CARCINOMA OF THE PROSTATE - RESULTS OF RADICAL RADIOTHERAPY (1970-1985)

Purpose: To determine the outcome and prognostic factors in patients with localized carcinoma of the prostate treated with external beam radiation therapy. Methods and Materials: A retrospective review of 999 patients with histologically confirmed adenocarcinoma of the prostate treated radically with megavoltage irradiation at the Princess Margaret Hospital between 1970 and 1985. Prognostic factors were analyzed using recursive partitionning method. Results: Overall survival at 5 and 10 years were 69.8% and 40.1% for the whole group. The cause-specific survival rates were 78.9% and 53.5%, respectively. The cause-specific survival rates were significantly different at 10 years by T stage, T1 being 79.0%, T2 66.0%, T3 55% and T4 22%. The overall clinical local control rates was 77% in the first 5 years following treatment. There was no statistically significant difference in the local control rates of T1 and T2 stage disease at 5 years, the combined rate being 88%. Significant differences were observed between other stages, being 76% for T3 and 55% for T4. At 10 years the control rate for T1 tumours was maintained for T1 stage disease (92%) but was significantly reduced for other stages, T2 75%, T3 67% and for T4 37%. In the whole group 33.5% of patients had distant metastases in the first 5 years. The distant relapse rates at 10 years were significantly different by T stage, being 20% for T1, 33% for T2, 55% for T3 and 87% for T4. Multivariate analysis demonstrated that only T stage and histological grade were independent prognostic covariates for cause-specific survival. Age was the only other independent variate in terms of overall survival. The late radiation related morbidity was 2.3% overall; 1.3% affecting rectum and recto-sigmoid and 1.0% arising in the bladder. Conclusion: In terms of survival the results of radiotherapy of intracapsular disease were excellent, but they were less satisfactory in patients with direct extracapsular extension. The assessment of local control was difficult and may have reflected more the lack of local disease progression rather than true local tumor control. The treatment was well tolerated and there were few serious late complications.