In a study reported in JAMA Oncology, Jiang et al found that breast density decreased over time among patients undergoing mammographic screening for breast cancer, but that the decrease was smaller in the affected breast among patients who developed breast cancer vs the decrease observed in individuals without breast cancer.
Study Details
The nested case-control cohort study was sampled from the Joanne Knight Breast Health Center Cohort at Washington University in St. Louis, consisting of 10,481 individuals free from cancer at entry and observed from November 2008 to October 2020. Routine screening mammograms were performed every 1 to 2 years, including volumetric percentage of breast density and change in volumetric breast density over time.
Key Findings
A total of 289 breast cancer cases were diagnosed. A total of 658 controls without a diagnosis of breast cancer matched for age at entry and year of enrollment were included. Among the study population, mean age at entry was 57 years; 14.9% were Black and 80.6% were White.
Among patients diagnosed with breast cancer, mean interval from last mammogram to date of breast cancer diagnosis was 2.0 years (10th percentile = 1.0 year; 90th percentile = 3.9 years).
When the mean volumetric density of both breasts for each patient was assessed, breast density at entry was higher for cases vs controls (P = .01). Breast density decreased over the up to 10 years of follow-up in both cases and controls. When density of both breasts was assessed, there was no difference in rate of density reduction between cases and controls (P = .11). However, analysis of density change separately in each breast showed a significantly slower rate of decline in density in the breast that developed breast cancer vs the decline in controls (P = .04).
The investigators concluded, “This study found that the rate of change in breast density was associated with the risk of subsequent breast cancer. Incorporation of longitudinal changes into existing models could optimize risk stratification and guide more personalized risk management.”
Graham A. Colditz, MD, DrPH, of the Division of Public Health Sciences, Department of Surgery, Washington University School of Medicine, is the corresponding author for the JAMA Oncology article.
Disclosure: The study was supported by the Breast Cancer Research Foundation and National Cancer Institute. For full disclosures of the study authors, visit jamanetwork.com.
