TargetScan helps doctors chart the location of cancerous tissue
Originally published in NYU Langone Medical Center's News & Views, November 2008
Some 200,000 American men will be diagnosed with prostate cancer this year, making it the most common male malignancy after skin cancer. Thanks to widespread PSA testing, 90 percent of these cases will have been detected early enough to be cured, but despite ongoing refinements in treatment, both surgical removal and irradiation of the prostate can leave men incontinent and/or impotent. These devastating side effects may one day be avoidable, however, if a new treatment fulfils its promise. In focal therapy (also known as a "male lumpectomy"), small areas of cancerous tissue are targeted and destroyed using ablative techniques such as freezing, insertion of radioactive seeds, or bombardment with high-intensity focal ultrasound. This spares the rest of the prostate and largely eliminates the risk of life-altering side effects.
One of the best hopes for making focal therapy a reality is TargetScan, a new biopsy device currently being evaluated at NYU. In a standard biopsy of the prostate, the urologist scans the organ with a handheld ultrasound probe while manipulating a needle with the other hand. TargetScan replaces both of these devices. Instead of a handheld scanner, a machine-mounted version produces a three-dimensional image of the prostate. The device is guided by a computerized template created by studying maps of the most likely locations of prostate cancer. These maps were generated through analysis of hundreds of surgically removed cancerous prostates. The device automatically extracts cores of tissue in a pattern that maximizes the chances of detecting malignant cells, while recording the exact locations from which the samples were drawn.
"How much TargetScan improves a doctor’s diagnostic ability will depend on how good he or she is at doing biopsies with the freehand technique," notes Samir Taneja, M.D., the study’s lead investigator, director of the Division of Urologic Oncology in the Department of Urology. "By employing a uniform technique, it equalizes detection rates among practitioners with different skill levels. This should reduce the need for second and third biopsies once it comes into general use."
An even more important advantage of the device is its ability to help doctors chart the location of cancerous tissue, explains Dr. Taneja. "I think the big benefit of TargetScan will be in staging and mapping cancers, not detection," he says. "This is extremely relevant to the next generation of treatment: focal therapy." Because PSA testing is now catching many cases of prostate cancer in their earliest stages, when cancerous growths are too minuscule to detect with conventional imaging, focal therapy is becoming more feasible than ever — provided there’s a way to locate the growths. "I think the mapping and targeting ability of TargetScan can fill this need," says Dr. Taneja. "We just have to understand how to use it."
TargetScan is already being used to guide seed implants and radiation therapy. Next, doctors need to learn how to link ablative technologies to the map created by the device — an application Dr. Taneja expects within the year — and to decide how to select candidates for focal ablative treatments. "At NYU, we’ve also begun to develop methods to link the TargetScan image to MRI scans," adds Dr. Taneja, "which should further improve targeting and diagnosis."