What Women Need to Know about Breast Density

High breast density may not require cancer screenings beyond mammograms

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) For women with dense breasts, cancer can be hard to detect — and the risk of getting it can be high. Even so, additional cancer screening tests may not be necessary.

A recent study found that more than half of women with extremely dense breasts did not have a high risk for getting certain aggressive cancers.

A mammogram (an X-ray of the breast) is the most common screening method for breast cancer, according to the National Cancer Institute.

While a mammogram can be effective in detecting cancer, it may miss tumors masked by dense tissue. Additional tests can find these missed tumors, but can also return incorrect results that identify abnormalities as cancer — sometimes called false-positives.

“[Mammograms have] sufficiently high breast cancer detection and reasonably low rates of false-positive results for routine use, even among women with dense breasts,” wrote lead study author Karla Kerlikowske, MD, of the San Francisco Veterans Affairs Medical Center. “We found that not all women with dense breasts are at sufficiently high risk for interval [breast] cancer to justify alternative screening methods.”

Interval breast cancer is a term given to aggressive cancers which develop within 12 months after a mammogram with normal results.

Alternative cancer screening methods may include ultrasonography, which uses ultrasound waves to see inside the body, and tomosynthesis, which takes multiple images of the breast.

Dr. Kerlikowske and team looked at data on 365,426 women ages 40 to 74 years who had undergone a mammogram. Nearly 2,700 of these women were diagnosed with breast cancer within 12 months of that mammogram.

Interval breast cancer rates were highest among women with extremely dense breasts. Cancer rates were also high for women with more than half dense tissue in their breasts.

In an accompanying editorial, Nicole Dolan, MD, and Mita S. Goel, MD, of Northwestern University Feinberg School of Medicine in Chicago, IL, wrote that alternative tests for women with dense breasts could substantially increase costs — with only small benefits.

“Annual supplemental screening with ultrasonography in women ages 40 to 74 with [varied] or extremely dense breasts would avert [less than 1 percent] of cancer deaths, result in 1,219 additional biopsies, and cost an additional $2,210,000 per 1,000 women screened,” wrote Drs. Dolan and Goel.

Many US states have laws requiring women be notified about alternative cancer screening if they have dense breasts.

This study was published May 18 in the journal Annals of Internal Medicine.

The National Cancer Institute funded this research. The authors disclosed no conflicts of interest.


Review Date: 
May 18, 2015
Last Updated:
May 20, 2015