Image-guided biopsy may improve prostate cancer diagnosis
Prostate cancer can be diagnosed using image-guided targeted biopsy, a UCLA team of physicians and engineers has demonstrated.
Traditionally found only by blind biopsy, a procedure that dates from the 1980s, prostate cancer now appears detectable by direct sampling of tumor spots found using Magnetic Resonance Imaging (MRI) in combination with real-time ultrasound, according to the UCLA study
The study indicates that the MRI and ultrasound fusion biopsy, which is much more accurate than conventional blind biopsy, may lead to a reduction in the numbers of prostate biopsies performed and allow for early detection of serious prostate cancers.
The study involved 171 men who were using active surveillance to monitor slow growing prostate cancers or men who had persistently elevated prostate specific antigen (PSA) --a protein produced by the prostate that can indicate the presence of cancer - but had prior negative biopsies.
The UCLA biopsies were done in about 20 minutes in an outpatient clinic setting under local anesthesia.
Annually, about 240,000 new cases of prostate cancer are discovered. Thus, about 75 percent of the biopsies are negative for cancer. However many of those men with negative biopsies but elevated PSA levels may still harbor malignant tumors that were missed by conventional biopsies, said study senior author Dr. Leonard S. Marks, a professor of urology and director of the UCLA Active Surveillance Program.
"Early prostate cancer is difficult to image because of the limited contrast between normal and malignant tissues within the prostate," Marks said.
"Conventional biopsies are basically performed blindly, because we can't see what we're aiming for. Now, with this new method that fuses MRI and ultrasound, we have the potential to see the prostate cancer and aim for it in a much more refined and rational manner," he noted.
The new targeting process is the result of four years of work funded by the National Cancer Institute and based in the Clark Urology Center at UCLA.
In this study, the volunteers undergo MRI first to visualize the prostate and any lesions. That information is then fed into a device called the Artemis, which fuses the MRI pictures with real-time, three-dimensional ultrasound, allowing the urologist to see the lesion during the biopsy.
"With the Artemis, we have a virtual map of the suspicious areas placed directly onto the ultrasound image during the biopsy. When you can see a lesion, you've got a major advantage of knowing what's really going on in the prostate. The results have been very dramatic, and the rate of cancer detection in these targeted biopsies is very high. We're finding a lot of tumors that hadn't been found before using conventional biopsies," Marks said.
Prostate cancer was found in 53 percent of 171 study volunteers. Of those tumors found by the fusion biopsy technique, 38 percent had a Gleason score of greater than seven, which indicates an aggressive tumor, more likely to spread than tumors with lower scores.
Once prostate cancer spreads, it's much more difficult to treat and survival decreases.
The UCLA study team included doctor-scientists from urology, radiology, pathology, the Center for Advanced Surgical and Interventional Technology (CASIT) and biomedical engineering.
The results have been released early online for the January 2013 issue of The Journal of Urology.