Background: Although the prognosis of stage IV gastric cancer is poor, some patients with stage IV gastric cancer had a long-term survival after gastrectomy. The objective of this study was to subclassify stage IV gastric cancer according to survival differences, evaluate the prognosis by substage, and identify the factors associated with patient survival in each substage.
Methods: The data from 1,176 patients who underwent gastric resection for stage IV gastric cancer between 1988 and 2007 at Tumor Hospital of Harbin Medical University were reviewed retrospectively. The patients were divided into three substages according to the survival differences: stage IVa (T1-2N3M0), stage IVb (T3N3M0 and T4N1-2M0), and stage IVc (T4N3M0 and TanyNanyM1). The clinicopathological characteristics as well as survival of the patients were evaluated retrospectively by substage.
Results: There were no significant differences in survival among T3N3M0, T4N1M0, and T4N2M0 groups (p = 0.884) and between T4N3M0 and TanyNanyM1 groups (p = 0.192). The 5-year survival rates in stage IVa (T1-2N3M0), stage IVb (T3N3M0 and T4N1-2M0), and stage IVc (T4N3M0 and TanyNanyM1) were 22.7%, 9.9%, and 2.2%, respectively (p < 0.001). Multivariate analysis showed the following independent prognostic factors for survival: subclassification, operation type, number of retrieved lymph nodes, curability, and chemotherapy for stage IV gastric cancer; curability, chemotherapy, and number of retrieved lymph nodes for stage IVa and IVb; chemotherapy and operation type for stage IVc. For 406 patients with curative resection in stage IVa and IVb, hematogenous recurrence (35.9%) was the dominant recurrence pattern in stage IVa, whereas the most common patterns of recurrence were peritoneal (40.8%) and locoregional recurrence (31.8%) in stage IVb.
Conclusions: Subclassification of stage IV gastric cancer into IVa (T1-2N3M0), IVb (T3N3M0 and T4N1-2M0), and IVc (T4N3M0, TanyNanyM1) may be helpful to predict the outcome and determine the therapeutic strategies for patients with stage IV gastric cancer.