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

Abstract

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.

PIP: During 1981-1983, 467 women underwent curettage for bleeding disorders at the University Hospital in Lund, Sweden. Hormonal receptor analyses and histological analyses were conducted for each patient. Frozen plasma remained after routine blood tests in 65 of these women (between 32-51 years old) and researchers analyzed the plasma for prolactin. In addition, staff took case histories on each patient, such as information on age when each woman began taking oral contraceptives (OCs). The interviewers did not know the patients' hormone and hormone receptor values. Women who began OC use 25 years old had a significantly higher ratio of 1n plasma prolactin and 1n estrogen receptor (ER) than the reamining women who underwent curettage (p=.047, Mann-Whitney U test). Researchers adjusted for age, duration of OC use, menstrual cycle phase, age at menarche, age at first full term pregnancy, and parity and found that none of these variables explained the effect of the starting age. Weak insignificant correlations existed between 1n plasma prolactin and early OC use (rs=.13) and between 1n ER and early OC use (rs=.16). 19% of the early starters had ratios more extreme than 95% of the not early starters. Similarly, an earlier breast cancer study revealed that 22% of the early starters had ratios more extreme than 95% of the not early starters. Research shows that OC use reduced the risk of carcinoma of the uterus, but OC use increases the risk of breast cancer. This study provides evidence that early OC use in humans may strongly affect hormonal levels and hormonal receptor status in the uterus years after the exposure occurred.