Tumor regression grades:Potential outcome predictor of locally advanced rectal adenocarcinoma after preoperative radiotherapy

AIM:To analyze tumor regression grade(TRG)for prognosis of locally advanced rectal adenocarcinoma(LARA)treated with preoperative radiotherapy.METHODS:One hundred and ninety patients with clinical stageⅡ/ⅢLARA were studied.All patients underwent radical surgery(between 2004 and 2010)after 30-Gy/10-fraction preoperative radiotherapy(preRT).All 190 patients received a short course of preRT and were reassessed for disease recurrence and survival;the slides of surgical specimens were reviewed and classified according to Mandard TRG.We compared patients with good response(Mandard TRG1 or TRG2)vs patients with bad/poor response(Mandard TRG3-5).Outcomes evaluated were 5-year overall survival(OS),5-year disease-free survival(DFS),and local,distant and mixed recurrence.Fisher’s exact test orχ2 test,logrank test and proportional hazards regression analysis were used to calculate the probability that Mandard TRG was associated with patient outcomes.RESULTS:One hundred and sixty-six of 190 patients(87.4%)were identified as Mandard bad responders(TRG3-5).High Mandard grade was correlated with tumor height(41.7%<6 cm vs 58.3%≥6 cm,P=0.050),yp T stage(75%yp T0-2 vs 25%yp T3-4,P=0.000),and yp N stage(75%yp N0 vs 25%yp N1,P=0.031).In univariate survival analysis,Mandard grade bad responders had significantly worse OS and DFSthan good responders(TRG1/2)(OS,83.1%vs 96.4%,P=0.000;DFS,72.3%vs 92.0%,P=0.002).In multivariate survival analysis,Mandard bad responders had significantly worse DFS than Mandard good responders(DFS 3.8 years(95%CI:1.2-12.2 years,P=0.026).CONCLUSION:Mandard grade good responders had a favorable prognosis.TRG may be a potential predictor for DFS in LARA after pre-RT.