Conformal proton beam therapy of prostate cancer - update on the Loma Linda University Medical Center experience

643 patients with localized prostate cancer were treated with protons alone or a combination of protons and photons. All treatment was planned on a 3-D planning system and all received doses between 74-75 CGE(Cobalt Gray Equivalent) at 1.8-2.0 CGE/day. Patients were evaluated for toxicity and response to treatment. Results: Five-year actuarial clinical and biochemical disease-free survival rates for the entire group are 89 and 79% respectively. A statistically significant difference in biochemical disease-free survival was seen between patients in the 'early' (T1b-2b, PSA<15) and 'advanced' (T1b-2b, PSA>15 or T2c-T4, PSA<50) subgroups (89% vs. 68% at 4.5 years, p<0.001). A PSA nadir of less than 0.51 ng/ml predicted for the highest chance of freedom from biochemical recurrence. Minimal radiation proctitis was seen in 21% of patients; toxicity of greater severity was seen in less than 1%. (orig.)