Safety of vaginal oestrogens for genitourinary symptoms in women with breast cancer.

BACKGROUND: Oestrogen deprivation is the mainstay of treatment for women with hormone receptor-positive breast cancer, but unfortunately it causes multiple side effects that can significantly impair quality of life. Genitourinary symptoms are very common and although these symptoms can be effectively managed with vaginal oestrogens, concerns about their safety in women with breast cancer limits their use. OBJECTIVE: The aim of this review is to provide a summary of the data on the safety of vaginal oestrogens in women with breast cancer to help general practitioners advise their patients in this situation. DISCUSSION: Although there are no large randomised prospective studies to assess safety, the current evidence suggests reassurance can be provided to the majority of women with a history of breast cancer considering vaginal oestrogens. Consultation with the oncology team is advised for women taking aromatase inhibitors, where the safety of vaginal oestrogens is less certain.

Use of menopausal hormone therapy beyond age 65 years and its effects on women's health outcomes by types, routes, and doses.

OBJECTIVES: The study aims to assess the use of menopausal hormone therapy beyond age 65 years and its health implications by types of estrogen/progestogen, routes of administration, and dose strengths. METHODS: Using prescription drug and encounter records of 10 million senior Medicare women from 2007-2020 and Cox regression analyses adjusted for time-varying characteristics of the women, we examined the effects of different preparations of menopausal hormone therapy on all-cause mortality, five cancers, six cardiovascular diseases, and dementia. RESULTS: Compared with never use or discontinuation of menopausal hormone therapy after age 65 years, the use of estrogen monotherapy beyond age 65 years was associated with significant risk reductions in mortality (19% or adjusted hazards ratio, 0.81; 95% CI, 0.79-0.82), breast cancer (16%), lung cancer (13%), colorectal cancer (12%), congestive heart failure (CHF) (5%), venous thromboembolism (3%), atrial fibrillation (4%), acute myocardial infarction (11%), and dementia (2%). For the use of estrogen and progestogen combo-therapy, both E+ progestin and E+ progesterone were associated with increased risk of breast cancer by 10%-19%, but such risk can be mitigated using low dose of transdermal or vaginal E+ progestin. Moreover, E+ progestin exhibited significant risk reductions in endometrial cancer (45% or adjusted hazards ratio, 0.55; 95% CI, 0.50-0.60), ovarian cancer (21%), ischemic heart disease (5%), CHF (5%), and venous thromboembolism (5%), whereas E+ progesterone exhibited risk reduction only in CHF (4%). CONCLUSIONS: Among senior Medicare women, the implications of menopausal hormone therapy use beyond age 65 years vary by types, routes, and strengths. In general, risk reductions appear to be greater with low rather than medium or high doses, vaginal or transdermal rather than oral preparations, and with E2 rather than conjugated estrogen.

Menopausal hormone therapy and risk of venous thromboembolism: The story so far.

Menopausal hormone therapy (MHT) is known to increase the risk of venous thromboembolism (VTE), which includes deep vein thrombosis, pulmonary embolism, and less frequently cerebral vein thrombosis, but the absolute risk for a given patient is very low. After starting MHT, the risk of VTE seems to be at its highest, declining to the non-HRT user baseline level of risk after stopping. Whether estrogen-only or estrogen-progestin HRT combination is linked to a similar risk of VTE is unclear from the available evidence. The aim of this study is to evaluate the risks of developing VTE in relation to different types as well as different modes of administration of MHT through a database search including PubMed, MEDLINE, Google Scholar, Cochrane Library, and others in order to provide the women carers with the up-to-date and evidence-based guidelines and recommendations while counseling the post-menopausal women enquiring on use of hormonal therapies either to alleviate the menopausal symptoms or to prevent the long-term sequelae of estrogen deficiency.

