Modified staging classification of gallbladder carcinoma on the basis of the 8th edition of the American Joint Commission on Cancer (AJCC) staging system.

PURPOSE: The 8th edition of the American Joint Commission on Cancer (AJCC) Staging System for gallbladder cancer (GBC) has been used in clinical practice, but we have found some deficiencies in this edition. METHODS: Survival analyses were performed to evaluate the application of various editions of the AJCC staging systems using the Surveillance, Epidemiology, and End Results (SEER) database (N = 9616 patients) and Fudan University Zhongshan Hospital (FUZH) database (N = 327 patients). A modified staging system was proposed based on the 8th edition of the AJCC Staging System. RESULTS: Although all N2 diseases were grouped into stage IVB as M1 in the 8th edition, some patients with N2 diseases could undergo R0 resection, and had longer survival than patients with M1 diseases had in both cohorts (p < 0.001 in SEER, p = 0.041 in FUZH). Furthermore, in the SEER database, stage IIIA patients aberrantly had poorer survival than stage IIIB patients had (p < 0.001). Therefore, we proposed a modified staging system by rearranging the substages. N2 disease was subdivided and reappraised according to T stage, and the aberrant survival reversal of stage IIIA and stage IIIB disease was also corrected. Through our modification, the C-index of the 8th AJCC Staging System was elevated from 0.596 [95% confidence interval (CI): 0.585-0.607] to 0.623 (95% CI: 0.612-0.634) for local disease in the SEER cohort. Similar findings were also observed in the FUZH cohort. CONCLUSION: Our modified 8th AJCC Staging System is more suitable for GBC and could be adopted for clinical practice.