Lactotroph hyperplasia in an estrogen treated male-to-female transsexual patient

Effects of antiandrogens on prolactin levels among transgender women on estrogen therapy: A systematic review

BACKGROUND

Gender-affirming hormone therapy for transgender women includes estrogen and antiandrogens (cyproterone acetate, spironolactone, or gonadotropin-releasing hormone agonists). Both estrogen and antiandrogens are reported to increase prolactin levels. The objective is to systematically review the evidence of the effects of antiandrogens on prolactin levels, hyperprolactinemia, and prolactinomas among transgender women on estrogen therapy.

METHODS

We searched PubMed, Embase, and PsycInfo up to May 2020. We included studies with at least 3 months follow-up that evaluated the effects of antiandrogens among transgender women and reported on prolactin levels, hyperprolactinemia, or image-confirmed prolactinomas. Two reviewers independently screened studies for eligibility, serially abstracted data, and independently assessed risk of bias and graded strength of evidence.

FINDINGS

We included 17 studies (16 publications): 8 prospective cohorts, 8 retrospective cohorts, and 1 cross-sectional study, each with a moderate to serious risk of bias. Among transgender women on estrogen, prolactin levels increased by over 100% with cyproterone acetate and by up to 45% with spironolactone. However, we were unable to isolate the effects of antiandrogens from estrogen therapy. We were unable to draw conclusions about effects of antiandrogens on hyperprolactinemia and prolactinomas.

INTERPRETATION

Prolactin levels may be increased in transgender women who are taking both estrogens and an antiandrogen. Future research is needed to determine the effects of different antiandrogens on prolactin levels separately from estrogen therapy. Ideally, future studies would be prospective, provide either a comparison of two different antiandrogens or compare combination of estrogen and antiandrogen therapy to estrogen alone, and control for possible confounders.

Ept7, a quantitative trait locus that controls estrogen-induced pituitary lactotroph hyperplasia in rat, is orthologous to a locus in humans that has been associated with numerous cancer types and common diseases

Pituitary adenoma is a common intracranial neoplasm that is observed in approximately 10% of unselected individuals at autopsy. Prolactin-producing adenomas, i.e., prolactinomas, comprise approximately 50% of all pituitary adenomas and represent the most common class of pituitary tumor. Multiple observations suggest that estrogens may contribute to development of prolactinoma; however, direct evidence for a causal role of estrogens in prolactinoma etiology is lacking. Rat models of estrogen-induced prolactinoma have been utilized extensively to identify the factors, pathways and processes that are involved in pituitary tumor development. The objective of this study was to localize to high resolution Ept7 (Estrogen-induced pituitary tumor), a quantitative trait locus (QTL) that controls lactotroph responsiveness to estrogens and was mapped to rat chromosome 7 (RNO7) in an intercross between BN and ACI rats. Data presented and discussed herein localize the Ept7 causal variant(s) to a 1.91 Mb interval of RNO7 that contains two protein coding genes, A1bg and Myc, and Pvt1, which yields multiple non-protein coding transcripts of unknown function. The Ept7 orthologous region in humans is located at 8q24.21 and has been linked in genome wide association studies to risk of 8 distinct epithelial cancers, including breast, ovarian, and endometrial cancers; 3 distinct types of B cell lymphoma; multiple inflammatory and autoimmune diseases; and orofacial cleft defects. In addition, the Ept7 locus in humans has been associated with variation in normal hematologic and development phenotypes, including height. Functional characterization of Ept7 should ultimately enhance our understanding of the genetic etiology of prolactinoma and these other diseases.

