Quality control of radiation therapy in multi-institutional randomized clinical trial for localized prostate cancer

The National Prostatic Cancer Project (NPCP) from 1978 through 1985 compared definitive radiation therapy for Stages B2, C, D1 lesions in those who received only radiation treatment to those who received two years of additional cyclophosphamide (Cytoxan) or estramustine phosphate (Emcyt) chemotherapy. Two hundred fifty-four patients were entered and 229 evaluated for compliance of the spatial localization of the prostate through review of the simulation and port films. In 78 per cent this was satisfactory, whereas in 12 per cent it was unsatisfactory, and another 10 per cent were not evaluable. The principle cause of an unsatisfactory rating was failure to adequately cover the prostatic target volume, especially the apex which was found to be variable in location. Routine use of retrograde urethrocystography is urged as part of the localization method in patients to receive definitive external beam radiation therapy for prostate cancer. The role and impact of quality assurance programs for radiotherapy in cooperative clinical study groups is reviewed and discussed.