Purpose: The optimal timing of surgery after preoperative radiotherapy in rectal cancer is unknown. The aim of this trial was to evaluate the role of the interval between preoperative radiotherapy and surgery.
Patients and methods: Patients with rectal carcinoma accessible to rectal digital examination, staged T2 to T3, NX, M0, were randomized before radiotherapy (39 Gy in 13 fractions) into two groups: in the short interval (SI) group, surgery had to be performed within 2 weeks after completion of radiation therapy, compared with 6 to 8 weeks in the long interval (LI) group. Between 1991 and 1995, 201 patients were enrolled onto the study.
Results: A long interval between preoperative radiotherapy and surgery was associated with a significantly better clinical tumor response (53. 1% in the SI group v 71.7% in the LI group, P =.007) and pathologic downstaging (10.3% in the SI group v 26% in the LI group, P =.005). At a median follow-up of 33 months, there were no differences in morbidity, local relapse, and short-term survival between the two groups. Sphincter-preserving surgery was performed in 76% of cases in the LI group versus 68% in the SI group (P = 0.27).
Conclusion: A long interval between preoperative irradiation and surgery provides increased tumor downstaging with no detrimental effect on toxicity and early clinical results. When sphincter preservation is questionable, a long interval may increase the chance of a successful sphincter-saving surgery.