The relation between radiographic features and determinants of risk of breast cancer.

Mammograms were obtained from 942 normal women aged over 30 years, and were classified by Wolfe's criteria. In women with an enhanced risk of breast cancer associated with a late age at first child or nulliparity, there was a significant increase in the proportion of P2 and DY mammographic patterns which are thought to be a radiological index of risk. There was a decrease in the proportion of P2 and DY grades in women using steroidal contraceptives. However, the association between radiological and epidemiological determinants of risk did not hold for age at menarche.