A comparative study of breast cell proliferation during hormone replacement therapy: effects of tibolon and continuous combined estrogen-progestogen treatment

The relationship between using estrogen and/or progesterone and the risk of mammary gland hyperplasia in women: a meta-analysis

BACKGROUND

As reported that the usage of estrogen and/or progesterone increases the risk of mammary gland hyperplasia (MGH) with conflicting results. Therefore, we conducted a meta-analysis to higher elucidate the relationship between hormones and MGH.

METHOD

PubMed, Embase, Web of Science, Cochrane Library, Chinese National Knowledge Infrastructure, and Wan-fang database were searched for studies until April 28, 2021.

RESULTS

Nine related studies were included in the present meta-analysis. We found that the usage of estrogen and/or progesterone had a significant association with increasing the risk of MGH (RR = 1.56, 95% CI: 1.13-2.15, p = .000). The subgroup results showed that the risk of MGH increased in the Mix population (RR = 1.72, CI: 1.58-1.88, p < .001) but no significant difference in the Asian population. Meanwhile, as for using estrogen plus progesterone (EPP) and postmenopausal women the risk of MGH, respectively, increased (RR = 1.74, CI: 1.22-2.47, p = .002) and (RR = 1.75, CI: 1.24-2.47, p = .001) but no significant different for using estrogen alone and premenopausal women.

CONCLUSIONS

This study findings indicated that using estrogen and/or progesterone might increase the risk of MGH in premenopausal and postmenopausal women.

Effects of progestogens used in menopause hormone therapy on the normal breast and benign breast disease in postmenopausal women

Hormone replacement therapy in menopause is used to improve climacteric syndrome in women whose quality of life is affected. However, given the wide variety of progestogens available, it is important to evaluate their differential benign changes (radiological, cellular, and clinical) on the breast. This review aimed to determine the different benign changes of progestogens used in postmenopausal combined hormone therapy on the breast (radiological, cellular, and clinical), in women without mammary pathology, in order to establish their safety profile. A systematic review of the literature was carried out with a balanced search strategy for the identification of relevant references in the MEDLINE, BVSalud, EMBASE, ProQuest, and Cochrane databases until November 2019. The search terms used were 'menopause' or 'hormonal replacement therapy' or 'progestins' or 'estrogen' or 'mastodynia' or 'benign breast disease' or 'mammography'. Data were collected from the 'eligible' articles by two researchers (ARF and SHA), and possible discrepancies in inclusion were resolved by consensus. A total of 1886 articles were identified; 60 full-text articles were reviewed, and 17 articles that met the inclusion criteria were included for the qualitative analysis. In conclusion, combined hormone replacement therapy is associated with benign effects on the breast, such as mastodynia and increased mammographic density.

A systematic review of non-hormonal treatments of vasomotor symptoms in climacteric and cancer patients

The cardinal climacteric symptoms of hot flushes and night sweats affect 24-93% of all women during the physiological transition from reproductive to post-reproductive life. Though efficacious, hormonal therapy and partial oestrogenic compounds are linked to a significant increase in breast cancer. Non-hormonal treatments are thus greatly appreciated.

This systematic review of published hormonal and non-hormonal treatments for climacteric, and breast and prostate cancer-associated hot flushes, examines clinical efficacy and therapy-related cancer risk modulation.

A PubMed search included literature up to June 19, 2014 without limits for initial dates or language, with the search terms, (hot flush* OR hot flash*) AND (clinical trial* OR clinical stud*) AND (randomi* OR observational) NOT review). Retrieved references identified further papers. The focus was on hot flushes; other symptoms (night sweats, irritability, etc.) were not specifically screened. Included were some 610 clinical studies where a measured effect of the intervention, intensity and severity were documented, and where patients received treatment of pharmaceutical quality. Only 147 of these references described studies with alternative non-hormonal treatments in post-menopausal women and in breast and prostate cancer survivors; these results are presented in Additional file 1.

