Reduced breast cancer incidence in women treated with subcutaneous testosterone,or testosterone with anastrozole: A prospective,observational study

Objectives

There is evidence that androgens are breast protective and that testosterone therapy treats many symptoms of hormone deficiency in both pre and postmenopausal patients. However, unlike estrogen and progestins, there is a paucity of data regarding the incidence of breast cancer in women treated with testosterone therapy. This study was designed to investigate the incidence of breast cancer in women treated with subcutaneous testosterone therapy in the absence of systemic estrogen therapy.

Study design

This is a 5-year interim analysis of a 10-year, prospective, observational, IRB approved study investigating the incidence of breast cancer in women presenting with symptoms of hormone deficiency treated with subcutaneous testosterone (T) implants or, T combined with the aromatase inhibitor anastrozole (A), i.e., T + A implants. Breast cancer incidence was compared with that of historical controls reported in the literature, age specific Surveillance Epidemiology and End Results (SEER) incidence rates, and a representative, similar age group of our patients used as a ‘control’ group. The effect of adherence to T therapy was also evaluated.

Results

Since March 2008, 1268 pre and post menopausal women have been enrolled in the study and eligible for analysis. As of March 2013, there have been 8 cases of invasive breast cancer diagnosed in 5642 person-years of follow up for an incidence of 142 cases per 100 000 person-years, substantially less than the age-specific SEER incidence rates (293/100 000), placebo arm of Women's Health Initiative Study (300/100 000), never users of hormone therapy from the Million Women Study (325/100 000) and our control group (390/100 000). Unlike adherence to estrogen therapy, adherence to T therapy further decreased the incidence of breast cancer (73/100 000).

Conclusion

T and/or T + A, delivered subcutaneously as a pellet implant, reduced the incidence of breast cancer in pre and postmenopausal women. Evidence supports that breast cancer is preventable by maintaining a T to estrogen ratio in favor of T and, in particular, by the use of continuous T or, when indicated, T + A. This hormone therapy should be further investigated for the prevention and treatment of breast cancer.     

Reduced breast cancer incidence in women treated with subcutaneous testosterone,or testosterone with anastrozole: A prospective,observational study

ObjectivesThere is evidence that androgens are breast protective and that testosterone therapy treats many symptoms of hormone deficiency in both pre and postmenopausal patients. However, unlike estrogen and progestins, there is a paucity of data regarding the incidence of breast cancer in women treated with testosterone therapy. This study was designed to investigate the incidence of breast cancer in women treated with subcutaneous testosterone therapy in the absence of systemic estrogen therapy.Study designThis is a 5-year interim analysis of a 10-year, prospective, observational, IRB approved study investigating the incidence of breast cancer in women presenting with symptoms of hormone deficiency treated with subcutaneous testosterone (T) implants or, T combined with the aromatase inhibitor anastrozole (A), i.e., T + A implants. Breast cancer incidence was compared with that of historical controls reported in the literature, age specific Surveillance Epidemiology and End Results (SEER) incidence rates, and a representative, similar age group of our patients used as a ‘control’ group. The effect of adherence to T therapy was also evaluated.ResultsSince March 2008, 1268 pre and post menopausal women have been enrolled in the study and eligible for analysis. As of March 2013, there have been 8 cases of invasive breast cancer diagnosed in 5642 person-years of follow up for an incidence of 142 cases per 100 000 person-years, substantially less than the age-specific SEER incidence rates (293/100 000), placebo arm of Women's Health Initiative Study (300/100 000), never users of hormone therapy from the Million Women Study (325/100 000) and our control group (390/100 000). Unlike adherence to estrogen therapy, adherence to T therapy further decreased the incidence of breast cancer (73/100 000).ConclusionT and/or T + A, delivered subcutaneously as a pellet implant, reduced the incidence of breast cancer in pre and postmenopausal women. Evidence supports that breast cancer is preventable by maintaining a T to estrogen ratio in favor of T and, in particular, by the use of continuous T or, when indicated, T + A. This hormone therapy should be further investigated for the prevention and treatment of breast cancer.     

