Abstract Abstract #4082 Background: Past studies have indicated that mammographic density is associated with not only breast cancer risk but also breast cancer risk factors in women living in western nations. However, to data, no such association has been shown among native Chinese women. The aim of this cross-sectional study was to investigate the effects of age, body mass index (BMI), age at menarche, parity, and menopausal status on mammographic patterns in women from a province of Northern China.
 Methods: Seven hundred and two women's mammograms and information of the breast cancer risk factors were obtained from Shanxi province cancer hospital in Northern China. Mammograms were assessed according to the Wolfe classification.
 Results: Age, BMI, parity, and menopause were inversely and independently related to high-risk mammographic parenchymal patterns. However, there was no statistically significant association between age at menarche and high mammographic density. Relative to subjects aged less than or equal to 35 years, subjects aged greater than 55 years had reduced 62% (OR = 0.38, 95% CI: 0.14 – 1.00) odds of having a high-risk pattern. In comparison to women whose BMI was less than or equal to 25, there was a 51% and 72% reduction in the odds of having high-risk mammographic patterns for those with BMI 25 to 30 and larger than or equal to 30 respectively (OR = 0.49, 95% CI: 0.32 - 0.74; OR = 0.28, 95% CI: 0.12 - 0.68 respectively). Women with more than three children had decreased 68% risk to have high mammographic density compared to those who were nulliparous (OR = 0.32, 95% CI: 0.1 – 1.0). Premenopausal women were more than four times likely to have a high-risk pattern than postmenopausal women (OR = 4.12, 95% CI: 2.17 – 7.87).
 Conclusion: Our findings demonstrated that mammographic parenchymal patterns are also associated with some risk factors of breast cancer in native Chinese women. This is consistent with most studies carried out in Western countries. Further studies are needed to determine the relationship between quantitative percentage density and breast cancer risk factors. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4082.