125Ibrachytherapy in younger prostate cancer patients : Outcomes in low- and intermediate-risk disease.

Abstract

To evaluate local recurrence in younger men treated with low-dose-rate (LDR) 125Ibrachytherapy (BT) for localized prostate cancer. A total of 192patients (≤65-years-old) were treated with LDR 125I-BT± hormone therapy. Local failure was defined as any prostate-specific antigen (PSA) rise leading to salvage treatment or biochemical failure according to the Phoenix definition. Abounce was defined as arise in the nadir of≥0.2 ng/mL followed by spontaneous return. Proportions were compared using Fisher's exact tests; continuous variables using the unpaired t-test or its non-parametric equivalent. Cox proportional hazards models were applied for multivariable survival analysis. Median follow-up was 66months. The 5‑year local recurrence-free survival was 96.1%. Biopsy-proven local recurrence developed in 13patients, 4had aPhoenix-defined recurrence at the last follow-up. Androgen deprivation therapy was started in 1patient without proven recurrence. Univariable risk factors for local recurrence were: at least 50% positive biopsies, intermediate risk, treatment with neoadjuvant hormone therapy, low preimplantation volume receiving 100% of the prescribed dose, and no bounce development. Hormone-naïve patients not attaining aPSA value<0.5 ng/mL during follow-up also had a higher risk of local recurrences. Cox regression demonstrated that the variables "at least 50% positive biopsies" and "bounce" significantly impacted local failure (hazard ratio, HR 1.02 and 11.59, respectively). Abounce developed in 70patients (36%). Younger patients and those treated with alower activity per volume had a higher chance of developing abounce in the Cox model (HR 0.99 and 0.04, respectively). For younger men, LDRBT is avalid primary curative treatment option in low-risk and is to consider in intermediate-risk localized prostate cancer.