Photo/IllutrationThe Asahi Shimbun

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A research team at Kobe University has developed a mammography screening technique using microwaves that is less painful, safer and more accurate than current equipment available.

The technology also can detect small tumors in the breast. An application to approve its use as medical equipment will be submitted with the government after clinical tests involving several hundred individuals during the next fiscal year. Current plans call for commercializing the technology from autumn 2021 at the earliest.

According to government statistics, about 14,000 women die of breast cancer each year in Japan.

The two main methods to detect breast cancer are mammograms and ultrasound tests. But mammograms involve X-rays that release radiation. The technique is also very painful because the breast is sandwiched between metal plates during the procedure.

While there is no pain or radiation involved in ultrasound tests, there are differences in the accuracy of results depending on the physical attributes of each patient.

According to Kenjiro Kimura, a professor of chemical and condensed matter physics at Kobe University who is part of the research team, the microwave beamed is very weak and about one-thousandth of the power of that used in cellular phones. An antenna emitting the microwave is moved over the surface of the breast.

X-ray mammograms may also miss tumors, especially among young women who have dense breast tissue. This is because the tissue, as well as tumors, both appear as white areas in the images on a mammogram.

In contrast, the microwave mammogram produces a highly accurate 3-D image of the tumor. Tests using the new microwave technology were carried out on about 300 breast cancer patients who had undergone X-ray mammograms and ultrasound tests. Tumors were detected in all of the patients.

In April, the government designated the microwave mammography technology as subject to early approval under a fast-track screening program.

One drawback of the microwave technology is that it can only be used to detect breast cancer. This is because microwaves can pass through fatty tissue that is the main component of breasts but not through muscle.

"In the breast, a tumor reflects back the microwave as though it was a mirror," Kimura explained. "This is the ideal method to use in detecting breast cancer among women."

Research teams at Shizuoka University, Kansai University and Hiroshima University are also trying to develop better mammography screening techniques using microwaves.