Selection criteria for treatment of rectal cancer with combined external and endocavitary radiation.

Abstract

The aim of this study was to identify factors predictive of recurrence of rectal tumors treated with combined external and endocavitary radiation. Seventy-two patients with rectal cancer were evaluated clinically and with transrectal ultrasound before combined external and endocavitary radiation. Ideal lesions were moderately differentiated, mobile, not ulcerated, <3 cm in diameter, and <12 cm from the anal verge. External radiation (4,500 cGy) was given during five weeks followed by endocavitary radiation (3,000 cGy x 2). Median follow-up was 31 (range, 7-93) months. Pretreatment transrectal ultrasound stages were uT1 (6 patients), uT2 (27 patients), and uT3 (39 patients). Clinical evaluation identified 26 ideal and 46 nonideal tumors. Overall recurrence was 36 percent; mean time to recurrence was 12 months. Ideal lesions recurred less than nonideal (15 vs. 48 percent; P = 0.01). Mobile lesions recurred less than tethered lesions (26 vs. 52 percent; P = 0.048). Transrectal ultrasound stage was predictive of recurrence (0 percent uT1, 22 percent uT2, and 51 percent uT3; P = 0.015). Surgery was possible in 14 of 17 patients with pelvic recurrence only; 11 patients (65 percent) had curative surgery. Distant metastases occurred in nine patients; all had pelvic recurrences, and six died of disease. Patients with uT3 or nonideal rectal cancers should not be offered combined external and endocavitary radiation for cure. Transrectal ultrasound stage is the only independent predictor of recurrence.