Breast Density Affects Screening Recommendations for Women in Their 40s

A new study suggests that breast cancer screening starting at age 40 may have an acceptable balance of risks and benefits for women with extremely dense breasts or a family history of the disease.

Researchers at Erasmus Medical Center (Rotterdam, The Netherlands) conducted a comparative modeling study involving a contemporary cohort of women eligible for routine screening with extremely dense breasts or first-degree relatives with breast cancer. According to previous studies, 9% of US women have a first degree relative with breast cancer, and 13% have Breast Imaging Reporting and Data System (BI-RADS) category 4 breast density.

The researchers then used data retrieved from the Surveillance, Epidemiology, and End Results (SEER) program, the Breast Cancer Surveillance Consortium (Bethesda, MD, USA; www.breastscreening.cancer.gov), and other sources to generate a model for assessing risks and benefits of screening at age 40 versus age 50 with different screening methods (film or digital) and screening intervals (annual or biennial). The main outcome measures were life-years gained, breast cancer deaths averted, false-positive mammography findings, and harm to benefit ratios.
Current guidelines, according to the researchers, agree that women aged 50 to 74 should get mammographic screening, with biennial screening of women ages 50 to 74 yielding (per 1,000 women) 6.3 breast cancer deaths averted, 109 life-years gained, and 883 false-positive findings--a ratio of 8.3 for false-positives to life-years gained. The recommendations for women in their 40s have been highly controversial, however, based on a finding of higher false positive rate in younger women.

The researchers concluded that for women in their 40s to reach the same 8.3 ratio, the threshold relative risk (RR) for screening would have to be 1.6-fold higher than average for biennial screening with film mammography; 1.9 times above average for biennial screening with digital mammography; 3.3 times above average for annual screening with film mammography; and 4.3-fold higher than average for annual screening with digital mammography. The study was published in the May 1, 2012, issue of the Annals of Internal Medicine.

“A potential difficulty with including breast density in screening recommendations is that breast density is not uniformly reported and requires baseline mammography examinations to determine breast density, introducing additional potential screening harms,” said lead author Nicolien van Ravesteyn, MSc, adding that the harm-benefit ratio for film mammography is more favorable than for digital mammography because film has a lower false-positive rate.


Related Links:

Erasmus Medical Center

Breast Cancer Surveillance Consortium