Radiotherapy for patients with prostate cancer

Background: Proton radiotherapy (PRT) is a sophisticated treatment modality for prostate cancer. The purpose of this study is to examine clinical results of prostate cancer treated with PRT. Materials and Methods: From Apr 2003 to Oct 2004, 290 males aged 48-85 (average 69) with histologically-proven cT1-3N0M0 prostate cancer (1997 UICC TNM) received PRT. Clinical T stage was classified T1a/T1b/T1c/T2a/T2b/T3a/T3b as 2/3/112/79/38/36/20. Initial prostate specific antigen (PSA) level was distributed 1.2 to 222 (mean 17.8ng/ml). Patients were stratified into three prognostic risk groups: Group A patients had a T1-T2a, PSA50 ng/ml irrespective of T factor. Eighty-three of 170 patients (49%) in group A received PRT with neoadjuvant androgen ablation (NAA) for 6 months, while 100 of 101 (99%) in group B were treated by NAA followed by PRT. All of 19 in group C were treated by NAA, PRT and adjuvant androgen ablation. PRT was planned with a 3D planning system using bilateral 2 fields; patients received 74GyE (gray equivalent, using a relative biologic equivalence factor of 1.1) of protons (190 to 230 MeV) at 2.0 GyE per fraction. GI and GU toxicity was scored according to the RTOG/EORTC Late Morbidity Grading Scale. Overall survival (OS) and biochemical disease free survival rate were calculated by Kaplan-Meier and Log-rank test. Multivariate analysis was examined by Cox proportional hazards model. Results: Five patients died from other disease including brain tumor, gall bladder cancer, cerebral hemorrhage, bronchitis, and pneumonia, in the follow-up period ranging from 53 to 72 months (median 62). Biochemical disease free survival/OS rates at 5 years was 88.2%/96.5% in all cases and was 97.6%/96.4%, 83.8%/97.0%, 52.1%/94.7%, in the group A, B, C, respectively. According to MSKCC risk criteria, 5 year biochemical disease free survival rates in favorable (n = 62)/intermediate (n = 106)/unfavorable (n = 116) were 98.2%/94.8%/76.3%, respectively. T factor, Gleason score, PPPB, PSA, HIBMC, MSKCC risk group were significant in univariate analysis for PSA failure and initial PSA is only prominent in the multivariate analysis. The GI toxicity rates of G0/G1/G2/G3 were 91.0%/4.8%/4.1%/0%, and the GU toxicity rates of G0/G1/G2/G3 were 85.5%/7.9%/5.5%/1.0%, respectively. Conclusions: Our proton radiotherapy showed excellent OS and biochemical disease free survival rates in patients with prostate cancer with minimum late morbidities.