Japanese team develops promising breast cancer detection method


A team of researchers from Tohoku University has developed a new method to detect breast cancer by combining a mammogram with an ultrasound in a procedure that appears to be more accurate than mammogram testing alone.

The team, lead by Noriaki Ohuchi, a professor at the university, divided roughly 73,000 women randomly into two groups — one group underwent traditional mammography X-ray testing while the other group was examined using both mammograms and ultrasound. The cancer detection rate was 1.5 times higher for the latter group, with the detection rate for early stage cancer being particularly high, according to the team.

The researchers said the new method is not perfect and that the examinees require further testing, which could be burdensome.

Because the effectiveness of the new method can only be properly assessed based on whether death rates fall over time, it could take another decade or longer to determine if the procedure is truly more accurate.

But the Tohoku University group questions that line of reasoning and believes it could take only a few years to be able to determine if the method is a viable alternative by looking at how many of those tested from the two groups develop cancer.

“It could be too early to recommend an examination that involves both ultrasound and a mammogram to local governments. But it could be an option, with additional costs, for those who are especially worried,” said Mamoru Fukuda, the head of St. Marianna University Breast & Imaging Center. “However, they must understand that they may be asked to take more invasive examinations.”

Mammography, or the examining of breast tissue using a special type of X-ray machine, has long been seen as an effective way to detect cancer, which boosts survival rates if cancerous tissue is discovered and treated in the early stages.

In October, the American Cancer Society revised its guidelines, saying women should have a mammogram exam every year after the age of 45 rather than 40 and once every two years after 55.

Another group of U.S. experts said in a statement that they are reluctant to recommend widespread mammograms for those in their 40s because of the negative side effects that could result from such regular testing.

During a mammogram, two plates attached to a special machine are used to squeeze the breast as flat as possible to take an X-ray. The procedure can detect cancer in its early stage before it forms into lumps, allowing for earlier treatment.

In the U.S. and other Western nations, the procedure, along with increased doctor visits, has greatly lowered the death rate from breast cancer.

“(The mammogram) is the only breast cancer procedure that has proven effective in lowering death rates,” said Ohuchi.

Still, decades of use in Western countries has also revealed shortcomings. For example, mammograms sometime show false-positive results, which are found after biopsies and other tests are performed.

In addition, high-density breast tissue and dense mammary glands can affect accuracy rates.

Mitsuhiro Tozaki, the chairman of the nonprofit Breast Cancer Imaging Network, who also heads Sagara Hospital Breast Center’s X-ray division, said with a mammogram, since both mammary glands and cancer show up as white shadows, it can be difficult to detect cancer in denser breast tissue.

In Japan, the health ministry has recommended that local governments conduct mammograms once every two years after the age of 40. Last year, a panel for the ministry stopped recommending palpation and visual examination to detect breast cancer but maintained its mammogram recommendation.

The decision was based on the fact that the rate of breast cancer for women in Western countries increases as they age while in Japan it peaks for those in their 40s and 50s. Mammography examination rates are also lower in Japan, at 40 percent. One reason is that more Japanese women have high-density breast tissue, making detection of the cancer more difficult.