[Discussion on pT3 staging in TNM staging of AJCC 8(th) edition gallbladder carcinoma]

Objective: To discuss the rationality of stage pT3 in the AJCC 8(th) TNM criteria of gallbladder carcinoma. Methods: A retrospective study was performed to analyze the clinical and pathological data of 88 patients with pT3 gallbladder carcinoma admitted to Department of Second Biliary Surgery of Eastern Hepatobiliary Surgery Hospital, affiliated to Naval Medical University from May 2013 to September 2018.pT3 stage tumors were divided into two groups: (1) pT3a stage: tumors had penetrated serosa but not directly invaded liver and/or an adjacent organ or structure; (2) pT3b stage: tumor penetrating serosa and directly invaded liver and/or an adjacent organ or structure. There were 45 patients with pT3a stage, including 15 males and 30 females, aged 36 to 80 years, with a median age of 59 years; 43 patients with pT3b, including 24 males and 19 females, aged 41 to 78 years old, median aged 63 years old.Patients with pT3a and pT3b were further divided into two groups respectively: radical resection group and extended radical resection group according to surgical radicalization. Independent sample t-test was used for comparison between two groups with normal distribution measurement data. Wilcoxon rank sum test was used between groups of non-normally distributed measurement data.The comparison of the count data was performed by χ(2) test or Fisher exact probability method. Survival analysis was performed using Kaplan-Meier method, and survival rate was compared using Log-rank test. Results: (1)Serum total bilirubin(15.6(90.3)mmol/L), albumin(40.2(4.8)mmol/L), and CA19-9(132.90(455.78)U/ml) levels in pT3b patients were higher than that in pT3a patients(10.2(6.8)mmol/L, 41.8(4.9)mmol/L, 14.35(36.27)U/ml), respectively(Z=-3.816, -1.966, -3.739, all P<0.05),postoperative complication rate in pT3b patients(24.4%) was higher than that in pT3a patients(8.9%)(P<0.05),postoperative hospital stay(12(7)days) and overall hospital stay((26±17)days) of pT3b patients were longer than that of pT3a patients((10±5) days and (19±7)days) (P<0.05). (2) The 1-, 3-, 5-year survival rates of pT3b and pT3a patients were 53%,22%,22% and 69%, 46%,38%,and the median survival time was 13 months and 26 months, respectively. The difference in survival rates between the two groups was statistically significant(χ(2)=5.117, P=0.024). (3)The 1-, 3-year survival rates of extended radical resection group(n=19) and radical resection group(n=24) in the pT3b stage were 73%, 36% and 28%, 7%, respectively.The survival time was 20 months and 9 months,respectively,and the difference in survival rates between the two groups was statistically significant(χ(2)=4.976, P=0.026). Conclusions: pT3 gallbladder carcinoma could be further subdivided into pT3a stage and pT3b stage based on the TNM criteria of AJCC 8(th) gallbladder carcinoma. Extended radical resection for pT3b gallbladder carcinoma should be further considered after comprehensive assessment of the patient's basic condition and surgical tolerance.