Is signet-ring cell carcinoma a specific entity among gastric cancers?

BACKGROUND: The prognosis and chemoresistance of signet-ring cell (SRC) gastric adenocarcinoma have been reported and debated, and the utility of perioperative chemotherapy for such a tumor has been questioned . This study was performed to assess the impact of the SRC type on survival following resection of gastric adenocarcinoma, and to assess whether the prognostic factors (including perioperative chemotherapy) for non-SRC adenocarcinoma differed from those for SRC adenocarcinoma.
METHODS: 1799 cases of adenocarcinoma that were consecutively treated from 1997 to 2010 in 19 French centers by subtotal or total gastrectomy were included in a retrospective study. A D2 lymphadenectomy was performed for antropyloric tumors, and a modified D2 for upper tumors. SRC adenocarcinoma was diagnosed based on the presence of isolated carcinoma cells containing mucin.
RESULTS: A total gastrectomy was performed in 979 (54.4 %) patients. SRC adenocarcinoma was diagnosed in 899 (50 %) patients. Patients with an SRC tumor were more frequently female, younger, and malnourished, had lower ASA scores, and had larger tumors than non-SRC patients. Median survival in patients with non-SRC carcinoma was 51 months, as compared to 26 months in patients with SRC carcinoma (p < 0.001). At multivariate analysis, SRC type remained an independent adverse prognostic factor (HR = 1.182). Factors that were prognostic in the SRC subgroup but not in the non-SRC subgroup were age >60 years, linitis, and involvement of adjacent organs. In contrast to non-SRC tumors, pre- and postoperative chemotherapy did not significantly impact on survival following resection of SRC adenocarcinoma.
CONCLUSION: In comparison to non-SRC adenocarcinoma, the SRC type has a worse prognosis, different prognostic factors, and is only poorly sensitive to perioperative chemotherapy. Non-SRC and SRC adenocarcinomas should be considered different entities in future therapeutic trials.