Definition of T3/4 and Regional Lymph Nodes in Gallbladder Cancer: Which Is More Valid, the UICC or the Japanese Staging System?

Abstract

The Union for International Cancer Control (UICC) and Japanese Society of Biliary Surgery (JSBS) staging systems differ in their staging of gallbladder cancer: they define hepatic invasion with or without invasion of another organ as T3 and either T3 or T4, respectively, and posterosuperior pancreatic lymph node (PSPLN) metastases as M1 and N2, respectively. We retrospectively evaluated the survival of 224 patients who had undergone macroscopically curative resection for gallbladder cancer and assessed the influence of the differences between the two staging systems on survival. JSBS staging stratified the survival curves better for stages III or IV. Fifty-seven patients were classified as UICC-T3 but JSBS-T4. These patients had better survival than did 43 patients with UICC-T4/JSBS-T4 and comparable survival to 17 patients with UICC-T3/JSBS-T3. UICC stage IIIB is composed of two subgroups: U-T2N1 (18 patients) and U-T3N1 (21 patients). Their 5-year survivals were 85 and 41%, respectively (P = 0.01). The latter was comparable to that of 28 T3N0 patients (35%, P = 0.93). The survival of the UICC-M1 patients with disease restricted to PSPLNs was significantly better than that of those with involvement beyond PSPLNs (5-year survival 35 vs. 17%; P = 0.04). Although UICC staging more accurately defines the T category, JSBS staging better stratifies the prognosis of patients with gallbladder cancer, mainly because UICC stage IIIB includes T1/2N1M0, which is associated with significantly better survival than T3N0M0. It would be appropriate to classify PSPLNs as regional lymph nodes.