Plasma prolactin levels in women at postmenopausal age with a family history of breast cancer or a prescription for antihypertensive Rauwolfia treatment.

An investigation was made of daytime plasma prolactin levels in three groups of women aged 50 to 64 years: (1) 139 women with a family history of breast cancer; (2) 50 women on Rauwolfia treatment for hypertension, and (3) 90 women of a control group. A significant difference in prolactin levels was found between groups 2 and 3 but not between 1 and 3. These findings are considered in relation to the results of a breast cancer screening programme in which the women took part. Here, it was the women with a family history of breast cancer who showed an increased breast cancer risk, whereas the risk in women on Rauwolfia was not significantly higher than expected on the basis of the experience among controls. It is concluded that the role of prolactin in the etiology of breast cancer is still not clear.