Abstract
PURPOSE: This study aimed to investigate the effects of dose escalation through focal boost (FB) to intraprostatic lesions (IPLs) as well as the role of gallium-68 prostate-specific membrane antigen positron-emission tomography ((68)Ga-PSMA-PET/CT) for staging and treatment planning in patients with Gleason score (GS) 10 prostate cancer (PCa) receiving definitive radiotherapy (RT) and androgen deprivation therapy (ADT). MATERIALS AND METHODS: We retrospectively analyzed data of 92 patients with GS 10 PCa who underwent definitive RT and ADT from March 2010 to October 2022. Freedom from biochemical failure (FFBF), prostate cancer-specific survival (PCSS), distant metastasis-free survival (DMFS), and overall survival (OS) rates were calculated using the Kaplan-Meier method. Survival outcomes were compared between patients staged with (68)Ga-PSMA-PET/CT and those staged with conventional imaging modalities as well as between those who received a simultaneous integrated boost (SIB) and those who did not. RESULTS: At a median follow-up time of 73 months, the 5‑year FFBF, PCSS, DMFS, and OS rates were 59.2%, 77.0%, 62.9%, and 67.6%, respectively. Disease progression was observed in 39 patients (42.4%), with most cases manifesting as distant metastasis (DM). A total of 56 patients (60.9%) were staged using (68)Ga-PSMA-PET/CT, while 43 patients (46.7%) received FB to IPLs. Patients staged with (68)Ga-PSMA-PET/CT had better FFBF and PCSS compared to those staged with conventional imaging. Patients undergoing an SIB had improved PCSS and DMFS. In the multivariable analysis, an ADT duration of 18 months or more was associated with improved FFBF, PCSS, DMFS, and OS. Application of an SIB was an additional independent predictor for improved FFBF, while staging with (68)Ga-PSMA-PET/CT was associated with better PCSS. CONCLUSION: We found that long-term ADT, increasing the radiation dose to primary tumor, and staging with (68)Ga-PSMA-PET/CT improved clinical outcomes. Additional research is needed for validation.