Complete Clinical Response With MRI Split Scar Sign as a Predictor to Complete Pathologic Response After Neoadjuvant Chemoradiation in Rectal Cancer

Patients with middle or low rectal cancer who have T3-4 and/ or N+ will be included. Patients will receive neoadjuvant chemoradiation in the form of pelvic irradiation by 50.4 thousands grays together with radio sensitization by 5-FU or oxaliplatin, 8 months after completion of neoadjuvant chemoradiation patients will be assessed clinically and radiologically. Complete clinical response is diagnosed if clinically no tumor is felt or just small scar and no tumor appears in MRI. Of these patients who achieve complete clinical response we will pick up cases who have split scar sign in the pelvic MRI. Patients will have total mesorectal excision 8-11 weeks after completion of neoadjuvant chemoradiation and pathologic complete response will be assessed. Correlation will be done between preoperative clinical response and postoperative pathologic response