Lessons to be learned from animal studies on hormones and the breast

The relation of hormone use by postmenopausal women to breast cancer risk has been controversial and unclear. A recent large randomized trial, the Women's Health Initiative (WHI) and a large observational study (Million Women Study) provided somewhat conflicting answers. The WHI found an increased incidence of breast cancer among women given hormone therapy (conjugated equine estrogen plus medroxyprogesterone acetate) but no increase in those given estrogen only therapy (conjugated equine estrogen alone). Whereas, the Million Women Study found an increased breast cancer risk among the estrogen plus progestin and the estrogen only users. This review brings comparative perspective to the issue of the effects of estrogen plus progestin versus estrogen only effects on breast cancer and is focused particularly on nonhuman primates. Although data from rodents is mixed, studies of monkeys suggest that estrogen only treatment has little or no effect on breast cell proliferation, and by inference, on breast cancer risk. On the other hand, data from both mouse and monkey studies strongly support the conclusion that the co-administration of a progestogen with an estrogen markedly increases breast cell proliferation and the potential for breast cancer promotion.     

Testosterone inhibits estrogen/progestogen-induced breast cell proliferation in postmenopausal women

OBJECTIVE: During the past few years serious concern has been raised about the safety of combined estrogen/progestogen hormone therapy, in particular about its effects on the breast. Several observations suggest that androgens may counteract the proliferative effects of estrogen and progestogen in the mammary gland. Thus, we aimed to study the effects of testosterone addition on breast cell proliferation during postmenopausal estrogen/progestogen therapy. DESIGN: We conducted a 6-month prospective, randomized, double-blind, placebo-controlled study. A total of 99 postmenopausal women were given continuous combined estradiol 2 mg/norethisterone acetate 1 mg and were equally randomly assigned to receive additional treatment with either a testosterone patch releasing 300 microg/24 hours or a placebo patch. Breast cells were collected by fine needle aspiration biopsy at baseline and after 6 months, and the main outcome measure was the percentage of proliferating breast cells positively stained by the Ki-67/MIB-1 antibody. RESULTS: A total of 88 women, 47 receiving active treatment and 41 in the placebo group, completed the study. In the placebo group there was a more than fivefold increase (P<0.001) in total breast cell proliferation from baseline (median 1.1%) to 6 months (median 6.2%). During testosterone addition, no significant increase was recorded (1.6% vs 2.0%). The different effects of the two treatments were apparent in both epithelial and stromal cells. CONCLUSIONS: Addition of testosterone may counteract breast cell proliferation as induced by estrogen/progestogen therapy in postmenopausal women.     

Postmenopausal testosterone therapy and breast cancer risk

Background: Testosterone therapy is being increasingly used in the management of postmenopausal women. However, as clinical trials have demonstrated a significantly increased risk of breast cancer with oral combined estrogen–progestin therapy, there is a need to ascertain the risk of including testosterone in such regimens. Objective: Evaluation of experimental and epidemiological studies pertaining to the role of testosterone in breast cancer. Design: Literature review. Setting: The Jean Hailes Foundation, Research Unit. Main Outcome Measures: Mammary epithelial proliferation, apoptosis and breast cancer. Results: In experimental studies, testosterone action is anti-proliferative and pro-apoptotic, and mediated via the AR, despite the potential for testosterone to be aromatized to estrogen. Animal studies suggest that testosterone may serve as a natural, endogenous protector of the breast and limit mitogenic and cancer promoting effects of estrogen on mammary epithelium. In premenopausal women, elevated testosterone is not associated with greater breast cancer risk. The risk of breast cancer is also not increased in women with polycystic ovary syndrome who have chronic estrogen exposure and androgen excess. However, in postmenopausal women, who are oestrogen deplete and have increased adipose aromatase activity, higher testosterone has been associated with greater breast cancer risk. Conclusion: Available data indicate the inclusion of testosterone in estrogen–progestin regimens has the potential to ameliorate the stimulating effects of hormones on the breast. However, testosterone therapy alone cannot be recommended for estrogen deplete women because of the potential risk of enhanced aromatisation to estrogen in this setting.     

Postmenopausal hormone therapy and breast cancer: a systematic review and meta-analysis

