Focal therapy may be viable option for low-grade prostate cancer

April 1, 2009

Focal therapy for prostate cancer has been surrounded by controversy due to the multifocal nature of the disease. Emerging evidence for a biologically dominant or index tumor, however, has the potential to shift the paradigm to focal therapy in carefully selected patients, according to experts speaking at the Medical Innovation Summit at Cleveland Clinic.

Cleveland-Focal therapy for prostate cancer has been surrounded by controversy due to the multifocal nature of the disease. Emer-ging evidence for a biologically dominant or index tumor, however, has the potential to shift the paradigm to focal therapy in carefully selected patients, according to experts speaking at the Medical Innovation Summit at Cleveland Clinic.

"Evidence is accumulating that focal therapy may be a reasonable alternative when the index tumor is low-grade, as determined by size and Gleason score," said J. Stephen Jones, MD, chairman of the department of regional urology at the Cleveland Clinic's Glickman Urological and Kidney Institute and associate professor of surgery (urology) at Cleveland Clinic Lerner College of Medicine, Case Western Reserve University.

Under these conditions, focal therapy offers patients a compromise between active surveillance and whole gland treatment, although several challenges must be overcome before it will be widely accepted in clinical practice.

A second stumbling block is the lack of capability to accurately characterize and image the index tumor for treatment, according to John Kurhanewicz, PhD, professor of radiology, urology, pharmacology, chemistry, and biomedical imaging at the University of California, San Francisco.

"Anatomic imaging alone lacks the specificity to detect cancer within the prostate, particularly early-stage disease, at diagnosis, and recurrent cancer after therapy," Dr. Kurhanewicz said. "This creates the need to add functional imaging to detect all clinically significant tumors and characterize them as aggressive or indolent."

Dr. Kurhanewicz proposes combining high-resolution magnetic resonance (MR)-based imaging with functional imaging modalities such as magnetic resonance spectroscopic imaging (MRSI), dynamic contrast imaging, and diffusion-weighted MR.

"Multiparametric imaging is the future-it must be fast, high resolution, sensitive, and specific," he said. "Major advances in imaging are needed before it can be the basis for prostate cancer treatment planning decisions."

He cited hyperpolarized 13C MRSI as one such advance with the potential to significantly impact patient care.

"This technology provides an unpre-cedented increase in signal-to-noise that allows high-resolution spatial and temporal imaging and may revolutionize the way we image men with prostate cancer," he said.

Therapy not for everyone

Widespread acceptance of focal therapy also requires more treatment options and more data on the long-term cancer control and side effects of those treatments, Dr. Jones noted. Currently, cryoablation is the primary treatment modality available for focal therapy, and outcome data are limited.

"It is available only at a few centers, and patients must have low-volume, low-risk disease," he stressed. "At Cleveland Clinic, we are proposing focal cryoablation as a controversial, cutting-edge treatment that has not yet been brought into the mainstream, and emphasizing that all patients who undergo this treatment must be followed carefully."

Patients must undergo a saturation biopsy (20 or more cores) prior to focal cryoablation. They also must agree to a second, post-treatment saturation biopsy, whole-gland treatment if additional high-grade tumors are detected, and long-term monitoring for disease progression.

"Ultimately, focal therapy may be most suited for younger men in whom potency is an issue, men with post-radiation failure, and older men who refuse active surveillance," Dr. Jones said. "Although it could be advantageous for a significant number of men, it will always be in the minority due to the nature of the disease."

Dr. Kurhanewicz has received grant funding from GE Healthcare. Dr. Jones is a proctor/speaker for Endocare.