External beam radiation monotherapy for prostate cancer

Background: To clarify the implications and limitations of external beam radiation monotherapy for localized prostate cancer, the long-term outcomes and prognostic factors were investigated. Methods: Between 1976 and 1994, 91 patients with untreated prostate cancer were treated with external beam radiation therapy alone. Thirty-two were classified as T1b, eight were T2a, four were T2b and 47 were T3. Pelvic lymphadenectomy was carried out in 69 cases; 57 were staged as pN0, eight were pN1, four were pN2 and 22 were pNX. Linac X-rays were used in 55 cases, fast neutron in 15 and a combination of the two in 21. No other therapy was given until relapse and when relapse was evident endocrine therapy was started. Results: The observation period ranged from 3 to 206 months with a median of 78 months. Local control rate and disease-free, cause-specific and overall survivals at 10 years were 74.0, 49.6, 74.2 and 39.2%, respectively. By univariate analysis, T category, pN category and histologic grade were significant prognostic indicators for disease-free survival. Multivariate analysis revealed that T category was an independent prognostic factor. In T2b and T3 diseases, pN0/1 patients demonstrated significantly better disease-free survival than pNX. Conclusions: A favorable long-term outcome was achieved by external beam radiation monotherapy in patients with minimally extended prostate cancer (T1b and T2a). For locally advanced disease (T2b and T3), staging pelvic lymphadenectomy would be useful for the selection of patients.