[Treatment results with external radiotherapy in prostate cancer]

External irradiation is an accepted curative treatment modality for patients with localized prostatic tumor. The 15-year results in patients treated by radical irradiation alone are presented. The determinant prognostic factors for local tumor control and disease free survival are analyzed.

135 patients with a histologically confirmed localized carcinoma of the prostate were treated at our department from May 1972 to January 1998. Fifty patients received Co-60 therapy; the linear accelerator and high energy photons were utilized in the remaining 80 patients. By tumor stage, 53 patients were B1, 49 B2 and 33 C. The mean follow-up was 61 months (range 1-180). Most patients were exposed to localized fields of irradiation; dose ranged from 50-74 Gy, fractionated at a dose of 180-200 cGy/day.

Overall local tumor control was 77% at 5 years and 73% at 15 years, with a disease free survival of 63% and 45% at 5 and 15 years, respectively. Local tumor control at 13 years was 71% for stage B1, 82% for B2 and 70% for C. The disease free survival at 13 years for stages B1, B2 and C were 46%, 49% and 36%, respectively. The BD and MD tumors had a 15-year disease free survival of 48% vs 32% for the PD tumors (p = 0.005). Patients with PSA < or = 20 ng/ml before treatment showed a disease free survival of 87% vs 48% for those with PSA > 20 ng/ml ((p = 0.011). Multivariate analysis showed dose to be a determinant prognostic factor for local tumor control (0.0432); dose and histological grade were determinants for disease free survival (p = 0.029 and 0.033).

This retrospective study found dose to be a determinant prognostic factor for local tumor control and both dose and histological grade were determinants for disease free survival. Radiotherapy is a therapeutic option for these patients. The results can be enhanced if the dose delivered to the prostate can be increased while maintaining the complication rate within the same ranges.