By: Dan Sperling, MD
A new article on focal laser ablation (FLA) by a collaborative team from NYU School of Medicine and the Sperling Prostate Center has been published in the journal Reviews in Urology.[i] The paper covers the principles of FLA, a summary of clinical trials, and the treatment experience from April 2013 to the present. The article was written by a collaborative team from New York University School of Medicine and the Sperling Prostate Center.
Noting the surge in early detection of low-risk disease since the start of the PSA era, the authors point out that many patients may have been overtreated (radical prostatectomy or whole gland radiation) at the expense of urinary and sexual complications. Patients choosing initial active surveillance are at risk of losing a treatment window, and as many as 41% will migrate to RP or radiation.
Clinicians now have the ability, before biopsy, to identify, locate and even characterize clinically significant prostate tumors through means of multiparametric MRI (mpMRI). The authors explain their reasoning, backed by peer-reviewed evidence, that a subset of prostate cancer patients would be candidates for a focal ablation (destruction) of identified clinically significant cancer as a management strategy that destroys the significant tumor, preserves quality of life, and avoids the anxiety of surveillance.
The principles of FLA are explained along three lines:
- How to accurately deliver laser energy to the target tissue,
- How to assure there is sufficient thermal energy for reliable destruction that can be monitored, and
- How to avoid damage to surrounding healthy tissue and neurovascular structures.
A review of studies that demonstrated effective ablation and mechanisms for monitoring the ablation process (MR thermometry) and aftereffects (mpMRI) provides information on the ability to achieve precise placement of the laser fiber, track tissue changes, and verify the zone of destruction. Eight clinical studies are cited, summarizing various approaches of administering FLA, the low-to-no incidence of side effects, and confirmed results. While no long-term efficacy data exists, short-term imaging and medium-term post treatment biopsy results attest to the extreme infrequency of leaving living cancer behind in the treated area.
The authors share their year of study (April 2013-April 2014) of 21 men who underwent focal laser ablation as part of a longitudinal outcomes study. According to the article, selection criteria included
- 10-year life expectancy
- 1-2 focal abnormalities on mpMRI suspicious for prostate cancer
- No Gleason 4 prostate cancer on random TRUS biopsy of the normal-appearing regions of the gland
- Focal abnormality size <15 mm
- No Gleason over 7 upon biopsy of the abnormality
Candidates received extensive counseling on the limited short-term data, and lack of long-term effectiveness data.
A detailed description of the treatment technique used in this study (type of anesthesia, placement of laser fiber, image verification) is provided. The follow-up protocol for each patient includes urinary and sexual function standardized questionnaires (pretreatment, 2 weeks post-treatment, 3 months post-treatment); mpMRI at 3 months post-treatment with 2-4 tissue cores sampled by targeted image-guided biopsy into the ablation zone; and a targeted image-guided biopsy as well as a random 12-core TRUS biopsy at 1 year after treatment.
At the time of writing, 13 patients had undergone a targeted biopsy into the ablation zone. Of these cases, 12 (92.3%) showed no cancer, while 1 patient had residual cancer. To date, no patients showed significant difference from their baseline urinary and sexual function following treatment.
An important point brought out by the authors concerns qualifying candidates for focal treatment. According to the article, “By definition, focal laser ablation mandates visualizing a focal abnormality on mpMRI that is biopsy-proven cancer. By mandating the presence of an imageable target, men with microscopic disease do not qualify as candidates for focal laser ablation.” Put differently, it is essential to identify and treat a significant index lesion, and it is equally important to not overtreat men with microscopic insignificant disease who are candidates for active surveillance.
In closing, the article makes a powerful case for collaboration between urologists and radiologists, who together can bring the best of prostate imaging and prostate cancer knowledge to such precision treatments as FLA. It will be worthwhile to invest the time in establishing such clinical alliances, because with its advantageous features “it is likely that focal laser ablation will be included in the armamentarium of urologists who embrace focal ablation of prostate cancer.”
[i] Lee T, Mendhiratta N, Sperling D, Lepor H. Focal laser ablation for localized prostate cancer: principles, clinical trials, and our initial experience. Rev Urol. 2014;16(2):55-65.