Prostate brachytherapy implant quality on biochemical control.

Abstract

128 Background: prostate brachytherapy at our institution was analyzed for implant quality on biochemical control. Methods: We treated 368 patients with clinically localized prostate cancer. All patients underwent 1 month CT based dosimetric analysis. Follow up data was available on 289 patients with a minimum follow up of 5 years. Gleason score was 6 in 80% (n=233), and 7 in 20% (n=56). Clinical stage was T1c in 90% of cases (n=260), T2a was 8% (n=23), T2b was <1% (n=3), T2c was < 1% (n=2). The initial prostate-specific antigen was < 10 ng/ml in 95% (n=274), 10.1-20 ng/ml in 5% (15).Patients with low risk disease ( clinical stage T1c, Gleason score 6 with a PSA < 10 ng/ml) n=228. Patients with intermediate risk disease Gleason 7 adenocarcinoma or with a PSA> 10 ng/ml < 20 ng/ml )n= 61. All patients were treated with I (125). All patients underwent a 1-month CT-based dosimetric analysis. The implant dose was defined as the dose delivered to 90% of the prostate volume on post implant dosimetry (D(90)). Results: At minimum follow up of 5 years overall freedom from biochemical failure was 91.4%. For Gleason grade 6 freedom from biochemical failure was 95%. For Gleason grade 7 freedom from biochemical failure was 77%. Based on PSA freedom from biochemical failure for PSA <10 ng/ml at diagnosis was 92 % and for PSA >10 ng/ml and <20 ng/ml was 80%. In patients with low risk disease ( clinical stage T1c, Gleason 6 adenocarcinoma with a PSA < 10ng/ml) the freedom from biochemical failure was 94%. In patients with intermediate risk disease (Gleason 7 adenocarcinoma or with a PSA >10 ng/ml <20 ng/ml ) freedom from biochemical failure was 84%. Patients with optimal dose implants n=264 freedom from biochemical failure was 95%. Patients with suboptimal dose implants n=25 freedom from biochemical failure was 52% Conclusions: With a minimum follow up of 5 years our data support the use of implant alone in low risk prostate cancer patients with a freedom from biochemical failure of 94%. Our data also shows the importance of implant quality in achieving optimal out comes.