Prostate cancer death is unlikely in high-risk patients following quality permanent interstitial brachytherapy

Objective: To evaluate cause-specific survival (CSS), biochemical progression-free survival (bPFS) and overall survival (OS) in high-risk prostate cancer brachytherapy patients.

Patients and methods: From April 1995 to June 2005, 284 patients with high-risk prostate cancer (Gleason score ≥ 8 or prostate-specific antigen > 20 ng/mL or clinical stage ≥ T2 c) underwent brachytherapy. Supplemental external beam radiation therapy was given to 257 (90.5%) patients and 179 (63.0%) received androgen deprivation therapy (ADT). Median follow up was 7.8 years. The median post-implant day 0 D90 was 118.9% of prescription dose. Patients with metastatic prostate cancer or castrate-resistant disease without obvious metastases who died of any cause were classified as dead from prostate cancer. Multiple parameters were evaluated for impact on survival.

Results: Twelve-year CSS, bPFS and OS were 94.2%, 89.0% and 69.7%. On multivariate analysis, bPFS was best predicted by percent positive biopsies and ADT. The analysis failed to identify any predictors for CSS, while OS was highly correlated with patient age, percent positive biopsies and diabetes. Fourteen percent of patients died from diseases of the heart, while 8%, 8% and 6% of patients died from non-prostate cancer, other causes and prostate cancer, respectively. When OS was stratified by patients with 0-3 vs ≥ 4 comorbidities, the 12-year OS was 73.0% and 52.7% (P = 0.036).

Conclusions: High-quality brachytherapy results in favourable bPFS and CSS for high-risk patients. Death from diseases of the heart is more than twice as likely as death from prostate cancer. Strategies to improve cardiovascular health may positively impact OS.