Expression of p53 and Rb reveal subtypes of gastric neuroendocrine carcinoma with distinct prognosis.

Gastric neuroendocrine carcinoma (NEC) is a rare tumor with a poor prognosis. Due to its rarity and disparity in prevalence across populations, there is limited data on gastric NEC. TP53 and RB1 genetic alterations or expression were reported for predictive value in neuroendocrine neoplasm and classification in pulmonary large cell NEC. This study investigated the genetic alteration and protein expression of TP53 and RB1 in gastric NEC. Thirty-nine patients were categorized as type A and B subtypes by p53 and Rb expression. Patients with concurrent abnormal p53 and Rb expression were defined as the type A group, and the remainder were defined as the type B group. Significant differences in TNM stages, tumor size, and lymph node metastasis were observed between the two subtypes. Type A characteristic is an independent predictor for worse overall survival (HR: 3.27; 95% CI: 1.12-9.58; p = .022). We further evaluated and compared immunotherapy-related markers, including PD-L1 expression, CD8 T cell infiltration, tumor mutation burden, and microsatellite instability in these two subtypes, whereas no significant differences were detected.