The most effective hot flush treatment is oestrogenic hormones, or a combination of oestrogen and progestins, though benefits are partially outweighed by a significantly increased risk for breast cancer development.

This review illustrates that certain non-hormonal treatments, including selective serotonin reuptake inhibitors, gabapentin/pregabalin, and Cimicifuga racemosa extracts, show a positive risk-benefit ratio.

Key points

Several non-hormonal alternatives to hormonal therapy have been established and registered for the treatment of vasomotor climacteric symptoms in peri- and post-menopausal women.

There are indications that non-hormonal treatments are useful alternatives in patients with a history of breast and prostate cancer. However, confirmation by larger clinical trials is required.

Effects of short-term estradiol and norethindrone acetate treatment on the breasts of normal postmenopausal women

OBJECTIVE

The aim of this study was to evaluate among postmenopausal women the effects of a 3-month treatment with estradiol (E2) alone or in combination with norethindrone acetate (NA) on expression of hormone receptors and proliferation in the breast as well as on lipids and climacteric symptoms.

METHODS

Sixty healthy postmenopausal women were computer-randomized into two groups, with one group receiving 1 mg of E2 and the other group receiving 1 mg of E2 and 0.5 mg of NA daily for 12 weeks. Before and after treatment, middle-needle biopsies were obtained for histology and investigation of the expression levels of estrogen receptors (ERs; ER-α and ER-β), progesterone receptors (PRs; PR-A and PR-B), androgen receptor (AR), the proliferation marker Ki67, and collagen. Climacteric symptoms were recorded, and serum was collected to measure lipoprotein levels.

RESULTS

Fifty-six women finished the 12-week study. Proliferating cells (Ki67-positive) were very rare in all but a few of the untreated women. There were proliferating cells in both E2- and E2/NA-treated groups; however, these were not widespread and limited to nests of cells that amounted to 2% of the total epithelial cells. Some of these nests were positive for human epithelial growth factor receptor 2. Treatments caused no marked changes in the expression of ER-α, ER-β, or AR. However, both treatments resulted in an increase in PR-A and PR-B expressions. The presence of collagen was clearly associated with a mammographic diagnosis of dense breasts, but neither hormone treatment affected breast density. Both E2 and E2/NA treatments were effective in relieving hot flashes and sweating without adverse effects on blood pressure, weight, and liver, kidney, and thyroid functions. A decrease in cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol was induced by E2/NA but not by E2.

CONCLUSIONS

This short-term prospective study shows that E2 and estrogen-progestogen treatment can up-regulate PRs but do not significantly affect ERs, AR, proliferation, or breast density.

Percutaneous estradiol/oral micronized progesterone has less-adverse effects and different gene regulations than oral conjugated equine estrogens/medroxyprogesterone acetate in the breasts of healthy women in vivo

Gene expression analysis of healthy postmenopausal women in a prospective clinical study indicated that genes encoding for epithelial proliferation markers Ki-67 and progesterone receptor B mRNA are differentially expressed in women using hormone therapy (HT) with natural versus synthetic estrogens. Two 28-day cycles of daily estradiol (E2) gel 1.5 mg and oral micronized progesterone (P) 200 mg/day for the last 14 days of each cycle did not significantly increase breast epithelial proliferation (Ki-67 MIB-1 positive cells) at the cell level nor at the mRNA level (MKI-67 gene). A borderline significant beneficial reduction in anti-apoptotic protein bcl-2, favouring apoptosis, was also seen followed by a slight numeric decrease of its mRNA. By contrast, two 28-day cycles of daily oral conjugated equine estrogens (CEE) 0.625 mg and oral medroxyprogesterone acetate (MPA) 5 mg for the last 14 days of each cycle significantly increased proliferation at both the cell level and at the mRNA level, and significantly enhanced mammographic breast density, an important risk factor for breast cancer. In addition, CEE/MPA affected around 2,500 genes compared with just 600 affected by E2/P. These results suggest that HT with natural estrogens affects a much smaller number of genes and has less-adverse effects on the normal breast in vivo than conventional, synthetic therapy.

