Clinical experience with supervoltage radiotherapy in carcinoma of the prostate: a preliminary report.

A review was done on 88 cases of carcinoma of the prostate treated with supervoltage radiotherapy and evaluated at regular intervals with post-treatment needle biopsies. A disturbing 58 per cent (45 of 77 cases) had histologic evidence of residual carcinoma at 1 year post-radiation. In 47 per cent (21 of 45 cases) of patients receiving 7,000 to 7,500R the biopsies were positive. No undue morbidity was experienced with radiation levels at 7,000R. Prostatic needle biopsy is considered mandatory for adequate clinical evaluation post-radiation. Since 41 per cent of patients judged radioresponsive on rectal palpation had positive biopsies at 12 months the data indicate considerable error in the clinical assessment of the irradiated prostate when reliance is placed solely on digital evaluation.