Age as a confounding factor in the association of mammographic dysplasia and estrogen receptor concentration in breast cancer.

We have examined the association between hormone receptor concentration in primary breast cancer and the mammographic pattern of the breast in which the cancer arose. A significant association was found between the concentration of estrogen receptor and the proportion of the breast volume occupied by the radiological signs of dysplasia. Both estrogen receptor concentration and dysplasia were found to be strongly associated with age. Estrogen receptor concentration rose with increasing age, while the age of patients with extensive dysplasia was substantially less than that of patients with no dysplasia. After taking age into account, no association remained between estrogen receptor concentration and mammographic dysplasia. Age is therefore a confounding factor in this association.