Mammographic Density Over Time in Women With and Without Breast Cancer

This study compared mammographic density over time between women who developed breast cancer (cases) and women who did not (controls). Cases had an initial negative mammographic screen and another three years later when cancer was diagnosed. Cases were matched to three controls with two successive negative screens by age, year of mammogram, BMI, parity, menopausal status and HRT use. Mammographic density was measured by Volpara (TM). There was a significant reduction in percentage density in the affected breast for cases (5.2 to 4.8 %, p < 0.001) and for the same matched breast in controls (4.9 to 4.5, p < 0.001). Similar results were found for the unaffected breast. After adjusting for density measures at the initial screen, case-control status was only significantly associated with fibroglandular volume in the unaffected breast (adjusted mean 45.8 cm(3) in cases, 44.0 cm(3) in controls, p = 0.008). The results suggest changes in mammographic density may be less important than initial mammographic density.