OBJECTIVE: There is a rapidly evolving debate on the indications and appropriate duration of therapy for postmenopausal hormone therapy. The objective of this meta-analysis was to examine the specific relationships of postmenopausal estrogen therapy (ET), postmenopausal combined (estrogen-progestogen) hormone therapy (CHT), and the incidence of breast cancer. DESIGN: We performed computerized searches of MEDLINE and CancerLit through September 2003 and reviewed reference lists of retrieved studies and meta-analyses. We included English-language studies that identified noncontraceptive postmenopausal hormone use; reported on the risks of "current use" of ET and/or CHT and breast cancer incidence; were case-control, cohort, or experimental; and reported either an odds ratio (OR), relative risk (RR), or HR with CIs. Two investigators were involved during all stages of study selection and independently extracted all data selected for inclusion in meta-analyses. RESULTS: Meta-analysis of 13 studies of ET and breast cancer (700,000 women) resulted in an OR of 1.16 (95% confidence limits [CL] 1.06, 1.28), with estimates for less than 5 years use 1.16 (1.02, 1.32) and more than 5 years use 1.20 (1.06, 1.37). Meta-analysis of eight studies of CHT and breast cancer (650,000 women) resulted in an OR of 1.39 (95% CL 1.12, 1.72), with estimates for less than 5 years use 1.35 (1.16, 1.57) and more than 5 years use 1.63 (1.22, 2.18). CONCLUSIONS: Data from observational studies support the association of increased but considerably different risks for breast cancer incidence among current users of ET and CHT. These represent the first pooled estimates for ET. CHT estimates correspond to those from randomized trials.     

New evidence regarding hormone replacement therapies is urgently required transdermal postmenopausal hormone therapy differs from oral hormone therapy in risks and benefits

Controversies about the safety of different postmenopausal hormone therapies (HTs) started 30 years ago and reached a peak in 2003 after the publication of the results from the Women Health Initiative (WHI) trial and the Million Women Study (MWS) [Writing group for the women's health initiative investigations. Risks and benefits of estrogen plus progestin in healthy postmenopausal women. JAMA 2002;288:321-33; Million women study collaborators. Breast cancer and hormone-replacement therapy in the million women study. Lancet 2003;362:419-27]. The single HT formulation used in the WHI trial for non hysterectomized women-an association of oral conjugated equine estrogens (CEE-0.625 mg/day) and a synthetic progestin, medroxyprogesterone acetate (MPA-2.5 mg/day)-increases the risks of venous thromboembolism, cardiovascular disease, stroke and breast cancer. The MWS, an observational study, showed an increased breast cancer risk in users of estrogens combined with either medroxyprogesterone acetate (MPA), norethisterone, or norgestrel. It is unclear and questionable to what extent these results might be extrapolated to other HRT regimens, that differ in their doses, compositions and administration routes, and that were not assessed in the WHI trial and the MWS. Significant results were achieved with the publication of the WHI estrogen-only arm study [Anderson GL, Limacher M, Assaf AR, et al. Effects of conjugated equine estrogen in postmenopausal women with hysterectomy: the Women's Health Initiative randomized controlled trial. JAMA 2004;291:1701-1712] in which hormone therapy was reserved to women who had carried out hysterectomy. What emerged from this study will allow us to have some important argument to develop.     

Histologic changes in the breast with menopausal hormone therapy use: correlation with breast density, estrogen receptor, progesterone receptor, and proliferation indices

OBJECTIVE: This retrospective study systematically compared mammographic density with histology in women receiving or not receiving menopausal hormone therapy (HT). DESIGN: This study was approved by the institutional review board. Twenty-eight postmenopausal women using HT were matched with 28 postmenopausal women not using HT at the time of breast cancer diagnosis. Noncancerous tissue from mastectomy specimens was examined histologically to quantitate the content of fibrous stroma, ducts, and lobule types 1, 2, and 3. Tissue samples were also evaluated for estrogen receptor, progesterone receptor, and Ki67 activity in the ducts and lobules. Breast density was quantified by digitizing the contralateral mammogram and computer-assisted interactive thresholding. RESULTS: High breast density in women using HT was correlated with greater fibrous stroma (P = 0.020) and lobule type 1 (P = 0.016). Breast density also correlated with Ki67 activity in the ducts (P = 0.031) and lobules (P= 0.023) for both groups combined. Estrogen and progesterone receptors did not correlate with either breast density or HT use. CONCLUSIONS: Increased fibrous stroma and lobule type 1 are associated with increasing mammographic density in women using HT, independent of estrogen and progesterone receptor up-regulation. These findings suggest that increased breast density may be mediated through a paracrine effect. The increase in breast cancer risk with HT use may be due to an increase in target lobule type 1 cells.     

