Breast Cancer Detection Catches a New Wave
By Noreen Parks
ScienceNOW Daily News
28 November 2006
A new technology that uses sound waves to probe tissue may prove to be a powerful weapon in the fight against breast cancer. The first clinical results from the system, reported in Honolulu today at a joint meeting of the Acoustical Society of America and the Acoustical Society of Japan, indicate that it is far more accurate than traditional mammography and does not expose patients to radiation or invasive procedures. Each year, more than 250,000 women in the United States learn that they have breast cancer, and more than 45,000 die from the disease. Roughly half of all women experience a mammogram-related cancer scare in their lifetimes. These false positives require biopsies on suspicious masses that eventually prove benign. Furthermore, because mammography measures tissue density, the rate of false negatives approaches 50% in women with dense breasts. Mammography also frequently fails to detect small tumors at early, curable stages.
In the quest for a more effective system, physicist Neb Duric of Wayne State University in Detroit, Michigan, and colleagues turned to ultrasound. They designed a Computed Ultrasound Risk Evaluation device, dubbed CURE, that sends pulsed sound waves from 256 ultrasound sensors surrounding a breast and measures how much sound is reflected, how quickly waves pass through the breast, and how the sound waves diminish. (These measurements distinguish the telltale traits of cancers, such as their shapes and stiffer, denser tissue.) After the minute-long scan, a computer assembles 50 to 70 cross-sectional images, providing a three-dimensional view of the breast. The combination of measurements provides an image with far better detail than a conventional mammogram, which uses x-rays.
To test the system, Duric’s team used CURE to evaluate 100 women whose mammograms had revealed suspicious masses. Subsequent biopsies showed 30 to have cancers. CURE found 90% of the cancers, including the smallest one, measuring 8 mm. Likewise, it identified 90% of the benign masses. In contrast, mammography’s false-negative rate ranges from 15% to 50%, whereas the rate of false positives is highly variable, depending on many factors, including radiological interpretation. With more fine-tuning, Duric believes CURE will be able to distinguish even smaller benign growths.
The system would need to pass multiyear regulatory trials to displace mammography as the chief breast-screening technique, but in the meantime it could be used as a follow-up on suspicious mammograms, Duric says. The multifaceted information the CURE system provides is impressive, says Kenneth Hanson, a medical imaging specialist at Los Alamos National Laboratory in New Mexico. “Its ability to differentiate cancers from benign masses holds great promise for this new breast-imaging system,” he adds.