Validation of the 8th Edition of the American Joint Committee on Cancer Staging System for Gallbladder Cancer and Implications for the Follow-up of Patients without Node Dissection

PURPOSE: The 8th edition of gallbladder cancer staging in the American Joint Committee on Cancer (AJCC) staging system changed the T and N categories. MATERIALS AND METHODS: In order to validate the new staging system, a total of 348 surgically resected gallbladder cancers were grouped based on the 8th edition of the T and N categories and compared with patients’ survival. RESULTS: Significant differences were noted between T1b-T2a (p=0.003) and T2b-T3 (p < 0.001) tumors, but not between Tis-T1a, T1a-T1b, and T2a-T2b tumors. However, significant survival differences were observed both by the overall and pair-wise (T1-T2, T2-T3) comparisons (all, p < 0.001) without dividing T1/T2 subcategories. When cases with ≥ 6 examined lymph nodes were evaluated, significant survival differences were observed among the entire comparison (p < 0.001) and pair-wise comparisons of N0-N1 (p=0.001) and N1-N2 (p=0.039) lesions. When cases without nodal dissection (NX) were additionally compared, significant survival differences were observed between patients with N0-NX (p=0.001) and NX-N1 (p < 0.001) lesions. CONCLUSION: The T category in the 8th edition of the AJCC staging system did not completely stratify the prognosis of patients with gallbladder cancer. Modification by eliminating T subcategories can better stratify the prognosis. In contrast, the N category clearly determines patients’ survival with ≥ 6 examined lymph nodes. The survival time in patients of gallbladder cancers without nodal dissection is between N0 and N1 cases. Therefore, close postoperative followed up is recommended for those patients.