Does Breast Density Decrease After Age 60?
Breast density is highest in younger women and can decrease around menopause as glandular tissue is replaced by fat, a process known as lobular involution. However, little is known about how breast density changes over time in women over age 60 or which factors influence these changes.
In a retrospective Korean study, investigators evaluated 674,993 women aged 60 years and older who were followed over a 10-year period (January 2009–December 2020) through six biennial screening cycles. Visual breast density was assessed on a mix of film, computed radiography, and digital 2D mammograms. The authors identified distinct breast density trajectories over time and examined associations between these patterns and known breast cancer risk factors.
Key Findings
- Five distinct breast density trajectories were identified. Most women had relatively stable breast density over time (grouped as those that were fatty, scattered density, or dense), but one group experienced a notable increase and another a notable decrease in density over the 10-year study period.¹
- Overall, 17.2% of women demonstrated increasing breast density over time, despite the expectation that density generally declines with aging.¹
- Older age, higher baseline body mass index (BMI), and weight gain during follow-up were associated with a lower likelihood of increasing breast density.²
- Family history of breast cancer, hormone replacement therapy use, later age at menopause, and prior hysterectomy were associated with a greater likelihood of persistently dense or increasing breast density.³
- Having more children and a longer duration of breastfeeding were associated with decreasing breast density over time.⁴
These findings suggest that breast density remains dynamic even in later life and may reflect cumulative hormonal, reproductive, genetic, and lifestyle influences. Monitoring changes in density over time may provide additional information about breast tissue aging beyond chronological age alone.
There were limitations to this work. Importantly, this study did not evaluate whether the identified density trajectories were directly associated with future breast cancer risk. Visual breast density assessment is subject to inter-reader variability and potential misclassification, particularly when comparing film and digital mammograms. Because the study population consisted of Korean women, the findings may not be fully generalizable to Western populations. Further research is needed to determine whether density trajectories are associated with subsequent breast cancer risk and whether they can help guide individualized screening and prevention strategies.
Detailed Results
¹ Five trajectory groups were identified among 674,993 women aged 60 years and older: Persistently Fatty (20.5%), Increasing Density (17.2%), Decreasing Density (10.8%), Persistently Scattered Density (36.1%), and Persistently Dense (15.4%).
² Older age was associated with a lower likelihood of increasing density [adjusted odds ratio (aOR) 0.98; P<.001]. Higher baseline BMI was similarly associated with lower odds of increasing density (aOR 0.96; P<.001). Women with higher BMI and those who gained weight during follow-up were less likely to exhibit increasing density trajectories.
³ Family history of breast cancer was associated with increased odds of increasing density (aOR 1.21; P<.001). Hormone replacement therapy use for more than 5 years (aOR 1.23; P<.001), prior hysterectomy (aOR 1.22; P<.001), and later age at menopause were also associated with increasing density or persistently dense trajectories.
⁴ Greater parity and a longer duration of breastfeeding were associated with decreasing breast density over time.