Contemporary results of permanent prostate seed implantation (PPI) versus conformal proton beam radiotherapy (CPBRT) to 79Gy.

4639 Background: A recent Phase III randomized trial demonstrated that CPBRT to 79 Gy rendered higher biochemical control (bNED) than 70 Gy (Zietman AL et al. Randomized Trial Comparing Conventional Dose (70.2GyE) and High-Dose (79.2GyE) Conformal Radiation in Early Stage Adenocarcinoma of the Prostate: Results of an Interim Analysis of PROG 95-09. Proceedings of ASTRO, 2004). Our retrospective analysis compares the bNED with PPI +/- external beam radiotherapy (EBRT) +/- short-term neoadjuvant hormonal therapy (nHT) with CPBT to 79 Gy.,Between 6/96 and 12/99 251 consecutive evaluable patients (pts) were treated with PPI at UCSF. Pts were included if pretreatment PSA, Gleason Score (GS) and T stage were available. Twenty-seven percent of pts received nHT, 12% EBRT, and 18% received both prior to PPI, none received long term HT. The median PSA was 6.6 ng/ml with 5% >15, 4% had T3 disease, and 82% had a GS < 7. Biochemical failure was assessed using the ASTRO consensus definition and included the 234 pts with at least 3 follow-up (fu) PSAs. Pts on the CPBT trial were treated between 1996 and 1999 with stages limited to T1b-T2b, PSA to < 15 ng/ml and 75% had a Gleason score (GS) <7. The median PSA was 6.3 ng/ml with no pt receiving nHT. Only the results of the 196 pts treated on 79 Gy arm were compared to our PPI pts.,With a median fu of 60 mos the 5 yr bNED estimate for the pts treated with PPI was 91% (95% CI: 87%-95%). Sixty-eight percent of pts achieved a PSA <0.1 and 90% <0.5ng/ml. Pts treated on the CPBT (med. fu of 48 mos.) appeared to be similar to those treated with PPI. Table 1 below summarizes the outcomes.,This non-randomized comparison suggests that pts treated with PPI +/- nHT +/- EBRT for clinically localized prostate cancer appear to have a bNED rate at least as high as pts treated with CPBT. There does not appear to be a compelling reason to recommend CPBRT as the treatment of choice unless morbidity can be proven to be substantially less. [Figure: see text] [Table: see text].