Survival Outcomes and Failure Patterns in Patients with Inoperable Non-Metastatic Pancreatic Cancer Treated with Definitive Radiotherapy.

This study investigated the long-term results, failure patterns, and prognostic factors of patients with initially inoperable non-metastatic pancreatic cancer (PC) receiving definitive radiotherapy (RT). Between January 2016 and December 2020, a total of 168 non-metastatic PC patients, who were surgically unresectable or medically inoperable, were enrolled to receive definitive RT, with or without chemotherapy. Overall survival (OS) and progression-free survival (PFS) were evaluated using the Kaplan-Meier method with a log-rank test. The cumulative incidence of locoregional and distant progression was estimated using the competing risks model. The Cox proportional-hazards model was used to determine the influence of prognostic variables on OS. With a median follow-up of 20.2 months, the median OS (mOS) and median PFS (mPFS) from diagnosis were 18.0 months [95% confidence interval (CI), 16.5-21.7 months] and 12.3 months (95% CI, 10.2-14.3 months), respectively. The mOS and mPFS from RT were 14.3 months (95% CI, 12.7-18.3 months) and 7.7 months (95% CI, 5.5-12.0 months), respectively. The corresponding 1-year, 2-year, and 3-year OS from diagnosis and RT were 72.1%, 36.6%, and 21.5% as well as 59.0%, 28.8%, and 19.0%, respectively. In a multivariate analysis, stage I-II (