Check Up: Monitoring prostate cancer

By Marie McCullough

Thomas Jefferson University researchers are using special ultrasound images to help identify prostate cancers that don't need urgent treatment, and monitor those tumors for signs of ominous changes.

Scientists far and wide have been scrambling to improve prostate cancer detection amid debate about the value of the PSA screening test. Last year, a federal panel said the test should not be used for routine screening because too many men wind up being treated for tumors that would never harm them- and suffer side effects such as incontinence and impotence.

Men usually reject the monitoring option because it involves annual prostate biopsies, and much anxiety.

In the Jefferson study, led by radiologist Ethan Halpern, the PSA test was used to identify men with a worrisome level of a blood protein shed by the prostate gland. But rather than automatically send the 272 men for biopsies, the researchers took ultrasounds enhanced by commercially made "microbubbles."

These microscopic, gas-filled spheres of fat are injected into the bloodstream, and they work by intensifying the reflective properties of ultrasound waves, so images have greater contrast.

The bubbles also can be used to evaluate blood flow. Since tumors grow their own blood supply, blood flow is a marker for cancer and for the aggressiveness of its growth, Halpern explained.

The microbubble-enhanced images were used to rate the likelihood of malignancy and target a spot for a biopsy that would then take six tissue samples via a needle. The men also had a regular biopsy, which took 12 samples from all over the prostate.

The regular biopsies found cancer in 105 men, compared with only 71 men with the targeted version, but the targeted biopsy was more likely to find aggressive tumors- those that need treatment. Thirty-nine men with positive targeted biopsies had "high grade" tumors, compared with 18 with positive regular biopsies.

A subsequent study will see if microbubble-enhanced ultrasound can be used to non-invasively watch and reassure men who opt for monitoring.

"The major drawback of the PSA is overtreatment," Halpern said. "If we can distinguish who should have [surgery] and who shouldn't, it changes the math."