The effect of transdermal testosterone on mammographic density in postmenopausal women not receiving systemic estrogen therapy

Effect of testosterone therapy on breast tissue composition and mammographic breast density in trans masculine individuals

BACKGROUND

The effect of gender-affirming testosterone therapy (TT) on breast cancer risk is unclear. This study investigated the association between TT and breast tissue composition and breast tissue density in trans masculine individuals (TMIs).

METHODS

Of the 444 TMIs who underwent chest-contouring surgeries between 2013 and 2019, breast tissue composition was assessed in 425 TMIs by the pathologists (categories of lobular atrophy and stromal composition) and using our automated deep-learning algorithm (% epithelium, % fibrous stroma, and % fat). Forty-two out of 444 TMIs had mammography prior to surgery and their breast tissue density was read by a radiologist. Mammography digital files, available for 25/42 TMIs, were analyzed using the LIBRA software to obtain percent density, absolute dense area, and absolute non-dense area. Linear regression was used to describe the associations between duration of TT use and breast tissue composition or breast tissue density measures, while adjusting for potential confounders. Analyses stratified by body mass index were also conducted.

RESULTS

Longer duration of TT use was associated with increasing degrees of lobular atrophy (p < 0.001) but not fibrous content (p = 0.82). Every 6 months of TT was associated with decreasing amounts of epithelium (exp(β) = 0.97, 95% CI 0.95,0.98, adj p = 0.005) and fibrous stroma (exp(β) = 0.99, 95% CI 0.98,1.00, adj p = 0.05), but not fat (exp(β) = 1.01, 95%CI 0.98,1.05, adj p = 0.39). The effect of TT on breast epithelium was attenuated in overweight/obese TMIs (exp(β) = 0.98, 95% CI 0.95,1.01, adj p = 0.14). When comparing TT users versus non-users, TT users had 28% less epithelium (exp(β) = 0.72, 95% CI 0.58,0.90, adj p = 0.003). There was no association between TT and radiologist's breast density assessment (p = 0.58) or LIBRA measurements (p > 0.05).

CONCLUSIONS

TT decreases breast epithelium, but this effect is attenuated in overweight/obese TMIs. TT has the potential to affect the breast cancer risk of TMIs. Further studies are warranted to elucidate the effect of TT on breast density and breast cancer risk.

Effect of testosterone therapy on breast tissue composition and mammographic breast density in trans masculine individuals

Objective

Determine the association between TT and breast tissue composition and breast tissue density in trans masculine individuals (TMIs).

Design

This is a cross-sectional study.

Setting

TMIs (n=444) underwent chest-contouring surgeries to treat their gender dysphoria between 2013 and 2019 at an urban medical center.

Participants

Of the 444 TMIs, 425 had pathology images analyzed by our deep-learning algorithm to extract breast tissue composition. A subset of 42/444 TMIs had mammography prior to surgery; mammography files were available for 25/42 TMIs and analyzed using a breast density software, LIBRA.

Main Outcomes and Measures

The first outcome was the association of duration of TT and breast tissue composition assessed by pathologists (categories of lobular atrophy and stromal composition) or by our algorithm (% epithelium, % fibrous stroma, and % fat). The second outcome is the association of TT and breast density as assessed by a radiologist (categorical variable) or by LIBRA (percent density, absolute dense area, and absolute non-dense area).

Results

Length of TT was associated with increasing degrees of lobular atrophy ( p <0.001) but not fibrous content ( p =0.821) when assessed by the pathologists. Every six months of TT was associated with decreased amounts of both epithelium (exp(β)=0.97, 95% CI 0.95-0.98, adj p =0.005) and stroma (exp(β)=0.99, 95% CI 0.98-1.00, adj p =0.051), but not fat (exp(β)=1.01, 95%CI 0.98-1.05, p =0.394) in fully adjusted models. There was no association between TT and radiologist's breast density assessment ( p =0.575) or LIBRA measurements ( p >0.05).

