31P Surgical and chemotherapeutic strategies for stage IV pancreatic neuroendocrine carcinoma according to the latest WHO classification

Chemotherapy is considered the primary treatment for stage IV pancreatic neuroendocrine carcinoma (pNEC). However, the optimal management of metastatic pNEC as defined by the updated WHO classification (2022) has not been adequately explored. This study analyzed the clinical features and prognostic factors of metastatic pNEC and assessed the efficacy of surgery and chemotherapy in these patients based on the latest classification. Data of stage IV pNEC patients diagnosed between 2004-2020 were extracted from the Surveillance, Epidemiology and End Results database. Cox regression was performed to identify prognostic factors with SPSS-29. Demographic, oncological and clinicopathological data were compared between groups with Chi-square test. Propensity score matching (PSM) was used to ensure comparability between groups. K-M plots were used to estimate overall survival (OS) and cause-specific survival (CSS). 267 patients were eligible for this study, including 16 (6.0%) patients who underwent palliative primary tumor resection. Primary tumor in pancreatic tail, surgery and chemotherapy were identified as independent protective factors by Cox regression (p=0.017, p<0.01, p<0.001, respectively). Patients who underwent surgery exhibited both a median OS and CSS of 26 months, compared to 7 months and 8 months for those who did not, respectively (p=0.002 for both OS and CSS). After PSM, surgery continued to be significantly associated with improved survival (p=0.016 for OS, p=0.007 for CSS). According to subgroup analysis without surgery, OS and CSS did not significantly differ between the chemotherapy and nonchemotherapy groups of large cell NEC (LCNEC) patients (p=0.276 for OS, p=0.208 for CSS). Conversely, chemotherapy significantly improved prognosis in small cell NEC (SCNEC) patients before (p<0.001 for both OS and CSS) and after PSM (p<0.001 for both OS and CSS). This study identified primary tumor in pancreatic tail, surgery and chemotherapy as protective factors for stage IV pNEC. Palliative primary tumor resection was associated with improved prognosis in selected patients. Further studies are required to confirm the effect of chemotherapy in LCNEC patients.