Salvaging failed radiation therapy: does the tumour location permit a less toxic approach?
Version of Record online: 4 JUL 2013
© 2013 BJU International
Volume 112, Issue 3, pages 279–280, August 2013
How to Cite
Davis, J. W. and Choi, S. (2013), Salvaging failed radiation therapy: does the tumour location permit a less toxic approach?. BJU International, 112: 279–280. doi: 10.1111/bju.12296
- Issue online: 4 JUL 2013
- Version of Record online: 4 JUL 2013
In the introduction to their manuscript in this issue of the BJUI, Meeks et al.  outline a significant challenge for physicians managing prostate cancer: from the estimated 240 000 diagnosed annually (USA) to the 120 000 choosing radiation, to the 40 000 estimated biochemical failures in the first 5 years who may benefit from additional local therapy to avoid local and/or systemic progression. The basis of these calculations was from conventional beam radiation , and although we expect dose-escalation strategies to perform better, the ideal management strategy remains to be identified. Indeed, Zelefsky et al.  showed that there was a higher risk of metastatic disease with external beam radiation therapy than with surgery for high-risk prostate cancer, although there was some confounding of the results due to the differences in salvage treatment. This confounding may be the key point: more acceptable salvage options may promote optimal local control and fewer progressions.
Certainly, the concern with salvage therapy after failed radiation is the toxicity, and the concept of achieving less urinary incontinence with cryotherapy or even focal cyrotherapy is attractive, as outlined by de Castro Abreu et al.  in this issue. In their parallel cohorts of total and focal salvage cryotherapy, urinary incontinence occurred in three (13%) of the 25 salvage total and zero of the 25 salvage focal therapies, and there was only one fistula in either series. However, the cancer control outcomes are different among these non-randomised and non-comparable cohorts: 87% disease-free survival for patients with bilateral disease treated with total cryotherapy and 54% disease-free survival for patients with unilateral disease treated with focal cryotherapy. These comparisons are limited, but one could hypothesise that salvage total therapy has improved disease control over salvage focal therapy.
Returning to the Meeks et al.  study, a cohort of 198 patients with biopsy confirmed radiation recurrence underwent a salvage prostatectomy at a single institution. Pre-treatment biopsies showed 48% and 13% Gleason sums 7 and 8–10, respectively, and multifocal location in 61% (92/151 patients). Salvage prostatectomies showed 56% advanced pathological stage and 35% Gleason 8–10, and multifocal location in 57%. In comparing specific biopsy locations to radical prostatectomy mapping, undetected cancers from biopsy ranged from 12% to 26%, and 58% upgrading. In patients with unilaterally localised biopsies, final pathology was unilateral in only half – a statistic that matches the PSA failure rate from focal therapy in the de Castro Abreu et al.'s  study. The authors point to a non-radiated biopsy-to-prostatectomy study and by comparison conclude that the accuracy of biopsy in radiated prostates is actually greater, perhaps due to the smaller radiated gland. But let's be clear – both groups had significant rates of multifocal disease and inaccuracies between biopsy and radical prostatectomy.
These two BJUI studies provide a developing agenda of what we know and do not know about salvage therapy for failed radiation:
- Local failure after radiation selects patients who probably have significant disease in terms of volume, stage, and grade, and should not be confused with the over-detection of low-volume, low-grade disease seen in primary treatments for PSA-screened disease.
- Salvage focal therapy for unilateral disease by biopsy may be less morbid but may be only 50% effective.
- The link between metastatic progression and PSA failure after failed salvage focal therapy is unknown, and completion treatment of the other side could be studied.
- The additive accuracy of post-radiation biopsy plus imaging is not established.
- We are basing most of our treatment recommendations on tumour morphology (histopathology, location, size) and surrogates (PSA failure definitions) rather than biology and survival.
- The current management of post-radiation local failure should consider total gland treatments as the standard and focal therapies as experimental.