The impact of immunotherapy on the survival of pancreatic adenocarcinoma patients who do not receive definitive surgery of the tumor

Background and Purpose: Immunotherapy has shown great efficacy in many cancers, but its role in pancreatic ductal adenocarcinoma (PDAC) remains unclear. The objective of this study was to investigate the impact of immunotherapy on the overall survival of PDAC patients who did not receive definitive surgery of the pancreatic primary tumor site using the National Cancer Database (NCDB). Materials and Methods: Patients with pancreatic adenocarcinoma who did not receive surgery were identified from NCDB. Cox proportional hazard models were employed to assess the impact of immunotherapy on survival after adjusting for age at diagnosis, race, sex, place of living, income, education, treatment facility type, insurance status, year of diagnosis, and treatment types such as chemotherapy and radiation therapy. Results: Of 263,886 patients who were analyzed, 911 (0.35%) received immunotherapy. Among patients who received chemotherapy (101,546), and chemoradiation (30,226) therapy, 555/101,546 (0.55%) received chemotherapy plus immunotherapy, and 299/3,022 (9.9%) received chemoradiation plus immunotherapy. In a multivariable analysis adjusted for the factors mentioned above, immunotherapy was associated with significantly improved OS (HR: 0.866 (0.800–0.937); P < 0.001) compared to no immunotherapy. Chemotherapy plus immunotherapy was significantly associated with improved OS (HR: 0.848 (0.766–0.938); P < 0.001) compared to chemotherapy without immunotherapy. Further, chemoradiation plus immunotherapy was associated with significantly improved OS (HR: 0.813 (0.707–0.936); P < 0.001) compared to chemoradiation alone. Conclusion: In this study, the addition of immunotherapy to chemotherapy and chemoradiation therapy was associated with significantly improved OS in PDAC patients without definitive surgery. The study warrants future clinical trials of immunotherapy in PDAC.