Initial results of a randomized controlled trial comparing clinical and pathological downstaging of rectal cancer after preoperative short‐course radiotherapy or long‐term chemoradiotherapy, both with delayed surgery

AIM: The aim of this study was to compare the downstaging achieved after long-course chemoradiotherapy (chRT) and short-term radiotherapy (sRT) followed by delayed surgery. METHOD: A randomized controlled trial was carried out. Eighty-three patients with resectable stage II and III rectal adenocarcinoma were randomized to receive long-course chemoradiotherapy (46) and short-term radiotherapy (5×5 Gy) (37). Surgery was performed 6 weeks after preoperative treatment in both groups. RESULTS: The R0 resection rate was 91.3% in the chRT and 86.5% in the sRT group (P=0.734). Sphincter preservation rates were 69.6%vs 70.3% (P=0.342) and postoperative complication rates were 26.1%vs 40.5% (P=0.221). There were more patients with early pT stage [pT0 (complete pathological response) pT1] in the chRT group [21.8%vs 2.7% (P=0.03)] and more patients with pT3 disease in the sRT group [75.7%vs 52.2% (P=0.036)]. There were no differences in pN stage and lymphatic or vascular invasion in either group. Pathological downstaging (stage 0 and I) was observed in eight (21.6%) patients in the sRT group and in 18 (39.1%) in the chRT group (P=0.07). Tumours were smaller after preoperative ChRT (2.5 cm vs 3.3 cm; P=0.04). CONCLUSION: Long-course preoperative chemoradiation resulted in greater statistically significant tumour downsizing and downstaging compared with short-term radiation, but there was no difference in the R0 resection rates. Similar postoperative morbidity was observed in each group.