Protocol for Evaluating the Efficacy and Safety of Radiotherapy for Prostate and Oligometastatic Lesions in Patients With Low-Burden Sensitive Oligometastatic Prostate Cancer: An Open, Exploratory Pilot Clinical Trial

Introduction The existing large prospective study demonstrates the benefits of primary radiotherapy in patients with low-volume oligometastatic prostate cancer (OMPC), and there is additional evidence of the benefits of local metastasis-directed therapy (MDT) for metastatic lesions. However, there are no results from a prospective study to demonstrate the efficacy of radiotherapy for prostate and oligometastases. Therefore, the aim of the protocol is to illustrate the efficacy of radiotherapy for prostate and oligometastatic lesions in patients with low-volume de novo hormone-sensitive OMPC. Methods and analysis This study involves a prospective, single-center, limited-sample, single-arm exploration of radiotherapy for prostate and oligometastatic lesions in patients diagnosed with low-volume hormone-sensitive OMPC. Eligible participants undergo thorough assessments and treatment involving endocrine therapy alongside radiation targeting metastatic lesions and the pelvic region. The primary site is treated with volumetric modulated arc therapy (VMAT), while metastatic sites are treated with either VMAT or stereotactic body radiation therapy (SBRT) depending on their location. All patients received radiation therapy for both the primary and metastatic lesions combined with endocrine therapy. Endocrine therapy with an antiandrogen (bicalutamide, for 4 weeks) androgen deprivation therapy combined with novel hormonal agents (acetate abiraterone) will be continued for 2 years. The primary objective is to evaluate progression-free survival-2 (PFS-2), while secondary endpoints include androgen deprivation therapy (ADT)-free survival, quality of life (QoL), overall survival, time to castration-resistant prostate cancer (CRPC), radiation-related complications, and endocrine therapy-related adverse events. Ethics and dissemination Approval was obtained from the ethics committee of the First Affiliated Hospital of Naval Medical University (CHEC2023-220). This is a single-arm exploration pilot trial evaluating radiotherapy for prostate and oligometastatic lesions in patients with OMPC. It aims to disseminate its findings through peer-reviewed journals and relevant medical conferences, with the intention of publication and presentation at these events. Trial registration numbers Clinicaltrials.gov identifier NCT06198387.