Short versus conventional preoperative radiotherapy of rectal cancer: indications.

PURPOSE: Preoperative radiotherapy (RT) at high-dose short-course or at conventional fractions for rectal cancer has proven effect in increasing the tumor control. The aim of this study was to test the impact of 2 different preoperative RT schemes on local recurrence, distant metastasis and survival rates and to defi ne the indications for each of them.

PATIENTS AND METHODS: The study included 84 patients with biopsy-proven rectal adenocarcinoma of the middle and lower third, clinically staged T2-T4, N0-2, M0. Group I patients (n=51) received a total dose of 25 Gy in 5 fractions of 5 Gy each for 5 consecutive days; operation was performed 3-5 days later. Group II patients (n=33) received a total dose of 50 Gy in 25 fractions of 2 Gy each in 5 weeks, followed by surgery after 4-5 weeks. Surgery included abdomino-perineal resection (APR) for tumors of the lower half of distal rectum, abdomino-transanal resection (ATR) for tumors of the upper half of distal rectum and anterior resection (AR) for tumors of the middle rectum.

RESULTS: After a median follow-up of 53 months (range 22-84) overall survival (OS) of all patients at 4 years was 84% and the distant metastasis-free survival (DMFS) 82%. For stage II patients only, OS and DMFS was 100% in both preoperative RT groups. For stage III patients, OS in group I and II was 72% and 70%, respectively (p >0.05) and DMFS 66% and 68%, respectively (p >0.05). Local recurrence - free survival (LRFS) for all stages was 94% with 5 x 5 Gy and 25 x 2 Gy; for stage ?? only it was 100% and for stage III only 90%. However, the use of short preoperative 5 x 5 Gy scheme for tumors of the lower third of the rectum and sphincter-saving surgery was accompanied with higher rates of local recurrence: 11% after 5 x 5 Gy vs. 0% after 25 x 2 Gy. Partial tumor regression with 50 Gy of conventional RT was achieved in 79% of the cases. Such regression was not possible to assess for the 5 x 5 Gy group since surgery was performed 3-5 days after RT. No late adverse effects on normal tissues were observed with any scheme of preoperative RT.

CONCLUSION: The conventional preoperative RT with 50 Gy proved more effective for advanced rectal cancer (T4 or N2) and for sphincter-saving resections for lower-lying tumors. The short scheme 5 x 5 Gy is appropriate for less advanced tumors (T2-3, N0-1), therefore requiring accurate clinical staging.