Last year 192,200 women were diagnosed with breast cancer in the United States. Of those women, 40,200 died. Because there is no proven way to prevent breast cancer, early detection is vital in reducing high mortality rates.
Susan Hagness, UW-Madison assistant professor of electrical and computer engineering and biomedical engineering, is researching a new breast cancer detection method called microwave mammography. Hagness said this new method will have advantages over X-ray mammography.
“X-ray mammography is the best method available today to detect non-palpable breast cancer, but it is not without inherent limitations and risks,” Hagness said.
Led by Hagness, UW researchers have been working to develop a better method. Hagness, who began this project as a graduate student at Northwestern University, formed a multidisciplinary team of researchers. The team has been working to combine engineering and medicine to develop a “microwave radar imaging method,” commonly called “microwave mammography.”
X-ray mammography misses approximately one out of every five malignant breast cancer tumors present at the time of the screening. This false-negative rate is high because mammography has limited sensitivity in women with dense breast tissue, who are most often younger women.
Hagness said this was a concern because the amount of this tissue, called fibroglandular tissue, may be an independent risk factor for developing breast cancer.
False positive results are also common, which occur when mammography results are read as abnormal when in fact, no cancer is present. Currently, 75 percent of all tested specimens turn out to be benign lesions.
X-ray mammography has other drawbacks, including uncomfortable breast compression and exposure to low doses of radioactive X-rays.
According to John Gofman, professor emeritus of molecular and cell biology at University of California-Berkeley, there is a clinical need for a better method of detection.
“X-rays are a proven cause of every major type of cancer,” he said. “Therefore, the decision to neglect X-rays really causes the future X-ray-induced cancers which could have been prevented.”
Gofman claims there is a moral obligation to attempt to obtain all the benefits of medical and dental X-rays at lower doses per procedure.
“In the clinical system we are working towards, the patient lies on her back so that the breast is naturally flattened, and a scanner containing a number of antennas is placed near the center of the breast,” Hagness explained. “Each antenna transmits a very short burst of low-power microwave energy and records the microwave echo.”
Hagness noted that a malignant tumor would create a strong reflection because its microwave properties are very different from that of normal breast tissue.
Microwave breast imaging is more effective than X-ray mammography because the intrinsic contrast between malignant and normal tissue at microwave frequencies is much greater than the contrast at X-ray frequencies. This implies that microwave imaging techniques have the potential for higher sensitivity in detecting early-stage tumors.
The other advantages of microwave mammography are the low-power microwave exposure, which are less risky than X-rays, and the fact that the procedure does not require painful breast compression.
“Microwaves, which are used every day in wireless communications, are much lower-frequency waves in comparison to X-rays and therefore harmless at low power levels,” Hagness said.
Though the research is going well, it is still in the preliminary phase, and Hagness did not offer any details about how soon it will be available.