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Long-term survival in men with Gleason score 9-10 treated with prostate brachytherapy and external beam irradiation

Login to Access Video or Poster Abstract: MP05-06
Sources of Funding: none

Introduction

Very high grade prostate cancer is associated with poor outcomes. We report on the long-term outcomes of men with Gleason score (GS) 9-10 prostate cancer treated by prostate brachytherapy (PSI) and external beam irradiation (EBRT).

Methods

Of 1981 men who were treated by PSI and followed 5-22 years (mean 10), GS was ≤6 in 1304 (65.8%), 7 in 466 (23.5%), 8 in 142 (7.2%) and 9-10 in 69 (3.5%). Men with positive bone or CT scans were excluded from implantation. 3 months of hormone therapy (NHT) was followed by Pd-103 implant to the prostate (dose 100 Gy) and 2 months later 45 Gy of conformal or image guided EBRT. NHT was given a median of 9 months. Within 2 months after treatment CT-based dosimetry was done with radiation doses converted to the biologic effective dose (BED). Biochemical freedom from failure (BFFF) was computed by the Phoenix definition, freedom from metastasis (FFM) in men with BF by absence of a positive bone or CT scan and cause-specific survival (CSS) by freedom from death in men with clinical recurrence. Association of risk features to GS 9-10 were compared by chi-square and linear regression (LR). Survival was computed by Kaplan-Meier estimates with comparisons by log rank and Cox hazard rates (HR).

Results

Mean age was 65.6 years (median 66, range 39-85); mean PSA was 9.4 ng/ml (median 6.7, range 0.3-300) and mean BED 194.6 Gy (median 200, range 15-299). Median BED for GS9-10 was 199 Gy2. BFFF, FFM and CSS by GS are shown in the table. The mean survival time for the 4 GS groups was: 1) 21.5 years (95%CI 21.2-21.8), 2) 19.2 years (95%CI 18.6-19.7), 3) 18.1 years (95%CI 17.2-19.1) and 4) 13.9 years (95%CI 13.1-14.8, p<0.001). Only clinical stage was associates with CSS with 15-year survival for ≤ T2a 100%, T2b-c 40.5% and T3 0% (p=0.025). Cox HR for CSS was significant for stage (p=0.055, HR 2.0) and BED (p=0.081, HR 0.985).

Conclusions

PBI combined with EBRT has excellent 15-year survival in men with GS 9-10 and clinical stage ≤ T2a. While 68% of men with T3 GS9-10 are alive at 10 years, at 15-year survival was 0. These men should be considered for alternate treatment strategies, possibly with early systemic therapy.

Funding

none

Authors
Nelson Stone
Richard Stock
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