Evaluation Of The Efficacy Of Postoperative Chemotherapy And Construction Of Related Prognostic Models In Elderly Patients With High-risk Stage Ⅱ Colorectal Cancer

Background:Chemotherapy is now widely used as adjuvant therapy in CRC patients,but adjuvant chemotherapy remains controversial in stage patients.Current guidelines recommend adjuvant chemotherapy only for stage patients with high-risk histopathological features,but it is unclear whether these patients benefit from adjuvant chemotherapy.In particular,the particular group that may face more age,elderly patients are often at poor risk and may face increased morbidity and mortality related to chemotherapy-related adverse effects,and the age segment is not divided in the latest guidelines.Purpose:To retrospectively study tumor prognosis,including cancer-specific survival(CSS)and overall survival(OS),in elderly patients with stage Ⅱ CRC after radl resection(with or without chemotherapy)to assess the true efficacy of chemotherapy in elderly patients with stage Ⅱ CRC undergoing radical surgery.Individualized assessment of potential survival benefit in elderly patients with stage Ⅱ CRC treated with chemotherapy after radical surgery by identifying additional high-risk factors and constructing the nomograms as predictive models for survival.The model is intended to help clinicians quantify the benefits of chemotherapy after radical surgery in patients with stage Ⅱ CRC and to make personalized treatment recommendations and decisions.Methods:In this study,retrospective analysis was used to collect the data of elderly patients with colon cancer after stage Ⅱ radical resection in the Department of General Surgery,the First Affiliated Hospital of YangZhou University from January 2013 to December 2016.The personal data of each case included age at diagnosis,gender,marital status,tumor site,tumor size,histology,grade,T stage,perforation obstruction and number of lymph nodes(nLN),carcinoembryonic antigen(CEA),geriatric nutrition index(GNRI),hypertension,diabetes mellitus,neutrophil to lymphocyte ratio(NLR),prognostic nutrition index(PNI).Propensity score matching(1:1)was performed according to whether chemotherapy was received or not.Colon cancer-cause-specific death(CSD)and non-colon cancer-cause-specific death(NCSD)were assessed using a competitive hazard regression model.Univariate and multivariate COX analysis were used to identify the risk factors for OS and CSS,and the nomogram were constructed to predict overall survival(OS)and cause-specific survival(CSS).The predictive power of the constructed model was evaluated by the concordance index(c-index)and the calibration curve.Results:A total of 259 patients were included in the study,of whom 114 received chemotherapy and 145 did not.After eliminating selection bias and uneven distribution of factors by propensity score matching,204 patients were included in the next study,including 110 patients with chemotherapy and 93 patients without chemotherapy.The distribution of chemotherapy subgroups was not statistically significant.Of the 204 patients included,a total of 84(41.3%)patients died,of which 51(60.7%)patients died of colon cancer,33 cases(39.2%)patients died of causes other than colon cancer.In this study,we found that in stage Ⅱ CC patients,CCSD and NCSD of patients receiving chemotherapy were lower than those of patients not receiving chemotherapy through competitive risk model and calculation of cumulative incidence.With the extension of follow-up time,the difference of NCSD between chemotherapy group and non-chemotherapy group gradually increased,so elderly patients can benefit from chemotherapy.The age of the patients was analyzed by univariate and multivariate COX analysis(p<0.001),nutritional index of the elderly(p=0.016),T stage(p=0.008),number of lymph nodes detected(p=0.002),tumor diameter(p=0.014)and CEA(p=0.018)were independent prognostic factors for OS,while geriatric nutritional index(p=0.004),T stage(p=0.013),number of lymph nodes(p=0.002),tumor diameter(p=0.007)and CEA(p=0.008)were independent prognostic factors for CSS.The 3-year and 5-year CSS and OS of chemotherapy and non-chemotherapy elderly stage Ⅱ colon cancer were constructed by COX multivariate analysis.The c index of chemotherapy and non-chemotherapy predicting 3-year and 5-year OS and CSS was 0.787 and 0.761,respectively.The c index of chemotherapy and non-chemotherapy predicting CSS was 0.744 and 0.801,respectively.The survival curve had good discrimination and calibration.Conclusion:Chemotherapy can improve the survival benefit of elderly patients with stageⅡ colon cancer undergoing radical surgery.The survival prediction model can be used to predict OS and CSS in patients with chemotherapy and in patients without chemotherapy,and to provide individualized treatment recommendations for patients with stage Ⅱ colon cancer undergoing radical surgery.