Low-dose salvage brachytherapy after first-line EBRT

The potential to use some form of second-line radiation therapy after failure of first-line radiation therapy has long been intriguing, and is highly dependent on the dose and precise volume of the target of first-line radiation therapy. To date there had been almost no published reports of the results of such salvage radiation therapy, although we are aware that there have been a gradually increasing number of clinical cases of such therapy — in various forms — being practiced out in the real world.

A recent, brief, retrospective report from Chang and Buyyounouski has provided outcomes data from five patients who received salvage brachytherapy for locally persistent prostate cancer after prior failure of treatment with dose-escalated external beam radiotherapy (EBRT).

All five patients

  • Were confirmed, by biopsy, prior to salvage therapy, as having local persistence of prostate cancer in only one lobe of the prostate (unilateral disease)
  • Were treated with unilateral, low-dose-rate brachytherapy administered through the implantation of permanent iodine-125 seeds (i.e., brachytherapy was used to treat only the lobe of the prostate in which the cancer persisted)

According to the authors:

  • Median patient follow-up was 41 months.
  • 5/5 patients (100 percent) were free of biochemical recurrence after salvage therapy.
  • The patients’ median post-salvage PSA level was 0.4 ng/ml.
  • 5/5 patients (100 percent) had low rates of acute genitourinary and gastrointestinal toxicities.
  • 3/5 patients (60 percent) exhibited an increased level of erectile dysfunction post-salvage therapy.

The authors conclude that this type of salvage radiation “appears to be a feasible option” in “carefully selected patients with local persistence of disease”, but also note that “Further study is needed to determine long-term results of this approach.”

This report provides concrete evidence that salvage radiation therapy is an effective and safe possibility after first-line radiation therapy for at least some patients. The full scope of the applicability of salvage radiation therapy after first-line radiation still needs to be explored because there is a wide range of potential opportunities under which to apply such salvage radiation therapy of different types.

Patients should be aware that repeat radiation therapy of any type is only going to be possible in a subset of men who fail first-line radiation therapy. The primary dangers associated with repeat radiation therapy come from being given an overly high total dose of radiation therapy to a specific area of the body over time, which can lead to both serious undesirable side effects and, perhaps even more importantly, initiation of secondary cancers.

One Response

  1. Focal salvage radiation in the form of LDR brachytherapy, HDR brachytherapy, and SBRT has been used effectively for primary radiation failure. In well-selected patients, it has been safe and effective. Like all kinds of salvage therapy, including radiation after RP failure, the main danger is increased urinary and rectal toxicity. (I have never seen reports of secondary cancers.) While focal salvage can restrict toxicity, local failures that are close to the rectum, bladder neck, or neurovascular bundles can be especially hard to re-treat without incurring toxicity.

    Fortunately, with innovations in dose escalation, combo therapy, and hypofractionation, local failures have been low. Katz recently reported that 20% of his SBRT failures were local, 80% distant. Innovations in PET and mpMRI imaging have helped identify local recurrences and define areas for focal re-treatment.

    Of course, focal ablation has been utilized as well. I would love to see a trial of protons used for this, which has not been yet done, to my knowledge. Perhaps even better would be the carbon ion therapy only available in Heidelberg and Japan.

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