HDR Brachytherapy Plus Stereotactic Ablative Prostate Radiotherapy for Patients With Intermediate and High-risk Prostate Cancer

Dose escalation is nowadays a standard strategy in radiotherapy for prostate cancer. Besides, it is believed that due to the radiobiology characteristics of prostate cells (low alpha/beta ratio), the delivery of higher radiation doses per fraction could theoretically improve the efficacy of the treatment. In this context, the combination of prostate brachytherapy and external beam radiotherapy (EBRT) has proven to be the most effective method of dose escalation significantly improving disease control in randomized clinical trials. Unfortunately, this strategy is also associated with an increased risk of acute and late adverse events compared to conventional EBRT alone. It has been proposed that this increase in adverse events could be related to the use Low-Dose-Rate (LDR) brachytherapy and that High-Dose-Rate (HDR) brachytherapy (a more modern and accurate procedure) could reduce this risk. On the other hand, Stereotactic Ablative Radiotherapy (SABR) is a high-precision radiation technique that allows the delivery of higher doses per fraction in fewer sessions, reducing the total treatment time. The investigators hypothesized that the combination of two highly conformal radiation techniques (HDR brachytherapy and SABR) could be well tolerated, while reducing total treatment time and therefore improving patient quality of life. This is a single arm Phase II clinical trial designed to test the feasibility, tolerability and impact on quality of life of the combination of High-Dose-Rate prostate brachytherapy and SABR for patients with intermediate and high-risk prostate cancer.