Phase II Study of Preoperative Helical Tomotherapy for Rectal Cancer

Abstract

To explore the efficacy and toxicity profile of helical tomotherapy in the preoperative treatment of patients with rectal cancer. Twenty-four patients with T3/T4 rectal cancer were included in this nonrandomized noncontrolled study. A dose of 46 Gy in daily fractions of 2 Gy was delivered to the presacral space and perineum if an abdominoperineal resection was deemed necessary. This dose was increased by a simultaneous integrated boost to 55.2 Gy when the circumferential resection margin was less than 2 mm on magnetic resonance imaging. Acute toxicity was evaluated weekly. Metabolic response was determined in the fifth week after the end of radiotherapy by means of fluorodeoxyglucose-positron emission tomography scan. A metabolic response was defined as a decrease in maximal standardized uptake value of more than 36%. The mean volume of small bowel receiving more than 15 Gy and mean bladder dose were 227 ml and 20.8 Gy in the no-boost group and 141 ml and 21.5 Gy in the boost group. Only 1 patient developed Grade 3 enteritis. No other Grade 3 or 4 toxicities were observed. Two patients developed an anastomotic leak within 30 days after surgery. The metabolic response rate was 45% in the no-boost group compared with 77% in the boost group. All except 1 patient underwent an R0 resection. Helical tomotherapy may decrease gastrointestinal toxicity in the preoperative radiotherapy of patients with rectal cancer. A simultaneous integrated radiation boost seems to result in a high metabolic response rate without excessive toxicity.