On sait que l'hormonothérapie ménopausique (MHT) augmente le risque de thromboembolie veineuse (TEV), qui comprend la thrombose veineuse profonde, l'embolie pulmonaire et, moins fréquemment, la thrombose veineuse cérébrale, mais le risque absolu pour un patient donné est très faible. Après le début du MHT, le risque de TEV semble être à son plus haut niveau, diminuant jusqu'au niveau de risque de base des non-utilisatrices de THS après l'arrêt. Les preuves disponibles ne permettent pas de savoir si un THS à base d'œstrogène seul ou d'association œstroprogestative est lié à un risque similaire de TEV. Le but de cette étude est d'évaluer les risques de développer une TEV par rapport à différents types ainsi qu'à différents modes d'administration du MHT grâce à une recherche dans des bases de données comprenant PubMed, MEDLINE, Google Scholar, Cochrane Library et autres afin de fournir aux femmes les soignants avec les lignes directrices et recommandations à jour et fondées sur des preuves tout en conseillant les femmes ménopausées qui se renseignent sur l'utilisation de thérapies hormonales, soit pour soulager les symptômes de la ménopause, soit pour prévenir les séquelles à long terme d'une carence en œstrogènes.

Risks and benefits of hormone therapy after menopause for cognitive decline and dementia: A conceptual review.

OBJECTIVE: The effects on the brain of hormone therapy after the onset of menopause remain uncertain. The effects may be beneficial, neutral, or harmful. We provide a conceptual review of the evidence. METHODS: We 1) provide a brief history of the evidence, 2) discuss some of the interpretations of the evidence, 3) discuss the importance of age at menopause, type of menopause, and presence of vasomotor symptoms, and 4) provide some clinical recommendations. RESULTS: The evidence and the beliefs about hormone therapy and dementia have changed over the last 30 years or more. Five recent observation studies suggested that hormone therapy is associated with an increased risk of dementia, and the association appears not to change with the timing of initiation of therapy. These harmful associations may be explained by a causal effect of hormone therapy on the brain or by several confounding mechanisms. We suggest that the use of hormone therapy should be customized for different subgroups of women. It may be important to subgroup women based on age at onset of menopause, type of menopause, and presence or absence of vasomotor symptoms. In addition, the effects may vary by type, dose, route, and duration of administration of estrogens and by the concurrent use of progestogens. DISCUSSION: The relation of hormone therapy with the risk of dementia is complex. Hormone therapy may have beneficial, neutral, or harmful effects on the brain. Hormone therapy should be guided by the clinical characteristics of the women being treated.

Exogenous Estrogen in the Development of Head and Neck Cancer.

Importance: Sex differences in head and neck cancer (HNC) incidence suggest a potential contribution of sex hormones. Objective: To assess the role of exogenous estrogen exposure in the development of HNC in female patients. Design, Settings, and Participants: This large multicenter cohort study using clinical records from the TriNetX real-world database included 20 years of data (through May 31, 2023) from 87 health care organizations. The TriNetX database was searched for medical records for female patients with and without exogenous estrogen exposure according to their chronological age. Cohort 1 included 731 366 female patients aged 18 to 45 years old with regular oral contraceptive (OC) intake and cohort 2 included 3 886 568 patients in the same age group who did not use OC. Cohort 3 comprised 135 875 female patients at least 50 years old receiving hormone replacement therapy (HRT), whereas cohort 4 included 5 875 270 patients at least 50 years old without HRT. Propensity score matching was performed for the confounders age, alcohol dependence, and nicotine dependence. Data analyses were performed in May 2023. Main Outcome and Measures: Diagnosis of HNC (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision: C00-C14), and after propensity score matching (1:1 nearest-neighbor greedy matching), a risk analysis to investigate risk differences and risk ratios (RRs) with a 95% CI. Results: Among the 718 101 female patients in each of cohorts 1 and 2 (mean [SD] age at diagnosis, 25.9 [6.7] years), those with OC intake had a higher risk of an HNC diagnosis (RR, 1.47; 95% CI, 1.21-1.78) than those without OC use. Among the 131 835 female patients in each of cohorts 3 and 4 (mean [SD] age, 67.9 [12.0] years), those with postmenopausal HRT intake had a lower risk of an HNC diagnosis (RR, 0.77; 95% CI, 0.64-0.92) than those without HRT use. Conclusions and Relevance: The findings of this cohort study illustrate a positive association between OC and a negative association between HRT and the development of HNC in female patients. Given the limitations of the TriNetX database, future research should include detailed information on the intake of OC and HRT and reproductive health information (eg, age at menarche/menopause, number of pregnancies) to more accurately define the strength and direction of the possible association between exogeneous estrogen exposure and the development of HNC in female patients.

Benign phyllodes tumour in a transgender woman receiving hormonal therapy.

