Breast cancer risk: Beware of breast density gain

Changes in breast tissue density may be predictive of breast cancer risk. A new study shows that breast density that remains high, or low density that increases over time, are the trajectories to watch most closely. Dense breasts are characterized by a higher proportion of glandular tissue and fibrous tissue than fatty tissue. This density can only be observed by mammography. Korean researchers, however, question the conclusions that can be drawn from a single mammogram. They suggest that the trajectory of breast density over time might provide a more accurate picture of breast cancer risk.“Normally, breast density decreases gradually over time,” explained the authors of the study published in the British Medical Journal. “An increase in density may therefore indicate a change in proliferative activity that would not be related to aging.”They followed more than a million Korean women over the age of 40 who had at least four mammograms between 2016 and 2021. Their breast density was classified according to the BI-RADS system (Breast Imaging Reporting and Data System). Participants who had already been diagnosed with cancer were excluded. Five trajectoriesBased on the mammogram results, the researchers were able to identify five trajectories among these women:low breast density that persists over timelow breast density that increases over timedense tissue containing more or less fat (BI-RADS 2-3) whose breast density decreases over timedense tissue containing more or less fat (BI-RADS 2-3) whose breast density increases over timehigh breast density (BI-RADS 3-4) that persists over timeEach of these trajectories was associated with a greater or lesser risk of developing breast cancer. Group 2 had a 1.6-fold (95% CI: 1.49-1.72) higher risk of breast cancer than group 1, the reference group. Women in groups 3 to 5 had the highest risk, with group 5 being three times more likely to develop breast cancer.The researchers hypothesize that increased breast density is not necessarily the direct cause of breast cancer, but rather a marker linked to other recognized risk factors.For example, groups with a higher risk of breast cancer also included a higher proportion of women with a family history of breast cancer, nulliparous women, women who didn't breastfeed, who smoked, who had menarche at a younger age, or who consumed alcohol. These results therefore suggest that future breast cancer risk prediction models should incorporate the trajectory of breast density, in addition to the individual analysis of each mammogram.Read the study: Trajectories of breast density change over time and subsequent breast cancer risk: longitudinal study.

Breast cancer risk: Beware of breast density gain

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