Modified AJCC staging of gastric neuroendocrine carcinoma based on T staging can improve the capacity of prognosis assessment.

BACKGROUND OR PURPOSE: This study was designed to determine the value of AJCC staging 7th edition and improved AJCC staging in assessing the prognosis of gastric neuroendocrine carcinoma (GNEC).

METHODS: In total, GNEC 475 patients in the Surveillance, Epidemiology, and End Results (SEER) database and 129 GNEC patients in our department undergoing resection were included. The former served as the test group, and the latter served as the validation group. Those with stage IIIb disease were allocated into four subgroups, and improved AJCC staging was established. The AIC and C indices were used to evaluate the capacities of different TNM staging.

RESULTS: Significant overlap between stages IIIb and IIIa in both the test and validation groups was found. In the test group, T staging and age at disease diagnosis were independent prognostic factors for patients with stage IIIb. Stage IIIb was divided into T1N1, T2N1, T3N1 and T4N1, and the improved AJCC staging-mTNM staging was created. In mTNM staging, the IIIb survival curve did not cross those of stages IIIa and IIb, which had a smaller AIC (2490 vs. 2507) value and larger C index (0.7624 vs. 0.7450, P = 0.228). Similar results were obtained for the validation group.

CONCLUSION: T stage was an independent factor influencing the prognosis of stage IIIb GNEC patients, and the improved AJCC staging proposed here has good prognostic value.