PPP03 Presentation Time: 10:48 AM

Very-high risk [VHR] prostate cancer [PC] is an aggressive subgroup with high risk of distant disease progression . According to a number of studies systemic treatment intensification with docetaxel reduces PC-specific mortality in men receiving external beam radiation therapy [EBRT] with androgen deprivation therapy [ADT]. Whether the addition of chemotherapy to combined modality of radiotherapy (EBRT + brachytherapy [BT] boost) with ADT improves outcomes in this group is unclear. A comparative analysis of the efficacy of EBRT, BT boost and ADT with or without neoadjuvant docetaxel chemotherapy in VHR PC patients. A total of 86 men diagnosed between 2016 and 2020 with VHR prostate cancer were stratified into 2 groups: EBRT plus BT boost and ADT (n = 66) or EBRT plus BT boost, ADT and neoadjuvant docetaxel chemotherapy (n = 20). Conformal EBRT was delivered with conventional fractionation to a total dose of 44-46 Gy to the prostate gland and seminal vesicles and the Ir-192 high-dose rate BT was delivered with one single fraction of 15 Gy. Neoadjuvant docetaxel was administered at 75 mg/m2 every 3 weeks for 4 cycles. A median duration of ADT, consisting of a gonadotropin-releasing hormone agonist, was 24 months. Median age was 66 years (range: 46-81 years). Median follow-up was 65 months (range: 21,5 - 108,7 months). The characteristics of the patient groups are presented in table 1. Six-years progression free survival [PFS] was 80,1% for the group with chemotherapy vs. 77,2% for no-chemotherapy group (p = 0,499). The presence of Gleason score 9-10 was associated with a statistically significant increase in the risk of PC recurrence (p = 0.013). Six-years overall survival [OS] was 100% and 82,8% for groups with and without chemotherapy respectively (p = 0,075). Six-years PC-specific survival [PCSS] was 100% and 93,4% for groups with and without chemotherapy respectively (p = 0,306). There was no statistically-significant difference in PFS, OS and PCSS in VHR prostate cancer patients received EBRT+BT+ADT with or without chemotherapy.