Conclusions

TT decreases breast epithelium and fibrous stroma, thus potentially reducing the breast cancer risk of TMIs. Further studies are warranted to elucidate the effect of TT on breast density and breast cancer risk.

Summary Box

Very little is known about the effect of gender-affirming testosterone therapy on cancer risks, such as breast cancer.Epidemiological studies had different conclusions about the association between testosterone and breast cancer in cisgender women (positive association) and trans masculine individuals (inverse association).More laboratory-based research are needed to understand the effect of testosterone on breast cancer risk in the understudied trans masculine population.Our study provides quantitative histological evidence to support prior epidemiological reports that testosterone may reduce breast cancer risk in trans masculine individuals.

Individual Benefits and Risks of Intravaginal Estrogen and Systemic Testosterone in the Management of Women in the Menopause, With a Discussion of Any Associated Risks for Cancer Development

ABSTRACT

Several formulations of intravaginal oestrogen are available for the treatment of genitourinary syndrome of menopause (GSM). These are safe and effective treatments for the symptoms of GSM. Licensed doses of intravaginal oestrogen do not elevate systemic estradiol levels above the normal postmenopausal range with long term use and there is no evidence of an increased risk of coronary heart disease, stroke, thromboembolism, colorectal cancer, endometrial cancer, breast cancer or breast cancer recurrence with their use. This should reassure both women and their healthcare professionals and should lead to more women receiving these localised, vaginally administered hormonal treatments. Available evidence also suggests a positive safety profile for transdermal testosterone treatment when delivered at physiological concentrations.

OUP accepted manuscript

In screening for breast cancer (BC), mammographic breast density (MBD) is a powerful risk factor that increases breast carcinogenesis and synergistically reduces the sensitivity of mammography. It also reduces specificity of lesion identification, leading to recalls, additional testing, and delayed and later-stage diagnoses, which result in increased health care costs. These findings provide the foundation for dense breast notification laws and lead to the increase in patient and provider interest in MBD. However, unlike other risk factors for BC, MBD is dynamic through a woman’s lifetime and is modifiable. Although MBD is known to change as a result of factors such as reproductive history and hormonal status, few conclusions have been reached for lifestyle factors such as alcohol, diet, physical activity, smoking, body mass index (BMI), and some commonly used medications. Our review examines the emerging evidence for the association of modifiable factors on MBD and the influence of MBD on BC risk. There are clear associations between alcohol use and menopausal hormone therapy and increased MBD. Physical activity and the Mediterranean diet lower the risk of BC without significant effect on MBD. Although high BMI and smoking are known risk factors for BC, they have been found to decrease MBD. The influence of several other factors, including caffeine intake, nonhormonal medications, and vitamins, on MBD is unclear. We recommend counseling patients on these modifiable risk factors and using this knowledge to help with informed decision making for tailored BC prevention strategies.

Risks of Testosterone for Postmenopausal Women

Transdermal testosterone therapy, dosed within premenopausal physiologic testosterone ranges, used alone or with menopausal hormone therapy for postmenopausal hypoactive sexual desire disorder, has shown short-term efficacy, with few androgenic side effects. After natural or surgical menopause, meaningful improvements include an additional satisfying sexual episode per month; improvement in desire, arousal, orgasm, pleasure, and responsiveness; and a reduction in distress. Long-term data on cardiovascular, cancer, and cognitive safety are lacking. No approved testosterone preparation is available for women. Compounded testosterone creams or reduced dosing of male-approved therapies represent off-label use. Injections or pellets cause supraphysiological testosterone levels and are not recommended.

Testosterone use in postmenopausal women

The physiological, clinical and therapeutic aspects of testosterone in women's health are still a matter of controversy and debate. Quality evidence data of clinical trials favors the use of transdermal testosterone in postmenopausal women with female sexual dysfunction causing distress. Doses of testosterone should approximate physiological testosterone levels found in premenopausal women, avoiding supraphysiological concentrations that expose women to adverse events. Short-term treatment periods have been shown to be effective and safe in postmenopausal women with hypoactive sexual desire disorder/dysfunction. However, long-term safety of testosterone use must be determined.

