Prognostic significance of neuroendocrine components in gastric carcinomas.

Background: Gastric neuroendocrine carcinomas (NECs) and mixed adenoneuroendocrine carcinomas (MANECs) are aggressive tumours but the prognostic significance of a neuroendocrine component in <30% of the tumour remains unclear. Here, the implication of neuroendocrine components in gastric carcinomas was assessed according to proportion.
Methods: Surgically resected primary gastric carcinomas with neuroendocrine morphology (NEM; n=88) from 2000 to 2012 at Asan Medical Center were retrospectively reviewed. Neuroendocrine differentiation (NED) was defined as immunopositivity for one of three neuroendocrine markers (synaptophysin, chromogranin or CD56) within the NEM area. To validate the prognostic significance of NED, these cases were compared with 650 randomly selected gastric adenocarcinomas without NEM from the same time period.
Results: Gastric carcinomas with NEM were reclassified as NEC (⩾70% NED, n=47), MANEC (30-70% NED, n=10), gastric carcinoma with 10-30% NED (GCNED, n=8) and carcinoma with <10% NED (n=23). The survival rates of patients with ⩾10% NED were significantly poorer than those with <10% NED but no survival difference was observed between NEC and MANEC. In univariate analyses, older age (⩾60years), larger tumour size (⩾4cm), advanced stage group, ⩾10% NED and lymphovascular or perineural invasion were indicative of a poor prognosis. Stage group and ⩾10% NED remained as independent prognostic factors by multivariate analysis.
Conclusions: A minor proportion (10-30%) of NED should not be overlooked in gastric carcinomas with NEM. NED should be carefully evaluated to predict patient outcomes and plan optimal additional therapies.
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