Mechanisms for differential effects between natural progesterone and synthetic progestogens on normal breast tissue

Both epidemiological studies and experimental data on normal breast tissue suggest increased cancer risk, proliferation and mammographic breast density (MD) during hormone therapy (HT) containing synthetic progestogens in traditional doses, and the relative risk or RR is approximately 1.5–3 (for women treated vs. untreated with the above therapies), proliferation levels of normal breast epithelial cells of around 10% and increase in MD in up to around 50% of women during treatment. Dose-response relationships have been inferred by correlations between progestogens as levonorgestrel, norethisterone acetate and medroxyprogesterone acetate on the one hand and proliferation and/or MD on the other hand, and of indications of lower relative risk of breast cancer with modern low or ultra-low dose HT. In contrast, natural progesterone endogenously during the menstrual cycle has a weak effect and exogenous estrogen in combination with oral micronized progesterone in HT has shown to yield an indifferent effect on proliferation. Furthermore, in epidemiological studies such as the French E3N cohort, these combinations have not shown any risk increase for breast cancer for at least 5 years of treatment. Experimental data supporting or not supporting the view that the main proliferative mechanism for natural progesterone is through binding to its nascent progesterone receptors is discussed as well as the pros and cons that the non-physiological higher proliferation levels induced by synthetic progestogens is mainly mediated through interaction with potent growth factors and their paracrine and/or cell signaling pathways.

Chinese medicinal herbs in relieving perimenopausal depression: a randomized, controlled trial

OBJECTIVE

To explore the effects of GengNianLe (GNL, also called perimenopausal depression relieving formula), a defined formula of Chinese medicinal herbs in relieving perimenopausal depression in Chinese women.

METHODS

Between September 2004 and April 2008, 47 Chinese women were randomized into a GNL group (n = 21) and a control group which received tibolone (n = 26) using a randomization chart. Depression was rated with the 24-item Hamilton Depression Scale (HAMD). The serum levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), and estradiol (E(2)) were detected before and after the treatment.

RESULTS

After 12 weeks of treatment, HAMD scores in both groups decreased significantly (p < 0.05) with no significant difference between the groups (p > 0.05). The levels of FSH decreased significantly and the level of E(2) increased significantly in both groups, and they changed more in the control group. No side-effect of treatment was reported in either group during treatment.

CONCLUSIONS

The Chinese medicinal formula GNL showed promise in relieving perimenopausal depression and merits further study.

New-onset breast tenderness after initiation of estrogen plus progestin therapy and breast cancer risk

BACKGROUND

Estrogen plus progestin therapy increases breast cancer incidence and breast tenderness. Whether breast tenderness during estrogen plus progestin therapy is associated with breast cancer risk is uncertain.

METHODS

We analyzed data from the Women's Health Initiative Estrogen + Progestin Trial, which randomized postmenopausal women with an intact uterus to receive daily conjugated equine estrogens, 0.625 mg, plus medroxyprogesterone acetate, 2.5 mg (n = 8506), or placebo (n = 8102). At baseline and annually, participants underwent mammography and clinical breast examination. Self-reported breast tenderness was assessed at baseline and at 12 months. The incidence of invasive breast cancer was confirmed by medical record review (mean follow-up of 5.6 years).

RESULTS

Of women without baseline breast tenderness (n = 14,538), significantly more assigned to receive conjugated equine estrogens plus medroxyprogesterone vs placebo experienced new-onset breast tenderness after 12 months (36.1% vs 11.8%, P < .001). Of women in the conjugated equine estrogens plus medroxyprogesterone group, breast cancer risk was significantly higher in those with new-onset breast tenderness compared with those without (hazard ratio, 1.48; 95% confidence interval, 1.08-2.03; P = .02). In the placebo group, breast cancer risk was not significantly associated with new-onset breast tenderness (P = .97).