Rat models of 17β-estradiol-induced mammary cancer reveal novel insights into breast cancer etiology and prevention

Numerous laboratory and epidemiologic studies strongly implicate endogenous and exogenous estrogens in the etiology of breast cancer. Data summarized herein suggest that the ACI rat model of 17β-estradiol (E2)-induced mammary cancer is unique among rodent models in the extent to which it faithfully reflects the etiology and biology of luminal types of breast cancer, which together constitute ~70% of all breast cancers. E2 drives cancer development in this model through mechanisms that are largely dependent upon estrogen receptors and require progesterone and its receptors. Moreover, mammary cancer development appears to be associated with generation of oxidative stress and can be modified by multiple dietary factors, several of which may attenuate the actions of reactive oxygen species. Studies of susceptible ACI rats and resistant COP or BN rats provide novel insights into the genetic bases of susceptibility and the biological processes regulated by genetic determinants of susceptibility. This review summarizes research progress resulting from use of these physiologically relevant rat models to advance understanding of breast cancer etiology and prevention.

Low estrogen doses normalize testosterone and estradiol levels to the female range in transgender women

OBJECTIVE

The ideal dosage of cross-sex hormones remains unknown. The aim of this study was to evaluate the luteinizing hormone, follicle-stimulating hormone, testosterone, estradiol and prolactin levels after low-dose estrogen therapy with or without cyproterone acetate in transgender women.

METHODS

The serum hormone and biochemical profiles of 51 transgender women were evaluated before gonadectomy. Hormone therapy consisted of conjugated equine estrogen alone or combined with cyproterone acetate. The daily dose of conjugated equine estrogen was 0.625 mg in 41 subjects and 1.25 mg in 10 subjects, and the daily dose of cyproterone acetate was 50 mg in 42 subjects and 100 mg in one subject.

RESULTS

Estrogen-only therapy reduced the testosterone, luteinizing hormone and follicle-stimulating hormone levels from 731.5 to 18 ng/dL, 6.3 to 1.1 U/L and 9.6 to 1.5 U/L, respectively. Estrogen plus cyproterone acetate reduced the testosterone, luteinizing hormone and follicle-stimulating hormone levels from 750 to 21 ng/dL, 6.8 to 0.6 U/L and 10 to 1.0 U/L, respectively. The serum levels of luteinizing hormone, follicle-stimulating hormone, testosterone, estradiol and prolactin in the patients treated with estrogen alone and estrogen plus cyproterone acetate were not significantly different. The group receiving estrogen plus cyproterone acetate had significantly higher levels of gamma-glutamyltransferase than the group receiving estrogen alone. No significant differences in the other biochemical parameters were evident between the patients receiving estrogen alone and estrogen plus cyproterone acetate.

CONCLUSION

In our sample of transgender women, lower estrogen doses than those usually prescribed for these subjects were able to adjust the testosterone and estradiol levels to the physiological female range, thus avoiding high estrogen doses and their multiple associated side effects.

Comparison of Male and Female Prolactinoma Patients Requiring Surgical Intervention

Objectives  Prolactinomas are the most common functional pituitary adenoma. Symptoms of a prolactinoma stem from hormonal causes (menstrual irregularities, galactorrhea, and reduced libido) or from tumor mass effect (visual changes and headache). Gender differences have been noted in prolactinomas, with males presenting with larger tumors and sequelae of mass effect, while females present commonly with hormonal symptoms. The purpose of this study is to evaluate differences in patient and disease characteristics, and outcomes between male and female prolactinoma patients undergoing surgery. Design  This was a retrospective chart review. Setting  This was done at the tertiary medical center. Participants  The medical records of prolactinomas patients who underwent endoscopic endonasal surgery between March 2008 and August 2016 were reviewed. Main Outcome Measures  Demographic information, tumor characteristics, and treatment characteristics and outcomes were collected. Statistical analysis was performed using chi-squared test or Student's t -test as applicable. Results  Seventy-nine patients were identified, 22 males and 57 females. The average age for males was 38 years and for females was 35 years. Males were more likely to present with decreased libido ( p  < 0.0001), whereas females more often presented with galactorrhea ( p  < 0.0001) and menstrual irregularities. Tumor size was larger in males ( p  = 0.0044) with higher likelihood of suprasellar extension ( p  = 0.0409) and cavernous sinus invasion ( p  = 0.0026). Males were more likely to have a subtotal resection rather than gross total resection ( p  = 0.0086) and less likely to have normalization of prolactin levels following surgery ( p  = 0.0019) Conclusion  Male prolactinoma patients tend to have larger tumors with more aggressive features. This may have a role in the differences in outcomes noted in this study.

