Radiotherapy of prostatic cancer: Stanford University experience

External beam irradiation has been used extensively in the treatment of primary prostatic carcinoma during the past 25 years. Actuarial survival rates of 79%, 58%, and 37% have been achieved at 5, 10, and 15 years, respectively, for patients with disease apparently limited to the prostate (nominal stage A and B; or T0, T1, and T2, status of lymph nodes unknown). The survival rates at the above intervals are 60%, 36%, and 22%, respectively, for patients with extracapsular extension (stage C, or T3 status of lymph nodes unknown). In more highly selected subgroups of patients, e.g., those with nodular lesions 1 cm or less in diameter, the survival stabilized at 80% by the 8th year, with the longest survivors now passing the 15th year. In 113 patients with nodular lesions occupying up to one half of one lobe, the probability of survival is just under 60% at 15 years. In a group of 51 staged Stanford patients, a study of the time to first evidence of metastases was comparable to the surgical group reported by the Uro-Oncology Research Group rather than the radiation therapy group, casting doubt that the difference in outcome between surgery and radiation therapy in stages A2 and B carcinoma of the prostate demonstrated in short-term follow-up by the Uro-Oncology Research Group is necessarily a fundamental observation. Both the clinical stage and the histopathologic grade can be correlated with lymphadenopathy, and lymphadenopathy, in turn, has a profound adverse influence on survival. Other factors which adversely affect survival include a delay in treatment of greater than six months, a radiation dose of less than 6500 rad and/or evidence of ureteral obstruction. The ability to sterilize the primary tumor with external beam irradiation appears related to the bulkiness of the disease, suggesting that, for larger tumors, the achievable dose by external beam therapy alone may be inadequate, and that some form of augmentation, such as the use of radiosensitizers, hyperthermia in conjunction with irradiation, or an interstitial supplement may be required to increase the rate of local sterilization.