Do dense breasts mean more imaging?

With more states mandating disclosures to women about breast density, patient counseling about alternatives to annual mammographic screening is becoming common. Use of an online tool that calculates a woman’s 5-year risk of invasive breast cancer, says a new study, may lead to more productive conversations for physicians and more targeted approaches to screening for women with dense breasts. 

More: Digital mammography better for screening dense breasts

The research, by investigators from the Breast Cancer Surveillance Consortium (BCSC), suggests that breast density shouldn’t be the sole criterion for deciding whether a woman needs supplemental imaging. Rather, the authors say, breast density should be combined with use of the BCSC Risk Calculator.

Designed for use by health professionals, the calculator takes into consideration a woman’s age, race/ethnicity, family history of breast cancer, history of breast biopsy, and BI-RADS breast density. The tool has been validated in 1.1 million women undergoing mammography in the United States, of whom 15,000 were diagnosed with invasive breast cancer.

In the new study, the BCSC authors looked at the BI-RADS breast density, BCSC 5-year breast cancer risk, and rate of interval cancers (invasive cancer ≤12 months after a normal mammogram) per 1000 mammograms. The prospective cohort included 365,426 women aged 40 to 74 who had 831,455 digital screening mammograms.

Rates of interval cancer were high in women with 5-year risk ≥1.67% and extremely dense breasts and in those with 5-year risk ≥2.50% who had heterogeneously dense breasts (24% of all women with dense breasts). The interval rate for advanced-stage disease was highest (>0.4 case per 1000 examinations) in women with 5-year risk ≥2.50% and heterogeneously or extremely dense breasts (21% of all women with dense breasts).

In contrast, 5-year risk was low to average (0% to 1.66%) for 51.0% of women with heterogeneously dense breasts and 52.5% of those with extremely dense breasts, with interval cancer rates of 0.58 to 0.63 and 0.72 to 0.89 case per 1000 examinations, respectively.

BSCS 5-year risk combined with BI-RADS breast density, the authors concluded, can identify women at high risk of interval cancer and help inform physician/patient discussions about alternative screening strategies. 

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