CONCLUSIONS

New-onset breast tenderness during conjugated equine estrogens plus medroxyprogesterone therapy was associated with increased breast cancer risk. The sensitivity and specificity of the association between breast tenderness and breast cancer were similar in magnitude to those of the Gail model. Trial Registration clinicaltrials.gov Identifier: NCT00000611.

Tibolone in postmenopausal women with systemic lupus erythematosus: a pilot study

OBJECTIVE

To determine the influence of the use of tibolone on the frequency of flares of systemic lupus erythematosus (SLE) in postmenopausal patients.

METHODS

Thirty patients with inactive or controlled SLE were included in the study. Patients were randomized to receive a 12-month course of either tibolona (2.5 mg/day) or placebo. The following were investigated: hypoestrogenism symptoms by Kupperman index, weight; anti-dsDNA antibodies; SLE flares (frequency) assessed by the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI); and biochemical profile (total cholesterol, high-density lipoprotein cholesterol [HDL-C], triglycerides, complement components [C3/C4], alpha1-acid glycoprotein, urea, creatinine, 24-h proteinuria, C-reactive protein and erythrocyte sedimentation rate).

RESULTS

The reduction in Kupperman index was greater in the patients using tibolone than in those using placebo. The mean SLEDAI was not different between the groups during the study as well as SLE flare frequency (tibolone: 2/15 [13.3%] vs. placebo: 1/15 [6.7%]; p=0.54). All cases of flares were considered mild to moderate. Although the groups were similar at the baseline evaluation, after 6 and 12 months of treatment lower values were found in the tibolone group for triglycerides (6 months: 161.6+/-30.9 mg/dl vs. 194.4+/-46.5; p=0.04; 12 months 163.7+/-29.8 mg/dl vs. 204.1+/-49.9 mg/dl; p=0.02; tibolone vs. placebo group, respectively) and for HDL-C (6 months: 40.7+/-10.7 mg/dl vs. 53.4+/-16.5; p=0.02; 12 months: 47.2+/-7.9 mg/dl vs. 63.2+/-16.3mg/dl; p<0.01; tibolone vs. placebo group, respectively). There were no differences between the two groups in any of the remaining variables.

CONCLUSION

In patients with inactive or stable SLE, the short-term use of tibolone did not significantly affect the frequency of flares. In addition, tibolone was well tolerated and effective to control hypoestrogenism related symptoms in SLE patients.

Safety and efficacy of tibolone in breast-cancer patients with vasomotor symptoms: a double-blind, randomised, non-inferiority trial

BACKGROUND

Vasomotor symptoms and bone loss are complications frequently induced by adjuvant treatment for breast cancer. Tibolone prevents both side-effects, but its effect on cancer recurrence is unknown. The aim of this study was to show non-inferiority of tibolone to placebo regarding risk of recurrence in breast-cancer patients with climacteric complaints.

METHODS

Between July 11, 2002, and Dec 20, 2004, women surgically treated for a histologically confirmed breast cancer (T(1-3)N(0-2)M(0)) with vasomotor symptoms were randomly assigned to either tibolone 2.5 mg daily or placebo at 245 centres in 31 countries. Randomisation was done by use of a centralised interactive voice response system, stratified by centre, with a block size of four. The primary endpoint was breast-cancer recurrence, including contralateral breast cancer, and was analysed in the intention-to-treat (ITT) and per-protocol populations; the margin for non-inferiority was set as a hazard ratio of 1.278. This study is registered with ClinicalTrials.gov, number NCT00408863.