We present a case of a transwoman taking hormonal feminisation therapy for over 20 years, who underwent surgical excision of a benign phyllodes tumour of the breast. Hormones progesterone and oestrogen act on breast epithelium to increase proliferation. For ciswomen, endogenous and exogenous oestrogen exposure over a lifetime is associated with increased risk for certain benign and malignant breast pathologies. Transwomen taking hormonal therapy may also be at an increased risk of breast disease.

Is There a Special Role for Ovarian Hormones in the Pathogenesis of Lobular Carcinoma?

Lobular carcinoma represent the most common special histological subtype of breast cancer, with the majority classed as hormone receptor positive. Rates of invasive lobular carcinoma in postmenopausal women have been seen to increase globally, while other hormone receptor-positive breast cancers proportionally have not followed the same trend. This has been linked to exposure to exogenous ovarian hormones such as hormone replacement therapy. Reproductive factors resulting in increased lifetime exposure to endogenous ovarian hormones have also been linked to an increased risk of lobular breast cancer, and taken together, these data make a case for the role of ovarian hormones in the genesis and progression of the disease. In this review, we summarize current understanding of the epidemiological associations between ovarian hormones and lobular breast cancer and highlight mechanistic links that may underpin the etiology and biology.

Menopausal hormone therapy and risk of sarcoidosis: a population-based nested case-control study in Sweden.

Sarcoidosis incidence peaks in women between 50 and 60 years old, which coincides with menopause, suggesting that certain sex hormones, mainly estrogen, may play a role in disease development. We investigated whether menopausal hormone therapy (MHT) was associated with sarcoidosis risk in women and whether the risk varied by treatment type. We performed a nested case-control study (2007-2020) including incident sarcoidosis cases from the Swedish National Patient Register (n = 2593) and matched (1:10) to general population controls (n = 20,003) on birth year, county, and living in Sweden at the time of sarcoidosis diagnosis. Dispensations of MHT were obtained from the Swedish Prescribed Drug Register before sarcoidosis diagnosis/matching. Adjusted odds ratios (aOR) of sarcoidosis were estimated using conditional logistic regression. Ever MHT use was associated with a 25% higher risk of sarcoidosis compared with never use (aOR 1.25, 95% CI 1.13-1.38). When MHT type and route of administration were considered together, systemic estrogen was associated with the highest risk of sarcoidosis (aOR 1.51, 95% CI 1.23-1.85), followed by local estrogen (aOR 1.25, 95% CI 1.11-1.42), while systemic estrogen-progestogen combined was associated with the lowest risk compared to never users (aOR 1.12, 95% CI 0.96-1.31). The aOR of sarcoidosis did not differ greatly by duration of MHT use. Our findings suggest that a history of MHT use is associated with increased risk of sarcoidosis, with women receiving estrogen administered systemically having the highest risk.

Cumulative exposure to estrogen may increase the risk of migraine in women.

BACKGROUND: Migraine is a common disorder, particularly affecting women during their reproductive years. This female preponderance has been linked to exposure to female sex hormones. METHODS: We used self-reported data from women born in 1943-1965 enrolled in the Norwegian Women and Cancer Study to examine the differences between women with migraine and women without migraine in a prospective design with respect to both endogenous and exogenous female sex hormone exposure. RESULTS: In total, 62,959 women were included in the study, of whom 24.8% reported previous migraine (n = 15,635). Using a Cox proportional hazards model, we found that higher age at menarche reduced the risk of migraine (hazards ratio (HR) = 0.96, 95% confidence interval (CI) = 0.95-0.98) and that oral contraceptive use and parity increased the risk of migraine (HR = 1.12, 95% CI = 1.06-1.18 and HR = 1.37, 95% CI = 1.29-1.46, respectively). CONCLUSIONS: Older age at menarche appears to reduce migraine risk, whereas oral contraceptive use and having children appear to increase the risk. Further research is required to investigate the causality of these associations.

Contraceptives and Thrombosis: An Intertwined Revolutionary Road.

