Concurrent Preoperative Radiotherapy With FOLFOX4 For Resectable Locally Advanced Low Rectal Cancer

Objective:To evaluate the tolerance and efficacy of preoperative concurrent chemoradiotherapy with FOLFOX4 for resectable locally advanced low rectal cancer.And compare the dose distribution of target volume,in normal tissues and organs for rectal cancer on Three Dimensional Conformal Radiotherapy(3D-CRT) and Intensity Modulated Radiotherapy(IMRT).Methods:From May 2007 to April 2008,11 untreated rectal cancer patients were allotted into this study.Pelvic radiothrapy was delivered with 3D-CRT/IMRT technique to a total dose of 45～50.4Gy,over 4.5～5 weeks.Two cycles of chemotherapy were given concurrently on week 1 and 4,with FOLFOX4,oxaliplatin 85 mg/m~2 iv on d1,leucovorin 200 mg/m~2,5-FU 400 mg/m~2 iv bolus and 5-FU 600 mg/m~2 iv continuous infusion in 22 hr with d1 and d2.Surgery was performed in 4-8 weeks with TME.T and N downstaging,pathological complete response(pCR),R0 resection,pathological Dworay stage,sphincter preservation rate.The toxicity during treatment was scored according to CTC3.0.At the same time,The clinical target volume(CTV),small bowel, bladder,pelvic bone marrow and femoral head were contoured on CT images.The CTV was contoured consisting of the tumor,local lymph node regions,mesorectum,presacral region and perineal region.The CTV was expanded by 1cm to create a planning target volume(PTV) in all directions.To every patient,a 3D-CRT and a IMRT treatment planning protocols were simulated using Eclipse treatment planning system.The difference of each treatment planning protocol on the target volume and normal structures by analysis of dose-volume histograms(DVH).Results:All Patients completed the preoperative chemoradiotherapy and surgery.They are all suffered R0 resection.Total sphincter preservation rate was 54.5%.Total downstaging were 72.1%.3 patients(27.3%) achieving pathologic complete response(pCR) and,in 1(9.1%),only a few residual cells were detected.Grade 3 to 4 toxicity occurred in 18.2% patients.Total postoperative complication was 18.2%.compared with the 3D-CRT,IMRT plans provided excellent coverage and the dose distribution of target volume.The IMRT as compared with the 3D-CRT,the mean and the maximum dose of normal structure was reduced,and the percentage volume of normal structures was reduced. Especially on the 45Gy level,the IMRT had advantage over the 3D-CRT.Conclusions:For resectable locally advanced low rectal cancer, preoperative concurrent chemoradiotherapy with FOLFOX4 can increase pathologic downstaging rate and complete response rate.It also has advantage in sphincter preservation and dosen't significantly increase Grade 3 to 4 toxicity and postoperative complication occurred.Plvic IMRT plan provided excellent coverage and the dose distribution of target volume,and is able to effectively protect the normal tissues and organs.