MRI-guided laser ablation shows promise for prostate cancer treatment

A team of researchers at the University of California, Los Angeles (UCLA) has found that focal laser ablation (the precise application of heat via laser to a tumor) is both feasible and safe in men with intermediate-risk prostate cancer. The Phase 1 study found no serious adverse effects or changes in urinary or sexual function six months after the procedure. The technique uses magnetic resonance imaging (MRI) to guide the insertion of a laser fiber into cancerous tumors. When heated, the laser destroys the cancerous tissue.

Related: Laser ablation treatment for prostate cancer has few to no side effects

If the laser technique, known as MRI-guided focal laser ablation, proves effective in further studies—especially using the new MRI-ultrasound fusion machine—it could improve treatment options and outcomes for men treated for such cancers, says study senior author Dr. Leonard Marks, a professor of urology and director of the UCLA Active Surveillance Program. Historically, prostate cancer has been treated with surgery and radiation, which can result in serious side effects such as erectile dysfunction and urinary incontinence.

Up until now, capturing an image of a prostate cancer has been difficult because prostate tissue and tumor tissue are so similar. Precise, noninvasive surgical treatment has proved difficult as a result. However, MRI improves the ability of physicians to perform precise, laser-based treatment. The new fusion-imaging method improves it even further, providing real-time ultrasound that more clearly delineates the tumor. By combining laser ablation with this fusion-imaging technique, the potential of laser ablation grows enormously.

Previous research at UCLA has demonstrated the value of using the same fusion imaging technique to perform biopsies to diagnose prostate cancers in men with rising prostate‐specific antigen (PSA) who had multiple negative conventional biopsies. Such biopsies are usually "blind," meaning physicians take a tissue sample based on what they believe is the location of a possible tumor.

The new study provides proof of principle that laser ablation can be done safely and effectively with MRI. In this case, eight men underwent ablation while in an MRI machine. Although none had serious side effects, longer-term follow-up is needed, as is a continued assessment of appropriate treatment margins to ensure cure, the researchers say.

The second study tested the fusion-MRI procedure on 11 men in a clinical setting. That study found the procedure was well tolerated under local anesthesia and resulted in no side effects. At four months follow-up, there were no changes in urinary or sexual function.

The laser treatment is not yet approved for use in prostate cancer by the FDA.

Full details of the work appear in the Journal of Urology; for more information, please visit http://dx.doi.org/10.1016/j.juro.2016.05.113.