Short-term preoperative radiotherapy results in down-staging of rectal cancer: a study of 1316 patients

Abstract

Background and purpose: This study was undertaken to investigate down-staging effects after short-term, high-fractionated preoperative radiotherapy. Material and methods: The relationships between preoperative radiotherapy 25–25.5 Gy given over 5–7 days and clinical variables (sex, age, tumour level, metastatic disease, and tumour size) and the risk of lymph node metastases were examined in 1316 patients with rectal adenocarcinoma by uni-, and multivariate analyses. Results: Irradiated specimens contained smaller tumours ( P < 0.00001) and nodal metastases were less common ( P < 0.001). In a logistic regression model, tumour size in cm was positively related to the risk for nodal spread (odds ratio, OR = 1.14, 95% confidence limits, CL, of OR 1.08–1.22) In the same model, radiotherapy decreased the risk for nodal involvement (OR 0.73, 95% CL 0.58–0.92. This risk was particularly reduced when the time interval between start of radiotherapy and surgery equalled 10 days or more. Conclusions: These results demonstrate a down-staging effect by a short course of preoperative radiotherapy which should be considered in the interpretation of radiotherapy trials and in the recruitment of patients for further postoperative adjuvant treatment.