PURPOSE: To prospectively assess the health-related quality of life (HRQOL) and changes in HRQOL during the first year after 3 different treatments for clinically localized prostate cancer. METHODS AND MATERIALS: Ninety men with T1-T2 adenocarcinoma of the prostate were treated with curative intent between May 1998 and June 1999 and completed a quality-of-life Functional Assessment of Cancer Therapy-Prostate (FACT-P) questionnaire before treatment (T0) and 1 month (T1), 3 months (T3), and 12 months (T12) after treatment. Forty-four men were treated with permanent source interstitial brachytherapy (IB), 23 received external beam radiotherapy (EBRT), and 23 men were treated with radical prostatectomy (RP). The mean age of the entire study population was 65.9 years (median 67, range 42-79). The mean pretreatment prostate-specific antigen level of the entire study population was 6.81 ng/mL (median 6.25, range 1.33-19.6). The Gleason score was