External-Beam Radiotherapy for Localized or Locally Advanced Prostate Cancer in Japan: A Multi-Institutional Outcome Analysis

Background: The outcomes of patients with localized or locally advanced prostate cancer treated with external-beam radiotherapy are not well known in Japan. Methods: Thirty-four institutions combined data on 679 patients with localized or locally advanced prostate cancer treated with a total dose � 60 Gy between 1995 and 2002. Results: With a median follow-up of 46 months, the 5-year overall, clinical progression-free, and biochemical relapse-free survival rate were 93.0, 95.3 and 71.9% for all patients, respectively. The 5-year progression-free, and biochemical relapse-free survival rates according to the risk group were 100%, 90.8% in the low-risk group, 98.3%, 75.7% in the intermediate-risk group and 93.6%, 67.6% in the high-risk group, respectively. The multivariate analysis for biochemical relapse-free survival revealed that prostate-specific antigen (relative risk, 1.002; 95% CI, 1.001 –1 .003; P ¼ 0.0041), Gleason score (relative risk, 1.166; 95% CI, 1.046 – 1.302; P ¼ 0.0055), T classification (relative risk, 2.897; 95% CI, 1.999–4.230; P ¼ 0.0000), pelvic irradiation (relative risk, 2.042; 95% CI, 1.328–3.273; P ¼ 0.0008), and androgen abletion (relative risk, 0.321; 95% CI, 0.240 –0 .427; P ¼ 0.0000) were significant prognostic factors. Only 1.1% of patients experienced late morbidity of Grade 3. Conclusion: Radiotherapy for prostate cancer seemed to be effective, with little risk of normal tissue complications.