The development of oral contraceptives (OCs) began in 1921 and continued in the following years until the first regulatory approval from the Food and Drug Administration was granted in 1960. However, it took several years to realize that OCs presented an important but not frequent risk of venous thrombosis. Several reports ignored this dangerous effect and only in 1967 the Medical Research Council clearly stated this as an important risk. Later, research led to the formulation of second-generation OCs containing progestins, which nevertheless presented an increased thrombotic risk. In early 1980s, OCs containing third-generation progestins were introduced into the market. Only in 1995, it became clear that these new compounds induced a higher thrombotic risk than that related to the second-generation progestins. It appeared clear that the modulating action of progestins was against the procoagulant activity of estrogens. Lastly, at the end of the 2000s, OCs containing natural estrogens and a fourth-generation progestin (dienogest) became available. The prothrombotic effect of those natural products was not different from that of preparations containing second-generation progestins. Moreover, research over the years has produced much data on risk factors associated with OCs use such as age, obesity, cigarette smoking, and thrombophilia. These findings allowed us to better assess the individual thrombotic risk (both arterial and thrombotic) of each woman before offering an OC. Furthermore, research has shown that in high-risk people the use of single progestin is not dangerous as far as thrombosis is concerned. In conclusion, the OCs road has been long and difficult but has led to a great and unthinkable scientific and social enrichment since the 1960s.

Associations of reproductive factors and exogenous estrogens with global and domain-specific cognition in later life.

INTRODUCTION: Few studies have comprehensively examined the impact of reproductive factors (i.e., reproductive window, parity, hormonal contraception [HC], and menopausal hormone therapy [MHT]) on global and domain-specific cognition in later life. METHODS: We studied a population-based sample of 2458 women (median age 74.2 years) residing in Olmsted County, Minnesota; participants underwent a clinical evaluation and comprehensive cognitive testing. RESULTS: The length of a woman's reproductive window was not associated with cognition. Higher parity was associated with greater cognitive decline in all domains. Ever HC use was associated with less decline in all domains. Ever MHT use was associated with greater decline in global cognition and all domain-specific z-scores except visuospatial; results were driven by women who initiated MHT 5 or more years after menopause. Additional adjustments for APOE and vascular-related covariates did not attenuate the results. DISCUSSION: Multiple reproductive risk factors are associated with cognitive decline in later life. HIGHLIGHTS: The length of a woman's reproductive window was not associated with cognition longitudinally. Greater parity was associated with greater cognitive decline longitudinally. Ever HC use was associated with less decline in global cognition and all domain-specific z-scores longitudinally (all p < 0.01). Ever MHT use was associated with greater decline in global cognition and all domain-specific z-scores except visuospatial longitudinally (all p < 0.01). The greatest cognitive decline was among women who initiated MHT more than 5 years after menopause.

Comparison of estrogenic components used for hormonal contraception.

Attempts have been made over the years to replace ethinyl estradiol (EE) in combined oral contraceptives (COCs) with the less potent natural estrogen estradiol (E2), or its prodrug, E2 valerate (E2V), to improve their safety and tolerability. Recently, a COC incorporating a novel weak natural estrogen, estetrol (E4), combined with drospirenone, has become available. We present a comparative analysis of the three prevailing estrogens used in COCs, focusing on their structure-function relationships, receptor-binding affinity, potency, metabolism, pharmacokinetic parameters, and pharmacodynamics. The binding affinity of EE to estrogen receptor (ER)α is twice that of E2, whereas its affinity for ERß is about one-half that of E2. E4 has a lower binding affinity for the ERs than E2. The high potency of EE is notable in its dramatic increase in estrogen-sensitive hepatic globulins and coagulation factors. EE and E2 undergo extensive and comparable metabolism, while E4 produces only a very limited number of metabolites. E4 has the highest bioavailability among the three estrogens, with E2 having <5%. Studies demonstrate consistent ovulation inhibition, although a higher dose of E4 (15 mg) in COCs is required to achieve follicular suppression compared to E2 (1-3 mg) and EE (0.01-0.035 mg). E2 and E4 in COCs may be less stimulatory of coagulant proteins than EE. Studies with E2/dienogest suggest a comparable risk of venous thromboembolism to EE/levonorgestrel, while data assessing risk with an E4-based COC are insufficient. Nevertheless, the E4-based formulation shows promise as a potential alternative to EE and E2 due to its lower potency and possibly fewer side effects.

Vaginal Estrogen Therapy Use and Survival in Females With Breast Cancer.