Safety and efficacy of testosterone for women: a systematic review and meta-analysis of randomised controlled trial data

BACKGROUND

The benefits and risks of testosterone treatment for women with diminished sexual wellbeing remain controversial. We did a systematic review and meta-analysis to assess potential benefits and risks of testosterone for women.

METHODS

We searched MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and Web of Science for blinded, randomised controlled trials of testosterone treatment of at least 12 weeks' duration completed between Jan 1, 1990, and Dec 10, 2018. We also searched drug registration applications to the European Medicine Agency and the US Food and Drug Administration to identify any unpublished data. Primary outcomes were the effects of testosterone on sexual function, cardiometabolic variables, cognitive measures, and musculoskeletal health. This study is registered with the International Prospective Register of Systematic Reviews (PROSPERO), number CRD42018104073.

FINDINGS

Our search strategy retrieved 46 reports of 36 randomised controlled trials comprising 8480 participants. Our meta-analysis showed that, compared with placebo or a comparator (eg, oestrogen, with or without progestogen), testosterone significantly increased sexual function, including satisfactory sexual event frequency (mean difference 0·85, 95% CI 0·52 to 1·18), sexual desire (standardised mean difference 0·36, 95% CI 0·22 to 0·50), pleasure (mean difference 6·86, 95% CI 5·19 to 8·52), arousal (standardised mean difference 0·28, 95% CI 0·21 to 0·35), orgasm (standardised mean difference 0·25, 95% CI 0·18 to 0·32), responsiveness (standardised mean difference 0·28, 95% CI 0·21 to 0·35), and self-image (mean difference 5·64, 95% CI 4·03 to 7·26), and reduced sexual concerns (mean difference 8·99, 95% CI 6·90 to 11·08) and distress (standardised mean difference -0·27, 95% CI -0·36 to -0·17) in postmenopausal women. A significant rise in the amount of LDL-cholesterol, and reductions in the amounts of total cholesterol, HDL-cholesterol, and triglycerides, were seen with testosterone administered orally, but not when administered non-orally (eg, by transdermal patch or cream). An overall increase in weight was recorded with testosterone treatment. No effects of testosterone were reported for body composition, musculoskeletal variables, or cognitive measures, although the number of women who contributed data for these outcomes was small. Testosterone was associated with a significantly greater likelihood of reporting acne and hair growth, but no serious adverse events were recorded.

INTERPRETATION

Testosterone is effective for postmenopausal women with low sexual desire causing distress, with administration via non-oral routes (eg, transdermal application) preferred because of a neutral lipid profile. The effects of testosterone on individual wellbeing and musculoskeletal and cognitive health, as well as long-term safety, warrant further investigation.

FUNDING

Australian National Health and Medical Research Council.

Testosterone therapy for women with low sexual desire: a position statement from the Brazilian Society of Endocrinology and Metabolism

OBJECTIVE

To summarize current evidence regarding testosterone treatment for women with low sexual desire.

MATERIALS AND METHODS

The Female Endocrinology and Andrology Department of the Brazilian Society of Endocrinology and Metabolism invited nine experts to review the physiology of testosterone secretion and the use, misuse, and side effects of exogenous testosterone therapy in women, based on the available literature and guidelines and statements from international societies.

RESULTS

Low sexual desire is a common complaint in clinical practice, especially in postmenopausal women, and may negatively interfere with quality of life. Testosterone seems to exert a positive effect on sexual desire in women with sexual dysfunction, despite a small magnitude of effect, a lack of long-term safety data, and insufficient evidence to make a broad recommendation for testosterone therapy. Furthermore, there are currently no testosterone formulations approved for women by the relevant regulatory agencies in the United States, Brazil, and most other countries, and testosterone formulations approved for men are not recommended for use by women.

CONCLUSION

Therefore, testosterone therapy might be considered if other strategies fail, but the risks and benefits must be discussed with the patient before prescription. Arch Endocrinol Metab. 2019;63(3):190-8.

