Neuroendocrine Cell Proliferation in Gastric and Gastroesophageal Carcinomas Following Neoadjuvant Therapy: Frequency and Association with Clinicopathological Parameters and Prognosis.

OBJECTIVE: This study aimed to determine the frequency of neuroendocrine cell proliferation (NCP) in the tumor bed and adjacent mucosa in gastric and gastroesophageal junction carcinomas that had received neoadjuvant therapy, and to elucidate its prognostic significance. MATERIAL AND METHODS: In 83 patients diagnosed with gastric or gastroesophageal junction adenocarcinoma who had received neoadjuvant therapy, the presence and the extent of NCP in the tumor bed and adjacent mucosa was examined and scored by chromogranin A immunohistochemistry and the association of this proliferation with other clinicopathological parameters was statistically analyzed. RESULTS: NCP was seen in the damaged, reparative or tumor-infiltrated mucosa in the tumor bed and the normal mucosa adjacent to the tumor in 46 cases (55.4%), as score 1 in 23 (27.7%), score 2 in 13 (15.7%) and score 3 in 10 (12%). This proliferation was not statistically associated with intestinal metaplasia (p=0.683) and atrophy (p=0.414). ypT stage was significantly correlated with NCP (p=0.015) however there was no significant association between NCP and survival. No statistically significant association was found between the other clinicopathological parameters and NCP. CONCLUSION: Non-neoplastic NCP both in the tumor bed and surrounding gastric mucosa is observed in a subset of cases following neoadjuvant therapy, and it does not appear to have any prognostic significance. However, further investigation is required to explore the cause of this proliferation.