Importance: Genitourinary syndrome of menopause can be treated with vaginal estrogen therapy. However, there are concerns about the safety of vaginal estrogen therapy in patients with breast cancer. Objective: To determine whether the risk of breast cancer-specific mortality was higher in females with breast cancer who used vaginal estrogen therapy vs females with breast cancer who did not use hormone replacement therapy (HRT). Design, Setting, and Participants: This cohort study analyzed 2 large cohorts, one each in Scotland and Wales, of females aged 40 to 79 years with newly diagnosed breast cancer. These population-based cohorts were identified from national cancer registry records from 2010 to 2017 in Scotland and from 2000 to 2016 in Wales and were followed up for breast cancer-specific mortality until 2020. Females were excluded if they had a previous cancer diagnosis (except nonmelanoma skin cancer). Data analysis was performed between August 2022 and August 2023. Exposure: Use of vaginal estrogen therapy, including vaginal tablets and creams, was ascertained from pharmacy dispensing records of the Prescribing Information System for the Scotland cohort and from general practice prescription records for the Wales cohort. Main Outcomes and Measures: The primary outcome was time to breast cancer-specific mortality, which was obtained from national mortality records. Time-dependent Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% CIs for breast cancer-specific mortality, comparing vaginal estrogen therapy users with HRT nonusers and adjusting for confounders, including cancer stage and grade. Results: The 2 cohorts comprised 49 237 females with breast cancer (between 40 and 79 years of age) and 5795 breast cancer-specific deaths. Five percent of patients with breast cancer used vaginal estrogen therapy after breast cancer diagnosis. In vaginal estrogen therapy users compared with HRT nonusers, there was no evidence of a higher risk of breast cancer-specific mortality in the pooled fully adjusted model (HR, 0.77; 95% CI, 0.63-0.94). Conclusions and Relevance: Results of this study showed no evidence of increased early breast cancer-specific mortality in patients who used vaginal estrogen therapy compared with patients who did not use HRT. This finding may provide some reassurance to prescribing clinicians and support the guidelines suggesting that vaginal estrogen therapy can be considered in patients with breast cancer and genitourinary symptoms.

Breast cancer risk association with postmenopausal hormone therapy: Health Insurance Database in South Korea-based cohort study.

CONTEXT: Although many physicians have been concerned that the menopausal hormones used currently in clinical practice may affect the risk of breast cancer, there are currently few informative updated studies about the associations between menopausal hormone therapy (MHT) and the risk of breast cancer. OBJECTIVE: This study aims to evaluate the association between the risk of breast cancer and MHT using the National Health Insurance Database in South Korea (HISK) cohort between 2002 and 2019 retrospectively. METHODS: Postmenopausal women over 40 years of age from 2003 to 2011 were selected as the subject population, and their follow-up data were collected until 2019. We analyzed the risk and mortality of breast cancer according to the type of MHT received, namely, tibolone, combined estrogen plus progestin by manufacturer (CEPM), oral estrogen, combined estrogen plus progestin by physician (CEPP), or topical estrogen. RESULTS: The risk of breast cancer increased in the CEPM group [hazard ratio (HR) 1.439, 95% CI 1.374-1.507, P-value < .001] in comparison with the non-MHT group. However, no significant associations were found between the use of tibolone, oral estrogen, CEPP, or topical estrogen and breast cancer risk in comparison with the non-MHT group (HR 0.968, 95% CI 0.925-1.012; HR 1.002, 95% CI 0.929-1.081; HR 0.929, 95% CI 0.75-1.15; HR 1.139, 95% CI 0.809-1.603). The mortality rate from breast cancer is lower in the MHT group in comparison with the non-MHT group, indicating that significant associations were found for tibolone, CEPM, and oral estrogen (HR 0.504, 95% CI 0.432-0.588; HR 0.429, 95% CI 0.352-0.522; HR 0.453 95% CI 0.349-0.588, P-value < .001). CONCLUSIONS: This study suggests that the risk of breast cancer is increased by drugs in the CEPM group but not by tibolone, oral estrogen, CEPP, or topical estrogen. The mortality rate from breast cancer is lower with MHT (tibolone, CEPM, oral estrogen) than without MHT.

Menopausal hormone therapy increases the risk of gallstones: Health Insurance Database in South Korea (HISK)-based cohort study.

