Results of external beam radiotherapy alone for incompletely resected carcinoma of rectosigmoid or rectum: Peter MacCallum Cancer Institute experience 1981-1990.

Abstract

To study the results of external beam radiotherapy treatment for incompletely resected nonmetastatic rectosigmoid and rectal carcinoma. A retrospective review was carried out of all patients (57) presenting to Peter MacCallum Cancer Institute from 1981 to 1990 with incompletely resected nonmetastatic rectosigmoid or rectal cancer who were treated with external beam radiotherapy. Three radiotherapy schedules were used: radical (50 to 60 Gy, 27 patients), high-dose palliative (45 Gy, 25 patients), and low-dose palliative (less than 45 Gy, 5 patients). Symptomatic response, overall survival, and the effect of prognostic factors on treatment outcome were evaluated. The median follow-up period for survivors was 49 months. Symptomatic response rates were 83% and 79% for the radical and high-dose palliative groups respectively. The estimated median survival time from presentation for all patients was 16.4 months (radical 26.1 months, high-dose palliative 15.7 months). Patients with microscopic residual disease survived significantly longer than patients with macroscopic residual disease (estimated median survival time 30.7 months vs. 14.3 months, p = 0.013). No dose response effect was seen between the radical group and high-dose palliative group. Microscopic residual disease at presentation was the only significant predictor of better survival. The conventionally fractionated course of 50 to 60 Gy was not significantly better in terms of palliation and overall survival than a shorter palliative course of 45 Gy. In future, preoperative chemoradiation should improve outcome by reducing the number of patients with incompletely resected cancer.