Background and purpose: To assess local control, survival and toxicity following primary radical external beam radiotherapy of rectal adenocarcinoma treated between 1978 and 1997, and to compare practices and outcomes between the two decades of study.
Patients and methods: A retrospective review of 271 patients who underwent primary radical external beam radiotherapy, without prior or concurrent chemotherapy, was conducted. All patients received radiation doses of at least 40 Gy. Most patients (82%) were followed until death.
Results: Tumor fixation was the only significant prognostic factor for complete response by multivariate analysis. Complete response rates for mobile, partially fixed and fixed tumors were 49, 22 and 9%, respectively. For patients with mobile, partially fixed and fixed tumors, overall 5 year survival was 48, 26 and 6%, respectively, and cancer specific 5 year survival was 59, 33 and 9%, respectively. On multivariate analysis, tumor fixation and CEA higher than 8.7 microg/L at presentation were associated with significantly shortened survival. Outcomes did not change significantly during the two decades of the study. RTOG grade 3 or higher acute (1.8%) and late (1.5%) toxicity occurred only in the first decade of study.
Conclusions: Radical external beam radiotherapy is a reasonable treatment option for rectal carcinoma for patients who are not surgical candidates or refuse surgery. However in patients with fixed tumors in this study, the outcome is poor and treatment should be considered palliative. Severe radiation toxicity is infrequent with current schedules and techniques of radiotherapy.