After failure of first-line radiation, both kinds of salvage brachytherapy are equally effective

A group of researchers at Memorial Sloan Kettering Cancer Center (MSKCC) reported in 2014 (see this link) on the outcomes of 42 patients with radio-recurrent prostate cancer treated with salvage high dose rate brachytherapy (sHDR-BT). The results were quite good - over two thirds had no evidence of further recurrence as of 5 years, and grade 3 toxicity (serious, requiring treatment) was limited to one patient with late-term urinary incontinence. Kollmeier et al. have now updated their results and compared them with outcomes of men treated with salvage low dose rate brachytherapy (sLDR-BT).

All patients were treated between 2003 and 2015, and all salvage treatments were whole gland, not focal or hemi-gland.

• 37 patients received sLDR-BT
• 61 received sHDR-BT
• 45% received adjuvant androgen deprivation therapy (ADT)
• All patients were screened for distant metastases with a CT or MRI and a bone scan at least
• All patients had biopsy-confirmed cancer in the prostate

After a median follow-up up 31 months:

• 3-year PSA relapse-free survival (RFS) was 60%
• Both therapies were similar
• RFS=39% for those with PSA doubling times (PSADT) less than 1 year vs. 72% for those with PSADTs of a year or more.
• No statistically significant differences in urinary or rectal toxicity between the two therapies: most returned to baseline function.
• sLDR-BT had a higher rate of acute urinary toxicity
• Erectile function was not measured because of high rates of pre-existing impotence and ADT usage

In the Fuller study of salvage SBRT (see this link), bRFS was 82% at 2 years, and ADT was not used. NIH will soon begin recruitment for a clinical trial of salvage SBRT (NCT03253744), which includes detection using the DCFPyL PET/CT - the best of the new generation. Dr. Kollmeier mentioned that MSKCC has treated a few select patients with salvage SBRT as well. They are also looking at using a more tailored approach: adding systemic therapy for higher grade recurrences and focal/hemi-gland treatment for less aggressive cases. MSKCC is on the leading edge of using the new generation of PET/MRI scans which will undoubtedly improve patient selection going forward.