Long-term outcome for very high-risk prostate cancer treated primarily with a triple modality approach to include permanent interstitial brachytherapy

Abstract Purpose To evaluate outcome in the most unfavorable subset of high-risk prostate cancer patients treated with a combination of supplemental external beam radiation therapy (EBRT) and brachytherapy. Methods and Materials Very high-risk prostate cancer was defined as follows: any Gleason score 10, Gleason score 8–9 with >50% of the biopsy cores positive for malignancy, Gleason score 8–9 with a prostate-specific antigen (PSA) >20 ng/mL, any clinical stage T3, or any PSA >40 ng/mL. One hundred thirty-one patients were identified who met the aforementioned criteria. The median followup was 6.6 years. One hundred twenty (91.6%) patients received supplemental EBRT and 100 (76.4%) received androgen deprivation therapy (median duration, 19.5 months; range, 4–36 months). The median postimplant day 0 D90 (i.e., the minimum percentage of the prescription dose that covers the planning target volume) was 121.9% of prescription dose. Multiple clinical treatment and dosimetric parameters were evaluated for impact on the evaluated survival parameters. Results The median pretreatment PSA and Gleason score were 11.0 ng/mL and 8. One hundred ten (84%) patients had a Gleason score ≥8. At 9 and 12 years, the cause-specific survival, biochemical progression-free survival, and overall survival were 91.0% and 86.5%, 87.3% and 87.3%, and 70.5% and 60.5%, respectively. The most common cause of death was heart disease (22.2%) with deaths from nonprostate cancer (12.7%) and prostate cancer (8.3%) being less likely. Conclusions Permanent interstitial brachytherapy usually with supplemental EBRT and androgen deprivation therapy results in excellent biochemical control and cause-specific survival in the most unfavorable subset of high-risk prostate cancer patients. Death from diseases of the heart was more than twice as likely as death from prostate cancer.