A systematic review of randomized controlled trials investigating the efficacy and safety of testosterone therapy for female sexual dysfunction in postmenopausal women

The clinical sequelae of oestrogen deficiency during menopause are undoubted. However, the pathophysiological role of testosterone during the menopause is less clear. Several randomized, placebo-controlled clinical trials suggest that testosterone therapy improves sexual function in postmenopausal women. Some studies suggest that testosterone therapy has additional effects, which include increased bone mineral density and decreased serum high-density lipoprotein (HDL) cholesterol. Furthermore, the long-term safety profile of testosterone therapy in postmenopausal women is not clear. This article will provide a concise and critical summary of the literature, to guide clinicians treating postmenopausal women.

The International Society for the Study of Women's Sexual Health Process of Care for Management of Hypoactive Sexual Desire Disorder in Women

The International Society for the Study of Women's Sexual Health process of care (POC) for management of hypoactive sexual desire disorder (HSDD) algorithm was developed to provide evidence-based guidelines for diagnosis and treatment of HSDD in women by health care professionals. Affecting 10% of adult females, HSDD is associated with negative emotional and psychological states and medical conditions including depression. The algorithm was developed using a modified Delphi method to reach consensus among the 17 international panelists representing multiple disciplines. The POC starts with the health care professional asking about sexual concerns, focusing on issues related to low sexual desire/interest. Diagnosis includes distinguishing between generalized acquired HSDD and other forms of low sexual interest. Biopsychosocial assessment of potentially modifiable factors facilitates initiation of treatment with education, modification of potentially modifiable factors, and, if needed, additional therapeutic intervention: sex therapy, central nervous system agents, and hormonal therapy, guided in part by menopausal status. Sex therapy includes behavior therapy, cognitive behavior therapy, and mindfulness. The only central nervous system agent currently approved by the US Food and Drug Administration (FDA) for HSDD is flibanserin in premenopausal women; use of flibanserin in postmenopausal women with HSDD is supported by data but is not FDA approved. Hormonal therapy includes off-label use of testosterone in postmenopausal women with HSDD, which is supported by data but not FDA approved. The POC incorporates monitoring the progress of therapy. In conclusion, the International Society for the Study of Women's Sexual Health POC for the management of women with HSDD provides a rational, evidence-based guideline for health care professionals to manage patients with appropriate assessments and individualized treatments.

HRT for women with premature ovarian insufficiency: a comprehensive review

BACKGROUND

Premature ovarian insufficiency (POI), often and misleadingly referred to as ‘premature menopause’, is defined as a loss of ovarian activity before the age of 40 years and is characterized by irregular or absent periods and reduced fertility. Symptoms include those associated with the natural menopause (night sweats and vaginal dryness), and with the long-term adverse effects of estrogen deficiency (osteoporosis and cardiovascular disease): the latter is believed to explain the shorter life expectancy associated with POI.

OBJECTIVE AND RATIONALE

The objective of the current review was to collect all relevant studies supporting recommendations on the indications, treatment options, and risks of hormone replacement therapy (HRT) (estrogen, progestogens and androgens) for women with POI.

SEARCH METHODS

The current review was written based on the best available evidence on the topic collected for the recently published ESHRE guideline on the management of women with POI. PUBMED/MEDLINE and the Cochrane library were searched in a stepwise approach. Relevant references were summarized in evidence tables, with assessment of the quality.

OUTCOMES

HRT is strongly recommended for women with POI, mainly for vasomotor and genito-urinary symptom relief. In addition, HRT has been shown to have a role in bone protection and probably also in primary prevention of cardiovascular disease. There is little evidence on the optimal type, regimen and dose of HRT; patient preference for route and method of administration of each component of HRT must be considered when prescribing, as should contraceptive needs. In women with POI, physiological replacement of estrogen (and progesterone) is essential for their health, and the controversies that surround the use of HRT in postmenopausal women do not apply.

LIMITATIONS, REASONS FOR CAUTION

N/A.

