A retrospective comparison of outcome and toxicity of preoperative image-guided intensity-modulated radiotherapy versus conventional pelvic radiotherapy for locally advanced rectal carcinoma

The aim of the study was to compare clinical outcomes and toxicity between 3d conformal radiotherapy (3dcrt) and image-guided intensity-modulated radiotherapy (ig-imrt) administered through helical tomotherapy in locally advanced rectal cancer (larc) patients receiving preoperative chemoradiotherapy. we reviewed 144 patients with stage ii-iii rectal cancer receiving preoperative fluoropyrimidine-based chemoradiotherapy followed by radical resection. tumor responses following chemoradiotherapy were evaluated using the dworak tumor regression grade (trg). of the 144 patients,45 received ig-imrt and 99 received 3dcrt. a significant reduction in grade 3 or 4 acute gastrointestinal toxicity (ig-imrt,6.7%; 3dcrt,15.1%; p = 0.039) was observed by ig-imrt. the pathologic complete response (pcr) rate did not differ between the ig-imrt and the 3dcrt group (17.8% vs 15.1%,p = 0.52). patients in the ig-imrt group had the trend of favorable tumor regressions (trg 3 or 4) compared with those in the 3dcrt group (66.7% vs 43.5%,p = 0.071). the median follow-up was 53 months (range,18-95 months) in the 3dcrt group and 43 months (range,17-69 months) in the ig-imrt group. four-year overall,disease-free,and local failure-free survival rates of the ig-imrt and 3dcrt groups were 81.6% and 67.9% (p = 0.12),53.8% and 51.8% (p = 0.51),and 88% and 75.1% (p = 0.031),respectively. larc patients treated with preoperative ig-imrt achieved lower acute gastrointestinal adverse effects and a higher local control rate than those treated with 3dcrt,but there was no prominent difference in distant metastasis rate and overall survival between two treatment modalities. © the author 2016.