Permanent alterations induced in plasma prolactin and estrogen receptor concentration in benign and malignant tissue of women who started oral contraceptive use at an early age.

In 65 young women undergoing curettage for benign uterine disorders a significant relationship was found between early oral contraceptive use (starting age less than 25 years) and a high ratio of ln plasma prolactin versus ln estrogen receptor concentration of the uterine mucosae (p less than 0.047, Mann-Whitneys U-test). Year of birth, age at menarche, age at first full term pregnancy, parity, menstrual cycle phase and duration of oral contraceptive use could not explain the results. Because similar results have previously been found for breast cancer patients using plasma prolactin and breast tumour estrogen receptor concentration, the findings indicate that early oral contraceptive use permanently alters plasma prolactin levels and estrogen receptor concentration, both in benign uterine tissue and in malignant breast tumours.