WIDER IMPLICATIONS

New areas of study on HRT for women with POI should focus on life expectancy, quality of life and neurological function. Furthermore, randomized controlled trials comparing transdermal estradiol with oral estrogens with regard to efficacy, patient satisfaction and side effects are urgently needed.

STUDY FUNDING/COMPETING INTERESTS

The authors received no funding for the review. The costs for the development of the ESHRE guideline were covered by ESHRE. The authors have no conflicts of interest to disclose.

Testosterone therapy for menopausal women

It has been suggested that there is a link between low circulating concentrations of testosterone and reduced sexual functioning in postmenopausal women,¹ and it has been more than 60 years since the effects of testosterone therapy for the management of menopausal symptoms were first reported.² Since then, testosterone supplementation has received growing attention for its potential role in maintaining sexual function in menopausal women. The National Institute for Health and Care Excellence guideline on the diagnosis and management of menopause recommends considering testosterone supplementation for women with low sexual desire if hormone replacement therapy (HRT) alone has been ineffective.³ However, in the UK no testosterone products are licensed for such use. A testosterone patch authorised by the European Medicines Agency in 2006 for use in women with surgical menopause was withdrawn from the market in 2012 for commercial reasons.⁴ Here, we provide an update on the evidence of the effectiveness and safety of testosterone supplementation in menopausal women.

Efficacy and safety of transdermal testosterone in postmenopausal women with hypoactive sexual desire disorder: a systematic review and meta-analysis

OBJECTIVE

To systematically review and summarize the existing evidence related to the efficacy and safety of transdermal T in postmenopausal women for the treatment of hypoactive sexual desire disorder (HSDD).

DESIGN

Systematic reviews and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

Seven randomized controlled trials enrolled 3,035 participants; 1,350 women were randomized to treatment with T patch, and 1,379 women were randomized to placebo.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Primary outcome: satisfying sexual episodes.

SECONDARY OUTCOMES

sexual activity, orgasm, Profile of Female Sexual Function domains (desire), personal distress score, adverse events, acne, increased hair growth, facial hair, alopecia, voice deepening, urinary symptoms, breast pain, headache, site reaction, total adverse events, serious adverse events, withdrawal from study, and follow-up rate.

RESULT(S)

The T group had significantly more satisfying sexual episodes, sexual activity, orgasms, desire, significant change in Personal Distress Scale score, androgenic adverse events, acne, and hair growth compared with the placebo group. There was no significant difference between the two groups in increase in facial hair, alopecia, voice deepening, urinary symptoms, breast pain, headache, site reaction to the patch, total adverse events, serious adverse events, reasons for withdrawal from the study, and the number of women who completed the study.

CONCLUSION(S)

The short-term efficacy in terms of improvement of sexual function and safety of transdermal T in naturally and surgically menopausal women affected by HSDD either on or not on estrogen progestin hormone therapy is evident from this systematic review. The use of transdermal T is associated with increase in androgenic adverse events such as acne but is not associated with any serious adverse events.

Androgens and Female Sexual Function and Dysfunction--Findings From the Fourth International Consultation of Sexual Medicine

INTRODUCTION

Androgens have been implicated as important for female sexual function and dysfunction.

AIM

To review the role of androgens in the physiology and pathophysiology of female sexual functioning and the evidence for efficacy of androgen therapy for female sexual dysfunction (FSD).

METHODS

We searched the literature using online databases for studies pertaining to androgens and female sexual function. Major reviews were included and their findings were summarized to avoid replicating their content.

MAIN OUTCOME MEASURES

Quality of data published in the literature and recommendations were based on the GRADES system.

RESULTS

The literature supports an important role for androgens in female sexual function. There is no blood androgen level below which women can be classified as having androgen deficiency. Clinical trials have consistently demonstrated that transdermal testosterone (T) therapy improves sexual function and sexual satisfaction in women who have been assessed as having hypoactive sexual desire disorder. The use of T therapy is limited by the lack of approved formulations for women and long-term safety data. Most studies do not support the use of systemic dehydroepiandrosterone therapy for the treatment of FSD in women with normally functioning adrenals or adrenal insufficiency. Studies evaluating the efficacy and safety of vaginal testosterone and dehydroepiandrosterone for the treatment of vulvovaginal atrophy are ongoing.