FINDINGS

Of the 3148 women randomised, 3098 were included in the ITT analysis (1556 in the tibolone group and 1542 in the placebo group). Mean age at randomisation was 52.7 years (SD 7.3) and mean time since surgery was 2.1 years (SD 1.3). 1792 of 3098 (58%) women were node positive and 2185 of 3098 (71%) were oestrogen-receptor positive. At study entry, 2068 of 3098 (67%) women used tamoxifen and 202 of 3098 (6.5%) women used aromatase inhibitors. The mean daily number of hot flushes was 6.4 (SD 5.1). After a median follow-up of 3.1 years (range 0.01-4.99), 237 of 1556 (15.2%) women on tibolone had a cancer recurrence, compared with 165 of 1542 (10.7%) on placebo (HR 1.40 [95% CI 1.14-1.70]; p=0.001). Results in the per-protocol population were similar (209 of 1254 [16.7%] women in the tibolone group had a recurrence vs 138 of 1213 [11.4%] women in the placebo group; HR 1.44 [95% CI 1.16-1.79]; p=0.0009). Tibolone was not different from placebo with regard to other safety outcomes, such as mortality (72 patients vs 63 patients, respectively), cardiovascular events (14 vs 10, respectively), or gynaecological cancers (10 vs 10, respectively). Vasomotor symptoms and bone-mineral density improved significantly with tibolone, compared with placebo.

INTERPRETATION

Tibolone increases the risk of recurrence in breast cancer patients, while relieving vasomotor symptoms and preventing bone loss.

FUNDING

Schering-Plough (formerly NV Organon, Oss, Netherlands).

Tibolone rapidly attenuates the GABAB response in hypothalamic neurones

Tibolone is primarily used for the treatment of climacteric symptoms. Tibolone is rapidly converted into three major metabolites: 3 alpha- and 3beta-hydroxy (OH)-tibolone, which have oestrogenic effects, and the Delta 4-isomer (Delta 4-tibolone), which has progestogenic and androgenic effects. Because tibolone is effective in treating climacteric symptoms, the effects on the brain may be explained by the oestrogenic activity of tibolone. Using whole-cell patch clamp recording, we found previously that 17beta-oestradiol (E(2)) rapidly altered gamma-aminobutyric acid (GABA) neurotransmission in hypothalamic neurones through a membrane oestrogen receptor (mER). E(2) reduced the potency of the GABA(B) receptor agonist baclofen to activate G-protein-coupled, inwardly rectifying K(+) (GIRK) channels in hypothalamic neurones. Therefore, we hypothesised that tibolone may have some rapid effects through the mER and sought to elucidate the signalling pathway of tibolone's action using selective inhibitors and whole cell recording in ovariectomised female guinea pigs and mice. A sub-population of neurones was identified post hoc as pro-opiomelanocortin (POMC) neurones by immunocytochemical staining. Similar to E(2), we have found that tibolone and its active metabolite 3 beta OH-tibolone rapidly reduced the potency of the GABA(B) receptor agonist baclofen to activate GIRK channels in POMC neurones. The effects were blocked by the ER antagonist ICI 182 780. Other metabolites of tibolone (3 alpha OH-tibolone and Delta 4-tibolone) had no effect. Furthermore, tibolone (and 3 beta OH-tibolone) was fully efficacious in ER alpha knockout (KO) and ER beta KO mice to attenuate GABA(B) responses. The effects of tibolone were blocked by phospholipase C inhibitor U73122. However, in contrast to E(2), the effects of tibolone were not blocked by protein kinase C inhibitors or protein kinase A inhibitors. It appears that tibolone (and 3 beta OH-tibolone) activates phospholipase C leading to phosphatidylinositol bisphosphate metabolism and direct alteration of GIRK channel function. Therefore, tibolone may enhance synaptic efficacy through the G(q) signalling pathways of mER in brain circuits that are critical for maintaining homeostatic functions.

Effects of tibolone and conventional HRT on the expression of estrogen and progesterone receptors in the breast

OBJECTIVE

There is evidence that long-term hormone replacement therapy (HRT) is associated with an increased breast cancer risk. The aim of this study was to assess the effects of tibolone on estrogen and progesterone receptors in comparison to the effects of conventional HRT in the breast of surgically postmenopausal macaques.

