Clinical Research Directory

PRO-BOOST-LC: Whole-Gland Boost Strategies Versus SBRT Monotherapy in PSMA-Staged Localized and Locally Advanced Prostate Cancer

PRO-BOOST-LC is a prospective, multicenter, randomized clinical trial designed for patients with localized prostate cancer who do not have evidence of lymph node or distant metastases based on modern PSMA PET imaging. Prostate cancer is one of the most common cancers in men. For patients with disease confined to the prostate, radiotherapy is a well-established and effective curative treatment option. Over the past decades, research has shown that delivering higher radiation doses to the prostate can improve cancer control and reduce the risk of disease recurrence. However, higher radiation doses may also increase the risk of side effects affecting urinary, bowel, and sexual function. For this reason, different radiation techniques have been developed to safely deliver higher doses while protecting surrounding healthy organs. Several approaches to radiation dose escalation are currently used in clinical practice. These include stereotactic body radiotherapy (SBRT), which delivers radiation in a small number of highly precise treatments, as well as brachytherapy, where radioactive sources are placed directly inside the prostate for a short time (high-dose-rate brachytherapy) or permanently (low-dose-rate brachytherapy). Although all these approaches are accepted and widely used, it is not known which strategy provides the best balance between cancer control, treatment-related side effects, and long-term quality of life, particularly when modern imaging techniques are used to accurately stage the disease. The PRO-BOOST-LC study aims to directly compare different radiation dose escalation strategies using a standardized treatment framework. All participants enrolled in the study will have localized prostate cancer staged with PSMA PET imaging to exclude metastatic disease. Participants will then be randomly assigned to one of four treatment groups. One group will receive SBRT alone to the prostate. The other three groups will receive a short course of external beam radiotherapy followed by an additional focused radiation boost delivered using one of three methods: high-dose-rate brachytherapy, low-dose-rate brachytherapy, or SBRT. All treatment approaches used in this study are established methods routinely applied in clinical practice. Randomization ensures that each participant has an equal chance of being assigned to any of the treatment groups. This allows the study to fairly compare outcomes between the different strategies. The main objective of the trial is to determine whether adding a radiation boost improves treatment outcomes compared with SBRT alone. The primary outcome measure is failure-free survival, which includes cancer recurrence, disease progression, the need for additional cancer treatment, or death from any cause. Secondary outcomes include the development of distant metastases, overall survival, treatment-related side effects, and patient-reported quality of life. Participants will be closely monitored throughout the study. Before treatment, patients will undergo clinical evaluation, blood tests including prostate-specific antigen (PSA), imaging studies, and quality-of-life assessments. During and after treatment, participants will attend regular follow-up visits. These visits will include clinical examinations, PSA testing, assessment of treatment-related side effects, and completion of standardized questionnaires evaluating urinary, bowel, and sexual function, as well as overall quality of life. Imaging studies, including PSMA PET scans, will be performed when clinically indicated to assess for possible disease recurrence or progression. The study is designed to follow participants for many years in order to capture both early and long-term outcomes. By using modern radiotherapy techniques, standardized treatment protocols, and comprehensive follow-up, PRO-BOOST-LC aims to generate high-quality evidence that will help guide future treatment decisions for patients with localized prostate cancer. The results of this trial are expected to improve understanding of how best to use radiation dose escalation to maximize cancer control while minimizing side effects and preserving quality of life in the era of advanced imaging and precision radiotherapy. Participation in this study does not involve experimental or unproven treatments. All radiation techniques used in PRO-BOOST-LC are approved, widely available, and considered standard of care in many treatment centers worldwide. The study focuses on optimizing how these existing techniques are combined and delivered, rather than introducing new drugs or devices. Participation may involve additional follow-up assessments and questionnaires compared with routine care, but treatment decisions are made within established clinical practice guidelines. Patients may or may not directly benefit from participation, but the information gained from this study may help improve future treatment strategies for men with localized prostate cancer.

