Purpose: We analyzed results of conformal proton radiation therapy for localized prostate cancer, with emphasis on biochemical freedom from relapse.
Methods and materials: Analyses were performed for 1255 patients treated between October 1991 and December 1997. Outcomes were measured on primarily in terms of biochemical relapse and toxicity.
Results: The overall biochemical disease-free survival rate was 73%, and was 90% in patients with initial PSA <or=4.0; it was 87% in patients with posttreatment PSA nadirs <or=0.50. Rates dropped with rises in initial and nadir PSA values. Long-term survival outcomes were comparable with those reported for other modalities intended for cure.
Conclusions: Conformal proton radiation therapy at the reported dose levels yielded disease-free survival rates comparable with other forms of local therapy, and with minimal morbidity. Dose-escalation strategies are being implemented to further improve long-term results.