients. The median follow-up was 30.4 months in the whole cohort and 97.2 months in survivors. The median survival was 30.4 months, with empirical 1- to 5-year rates of 85.5%, 59.6%, 43.2%, 32.1%, and 27.5%. A favorable pathological profile was associated with 5-year survival, albeit 25.7% of long-survivors received an R1 resection, and 28.8% had N2 disease. The median recurrence-free survival was 17.2 months. At landmark analyses, baseline prognostic lost strength over time, with no independent predictors of survival being identified in the sets of patients alive at 4 and 5 years. There was a significant amount of unobserved heterogeneity in the early postoperative period. The 5-year post-pancreatectomy empirical survival was 27.5%. Dynamic analyses showed a time-varying structure of prognostic variables and a substantial impact of unobserved tumor characteristics that may drive the disease course under the selective pressure of surgical resection and adjuvant chemotherapy.