Prior hormone therapy and breast cancer risk in the Women's Health Initiative randomized trial of estrogen plus progestin

OBJECTIVES: To assess the extent to which prior hormone therapy modifies the breast cancer risk found with estrogen plus progestin (E+P) in the Women's Health Initiative (WHI) randomized trial. METHODS: Subgroup analyses of prior hormone use on invasive breast cancer incidence in 16,608 postmenopausal women in the WHI randomized trial of E+P over an average 5.6 years of follow-up. RESULTS: Small but statistically significant differences were found between prior HT users and non-users for most breast cancer risk factors but Gail risk scores were similar. Duration of E+P use within the trial (mean 4.4 years, S.D. 2.0) did not vary by prior use. Among 4311 prior users, the adjusted hazard ratio (HR) for E+P versus placebo was 1.96 (95% confidence interval [CI]: 1.17-3.27), significantly different (p=0.03) from that among 12,297 never users (HR 1.02; 95% CI: 0.77-1.36). The interaction between study arm and follow-up time was significant overall (p=0.01) and among never users (p=0.02) but not among prior users (p=0.10). The cumulative incidence over time for the E+P and placebo groups appeared to cross after about 3 years in prior users, and after about 5 years in women with no prior use. No interaction was found with duration (p=0.08) or recency of prior use (p=0.17). Prior hormone use significantly increased the E+P hazard ratio for larger, more advanced tumors. CONCLUSION: A safe interval for combined hormone use could not be reliably defined with these data. However, the significant increase in breast cancer risk in the trial overall after only 5.6 years of follow-up, initially concentrated in women with prior hormone exposure, but with increasing risk over time in women without prior exposure, suggests that durations only slightly longer than those in the WHI trial are associated with increased risk of breast cancer. Longer-term exposure and follow-up data are needed.     

Androgens and the breast

There is increasing interest in the role of androgens in the treatment of women but little is known about their long-term safety. There are also very few studies on testosterone therapy and breast cancer risk. However, some observations support the concept that androgens may counteract the stimulatory effects of estrogen and progestogen in the mammary gland. Mammographic breast density and breast cell proliferation could be regarded as surrogate markers for the risk of breast cancer. Recently the addition of testosterone to a common estrogen/progestogen regimen was found to inhibit the stimulatory effects of hormones on breast cell proliferation. The effects of testosterone alone on the postmenopausal breast remain to be investigated.     

Endocrinology in cancer of the breast. Status and prospects.

Breast cancer is the result of a multistage carcinogenic process. Initiation, promotion, dependency and autonomy make up a sequence of experimentally distinguishable phases of this process. Progression--the transition from dependency on hormonal support to autonomy--is demonstrable clinically. High-affinity saturatable estrogen binding by breast cancer cytosols distinguishes endocrine-responsive mammary neoplasms from autonomous breast cancers. Approximately 70% of neoplasms containing estrogen-recepor protein at a level of 2.5 femtomoles per mg. protein or higher regress after endocrine ablation (ovariectomy in premenopausal women; adrenalectomy or hypophysectomy in postmenopausal women). Only about 5% of neoplasms lacking the receptor will respond to these maneuvers. Estrogen-receptor content also predicts clinically for estrogen and androgen responsiveness, and experimentally for prolactin dependency. Fifty per cent of primary breast cancers in women are receptor-positive. Normal breast tissue and benign breast lesions characteristically lack receptor protein. The receptor proteins appear to be induced in neoplastic cells during mammary carcinogenesis in endocrinologic settings where non-cancerous breast cells do not contain free receptor in large amounts and fail to manifest endocrinologic growth stimulation. Implications of these findings for endocrinologic management of disseminated mammary cancer, adjuvant therapy, and breast cancer prevention are discussed.     

Memory impairments with adjuvant anastrozole versus tamoxifen in women with early-stage breast cancer

OBJECTIVE: Hormones have been implicated as modulators of cognitive functioning. For instance, results of our previous work in women with breast cancer showed that cognitive impairment was more severe and involved more memory domains in those who received adjuvant tamoxifen therapy compared with women who received chemotherapy alone or no adjuvant therapy. Recently aromatase inhibitors such as anastrozole have been used in lieu of tamoxifen for the adjuvant treatment of postmenopausal women with hormone receptor-positive, early-stage breast cancer. Plasma estrogen levels are significantly lower in women who receive anastrozole compared with those who receive tamoxifen. We hypothesized, therefore, that anastrozole would have a more profound effect on cognitive function than tamoxifen, a mixed estrogen agonist/antagonist. DESIGN: To test this hypothesis we compared cognitive function in women with early-stage breast cancer who received tamoxifen with those who received anastrozole therapy in a cross-sectional study. We evaluated cognitive function, depression, anxiety, and fatigue in 31 postmenopausal women with early-stage breast cancer who were between the ages of 21 and 65 years and treated with tamoxifen or anastrozole for a minimum of 3 months. RESULTS: The results showed that women who received anastrozole had poorer verbal and visual learning and memory than women who received tamoxifen. CONCLUSIONS: Additional, prospective studies are needed to validate and confirm the changes in cognitive function associated with hormone therapy for breast cancer.     

