External beam radiation therapy for clinically localized prostate cancer
Radiation therapy is used in approximately one-third of patients newly diagnosed with prostate cancer. External beam radiotherapy alone to doses of 75.6 Gy or higher is appropriate for patients with low risk disease (T1, GS<7, PSA≤10 ng/ml). For intermediate or high risk disease, numerous randomized trials indicate that outcomes are improved by addition of androgen deprivation. In the postoperative setting, Level I evidence supports the use of adjuvant radiotherapy for certain pathologic feature’s (pathologic T3 or positive surgical margins) but debate continues whether early salvage radiotherapy (post-operative PSA <0.5 ng/ml) will be just as effective. Radiation technology continues to improve, with both intensity-modulated and image-guided radiotherapy commonly available. These techniques allow significant reduction in dose to normal tissues, lowering the risk of radiation toxicities. Additionally, this technology has allowed for hypofractionation (fewer, larger treatment fractions) which significantly shorten treatment courses.
