Prognostic value of immunohistochemistry in gastric neuroendocrine (carcinoid) tumors

Three subtypes of enterochromaffin-like cell tumors (carcinoids) have been described: type I, associated with chronic atrophic gastritis; type II, multiple endocrine neoplasia 1 and Zollinger-Ellison syndrome; and type III, sporadic tumors. Objectives: (i) To investigate the immunoexpression of Ki-67, p53 and Bcl-2 proteins in enterochromaffin-like cell (carcinoid) tumors and 00 to evaluate the prognostic value of these markers. Methods: Fifty-four samples from 21 patients with gastric carcinoid tumors were sectioned and immunostained using avidin-biotin peroxidase method. Results: The mean age was 62.2 +/- 11.4 years (36-83 years-old) and 13 (61.9%) were women. Type I lesions were detected in 61.9% and type III in 38.1%. Tumors were single in 10 (476%) and were multiple and/or multicentric in II (52.4%). Nuclear p53 immunoreactivity was observed in 6/21 patients (28.6%), and all of them were type III tumors (6/8), compared with no p53 expression in type I (0/13), P=0.0002. p53 expression was also associated with high degree of cell proliferation (Ki-67-positive nuclear cells), P=0.00001. Bcl-2 expression was either unreactive or weakly positive in all tumor lesions. The mean follow-up period was 50.4 months (SD=45.2), varying from 6 to 144 months. Overall survival time of patients with positive p53 expression and high proliferative rate was significantly lower than that of negative patients (14.4 vs 123 months, P=0.0007). Conclusions: (i) p53 immunoexpression associated with high proliferative rate was useful to distinguish between type I and type III gastric carcinoid tumors and (ii) these markers were able to predict a shorter survival.