Estrone

Exogenous (external) estrone has been proven to be a known carcinogen for human females. Exposure to estrone can cause breast tenderness or pain, cervical hyper secretion, menstrual disorders including menorrhagia and metrorrhagia, nausea, headache, hypertension, leg cramps, vision disturbances, and endometriosis pain in women. Mothers lactating can also experience a decrease in the production of breast milk. Estrone can be found in the urine of pregnant women and can also be excreted in feces. 

In men, estrone has been known to cause anorexia, nausea, vomiting, and erectile dysfunction. Estrone is relevant to health and disease states because of its conversion to estrone sulfate, a long-lived derivative. Estrone sulfate acts as a reservoir that can be converted as needed to the more active estradiol. 

Production and regulation

Estrone is the main representative of the endogenous estrogens and is produced by several tissues, especially adipose tissue. Estrone is the result of the process of aromatization of androstenedione ( endogenous androgen steroid hormone and intermediate in the biosynthesis of testosterone) that occurs in fat cells.

Hormonal effects

Obese women have higher plasma concentrations of endogenous (internal) estrone. Some study showed higher plasma levels of estrone in obese patients with coronary artery disease (CAD) or at high risk for coronary heart disease. The same study also showed that increased plasma levels of estrone were associated with a nonsignificant trend toward a lower incidence of cardiovascular events. 

The levels of circulating estrogens, including estrone (E1) and estrone sulfate, are positively related to the development and growth of breast cancer in postmenopausal females. They participate in the proliferation and apoptosis of breast cells, increasing the likelihood of DNA mutations and carcinogenesis. There have been several recent reports demonstrating the relationship between various estrogen metabolites and breast cancer risk.
Consequently, estrone and estrone metabolites have been the main targets in studies of breast carcinogenesis and drug therapy mechanisms.