CONCLUSION

Available data support an important role of androgens in female sexual function and dysfunction and efficacy of transdermal T therapy for the treatment of some women with FSD. Approved T formulations for women are generally unavailable. In consequence, the prescribing of T mostly involves off-label use of T products formulated for men and individually compounded T formulations. Long-term studies to determine the safety of T therapy for women and possible benefits beyond that of sexual function are greatly needed.

The safety of testosterone therapy in women

Hypoactive sexual desire disorder (HSDD), a subset of female sexual dysfunction, causes personal distress for surgically and naturally postmenopausal and premenopausal women. HSDD has a multi-factorial etiology, including psychosocial factors such as relationship issues and medical factors such as medications, chronic illnesses, and hormonal effects. Although no androgen therapies for female sexual dysfunction are currently approved for use in Canada, clinical trials support the efficacy and short-term safety of testosterone therapy for HSDD. We review the scientific evidence for the safety of testosterone therapy for HSDD.

Androgen treatment of postmenopausal women

Testosterone is physiologically important for women. Serum testosterone levels decline with age, with the most precipitous fall being prior to menopause. There is no level of testosterone which defines a woman as being testosterone deficient. However, there is substantial high quality evidence to support the use of testosterone for the treatment of hypoactive sexual desire disorder in postmenopausal women. Although preliminary data suggests testosterone has favorable effects on bone and muscle mass, cognitive function and the cardiovascular system, further research regarding its therapeutic effects in these domains is warranted. As no testosterone product has been approved for women there is extensive off-label prescribing of testosterone products for women as well as the prescription of compounded therapy. This raises serious safety concerns and together with the evidence for the negative impact of FSD on quality of life, highlights the need for an approved testosterone formulation for women. This article is part of a Special Issue entitled 'Menopause'.

Role of KLF5 in hormonal signaling and breast cancer development

Steroid hormones, including ovarian steroid hormones progesterone and estrogen and androgen, play vital roles in the development of normal mammary gland and breast cancer via their receptors. How these hormones regulate these physiological and pathological processes remains to be elucidated. Krüppel-like factor 5 (KLF5) is a transcription factor playing significant roles in breast carcinogenesis, whose expression has been shown to be regulated by hormones. In this review, the relationships among hormonal signaling, KLF5, and breast cancer are summarized and discussed.

Androgen replacement therapy in women

Female androgens are derived from either the adrenal and peripheral conversion of the adrenal sex steroid precursor, dehydroepiandrosterone, or from direct ovarian production. Adrenal insufficiency or bilateral oophorectomy (surgical menopause) result in severe androgen deficiency, which can be clinically associated with impaired libido, drive and energy. Physiological menopause does not necessarily lead to androgen deficiency. The previously suggested definition of female androgen deficiency syndrome, as the concurrent presence of low androgen levels and low libido, is not precise enough and may lead to overdiagnosis. Current replacement options include transdermal testosterone or oral dehydroepiandrosterone treatment, both of which have been shown to result in significant improvements, in particular in libido and mood, while long-term effects on body composition, cardiovascular and cancer risk are less documented. Owing to these concerns, androgen replacement should be reserved for women with severe androgen deficiency due to an established cause and matching clinical symptoms.

The safety of postmenopausal testosterone therapy

Testosterone is increasingly used as part of postmenopausal HRT regimens. Unfortunately, few androgenic preparations designed specifically for use in women have been approved by regulatory authorities. Ongoing concerns exist surrounding the potential long-term effects of testosterone therapy. Here, we review the most recent data on postmenopausal testosterone therapy, focusing particularly on the effects of testosterone on breast, endometrium and cardiovascular health.

