Focal Laser Ablation of Prostate Cancer: Phase I Clinical Trial

Focal laser ablation is an investigational technique to treat prostate cancer in a region confined manner via a process known as coagulation necrosis. It heavily relies on localized heating of the prostate via a fiber coupled infrared laser. Some advantages of FLA is that it can control cancer with little treatment in regards to morbidity, and does not need the use of general anesthesia. This phase I trial study examines the safety of transrectal magnetic resonance imaging guided (in-bore) focal laser ablation in men with intermediate risk prostate cancer.

The patients in the trial were 8 men, age 58 to 72 years with intermediate risk prostate cancer, diagnosed by magnetic resonance-ultrasound fusion biopsy. Focal laser ablation was performed by inserting a cylindrically diffusing, water cooled laser fiber into magnetic resonance visible regions of interest, followed by interstitial heating at 10 to 15 W for up to 3 minutes. Secondary safety monitors were inserted to assess the accuracy of magnetic resonance thermometry. Comprehensive magnetic resonance-ultrasound fusion biopsy was performed after 6 months. Adverse events and health related quality of life questionnaires were recorded.

The results of the phase 1 clinical trials revealed that focal laser ablation was successful in all 8 subjects. This is because no grade 3 or greater adverse events occurred, and no changes in International Prostate Symptom Score or International Index of Erectile Function 5 were observed. Ablation zones, as measured by post treatment magnetic resonance imaging, had a median volume of 3 cc or 7.7% of prostate volume. The quality of life questionnaires (I-PSS and SHIM) showed no statistically significant changes in either metric was observed after 6 months (p>0.05). Prostate specific antigen decreased in 7 men (p<0.01).

In conclusion, the investigators determined that focal laser ablation of the prostate is safe procedure done in men with intermediate risk prostate cancer. This is because there are no series adverse events or significant changes in urinary or sexual functions at 6 months. The comprehensive biopsy follow-up indicates that larger treatment margins than previously thought necessary may be required for complete tumor ablation. Future studies are needed to establish FLA as an acceptable treatment alternative, such as its long-term efficacy, which patients may be the best candidates, and patient satisfaction. Overall, the results of this paper justifies further research for FLA, and hopefully translating it into a conventional clinically procedure in the future.

Authors: Shyam Natarajan, Steven Raman, Alan M. Priester, James Garritano, Daniel J. A. Margolis,* Patricia Lieu, Maria L. Macairan, Jiaoti Huang, Warren Grundfest and Leonard S. Marks†

Affiliations: Department of Urology (SN, PL, MLM, LSM), Department of Bioengineering (SN, AMP, JG, WG), Center for Advanced Surgical and Interventional Technology (SN, AMP, JG, WG, LSM), Department of Radiology (SR, DJAM) and Department of Pathology (JH), University of California, Los Angeles, Los Angeles, California

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Reference:

Lindner U, Weersink R, Haider M et al: Image guided photothermal focal therapy for localized prostate cancer: phase I trial. J Urol 2009; 182: 1371.
McNichols R, Kangasniemi M, Gowda A et al: Technical developments for cerebral thermal treatment: water-cooled diffusing laser fibre tips and temperature-sensitive MRI using intersecting image planes. Int J Hyperthermia 2004; 20: 45.

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