Decline in mammographic density greatest during menopause
Age-associated declines in mammographic density (MD), while occurring pre- and postmenopausally, are most pronounced during menopause, a new study reports.
This trend is consistent worldwide and across a wide variety of ethnic and geographical groups suggesting an underlying innate biological mechanism.
Analysis of 11,423 women (35 to 85 years of age) showed that postmenopausal women had lower percent MD (PD; difference, -0.46 cm; 95 percent CI, -0.53 to -0.39) and lower dense area (difference, -0.55 cm; -0.65 to -0.45) compared with premenopausal women of the same age.
On the other hand, nondense area (difference, 0.32 cm; 0.21 to 0.43) was larger in postmenopausal women than in premenopausal women of the same age.
In premenopausal women, every 10-year increase in age was associated with decreases in PD (difference, -0.24; -0.34 to -0.14) and dense area (difference, -0.27; -0.41 to -0.14). Changes in PD and dense area were not associated with changes in breast area.
PD (difference, -0.38; -0.44 to -0.33) and dense area (difference, -0.32; -0.39 to -0.24) also decreased in postmenopausal women with every 10-year increase in age. In contrast to premenopausal women, a corresponding increase in breast area (difference, 0.34; 0.24 to 0.39) was observed in postmenopausal women.
While there were variations in the trend when the women were grouped according to reproductive factors (parity and age at first birth), there were no significant variations across the different ethnic groups except for larger decreases in PD in Malay and South Asian women.
Information was retrieved from the International Consortium on Mammographic Density. Participants were free of breast cancer and were categorized as pre- (n=4,534) or postmenopausal (n=6,481). MD was measured using the Cumulus method.