Pancreatic cancer with liver metastasis benefits from chemoradiotherapy compared to chemotherapy alone: a retrospective cohort study from the Surveillance, Epidemiology, and End Results (SEER) database.

Background: Pancreatic cancer with metastasis carries a poor prognosis. Whether chemoradiotherapy (CRT) offers additional benefit over chemotherapy (CT) alone for metastatic pancreatic cancer remains unclear. This study aimed to evaluate the efficacy of CRT compared with CT alone in patients with metastatic pancreatic cancer and to investigate the consistency of the effect across different metastatic sites using the Surveillance, Epidemiology, and End Results (SEER) database. Methods: Patients diagnosed with metastatic pancreatic cancer from 2010 to 2015 were identified from the SEER database. Inclusion criteria were age ≥18 years, pathologically confirmed pancreatic cancer, survival time of at least 3 months, documented CT and radiotherapy (RT) status, and complete clinical and follow-up data. Propensity score matching was used to balance the baseline characteristics. Kaplan-Meier survival analysis and Cox regression analysis were performed to compare overall survival (OS) and cancer-specific survival (CSS) between the CRT and CT groups. Subgroup analysis was conducted based on the metastatic sites. Results: A total of 11,861 patients were included, with 11,051 in the CT group and 810 in the CRT group. CRT was associated with significantly improved OS [hazard ratio (HR) =0.89, P=0.018] and CSS (HR =0.85, P=0.003) compared with CT alone after matching. Subgroup analysis revealed that CRT provided survival benefits for patients with liver metastasis but not for those with bone, lung, or brain metastases. Among patients with multiple organ metastases involving the liver, CRT conferred a survival advantage. Conclusions: CRT was associated with improved survival compared with CT alone in metastatic pancreatic cancer, particularly among patients with liver metastases. For those patients, the addition of local RT to CT may result in better outcomes.