PRO-BOOST-N: Prostate-First Versus Combined Prostate and Nodal Dose Escalation in PSMA PET-Staged Node-Positive Prostate Cancer

Patients with prostate cancer and pelvic lymph node involvement (cN1M0) identified on PSMA PET imaging represent a biologically aggressive yet potentially curable disease population. Contemporary management relies on multimodality treatment combining definitive radiotherapy to the prostate and pelvic lymph nodes with long-term androgen deprivation therapy (ADT), often intensified with androgen receptor pathway inhibitors. Despite these advances, a substantial proportion of patients still develop distant metastatic disease, highlighting the need to optimize local-regional treatment strategies in the era of molecular imaging. The introduction of PSMA PET has fundamentally altered staging accuracy in prostate cancer, enabling earlier and more precise detection of pelvic nodal disease. However, most existing evidence guiding radiotherapy dose prescription in node-positive prostate cancer originates from the pre-PSMA era. As a result, it remains unclear how best to integrate prostate-directed and nodal-directed dose escalation strategies when disease extent is defined by modern molecular imaging. In particular, it is unknown whether long-term disease control is primarily driven by durable intraprostatic tumor eradication, by aggressive treatment of involved lymph nodes, or by a combination of both. PRO-BOOST-N is a prospective, multicenter, randomized phase II/III clinical trial designed to address this critical evidence gap. The trial evaluates prostate-first versus combined prostate and nodal dose escalation strategies in patients with PSMA PET-staged node-positive (cN1M0) prostate cancer treated within a standardized ultrahypofractionated whole-pelvis radiotherapy framework. All enrolled patients indicated for definitive treatment undergo mandatory baseline PSMA PET/CT to confirm pelvic lymph node involvement and exclude distant metastatic disease. All patients receive a uniform radiotherapy backbone consisting of ultrahypofractionated whole-pelvis radiotherapy delivered in five fractions, combined with long-term ADT. Use of androgen receptor pathway inhibitors is permitted and encouraged according to contemporary clinical practice and local availability, ensuring the relevance of the trial to real-world treatment settings. Using a 2×2 factorial randomized design, PRO-BOOST-N evaluates two independent treatment factors. The primary randomized comparison assesses whether ablative prostate dose escalation improves oncologic outcomes compared with contemporary SBRT-based definitive prostate radiotherapy without additional boost. Prostate dose escalation may be delivered using one of three protocol-defined modalities-high-dose-rate brachytherapy, low-dose-rate brachytherapy, or single-fraction SBRT-according to institutional expertise. This comparison directly tests the hypothesis that durable intraprostatic disease control is the dominant determinant of long-term systemic disease suppression in node-positive prostate cancer. The key secondary, hierarchically tested comparison evaluates the role of nodal dose escalation by comparing two predefined dose levels delivered to PSMA PET-positive pelvic lymph nodes. These dose levels reflect intermediate versus higher nodal boost strategies based on biologically effective dose concepts specific to prostate cancer radiobiology. To ensure patient safety and protocol feasibility, organ-at-risk-driven nodal dose de-escalation is permitted within the higher-dose arm, without altering randomization assignment. The primary endpoint of the trial is metastasis-free survival. Secondary endpoints include overall survival, radiographic progression-free survival assessed primarily using PSMA PET imaging, intraprostatic and regional nodal control, time to castration-resistant prostate cancer, time to next systemic therapy, treatment-related toxicity graded according to CTCAE version 5.0, and patient-reported outcomes assessing urinary, bowel, sexual, and global quality of life. By prospectively and hierarchically evaluating prostate and nodal dose escalation strategies within a modern PSMA PET-guided and ultrahypofractionated radiotherapy platform, PRO-BOOST-N aims to define the optimal radiotherapy intensification approach for patients with node-positive prostate cancer. The results of this study are expected to directly inform clinical practice, guideline development, and future treatment individualization in the PSMA PET era.