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Published on: February 6, 2019
Relapse patterns after low-dose-rate prostate brachytherapy
David S Lamb1, Lynne Greig2, Trevor FitzJohn3
1School of Biological Sciences, Victoria University of Wellington, New Zealand; Radiation Oncology, Southern Cross Hospital, Wellington, New Zealand.
Purpose:
When biochemical failure (BF) develops after low-dose-rate prostate brachytherapy, the relapse site is frequently not found. We set out to find whether prostate-specific membrane antigen positron emission tomography -CT (PSMA PET-CT) scanning has improved knowledge of relapse patterns.
Methods And Materials:
A database was analyzed, which contained information and long-term followup on 903 men who had an iodine-125 seed implant as monotherapy for early-stage prostate cancer. There was a total of 68 BFs.
Result:
In 38 men developing BF before PSMA PET-CT scanning was available, the site of relapse was local in six, distant in twelve, and unknown in twenty. In 30 men developing BF more recently who had a PSMA PET-CT scan, the relapse site was demonstrated in all cases, and 19 (63%) men had relapsed at the prostate base. Radiation dosimetry of base relapses and paired controls demonstrated that implants routinely delivered a lower radiation dose to the base than to the rest of the prostate. Eight of seventeen cases found to have prostate relapse only underwent salvage prostatectomy.
Conclusion:
PSMA PET-CT scanning is highly effective in demonstrating the relapse site(s) when BF develops after low-dose-rate prostate brachytherapy. Knowledge of the relapse site increases management options for men developing BF.