METHOD

Sixty macaques were bilaterally ovariectomized 3 months before hormonal treatment was initiated. The animals were randomized into four treatment groups, including tibolone (TIB), conjugated equine estrogens (CEE), conjugated equine estrogens+medroxyprogesterone acetate (CEE+MPA) and control animals (C). After 2 years treatment, breast tissues were collected, fixed and paraffin embedded. Immunohistochemistry assays with monoclonal antibodies for estrogen receptors (ERalpha and ERbeta) and progesterone receptors (PRA and PRB) were performed.

RESULTS

The expression of ERalpha was markedly decreased in the CEE+MPA group as compared to C and TIB groups. The TIB group was not different from the C and CEE groups. No significant differences were found for ERbeta immunostaining. The expression of PRA was strongly increased in the TIB group as compared to the C and CEE+MPA groups. Immunostaining of PRB was increased in the CEE and TIB treated animals as compared to both C and CEE+MPA groups.

CONCLUSIONS

Tibolone increased the expression of both PRA and PRB, without affecting ERalpha and ERbeta expression in the macaque breast. These findings indicate that the effects of tibolone in breast tissue could be mediated via differential regulation of PRA and PRB isoforms and therefore distinct from those observed with conventional HRT.

The effects of tibolone in older postmenopausal women

BACKGROUND

Tibolone has estrogenic, progestogenic, and androgenic effects. Although tibolone prevents bone loss, its effects on fractures, breast cancer, and cardiovascular disease are uncertain.

METHODS

In this randomized study, we assigned 4538 women, who were between the ages of 60 and 85 years and had a bone mineral density T score of -2.5 or less at the hip or spine or a T score of -2.0 or less and radiologic evidence of a vertebral fracture, to receive once-daily tibolone (at a dose of 1.25 mg) or placebo. Annual spine radiographs were used to assess for vertebral fracture. Rates of cardiovascular events and breast cancer were adjudicated by expert panels.

RESULTS

During a median of 34 months of treatment, the tibolone group, as compared with the placebo group, had a decreased risk of vertebral fracture, with 70 cases versus 126 cases per 1000 person-years (relative hazard, 0.55; 95% confidence interval [CI], 0.41 to 0.74; P<0.001), and a decreased risk of nonvertebral fracture, with 122 cases versus 166 cases per 1000 person-years (relative hazard, 0.74; 95% CI, 0.58 to 0.93; P=0.01). The tibolone group also had a decreased risk of invasive breast cancer (relative hazard, 0.32; 95% CI, 0.13 to 0.80; P=0.02) and colon cancer (relative hazard, 0.31; 95% CI, 0.10 to 0.96; P=0.04). However, the tibolone group had an increased risk of stroke (relative hazard, 2.19; 95% CI, 1.14 to 4.23; P=0.02), for which the study was stopped in February 2006 at the recommendation of the data and safety monitoring board. There were no significant differences in the risk of either coronary heart disease or venous thromboembolism between the two groups.

CONCLUSIONS

Tibolone reduced the risk of fracture and breast cancer and possibly colon cancer but increased the risk of stroke in older women with osteoporosis. (ClinicalTrials.gov number, NCT00519857.)

Effects of tibolone on estrogen biosynthesis in the mammary tissue of postmenopausal monkeys

OBJECTIVE

To evaluate the long-term effects of tibolone on estrone sulfate (E1S)-sulfatase activity in breast tissue in a primate model (Macaca fascicularis) in comparison with conventional hormone therapies.

DESIGN

Ovariectomized female animals (n = 112) were randomized into five groups and treated for 2 years. Treatment included tibolone at 0.05 mg/kg (LoTib, n = 23) or 0.2 mg/kg (HiTib, n = 23), conjugated equine estrogens at 0.042 mg/kg (CEE, n = 24), CEE + medroxyprogesterone acetate at 0.167 mg/kg (CEE+MPA, n = 21), or placebo (controls, n = 21). E1S-sulfatase activity was evaluated by incubating homogenized breast tissue with [H]-E1S. Thin-layer chromatography was performed to separate the products estrone (E1) and estradiol (E2). Histomorphometry was performed to measure the amount of epithelial and fat tissue in the mammary gland.

