Purpose: To assess the difference in biochemical freedom from relapse (BFR) between patients with clinically localized prostate cancer having Gleason Grade (GG) 3 + 4 vs. 4 + 3 disease treated with permanent prostate brachytherapy (PPB).
Methods and materials: One thousand twenty-nine consecutive T1/T2 patients underwent PPB with Gleason sum 6, 7, or 8 adenocarcinoma of the prostate. Treatment consisted of transperineal ultrasound-guided implant as monotherapy or in combination with external beam radiation and/or neoadjuvant androgen ablation (NAAD). The Kattan modification of the ASTRO consensus definition that censors patients with rising follow-up PSA values early was used to measure BFR. Kaplan-Meier actuarial survival was calculated and compared using the log-rank test. Cox proportional hazards regression was performed to assess the role of Gleason grade, initial PSA value, stage, the addition of external beam radiotherapy, and the addition of NAAD.
Results: The median follow-up for all 1029 patients is 46 months (range: 3-108 months) with a BFR at 5 years of 78.2% and at 7 years of 76.2%. The 7-year BFR for patients with GG 3 + 3 was 81.8%, GG 3 + 4 was 78.4%, GG 4 + 3 was 56.7%, and GG 4 + 4 was 50.7% (p < 0.0001). Cox regression analysis identified that the Gleason grade (p < 0.0001), initial PSA value (p = 0.001), D90% (p < 0.0001), and clinical stage (p = 0.016) were associated with biochemical recurrence, whereas NAAD (p = 0.057) and external beam radiotherapy (p = 0.356) were not.
Conclusions: Gleason sum 7 tumors in patients treated with PPB represent a heterogeneous group of patients based on the differentiation of Gleason Grade 3 + 4 tumors vs. 4 + 3 disease. This information confirms similar conclusions identified in patients treated with external beam radiation and is useful when determining prognosis after PPB.