Breast cancer: hormones and other risk factors

In North America and Northern Europe, breast cancer incidence rates begin increasing in the early reproductive years and continue climbing into the late seventies, whereas rates plateau after menopause in japan and less developed countries. Female gender, age and country of birth are the strongest determinants of disease risk. Family history and mutations in the BRCA1 and BRCA2 genes are important correlates of lifetime risk. Genetic polymorphisms associated with estrogen synthesis and metabolism are currently under study. Atypical hyperplasia and molecular alterations in benign breast lesions appear to be involved in the pathogenesis of invasive carcinoma. In postmenopausal women, increased breast density on mammograms increases risk. Bone density and breast cancer are associated, presumably through the mechanism of endogenous estrogen levels. Serum estrogen levels are higher in breast cancer cases than controls. Many established risk factors for breast cancer may function through and endocrine mechanism. Current use of oral contraceptives and prolonged, current or recent use of hormone replacement therapy moderately increase risk. Tamoxifen and possibly other selective estrogen receptor modulators reduce breast cancer risk in high risk women. Relationships between various dietary micro and macronutrients and breast cancer have been suggested but require evaluation in clinical trials. Whereas alcohol consumption is associated with increased risk, most environmental factors, including polychlorinated compounds and electromagnetic fields, are not. Conclusion: Breast cancer etiology is becoming clearer through the study of molecular alterations in germline and somatic cell genes, and the interaction of these genes with steroid hormones and relevant growth factors. This knowledge should be useful for breast cancer prevention.     

Rationale for using raloxifene to prevent both osteoporosis and breast cancer in postmenopausal women

Both osteoporosis with fracture and breast cancer are important health issues for postmenopausal women. It is well known that estrogen and estrogen receptors (ERs) play an important role in the pathogenesis of both diseases. In past decades, hormone therapy (HT), mainly estrogen plus progestin (EPT), has been frequently used for the purpose of preventing and treating postmenopausal osteoporosis because of its efficacy, but it also contributes to a significant increase in breast cancer. Currently, there is a dilemma regarding the use of estrogen for postmenopausal women. Fortunately, an increasing understanding of the action of estrogen has led ultimately to the design of new drugs that work by virtue of their interaction with the ER; these drugs have come to be known as selective estrogen receptor modulators (SERMs), and are not only effective in preventing osteoporosis and managing those with osteoporosis, but also in decreasing the incidence of breast cancer. Among these SERMs, raloxifene may be the most attractive agent based on the evidence from five recent large trials (Multiple Outcomes of Raloxifene Evaluation [MORE], Continuing Outcomes Relevant to Evista [CORE], Raloxifene Use for the Heart [RUTH], Study of Tamoxifen and Raloxifene [STAR], and Evista Versus Alendronate [EVA]). The former three trials showed that raloxifene not only decreases the incidence of osteoporosis-associated fractures, but also has efficacy in breast cancer prevention. The head-to-head comparison with the anti-fracture agent alendronate (EVA trial) and the chemoprevention agent tamoxifen (STAR trial) further confirmed that raloxifene is a better choice. We concluded that since there is an absence of a therapeutic effect on relieving climacteric symptoms and there is the presence of a potential risk of thromboembolism in the use of raloxifene, this drug can be prescribed for clear indications, such as the management of osteoporosis, the prevention of fracture, and decreasing the incidence of invasive breast cancer, with careful monitoring for thromboembolism. It is reasonable to use raloxifene as an appropriate medicine that targets climacteric symptom-free postmenopausal women because of its overall favorable risk-benefit safety profile using the global index proposed by the Women's Health Initiation (WHI).     

Safety of testosterone use in women

Female sexual desire appears to be in part androgen dependent, which has lead to the use of testosterone in women for low libido. Despite this benefit, the long-term safety of testosterone as a hormone replacement or therapy has not been well established. Side effects of testosterone therapy include mild and reversible acne and hirsuitism, as well as changes to the lipid profile with oral, but not transdermal testosterone. Short-term studies, up to 2 years, have shown that for serum plasma testosterone levels at the upper portion or slightly above the reference range for reproductive-aged women, testosterone does not increase the risk of hepatotoxicity, endometrial hyperplasia, or behavioral hostility. No adverse cardiovascular effects including changes in blood pressure, blood viscosity, arterial vascular reactivity, hypercoagulable states, and polycythemia have been shown. Data is mixed with outcomes of breast cancer risk, with some experimental studies suggesting a decrease in estrogen-induced breast epithelial proliferation with low dose testosterone. Additionally, models of superphysiologic testosterone levels, such as polycystic ovarian disease, have not shown an increased risk of breast cancer. As with all hormone therapy in postmenopausal women, testosterone therapy should be individualized and requires that each woman weigh the risk and benefits. Nevertheless, only long-term safety studies will provide conclusive evidence as to testosterone safety in women.     

