Association of abnormal nipple aspirate cytology and mammographic pattern and density.

The pattern and density of mammograms have been shown to be associated with proliferative histopathology and an increased risk of breast cancer. We recently found that epithelial atypia in nipple aspirate fluid obtained 10-18 years earlier was associated with an increased risk of breast cancer. In the present study we examined the association between the cytology of nipple aspirate fluid and mammographic patterns in 588 volunteers recruited from the mammography clinic at the University of California. Nipple aspirate fluid cytology was classified according to the most severe epithelial change present and mammograms were classified by the Wolfe method and the percentage area of density. A direct relationship was found between mammographic density and cytological abnormality. When controlled for age, body mass index, previous biopsy, and calcification, the odds ratios of high density mammograms (over 50%) with nipple aspirate fluid cytological atypia was 4.4 (95% confidence interval, 0.9-21.5; P = 0.08) when normal cytology was the referent. These preliminary findings indicate that highly dense mammograms are associated with cytological atypia and are consistent with studies reporting an association of histological hyperplasia and atypical hyperplasia with severe mammographic findings. If confirmed by further studies, nipple aspirate cytology may be a useful adjunct to mammographic patterns in the prediction of breast cancer risk, especially among premenopausal women.