Introduction: The impact of adjuvant sequential chemoradiotherapy (CRT) on survival in resected pancreatic ductal adenocarcinoma (PDAC) remains unclear and warrants further investigation.
Methods: NCDB patients with R0/R1 resected PDAC who received adjuvant chemotherapy without CRT or followed by CRT per RTOG-0848 protocol were included. Cox regression for 5-year overall survival (OS) was performed and used to construct a pathologic nomogram in patients who did not receive CRT. A risk score was calculated and patients were divided into low-risk and high-risk groups. Patients from each risk stratum were matched for the receipt of CRT to assess the added benefit of CRT on survival. The Kaplan-Meier analysis was performed to compare OS.
Results: A total of 7146 patients were selected, 1308 (18.3%) received CRT per RTOG-0848. Cox regression concluded grade, T stage, N stage, node yield < 12, R1, and LVI as significant predictors of 5-year OS which were used to construct the risk score. Matched analysis in low-risk patients (score 0-79) showed no difference in OS between CRT vs. no CRT (47.6 ± 5.7 vs. 45.1 ± 3.9 months; p = 0.847). OS benefit was 3% at 1 year, - 4% at 2 years, and 4% at 5 years. In high-risk patients (score 80-100), median OS was higher in CRT vs. no CRT (24.8 ± 0.7 vs. 21.7 ± 0.8 months; p = 0.043). Absolute OS benefit was 13% at 1 year, 5% at 2 years, and - 1% at 5 years.
Conclusion: CRT has a short-lived impact on OS in resected PDAC that is only evident in high-risk patients. In this subset, survival benefit peaks at 1 year and subsides at 3 to 5 years following PDAC resection.
Keywords: Adjuvant chemoradiation; Pancreas cancer; RTOG 0848; overall survival.
© 2021. The Society for Surgery of the Alimentary Tract.