OBJECTIVE: To determine whether menopausal hormone therapy (MHT) increases the risk of gallstones and gallbladder cancer. DESIGN: A retrospective cohort study. PATIENTS OR OTHER PARTICIPANTS: Data from the Korea National Health Insurance Corporation was obtained between January 1, 2002, and December 31, 2019. INTERVENTIONS: Participants were divided into MHT and non-MHT groups; the MHT group was analyzed in detail by dividing participants into tibolone, combined estrogen plus progestin by the manufacturer (CEPM) or physician (CEPP), oral estrogen alone, and topical estrogen subgroups. MAIN OUTCOME MEASURES: The incidence of gallstones and gallbladder cancer was compared between the two groups. RESULTS: This study enrolled 1,004,034 and 381,711 patients in the non-MHT and the MHT groups, respectively. The incidence of gallstones was 2.6% in the non-MHT group and 3.4%, 2.6%, 3.4%, 3.2%, and 4.4% in the tibolone, CEPM, oral estrogen alone, CEPP, and topical estrogen groups, respectively. Cox proportional hazard analysis revealed that all hormones increased the risk of gallstones ([tibolone] hazard ratio [HR]: 1.347, 95% confidence interval [CI]: 1.309-1.387, [CEPM] HR: 1.146, 95% CI: 1.1-1.19, [oral estrogen alone] HR: 1.241, 95% CI: 1.18-1.305, [CEPP] HR: 1.164, 95% CI: 1.01-1.341, [topical estrogen] HR: 1.602, 95% CI: 1.295-1.983). However, the risk of gallbladder cancer did not change with any hormone therapy. CONCLUSIONS: All types of MHT including tibolone, increased the risk of gallstones. This risk was the highest with topical estrogen, which may be a result of selection bias due to concerns regarding the adverse effects of CEE and MPA.

Menopausal hormone therapy and central nervous system tumors: Danish nested case-control study.

BACKGROUND: Use of estrogen-containing menopausal hormone therapy has been shown to influence the risk of central nervous system (CNS) tumors. However, it is unknown how the progestin-component affects the risk and whether continuous versus cyclic treatment regimens influence the risk differently. METHODS AND FINDINGS: Nested case-control studies within a nationwide cohort of Danish women followed for 19 years from 2000 to 2018. The cohort comprised 789,901 women aged 50 to 60 years during follow-up, without prior CNS tumor diagnosis, cancer, or contraindication for treatment with menopausal hormone therapy. Information on cumulative exposure to female hormonal drugs was based on filled prescriptions. Statistical analysis included educational level, use of antihistamines, and use of anti-asthma drugs as covariates. During follow-up, 1,595 women were diagnosed with meningioma and 1,167 with glioma. The median (first-third quartile) follow-up time of individuals in the full cohort was 10.8 years (5.0 years to 17.5 years). Compared to never-use, exposure to estrogen-progestin or progestin-only were both associated with increased risk of meningioma, hazard ratio (HR) 1.21; (95% confidence interval (CI) [1.06, 1.37] p = 0.005) and HR 1.28; (95% CI [1.05, 1.54] p = 0.012), respectively. Corresponding HRs for glioma were HR 1.00; (95% CI [0.86, 1.16] p = 0.982) and HR 1.20; (95% CI [0.95, 1.51] p = 0.117). Continuous estrogen-progestin exhibited higher HR of meningioma 1.34; (95% CI [1.08, 1.66] p = 0.008) than cyclic treatment 1.13; (95% CI [0.94, 1.34] p = 0.185). Previous use of estrogen-progestin 5 to 10 years prior to diagnosis yielded the strongest association with meningioma, HR 1.26; (95% CI [1.01, 1.57] p = 0.044), whereas current/recent use of progestin-only yielded the highest HRs for both meningioma 1.64; (95% CI [0.90, 2.98] p = 0.104) and glioma 1.83; (95% CI [0.98, 3.41] p = 0.057). Being an observational study, residual confounding could occur. CONCLUSIONS: Use of continuous, but not cyclic estrogen-progestin was associated with increased meningioma risk. There was no evidence of increased glioma risk with estrogen-progestin use. Use of progestin-only was associated with increased risk of meningioma and potentially glioma. Further studies are warranted to evaluate our findings and investigate the influence of long-term progestin-only regimens on CNS tumor risk.