Association between changes in mammographic density category and the risk of breast cancer: A nationwide cohort study in East‐Asian women

Abstract

Breast density is strongly associated with breast cancer risk; however, studies on the association between density changes and breast cancer risk have controversial results. The aim of our study was to determine the association between breast density changes and breast cancer risk in East‐Asian women. We included 3 301 279 women aged ≥40 years screened for breast cancer twice during 2009 to 2010 and 2011 to 2012. Data were obtained from the National Health Insurance Service (NHIS) database. Breast density was evaluated using the Breast Imaging‐Reporting and Data System (BI‐RADS). Relative risk (RR) and 5‐year risk of developing breast cancer according to density category changes were calculated. Overall, 23.0% of the women had a higher breast density and 22.2% of the women had a lower breast density in second screening compared to the first. An increase in the BI‐RADS density category between two subsequent mammographic screenings was associated with an increase in breast cancer risk and vice versa in terms of RR. The 5‐year breast cancer risk was affected by the initial BI‐RADS density category, changes in density category and patients' characteristics such as age, menopausal status and family history of breast cancer. In patients with breast cancer family history, the 5‐year breast cancer risk was prominent, at a maximum of 2.39% (95% CI = 1.23‐3.55) in women with breast density category of 2 to 4. Changes in the BI‐RADS density category were associated with breast cancer risk. Longitudinal measures of BI‐RADS density may be helpful in identifying high‐risk women, especially those with a breast cancer family history.

Mammographic Density Changes over Time and Breast Cancer Risk: A Systematic Review and Meta-Analysis

“…We analyzed data from nine different studies [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ] published between 1998 and 2021, where six of them were designated as cohort and three were designated as case–control studies. Table 1 summarizes the characteristics of the included studies.…”

“…Looking at study-level results, the use of qualitative classifications systems for breast density seems to be more often associated with breast cancer risk, compared with a quantitative analysis of breast density [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. However, the type of measure for breast density was not found to be statistically significant as an explanatory factor in any of the meta-regression analysis performed.…”

“…The definition of change in breast density varied among eligible studies. Four studies used BI-RADS classification (A, almost entirely fat; B, scattered fibroglandular; C, heterogeneously dense; and D, extremely dense) [ 14 , 16 , 17 , 20 ]. Two studies used changes in the percent of density, categorized four ways (i.e., <5%, 5–25%, >25–50%, and >50%) [ 19 , 21 ] One study used a fixed percent of change in the percent of density (+/−5%), using breast density changes as a continuous variable [ 18 ].…”

“…Several studies have investigated the potential association between changes in breast density over time and breast cancer risk with conflicting results, making the interpretation of current evidence in clinical practice difficult [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ].…”

Clinical Factors Associated with Asymptomatic Women Having Inconclusive Screening Mammography Results: Experiences from a Single Medical Center in Taiwan

“…High breast density, incomplete assessment, and the elevated breast cancer risk are interrelated. Beside premenopausal status, clinical factors such as increasing height, higher levels of education, and later first birth were associated with higher mammography density [ 23 ], and the change of mammography density in follow-up screening study was associated with breast cancer risk, reported recently in East Asian women [ 24 ]. Therefore, the national policy of only taking age and familial breast cancer history into consideration as criteria for women to undergo breast cancer screening in Taiwan may need to put more emphasis on the other clinical factors and arrange alternative and effective examination.…”