In a first-ever study, researchers from Tohoku University have found that ultrasound screening combined with mammography aid in early detection of breast cancer.
Results of a randomized controlled trial involving more than 70,000 women and examining the effectiveness of ultrasonography in breast cancer screening were published in the online edition of the British medical journal The Lancet on Thursday.
The project, called the Japan Strategic Anti-cancer Randomized Trial (J-START), funded by the health ministry, involved 42 medical organizations nationwide studying 72,998 women aged 40 to 49 from 2007 through 2011.
The women were divided into two groups and underwent either mammography combined with an ultrasound or mammography alone. The tests were repeated after two years from the initial screenings.
The study, led by Noriaki Ouchi and Akihiko Suzuki from Tohoku University’s School of Medicine, confirmed that ultrasound testing along with mammography led to a higher rate of breast cancer detection, at 0.5 percent, while the detection rate stood at 0.33 percent for the group undergoing mammography alone.
According to the researchers, the combined tests may also help detect cancers in their earliest two stages, where the cancer has not spread to nearby tissue.
The use of ultrasonography led to the discovery of 65 more cases — 144 in total — in those two early stages. However, no significant difference was discovered in more advanced stages of cancer.
To date, mammography has been the only proven method for breast cancer detection that reduces mortality.
But experts argue the technique has its flaws, often missing tumors in young women or women with dense breasts, meaning breasts with leaner, less-fatty tissue, which is common for women aged below 50 and especially in Asian populations.
The Japanese Breast Cancer Society introduced mammography in Japan in fiscal 2000.
The age requirement was lowered from the initial 50 to 40 in fiscal 2004, with examinations featuring both mammography and visual and physical checks by physicians.
In Japan, women aged 40 or over, believed to be at the highest risk, are currently advised to undergo mammography screenings every two years.
Ultrasonography alone has not been proven scientifically efficient to detect breast cancer, and the skills of technicians who read ultrasound images vary, which means there are risks of misdiagnosis.
Ultrasound, on the other hand, is considered well-suited for pregnant women, as it does not involve irradiation, and the test is less painful than mammography.
According to the Japan Cancer Society, breast cancer — the fifth-largest cause of cancer deaths among Japanese women — killed 13,000 women in the country last year.
But the question of whether the findings will be integrated in state-sponsored screening programs will require further debate, a health ministry official said.
Calling the results a valuable contribution, an official at the ministry’s section in charge of cancer prevention strategies said that more evidence will be needed to introduce the use of ultrasound waves in breast cancer screenings.
“Because this is research that draws a lot of public attention, we believe that in the near future these findings, along with other evidence, will need to be picked up in a debate (involving more experts),” the official said.
“We need more evidence to prove these procedures will help reduce patient mortality.”