Breast cancer risk in the WHI study: the problem of obesity

In the climacteric, about 40% of the women have occult breast tumors the growth of which may be stimulated by hormones. Many genetic, reproductive and lifestyle factors may influence the incidence of breast cancer. Epidemiological data suggest that the increase in the relative risk (RR) of breast cancer induced by hormone replacement therapy (HRT) is comparable with that associated with early menarche, late menopause, late first birth, alcohol consumption, etc. One of the most important risk factors is obesity which exceeds the effect of HRT by far, and in overweight postmenopausal women the elevated risk of breast cancer is not further increased by HRT. As in the WHI study the majority of women was overweight or obese, this trial was unsuitable for the investigation of breast cancer risk. In the women treated with an estrogen/progestin combination, the RR of breast cancer rose only in those women who have been treated with hormones prior to the study, suggesting a selection bias. In the women not pretreated with hormones, it was not elevated. In the estrogen-only arm of the WHI study, there was no increase but a steady decrease in the RR of breast cancer during 6.8 years of estrogen therapy. This result was unexpected, as estrogens are known to facilitate the development and growth of breast tumors, and the effect is enhanced by the addition of progestins. Obese women are at high risk to develop a metabolic syndrome including insulin resistance and hyperinsulinemia. In postmenopausal women, elevated insulin levels are not only associated with an increased risk for cardiovascular disease, but also for breast cancer. This might explain the effects observed in both arms of the WHI study: HRT with relative low doses of estrogens may improve insulin resistance and, hence, reduce the elevated breast cancer risk in obese patients, whereas this beneficial estrogen effect may be antagonized by progestins. The principal options for the reduction of breast cancer risk in postmenopausal women are the prevention of overweight and obesity to avoid the development of hyperinsulinemia, the medical treatment of insulin resistance, the use of low doses of estrogens and the reduction of exposure to progestins. The latter might include long-cycles with the sequential use of appropriate progestins every 3 months for 14 days. There are large inter-individual variations in the proliferative response to estrogens of the endometrium. Control by vaginalsonography and progestin challenge tests may help to identify those women who may be candidates for low-dose estrogen-only therapy.     

Apocrine sweat gland obstruction by antiperspirants allowing transdermal absorption of cutaneous generated hormones and pheromones as a link to the observed incidence rates of breast and prostate cancer in the 20th century

Breast and prostate cancer share similarities and likely represent homologous cancers in females and males, respectively. The role of hormones such as testosterone and estrogen in carcinogenesis is well established. Despite worldwide research efforts, the pathogenesis of these diseases is largely not well understood. Personal care products containing estrogens or xenoestrogens have raised concern as a breast cancer risk, especially in young African-American women. In the United States (US) there is a parallel rise in the incidence in breast and prostate cancer compared to selected non-hormone dependent tumors. Observed US and global breast and prostate cancer incidence increases were occurring before exogenous hormone replacement and xenoestrogen exposure were commonplace. An unintentional, inadvertent, and long term hormone exposure may occur from transdermal absorption of sex hormones and pheromones (androgens) from axillary apocrine sweat gland obstruction by aluminum-based antiperspirants. The global rise in antiperspirant use parallels rises in breast and prostate cancer incidence and mortality rates. A multi-disciplinary literature based set of evidence is presented on how such a link is possible, to prompt confirmatory investigations in the pursuit of unmet needs in breast and prostate cancer etiology and prevention.     

Aromatase inhibitors in breast cancer

Estrogens play important roles in breast cancer development and progression. In postmenopausal women, traditional endocrine therapies such as tamoxifen have sought to inhibit estrogen action by targeting the estrogen receptor itself. However, newer treatments are evolving that target estrogen production in postmenopausal tissues through inhibition of the aromatase enzyme. Clinical data demonstrate that these aromatase inhibitors are superior to tamoxifen as adjuvant therapy for breast cancer and have now replaced tamoxifen as first line therapy in a number of treatment regimens for postmenopausal breast cancer patients.