Breast Density Not Linked to Cancer Incidence

A new study suggests that breast density may not actually be a strong predictor of cancer risk after all.

Researchers at Health Center Osijek (Croatia) conducted a retrospective study involving 52,962 mammography exams performed in women aged 50–69 over a period of five years at five different mammography facilities in the vicinity of Osijek (Croatia). Two radiologists read the mammograms independently and determined breast density according to standard criteria. The researchers then compared data between patients in the low-density breast tissue group and the high-density group.

The researchers found that the majority of screened women had low breast density. Of the 230 women with detected breast cancers, almost half were from the group with the lowest-ranked breast density, while slightly less than 3% came from women in the highest breast density category. When the researchers matched the women who had a detected cancer with control participants of the same age and from the same locales that did not have cancer, they found no significant difference in mammographic density.

Women with low mammographic density made up 83% of the patients in the breast cancer group, compared with 89% in the control group, while high mammographic density was found in 17% of the breast cancer patients and 11% of women in the control group. The study also failed to find a strong association between higher mammographic densities and a higher risk of breast cancer among postmenopausal women. The study was presented at the Radiological Society of North America (RSNA) annual meeting, held during November-December 2015 in Chicago (IL, USA).

“We wanted to find out if breast cancer patients had more dense breast tissue than the healthy women. Also, we wanted to see what the percentage of dense breasts was in our postmenopausal population and, consequently, determine the value of mammography screening for this group,” said lead author and study presenter Natasa Katavic, MD, of the department of radiology. “We found that there was no significant difference in breast density between breast cancer patients and the control group in the screening program.”

Prior research has suggested an association between breast density and breast cancer; in addition, cancers in dense breast tissue are more difficult to see on mammograms. As a result, some women with dense breasts are advised to get supplementary screening with ultrasound or magnetic resonance imaging (MRI).

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