Mammography is considered the gold standard in early breast cancer detection but some members of the medical community had hopes that adding ultrasound screening would improve the detection rate even further.  A recent study funded by the Avon Foundation and the National Cancer Institute has brought mixed reviews.

The trial, conducted by ACRIN, or the American College of Radiology Imaging Network, headquartered at Brown University, involved statistical analysis of 2,809 women who had participated in 21 clinical trials in the United States, Canada, and Argentina.  All study participants were considered at substantial risk for developing breast cancer and were age 25 or older, had a family history of breast cancer, had dense breasts, and had already undergone a breast biopsy.

Jeffrey Blume, a biostatistician and the trial’s methodologist, led the research team.  Blume serves as deputy director of ACRIN’s Biostatistics and Data Management Center and is an associate professor of Brown’s Department of Community Health.  According to Blume, adding ultrasound screening does reveal more incidences of breast cancer but it also significantly increases the risk of a false positive reading, which leads to biopsies that would otherwise be unwarranted.

Analysis revealed that mammography alone detected breast cancer in 8 of every 1,000 women during the first year of study.  Twenty-five out of 1,000 women received a biopsy because of a false positive outcome.

When ultrasound was added to mammography screening, 12 out of every 1,000 study participants were found to have breast cancer but 93 of every 1,000 underwent biopsies after their screening resulted in a false positive reading.

Essentially, adding the ultrasound screening exposed 4 new cases of breast cancer for every 1,000 women but led to a four-fold increase in false positive readings, or 68 additional false positive results for every 1,000 women thus screened.  Even when both methods of screening are used, 20% (one in five) cases of breast cancer is missed.

The research team concludes that the benefits of additional screening are offset by the high number of false positive outcomes, suggesting the double screening should be reserved for only women who are found to be at high risk of developing the disease.

The May 13 issue of the Journal of the American Medical Association (JAMA) carries full details of the study’s findings.