Dosimetric benefits and preclinical performance of steerable needles in HDR prostate brachytherapy.

Prostate cancer patients with an enlarged prostate and/or excessive pubic arch interference (PAI) are generally considered non-eligible for high-dose-rate (HDR) brachytherapy (BT). Steerable needles have been developed to make these patients eligible again. This study aims to validate the dosimetric impact and performance of steerable needles within the conventional clinical setting. HDR BT treatment plans were generated, needle implantations were performed in a prostate phantom, with prostate volume > 55 cm3 and excessive PAI of 10 mm, and pre- and post-implant dosimetry were compared considering the dosimetric constraints: prostate V100 > 95 % (13.50 Gy), urethra D0.1cm3 < 115 % (15.53 Gy) and rectum D1cm3 < 75 % (10.13 Gy). The inclusion of steerable needles resulted in a notable enhancement of the dose distribution and prostate V100 compared to treatment plans exclusively employing rigid needles to address PAI. Furthermore, the steerable needle plan demonstrated better agreement between pre- and post-implant dosimetry (prostate V100: 96.24 % vs. 93.74 %) compared to the rigid needle plans (79.13 % vs. 72.86 % and 87.70 % vs. 81.76 %), with no major changes in the clinical workflow and no changes in the clinical set-up. The steerable needle approach allows for more flexibility in needle positioning, ensuring a highly conformal dose distribution, and hence, HDR BT is a feasible treatment option again for prostate cancer patients with an enlarged prostate and/or excessive PAI.

Long-term Overall Survival after External Beam Radiotherapy for Localised Prostate Cancer.

AIMS: Knowledge on survival probabilities is essential for determining optimal treatment strategies. We studied overall survival and associated prognostic factors in Dutch patients with localised prostate cancer (PCa) selected for external beam radiotherapy. MATERIALS AND METHODS: For this single-centre retrospective cohort study, we identified all T1-T3 PCa patients (aged 55-80 years) in the radiotherapy planning database with a start date between January 2006 and December 2013, treated with 72-78 Gy in 2 Gy fractions to the prostate ± seminal vesicles (n = 1536). Long-term androgen deprivation therapy (ADT) was predominantly prescribed in the case of extracapsular disease (>T3). Overall survival was estimated using the Kaplan-Meier method. Prognostic factors were evaluated in Cox regression models for the intermediate-risk and high-risk groups. RESULTS: The median follow-up was 12 years for patients who were alive. Ten-year survival rates were 79.0% for low-risk (n = 120), 59.9% for intermediate-risk (n = 430) and 56.8% for high-risk patients (n = 986). A higher age, higher comorbidity score, active smoking and Gleason score ≥8 had a statistically significant negative impact on overall survival at multivariable analysis. ADT was associated with superior overall survival in the high-risk group translating into overall survival rates similar to the intermediate-risk group. CONCLUSIONS: Although PCa patients selected for external beam radiotherapy are typically in good health, their comorbidity score and smoking habits appeared to be dominant predictors for overall survival. Overall survival rates within the high-risk group varied, showing improved overall survival with ADT prescription and worse overall survival in the case of Gleason score ≥8.