Endogenous Estrogen Exposure Research Articles

Estrogen and the Breast

Breast estrogen receptors are the same for both endogenous and exogenous hormones. Multiple epidemiologic studies reveal that prolonged endogenous estrogen exposure increases breast cancer risk. Although conflicting, many studies exhibit an increased breast cancer risk for exogenous estrogen exposure. This literature analysis is intended to increase our understanding of the relationship between estrogens and breast cancer risk.

Maternal and Gestational Factors in Cryptorchidism

Previous epidemiological studies of cryptorchidism have led to the hypothesis that the risk of undescended testis is associated with excess oestrogen exposure during pregnancy. A case-control study was undertaken to test this hypothesis, comparing mothers of affected boys (244) and normal male births (488) born within six months of a case selected randomly from the British Columbia population. Information was collected on the mother's reproductive history, family history, and past medical history, and events surrounding all pregnancies ending in a birth. The results were analysed using both the population-based sample of male births and the male sibs of cases as control groups. Neither exogenous oestrogen exposure, nor any of the pregnancy-related variables hypothesized to be indirect indicators of endogenous oestrogen exposure, including bleeding and nausea and/or vomiting, were found to be significantly associated with risk of undescended testes in either comparison. More mothers with later index births reported menstrual irregularity greater than half the time, and smoking, thought to have a protective effect, was more prevalent among case mothers than control mothers. No other variables were significantly different between case and control mothers. The results of this study do not support the hypothesis that elevated exogenous or endogenous oestrogen exposure during pregnancy increases the risk of undescended testis in male children.

Risk factors for adenomatous endometrial hyperplasia: a case-control study.

A population-based case-control study of histologically confirmed endometrial neoplasia was conducted in Toronto, Canada, between 1977 and 1978. Pathologic slide review resulted in classification of patients to diagnostic categories of endometrial carcinoma, endometrial carcinoma in situ, and endometrial hyperplasia. This report concerns the subset of patients classified as having adenomatous endometrial hyperplasia. Two age-matched neighborhood controls were selected for each case, and analyses included only those case-control sets in which the case and at least one control were concordant on menopausal status. Among postmenopausal women (87 cases and 151 controls), noncontraceptive estrogen use was a statistically significant risk factor (adjusted odds ratio (OR) = 6.7), as was heavy body weight relative to height (Quetelet index) (adjusted OR = 3.2). Long-term (5+ years) estrogen use conferred an estimated relative risk of more than 20, but use of oral contraceptives did not alter risk significantly. Among premenopausal women (62 cases and 97 controls), a high Quetelet index appeared to be a significant protective factor, even when adjusted for oral contraceptive use (adjusted OR = 0.2). While oral contraceptive use was not associated with a change in risk, long duration of use was highly, but statistically not significantly, protective against hyperplasia. The data for pre- and postmenopausal women indicate that both endogenous and exogenous estrogen exposure are important factors in the etiology of adenomatous endometrial hyperplasia.