Autonomous prolactin secretion in two male-to-female transgender patients using conventional oestrogen dosages

Oestrogen-induced prolactinomas have been reported in male-to-female (MTF) transgender patients after excessive oestrogen self-administration. Here, two prolactinoma cases after 14 years (case 1) and 30 years (case 2) of relatively low-dose oestrogen treatment are reported. Both resolved after treatment with dopamine agonists. During the first year of oestrogen treatment the patient in case 1 showed a remarkable (7.2-fold) increase in serum prolactin concentration, returning to within the normal range for 13 years until the start of autonomous prolactin secretion. It is hypothesised that this strong first-year prolactin response may be a sign of increased pituitary oestrogen sensitivity. Therefore the patient's increase in prolactin concentration during the first 18 months was compared to 74 matched control patients from a database, and this increase was found to be significantly greater in the case patient. It is suggested that in MTF patients an excessive first year increase in serum prolactin concentration may identify patients at risk for autonomous prolactin secretion later in life.

Pathogenesis of prolactinomas

In recent years the demonstration that human pituitary adenomas are monoclonal in origin provides further evidence that pituitary neoplasia arise from the replication of a single mutated cell in which growth advantage results from either activation of proto-oncogenes or inactivation of tumor suppressor genes. However, with the exception of one RAS mutation identified in a single unusually aggressive prolactinoma resistant to dopaminergic inhibition that resulted to be lethal, no mutational changes have been so far detected in prolactinomas. In the absence of genetic changes, modifications in the level of expression of oncogenes or tumor suppressor genes have been detected in these tumors, although it is unknown whether these changes have a causative role or are a secondary event. Indeed, our knowledge on the molecular events involved in lactotroph proliferation is even more limited in comparison to the other tumor types, since these tumors are very infrequently surgically removed and therefore available for molecular biology studies. In this respect, it is worth noting that the molecular and biological abnormalities so far described in prolactinomas mainly concern aggressive and atypical tumors and likely do not apply to the typical prolactinomas, that are characterized by good response to medical treatment and a very low growth rate.

Functional role of estrogen in pituitary tumor pathogenesis

Pituitary hyperplasia and lactotroph replication are induced by estrogen. The product of the pituitary tumor transforming gene (PTTG) exhibits in vitro and in vivo transforming activity and induces basic bFGF secretion, thereby modulating pituitary angiogenesis and tumor formation. We demonstrated previously that pituitary pttg is induced by estrogen and bFGF, the latter being expressed in a concordant fashion with pttg in experimental and human pituitary adenomas. We now elucidate the role of estrogen in paracrine regulation of pituitary tumorigenesis by PTTG. Coincident with the circulating rat estradiol surge and maximal pituitary proliferation, pituitary pttg mRNA, bFGF, and VEGF expression increased approximately threefold during proestrus and estrus. Osmotic mini-pump coinfusion of estrogen and antiestrogen abrogated estrogen-induced pituitary pttg expression in vivo, suppressed serum PRL concentrations by 88%, and attenuated prolactin-secreting pituitary tumor growth by 41% in rats. Antiestrogen treatment of primary human pituitary tumor cultures reduced PTTG expression approximately 65%. Pituitary pttg, bFGF, and VEGF are cyclically expressed during the rat estrus cycle, concordantly with estrogen levels. Because anti-estrogens reduced PTTG expression in human pituitary tumors in vitro and suppressed experimental tumor growth in vivo, concomitantly with reduced PRL secretion, these results indicate a role for selective antiestrogens in treating pituitary tumors.