The following is a summary of “Long-term outcomes of SBRT for PSMA PET detected oligometastatic prostate cancer,” published in the August 2023 issue of Oncology by Mohan et al.
Oligometastatic prostate cancer is a challenging clinical scenario. Researchers performed a retrospective study to analyze SBRT to defer androgen deprivation and may deliver sustained biochemical failure (BF) free survival in selected patients.
This single-institution study evaluated PSMA-PET directed SBRT without initial ADT for oligo-metachronous prostate cancer (PCa). Patients received treatment for bones (24 Gy in 2 fractions) and lymph nodes (30 Gy in 3 fractions). The main outcomes measured were time to biochemical failure, secondary endpoints included time to palliative ADT, toxicity, patterns of failure, and survival. Exclusion criteria were ADT use with SBRT, short disease-free interval, or >3 metastases on PSMA-PET.
The study included 103 patients with oligo-metachronous PCa; the median follow-up was 5 years (November 2014 to December 2019). PSMA-PET directed treatments without initial ADT. The nodal-only disease was observed in 64 patients, bone-only disease in 35, and mixed in 4. About 15% were free of any BF at 5 years (median time to BF: 1.1 years), and 32% (33/103) of patients had further curative-intent radiation treatment following their first BF after SBRT, including subsequent SBRT. About 8 patients underwent potentially curative treatment for their second or third relapse. Allowing for salvage treatment, 29/103 (28%) were biochemically disease-free at the last follow-up. At 5 years, 39% of patients had never received any ADT, and 55% had not started ADT for relapse (median time to ADT for relapse: 5.5 years). There were 2 grade 3 toxicities (rib fracture and lymphoedema) and no local failures.
The study concluded that PSMA-PET guided SBRT for oligo-metachronous PCa recurrence is effective and safe, with over 50% of patients ADT-free at 5 years.