Androgens and breast cancer risk

Transdermal testosterone supplementation is a treatment option for postmenopausal women with distressful decreased libido. Side effects are minor, but there is a long-term safety concern with respect to breast cancer, as women with high testosterone serum levels appear to be at a significantly increased risk to have or to develop breast cancer within a few years. Epidemiological studies of sufficient duration to study long-term effects of testosterone supplementation are limited, both in number and in methodological quality and are, therefore, inconclusive. Preclinical studies do not provide evidence for an androgen receptor-mediated stimulating effect of androgens on breast epithelium. However, one biologically plausible possibility, which cannot be ruled out, is that exogenous androgens become mitogenic after aromatization into bioactive oestradiol, either in peripheral fat or within the breast or even within small occult tumours. The evidence available so far makes counselling women interested in testosterone supplementation for distressful low sexual desire, more of an art than science.

Androgens and breast cancer

The role of androgens on breast cancer development and progression has not been fully elucidated. Several in vivo and in vitro studies demonstrate that androgens have an inhibitory effect on the mammary epithelium, whereas the majority of epidemiological studies report a positive association between high androgen levels and risk of breast cancer. Expression of the androgen receptor is a positive prognostic factor. Understanding the role of androgens in breast carcinogenesis is important because many women use testosterone replacement for the alleviation of symptoms brought on by menopause, in particular high-risk women who undergo surgical menopause at an early age. We overview the literature examining a role of androgens in the etiology of breast cancer.

Cardiovascular and cancer safety of testosterone in women

PURPOSE OF REVIEW

To examine the recent data pertaining to the relationships between testosterone and cardiovascular disease (CVD) and cancer in women.

RECENT FINDINGS

Despite the entrenched belief that higher blood levels of testosterone increase the risk of CVD in women, data from recent observational studies mostly show an inverse relationship between testosterone and CVD risk. One pilot study suggests favorable effects of nonoral testosterone treatment of women with established congestive cardiac failure which merits further evaluation. The relationship between endogenous testosterone production and breast cancer risk remains contentious, with recent studies indicating either no relationship, or a possible increase in risk when estrone and estradiol are not taken into account. No randomized controlled trial of testosterone therapy has been sufficiently large or of sufficient duration to establish whether such treatment may influence breast cancer occurrence. There does not appear to be an association between testosterone and endometrial cancer, or other malignancies on review of published studies.

SUMMARY

Testosterone is inversely associated with increased CVD risk in women, whereas low sex hormone binding globulin increases CVD risk. The relationship between testosterone and breast cancer remains unclear, although a clear signal of risk has not emerged from studies of women treated with testosterone therapy over the past decade.

Testosterone and risk of breast cancer: appraisal of existing evidence

The objective of this review was to examine data from preclinical, clinical and epidemiological studies to evaluate if testosterone (T) poses increased risk of breast cancer in women. Appraisal of the existing literature produced several lines of evidence arguing against increased breast cancer risk with T. These include: (i) Data from breast tumor cell lines treated with androgens did not corroborate the notion that T increases breast cancer risk. On the contrary, androgens appear to be protective, as they inhibit tumor cell growth. (ii) Many of the epidemiological studies claiming an association between T and breast cancer did not adjust for estrogen levels. Studies adjusted for estrogen levels reported no association between T and breast cancer. (iii) Data from clinical studies with exogenous androgen treatment of women with endocrine and sexual disorders did not show any increase in incidence of breast cancer. (iv) Women afflicted with polycystic ovary disease, who exhibit high levels of androgens do not show increased risk of breast cancer compared to the general population. (v) Female to male transsexuals, who receive supraphysiological doses of T for long time periods prior to surgical procedures, do not report increased risk of breast cancer. (vi) Finally, women with hormone responsive primary breast cancer are treated with aromatase inhibitors, which block conversion of androgens to estrogens, thus elevating androgen levels. These women do not experience increased incidence of contralateral breast cancer nor do they experience increased tumor growth. In conclusion, the evidence available strongly suggests that T does not increase breast cancer risk in women.