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 percent 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 31 months:

  • 3-year PSA relapse-free survival (RFS) was 60 percent.
  • Both therapies were similar.
  • RFS was 39 percent for those with PSA doubling times of less than 1 year vs. 72 percent for those with PSA doubling times of a year or more.
  • there were 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 stereotactic body radiation therapy (SBRT; see this link), biochemical RFS was 82 percent at 2 years, and ADT was not used. The National Institutes of Health will soon begin recruitment for a clinical trial of salvage SBRT (NCT03253744), which includes detection using the DCFPyL PET/CT scan — 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.

Editorial note: This commentary was written by Allen Edel for The “New” Prostate Cancer InfoLink.

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