For the treatment for intermediate- and high-risk prostate cancer, Cyberknife boost will be used after 4 weeks of intensity modulated radiotherapy to pelvis. The boost doses are 18 Gy and 21 Gy in 3 fractions, respectively. The investigators plan to evaluate the toxicity of two dose groups and decide the appropriate dose for Cyberknife boost. Also, PSA control will be evaluated.

Inclusion Criteria:

• Pathologically confirmed intermediate- or high-risk prostate cancer within 6 months after enrollment
• ECOG performance status 0-1
• Appropriate values of blood tests within 6 months after enrollment Absolute neutrophil count (ANC) ≥ 1500 cells/mm3 Platelets ≥ 50,000 cells/mm3 Hemoglobin ≥ 8.0 g/dl
• Appropriate values of kidney function within 6 months after enrollment Creatinine < 2.0 ng/dL
• Appropriate values of liver function within 6 months after enrollment total bilirubin < 1.5 X maximum normal value alanine aminotransferase or aspartate aminotransferase < 2.5 X maximum normal value

Exclusion Criteria:

• Presence of distant metastasis
• Presence of pelvic LN metastasis
• History of androgen deprivation therapy within 6 months after enrollment
• History of definitive treatment for prostate cancer (e.g., radical prostatectomy)
• History of pelvic irradiation
• Double primary cancer other than skin/thyroid cancer