Preoperative radiotherapy in resectable rectal cancer: a prospective randomized study of two different approaches.

Background: Preoperative radiotherapy in resectable rectal cancer has a number of potential advantages, most importantly reducing local recurrence, increasing survival and down-staging effect.

Purpose: This prospective study was designed to compare between two different approaches of preoperative radiotherapy, either short course or long course radiotherapy. The primary endpoint is to evaluate the local recurrence rate, overall survival (OS) and disease free survival (DFS). The secondary endpoint is to evaluate downstaging, treatment toxicity and ability to do sphincter sparing procedure (SSP), aiming at helping in the choice of the optimal treatment modality.

Patients And Methods: This is a prospective randomized study of patients with resectable rectal cancer who presented to the department of Clinical Oncology and Nuclear Medicine, Mansoura University during the time period between June 2007 and September 2009. These patients received preoperative radiotherapy and were randomized into two arms: Arm 1, short course (SCRT) 25Gy/week/5 fractions followed by surgery within one week, and arm 2, long course preoperative radiotherapy (LCRT) 45Gy/5 weeks/25 fractions followed by surgery after 4-6 weeks. Adjuvant chemotherapy was given 4-6 weeks after surgery according to the postoperative pathology.

Results: After a median follow-up of 18 months (range 6 to 28 months), we studied the patterns of recurrence. Three patients experienced local recurrence (LR), two out of 14 (14.2%) in arm 1 & one out of 15 patients (6.7%) in arm 2, (p=0.598). Three patients developed distant metastases [two in arm 1 (14.2%) & one in arm 2 (6.7%), p=0.598]. Two-year OS rate was 64±3% & 66±2%, (p= 0.389), and the 2-year DFS rate was 61±2% & 83±2% for arms 1 & 2, respectively (p=0.83). Tumor (T) downstaging was more achieved in LCRT arm with a statistically significant difference, but did not reach statistical significance in node (N) down-staging. SSP was more available in LCRT but with no statistically significant difference (p=0.082).

Conclusion: This work showed that there was no statistically significant difference between SCRT & LCRT as regard local control, distant metastasis, and rate of SSP, OS and DFS, while there was a statistically significant difference as regard down-staging in favor of LCRT. Further follow up is needed to determine late toxicity and difference in survival.

Key Words: Resectable rectal cancer - Preoperative radiotherapy - Short course radiotherapy - Long course radiotherapy.