Age and race related changes in mammographic parenchymal patterns.

The relationship between breast parenchymal patterns and age was examined in a nonselected, nonreferred group. The three major racial-ethnic subgroups represented have markedly different incidences of breast cancer, with Anglos (nonHispanic caucasians), Hispanics, and American Indians having higher to lower incidence rates of breast cancer, respectively. Mammograms were performed in 519 victims of nonhospital, nonnatural or unexplained deaths in New Mexico. The percentage of dense breast patterns (DY + P2) decreased with age for all groups. American Indian women showed a much earlier shift to a lower density parenchymal pattern than Anglo or Hispanic women. At older ages Indian women continued to have a slightly lower percentage of dense breast patterns than the other groups. The changes in breast parenchymal pattern with age and ethnic groups may reflect factors related to risk of breast cancer.