Adding Ultrasound to Breast Screening Results in Higher Rate of Cancer Detection for Women in Japan
Adding ultrasound to standard mammography tests in breast screening could result in improved rates of detection for breast cancer in women in Japan, according to a study published in The Lancet.
Researchers led by Professor Noriaki Ohuchi, from Tohoku University Graduate School of Medicine, in Miyagi, Japan, recruited more than 70,000 women in Japan aged between 40 and 49 to participate in the J-START trial. One-half were offered the usual mammography screening, and one-half were offered ultrasound testing in addition to mammography, with two screening sessions taking place over two years.
The results show that ultrasound combined with mammography resulted in correct identifications of cancer in more than 9 out of 10 cases (91% sensitivity), whereas for women given mammography alone, just over three quarters of tests correctly identified breast cancer (77% sensitivity).
Breast cancer already affects large numbers of women in Europe and the United States, but rates are increasing rapidly in Japan and other Asian countries. Early detection and treatment is critically important for reducing deaths from the disease, and many developed countries have implemented mammography screening programs for the women most at risk.
In Asia, breast cancer tends to present at an earlier age than in Europe or the United States, and Asian women have denser breast tissue, both of which are known to reduce the accuracy of mammography. As such, detection using standard mammography screening based on European and US practice might miss cases of breast cancer in Asian countries.
In addition to accurately detecting more cases of breast cancer, adding ultrasound to mammography detected more cancers at an early stage (144 cancers at stage 0 or 1, compared to 79 cancers at stage 0 or 1 detected by mammography alone). The addition of ultrasound also resulted in fewer interval cancers (which appear after a negative test result between scheduled rounds of screening), leading researchers to conclude that adding ultrasound to mammography screening detected additional cancers, compared to mammography alone.
While previous studies have suggested that the addition of ultrasound might lead to an excessively high rate of 'false positive' results (where screening results falsely indicate that a cancer is present), these results suggest that the difference in false positive rates between the two testing protocols was small, and could be further reduced by ensuring that mammography and ultrasound test results are analyzed together.
"Our results suggest that adding ultrasound to mammography results in more accurate screening results for women in Japan, which could ultimately lead to improved treatment and reduced deaths from the disease," says Ohuchi. "Further work will now be needed to see if these results can be extended to other countries in Asia. In addition, long-term follow-up of these results will determine whether including ultrasound tests in breast cancer screening ultimately affects the likelihood of successful treatment and survival, as we would expect."
Source: The Lancet