Influence of pretreatment and treatment factors on intermediate to long-term outcome after prostate brachytherapy.
ABSTRACT We describe how treatment factors influence biochemical freedom from failure, local control, freedom from metastasis and cause specific survival in patients treated with prostate brachytherapy.
We followed 2,111 men who underwent brachytherapy a median of 6 years (range 2 to 17). Median prostate specific antigen was 7 ng/ml. Of the men 1,455 (68.9%) had clinical stage T2a or less and 1,428 (67.6%) had Gleason score less than 7. A total of 1,171 patients (55.5%) received (125)I, 221 (10.4%) received (103)Pd and 719 (34.1%) received supplemental external beam irradiation combined with (103)Pd. Post-implant dosimetry was done 30 days after implantation with doses converted to the biologically effective dose. Prostate biopsy was done 2 years after permanent prostate brachytherapy in 586 men (27.8%). Survival functions were determined by the Kaplan-Meier method and Cox regression with proportions tested by the log rank test.
The 12-year biochemical freedom from failure rate was 78.6%, and stage, Gleason score, prostate specific antigen and biologically effective dose were significant predictors (p = 0.007, <0.001, 0.005 and <0.001, respectively). In 964 patients at low risk the biochemical freedom from failure rate was 88.1% and significant predictors were hormonal therapy (p = 0.030), prostate specific antigen (p = 0.026) and biologically effective dose (p = 0.003). In 499 patients at intermediate risk the biochemical freedom from failure rate was 79.2% with biologically effective dose a significant predictor (p <0.001). In 648 men at high risk the biochemical freedom from failure rate was 67% and significant predictors were hormonal therapy, Gleason score and biologically effective dose (p = 0.036, <0.001 and 0.012, respectively). The local failure rate was 7.3% with biologically effective dose a significant predictor (p <0.001). Prostate biopsy was positive in 21 of 121 cases (21.5%) for a biologically effective dose of 150 Gy2 or less, in 14 of 248 (5.6%) for greater than 150 to 200 Gy2 and in 3 of 193 (1.6%) for greater than 200 Gy2 (p <0.001). The 12-year freedom from metastasis rate was 95.2% with Gleason score a significant predictor (p <0.001). Cause specific survival at 12 years was 94.5% with Gleason score and biologically effective dose significant predictors (p <0.001 and 0.027, respectively).
Permanent prostate brachytherapy yields excellent long-term oncologic outcomes. High biologically effective dose may need to be delivered to achieve successful biochemical freedom from failure, local control and cause specific survival.
- Brachytherapy 12/2013; · 1.22 Impact Factor
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ABSTRACT: Purpose To demonstrate the feasibility of using high-dose-rate (HDR) brachytherapy to deliver 125% of the prescription dose to the dominant intraprostatic lesion (DIL) as defined on multiparametric MRI while respecting critical organ dose constraints. Methods and Materials Twenty-six patients with biopsy-proven predominantly unilateral prostate cancer consented to a university ethics–approved Phase 2 study of selective dose escalation. Combined information from endorectal T2 MRI sequences, dynamic contrast enhancement, and apparent diffusion coefficient maps was used to contour the DIL and prostate. Images were fused to intraoperative transrectal ultrasound for transposition of the DIL. Treatment consisted of two fractions of 10 Gy HDR brachytherapy to the entire prostate with 12.5 Gy to the DIL, combined with 46 Gy in 23 fractions of external beam radiotherapy. Results All patients had intermediate- or high-risk disease; 25 of 26 had a visible DIL (mean volume, 2.9 cm3; SD, 1.8). Mean percentage of prostate receiving prescription dose (V100) was 98.1% (SD, 1.2). Mean dose to 90% of the DIL was 13.4 Gy (SD, 1.0). The coverage of the DIL was excellent with a mean of 95.7% (SD, 5.0) receiving the planned escalation of 25%. Established dose constraints to rectum and urethra were respected in all cases; where DIL coverage was limited by proximity to urethra or rectum, a mean dose to 90% of the DIL of 12.3 Gy was achieved. Conclusions Modest dose escalation to the DIL (25–30%) using ultrasound-planned HDR brachytherapy is feasible for selected intermediate- and high-risk patients while respecting critical organ constraints and is achievable within the practice setting of a community cancer center.Brachytherapy 01/2014; · 1.22 Impact Factor
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ABSTRACT: Gum arabic-coated radioactive gold nanoparticles (GA-(198)AuNPs) offer several advantages over traditional brachytherapy in the treatment of prostate cancer, including homogenous dose distribution and higher dose-rate irradiation. Our objective was to determine the short-term safety profile of GA-(198)AuNPs injected intralesionally. We proposed that a single treatment of GA-(198)AuNPs would be safe with minimal-to-no evidence of systemic or local toxicity.International Journal of Nanomedicine 01/2014; 9:5001-11. · 4.20 Impact Factor