Phase II study of preoperative helical tomotherapy for rectal cancer

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.