High Dose Rate Endorectal Brachytherapy for Patients With Curable Rectal Cancer

Over the past three decades, local-regional tumor control in rectal surgery has dramatically changed with the recognition of the importance of achieving tumor-free circumferential resection margins. This has led to the use of standardized total mesorectal excision (TME), with significant improvement in local control. Preoperative external beam radiation therapy (EBRT) has further increased the success of TME by reducing the rate of local relapse by half. However, the significant long term complication associated with EBRT is the price attached to this additional benefit. High Dose Rate Endocavitary Brachytherapy (HDREBT) appears to carries similar local control benefit but with minimal acute and long term complication rates. HDREBT technology was originally developed at McGill University. It uses the advantages of the modern imaging techniques to better visualize and target the local disease. From 1998 to 2008, 285 rectal cancer patients have been treated with preoperative HDREBT. All patients had endorectal ultrasound and pelvic Magnetic Resonance Imaging (MRI) for pretreatment tumour staging. At a median follow-up of 55 months, the 5 years actuarial local relapse rate was 5% with a disease free survival rate (DFS) of 65% and overall survival rate (OS) of 68%. At the time of surgery 27% had complete pathological response (PCR) and 37% had only microscopic residual disease. Grade III acute proctitis occurred in only 1% of the patients and there were no long term pelvic fracture. The present data suggests that HDREBT is an effective approach for rectal cancer patients requiring preoperative radiation therapy, with favorable acute and delayed toxicity profile. However, firm conclusions can only be drawn from a phase III multi-institutional study.