| Objective : To evaluate the effectiveness of the AJCC/UICC p TNM classification of gastric cancer in the 8th edition compared with the 7th edition.The shortage of new classification was present and proposed classification system was suggested.Methods: The date of patients with gastric cancer who underwent radical gastrectomy at the Affiliated Hospital of Qingdao University between 2007 and 2012 were analyzed.A total of 2059 patients were involved in this study.The effectiveness was compared between the 7th and 8th edition of p TNM classification based on this database.Then the new classification system was present and verified.Results: A total of 2059 eligible patients entered the study,involving 1509(73.3%)male patients and 550(26.7%)female patients with ratio of 2.74:1(median age: 62 years,rage:29-91 years).321(15.6%)patients were diagnosed as early gastric cancer,and1738(84.4%)with advanced cancer.The total number of harvested lymph nodes were68187(mean+SD:33.12±12.614;median 30,range 16-78),with 8279 positive lymph nodes(mean+SD:4.02±5.769;median 2,range 0-53).The median follow-up time was1159 days(range 30-3849 days).In the 7th edition,the proportion of patients in each groups were as follow: stage IA(277,13.5%),stage IB(205,10.0%),stage IIA(312,15.2%),stage IIB(304,14.8%),stage IIIA(318,15.4%),stage IIIB(370,18.0%),stage IIIC(273,13.3%).While in the 8th edition,the proportion were:stage IA(277,13.5%),stage IB(205,10.0%),stage IIA(312,15.2%),stage IIB(304,14.8%),stage IIIA(489,23.7%),stage IIIB(359,17.4%),stage IIIC(113,5.5%).Among them,399patients(19.38%)reclassified in the 8th edition compared with the 7th edition.4 factors were identified as independent risk factors,including N stage,T stage,types of gastrectomy and secondary surgery.HR analysis suggested significant difference between N3 a and N3 b when compared with N0(7.703 in N3 a versus 13.228 in N3 b,respectively).In the Kaplan-Meier survival curves,the N3 a and N3 b groups also differed significantl(p< 0.001).In subgroups analysis,the comparison between T3N3 a and T3N3 b was statistically significant,so was the comparison between T4 a N3a and T4 a N3b,but not between T2N3 a and T2N3b(p=0.548).In the analysis of the group that changed in stages,the 8th edition seems to be more suitable for T3N3 b and T4 a N2,but not in T2N3 b,T4a N3 a,T4b N0 and T4 b N2.In the final classification analyses,the survival curves of version 7 and 8 are both well separated(expect for IIA and IIB,P=0.124),with no statistical difference.When evaluating the predictive power of the models by concordance index(c-index),we found no significant difference between 7th and 8th edition(c-index0.7481,95% CI 0.7150-0.7812 in the 7th edition vs c-index 0.7488,95% CI0.7157-0.7819 in the 8th edition).Under this premise,the proposed p TNM staging systemhas statistical difference in all stages of survival,and the predictive power of the model is improved(the proposed scheme c-index is 0.7524,95%CI:0.7193-0.7855).Conclusions: The p TNM classification in the 8th edition of gastric cancer is reasonable(expect for IIA and IIB),especially in the separation of N3 a and N3 b,but there was no advantage in the final classification compared with the 7th edition.The proposed classification can be used to evaluate the prognosis of patients better,and its predictive power is improved than the 7th and 8th edition.The new classification system needs further verifications. |
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