Predicting local recurrence of carcinoma of the rectum after preoperative radiotherapy and surgery

Abstract

A prospective study of prognostic factors has been carried out in a group of 186 patients with tethered rectal carcinomas. Of these, 97 were randomized to surgery alone and 89 to receive preoperative radiotherapy (20 Gy in four fractions). DNA ploidy was determined by flow cytometry. DNA aneuploidy was detected in 60 patients (62 per cent) in the surgery only group, but in only 33 patients (37 per cent) after radiotherapy (P less than 0.01). There was a significant reduction in local recurrence in irradiated patients (P less than 0.0001). DNA diploid tumours were less likely to recur locally. This was more marked in the radiotherapy group (P = 0.01) than in the surgery only group (P = 0.06). After radiotherapy, only the surgeons' assessments of a 'curative' resection and DNA ploidy were independent predictors of local recurrence in multivariate regression analysis, whilst Dukes' classification was not. In conclusion, DNA ploidy may indicate response to radiotherapy and is an important predictor of subsequent local tumour progression.