Comparsion Of Therapeutic Effects,Toxicity,and Immune Function Among IMRT,3D-CRT And CRT On Locally Advanced Middle And Low Rectal Cancer

Objective:To investigate therapeutic effects,toxicity and immune function among IMRT,3D-CRT and CRT on locally advanced middle and low rectal cancer.To provide reference for the selection of radiotherapy methods in neoadjuvant therapy of rectal cancer.Methods:we retrospectively reviewed 93 patients with a clinical stage of cT3N+M0 or cT4N0/+M0,who have finished preoperative neoadjuvant chemoradiotherapy and own complete data,between January 2015 and December 2016 in department of colorectal surgery of the Third Affiliated Hospital of Kunming Medical University.According to radiotherapy modes,Patients were divided into IMTR group(17 cases),3D-CRT group(28 cases)and CRT group(48 cases).Radiotherapy regimen:CRT(once a day,five times a week,a total of 5 weeks,a single dose of 2.0Gy,the total dose of 50Gy),3D-CRT and IMRT(once a day,five times a week,a total number of 23-28 times,a single dose of 1.8-2.0 Gy,a total dose of 45.0-50.4Gy.chemotherapy regimen:capecitabine,825 mg/m2,twice daily for 5 days/week during radiotherapy.Curative effects,toxicity and immune status were compared among the 3 groups.Results:No significant difference was shown in general characteristic among the three groups(all P>0.05).The permanent stoma rates in IMRT group(5/17,29.4%)and 3D-CRT group(9/28,32.1%)is lower than that in CRT group(28/48,58.3%)[(x2=7.982,P=0.030)],but,no different between IMRT group and 3D-CRT group(x2=0.037,P=0.848).PCR rate in 3D-CRT group[39.3%(11/28)]is higher than that in CRT group and IMRT group[12.5%(6/48),23.5%(5/17)](x2=7.407,P 0.025),but no difference was shown between CRT and IMRT group(x2=22.554,P=0.110).No ?° or ?° toxicity occured in all of the patients,and no significant difference was shown in the incidence of gastrointestinal reaction,radiation dermatitis,bone marrow suppression,liver and kidney damage(all P>0.05).After neoadjuvant chemoradiotherapy,CD3+/CD4+rate in IMRT group and the CRT group was decreased significantly[(31.1±10.9)vs.(23.1±9.3),(33.6±7.2)vs.(27.4± 10.7);P<0.05],CD3+/CD8+cells rate was increased significantly[(24.8±10.9)vs.(36.1±15.2),(24.0±8.3)vs.(30.9±14.4);P<0.05],but there was no significant change in 3D-CRT group(P>0.05).CD4+/CD8+rate was decreased in IMRT group[(1.6±1.0)vs.(0.8±0.6),t=3.838,P=0.003],but no significant change in CRT and 3D-CRT group after treatment(all P>0.05).Conclusions:IMRT and 3D-CRT can reduce the rate of permanent stoma,and 3D-CRT can increase PCR rate.No obvious advantage was shown in IMRT as compared with 3D-CRT in the short-term efficacy,and a significant immunosuppressive status might be shown in patients.Therefore,3 D-CRT is recommended as the best preoperative treatment strategy for patients with locally advanced middle and low rectal cancer,especially for patients with immunosuppression satus.