April 10, 2002
     Prostate Cancer

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Trial looks to improve diagnosis of prostate cancer

PHILADELPHIA -- Apr. 10, 2002 (Cancer Digest)-- Looking to improve the diagnosis of prostate cancer, researchers are conducting the first large-scale clinical trial in the nation to find out whether a form of ultrasound can improve detection and cut the cost of diagnosis.

The trial is being led by radiologists and urologists at Thomas Jefferson University Hospital and Jefferson's Kimmel Cancer Center in Philadelphia and is supported by a three-year grant from the Department of Defense. They will look at 300 patients who are at high risk for prostate cancer, using a combination of ultrasound and biopsy to try to improve the accuracy of cancer diagnoses.

The key to the trial's success, says Dr. Ethan Halpern, who is leading the study, lies in the nature of the cancerous tumor itself. Cancerous tissue in the prostate may have up to twice as many blood vessels as does healthy tissue. Many researchers believe that without this additional blood supply, cancerous tumors cannot grow and spread.

Dr. Halpern believes that by using contrast-enhanced ultrasound, "we can find areas in the prostate that have more blood vessels," enabling physicians to direct biopsies there. At the same time, he says, "we hope to show that those areas in the prostate that don't have more vessels don't require biopsy."

The contrast agent being studied, Imavistä (AF0150), is awaiting final approval from the U.S. Food and Drug Administration (FDA). Dr. Halpern is evaluating the enhancement provided by Imavist with conventional Doppler imaging as well as a newer harmonic gray scale inversion technique.

Dr. Halpern, who is co-director of the Jefferson Prostate Diagnostic Center, thinks contrast-enhanced ultrasound, may be a better way. It can detect vessels smaller than 1 mm, about the thickness of a hair.

"We'd like to find the clinically significant cancers that will impact a person," he says. "By looking for cancers located in vessel-rich tissue, we're hoping that not only will we improve the detection of cancer, we'll improve the detection of clinically significant cancers that will more likely be dangerous to the patient. It may not be important if we miss tumors with fewer vessels because we think they will be less dangerous." Cancers that are vascular-rich, he notes, are more likely to spread.

In the study, every patient will be evaluated first with both standard "gray scale" and Doppler ultrasound. The exam is repeated twice, once before infusion of the contrast agent and again during the infusion. A biopsy of suspicious areas in each part of the prostate is performed during infusion of the contrast agent.

The researchers plan to follow the patients with positive biopsies for three years to see if contrast-enhanced imaging can also predict which cancers are more aggressive and more likely to return after treatment.

Currently, when cancer is suspected, say by a high or rising PSA, the standard procedure is the sextant biopsy -- bits of tissue are extracted from six areas of the prostate gland and examined under a microscope for evidence of cancer. But since no one knows where the cancer is, a negative result doesn't rule out cancer. If the PSA continues to go up, another sextant biopsy is performed three to six months later.

As a result, biopsies of the prostate are performed on areas that are only best guesses where cancer may lie. Some 200,000 cases of prostate cancer are diagnosed annually in the United States, yet only one in three persons receiving a biopsy is found to have cancer. Halpern's team hopes to improve on that biopsy rate.

"If this new method is shown to be sensitive for detection of moderate- to-high-grade cancers of the prostate, many future patients could avoid biopsy," Halpern says.

Physicians who want to refer patients for biopsy and evaluation by the center should call 215-955-7544. For more information regarding the study, call the study coordinator, Dara DelCollo, at 215-955-2686 or 1-800-JEFF-NOW.