Construction And Clinical Application Of A New Clinical Staging System For Colorectal Cancer Based On Lymph Node Ratio

Purpose(AJCC)'s colorectal cancer(TNM)staging system is widely used to predict postoperative survival in patients with colorectal cancer and to guide adjuvant chemotherapy that may be needed after radical resection.However,in the current TNM staging system of AJCC,there is not only the "survival paradox" between ?A stage and ? stage of colorectal cancer,but also based on the absolute number of metastatic lymph nodes.The minimum number of 12 lymph nodes was required to ensure the accuracy of N staging.Therefore,there is a lack of a reliable staging system for predicting the prognosis of colorectal cancer patients with insufficient lymph node harvest.The main purpose of this study is to try to construct a new clinical staging system for colorectal cancer based on LNR,which can not only improve the "survival paradox" of the existing staging system.It can be used as an effective supplement to the existing TNM staging system of AJCC to predict the prognosis of colorectal cancer patients with insufficient lymph node harvest.Methods25766 colorectal cancer patients who underwent enterectomy and had a total lymph node harvest of less than 12 were selected from the(The Surveillance,Epidemiology,and End Results,SEER)database of the National Cancer Institute as a training set(training set).The LNR in the training set was divided into five LNR groups with the boundary of 0,0.155,0.3875 and 0.707.Combined with the T stage of AJCC and LNR grouping,the 5-year survival rate of each survival combination was calculated by K-M test,and the TNRM staging system was constructed.The intra-group staging comparison between the TNM staging system and the TNRM staging system of the 8th edition of AJCC and the verification of the monotonic decreasing trend of each staging curve were carried out,and the superiority of the TNRM staging system over the AJCC staging system was verified in the external verification set(validation set).External verification set,follow-up data of patients after resection of colorectal cancer in gastrointestinal center from August 2012 to December 2016 were followed up by telephone from Subei people's Hospital affiliated to Yangzhou University.The main purpose of this study is to obtain the relevant information of postoperative survival status,radiotherapy and chemotherapy,tumor recurrence and so on,and finally obtain the effective follow-up data of 635 cases,which are used for external verification.ResultsFinally,24007 colorectal cancer patients with non-long-term metastasis in SEER database were divided into LNR grouping and new staging system construction.The median examination of lymph nodes in the training set was 8.The LNR cutoff value was obtained by classification and regression tree analysis.The queue was successfully divided into 5 LNR groups.Univariate and multivariate analysis showed that N score and LNR score of AJCC were independent risk factors for the whole cohort.Combined with the survival combination of T stage and LNR grouping,according to the heterogeneity of the 5-year survival rate and the survival curve of the survival combination,A new TNRM staging system including ? stage,?A stage,?B stage,?A stage,?B stage,?C stage and IV stage was developed.After internal comparison and external verification,compared with AJCC's TNM staging system,TNRM staging system shows better high-risk identification and prognosis stratification ability,and successfully avoids the problem of "survival paradox".ConclusionThe existing AJCC staging system has a serious "survival paradox" for judging the prognosis of patients with insufficient lymph node harvest(LNs<12).For patients undergoing limited lymph node analysis,our proposed TNRM staging system can predict the prognosis of patients with colorectal cancer more accurately and can be used as an effective supplement to the existing staging system.