Correlates of high-density mammographic parenchymal patterns by menopausal status in a rural population in Northern Greece.

Reproductive factors affect breast cancer risk, but less is known of their associations with mammographic density and whether these differ by menopausal status. We report on a cross-sectional study of 1946 pre- and 3047 post-menopausal women who joined a breast screening programme in Northern Greece during 1993-1997. The odds of having a high-density Wolfe pattern (P2/DY) was inversely associated with age (P for linear trend <0.001) in both pre- and post-menopausal women and, for post-menopausal women, with years since menopause (P < 0.001). The odds of a P2/DY pattern declined with higher parity (P < 0.001) and younger age at first pregnancy (P = 0.05) in both pre- and post-menopausal women. They also decreased with the duration of breast-feeding in pre-menopausal women (P = 0.03 in pre- and P = 0.69 in post-menopausal women; test for interaction with menopausal status: P = 0.07). Age at menarche, age at menopause and the number of miscarriages/abortions were not associated with mammographic density. Age at first pregnancy and parity were strong correlates of mammographic density in pre- and post-menopausal women while duration of breast-feeding appeared to be particularly important in pre-menopausal women.