Short versus conventional preoperative radiotherapy of rectal cancer: indications

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.

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.

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.

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.