RESULTS

Significantly more E2 than E1 was produced in all groups. E1S-sulfatase activity did not differ among the groups. E1S-sulfatase activity was highest in HiTib animals with less fatty breasts (5.9 fmol total estrogen/mg of protein/min; P < or =0.05) and lowest in HiTib animals with more fatty breasts (2.8 fmol total estrogen/mg of protein/min; P = 0.004 relative to less fatty breasts).

CONCLUSIONS

We conclude that tibolone had a differential effect on local estrogen biosynthesis in animals with high and low breast fat content. Therefore, breast tissue composition affects the steroidogenic response to hormonal treatment.

In vitro effects of tibolone and its metabolites on human vascular coronary cells

OBJECTIVES

Tibolone is a tissue selective compound with estrogenic, androgenic and progestogenic properties in classical bioassays. It is used for alleviation of menopausal symptoms and for osteoporosis prophylaxis in postmenopausal women. Only few data are available regarding the effects of tibolone on the cardiovascular system. We investigated therefore the in vitro effects of tibolone and its metabolites on the vasculature under special controlled conditions, using human female coronary endothelial and smooth muscle cells.

METHODS

The effect on the production of the following markers in endothelial cells from human female coronary arteries was evaluated: nitric oxide synthase, prostacyclin, endothelin, plasminogen-activator-inhibitor-1 (PAI-1), E-Selectin, Intercellular adhesion molecule (ICAM-1), monocyte attracting protein-1 (MCP-1) and the precursor of matrix metalloproteinase-1 (pro-MMP-1). Tibolone, its metabolites, estradiol (E2), E2/norethisterone (NET) and E2/medroxyprogesterone acetate (MPA) were tested at 0.1 microM and 1 microM. The markers were determined by enzyme immunoassays in the cell supernatant. Cell proliferation of smooth muscle cells from female coronary artery was measured by an adenosine triphosphate-assay.

RESULTS

Tibolone, its 3-hydroxy metabolites, E2/NET, E2/MPA and estradiol alone had significant effects on the synthesis of all markers tested. The magnitude of the tibolone effects, however, was mostly smaller than that of E2/NET and E2/MPA. Concerning smooth muscle cells tibolone and its 3-hydroxy metabolites also elicited an inhibition of the proliferation compared to control values. The strongest effect here was found for E2/NET and E2 alone, whereas E2/MPA had no effect.

CONCLUSION

The results of this in vitro study conducted with cells of the most important vascular bed with respect to the problem of cardiovascular risk suggest that tibolone can positively influence the vasculature. However, these tibolone effects may depend on intact vascular cells and may vary due to the different atherosclerotic stages of the vessels. Thus, experimental studies are useful to explore mechanisms, but clearly cannot replace clinical studies.

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.

An isopropanolic extract of black cohosh does not increase mammographic breast density or breast cell proliferation in postmenopausal women

OBJECTIVE

The aim of this study was to determine the effects of the isopropanolic extract of black cohosh (Remifemin) on mammographic breast density and breast epithelial proliferation in healthy, naturally postmenopausal women with climacteric symptoms.

DESIGN

This was a prospective, open, uncontrolled drug safety study in which baseline status was compared with status after 6 months of treatment by blinded observers. A total of 74 women were treated with 40 mg black cohosh daily, and 65 women completed the study. Mammograms were performed, and breast cells were collected by percutaneous fine needle aspiration biopsies at baseline and after 6 months. Mammographic density was quantified according to the Wolfe classification or a percentage scale. Breast cell proliferation was assessed using the Ki-67/MIB-1 monoclonal antibody. Safety was monitored by adverse event reporting, laboratory assessments, and measurement of the endometrium by vaginal ultrasound.

RESULTS

None of the women showed any increase in mammographic breast density. Furthermore, there was no increase in breast cell proliferation. The mean change +/- SD in proportion of Ki-67-positive cells was -0.5% +/- 2.4% (median, 0.0; 95% CI = -1.32 to 0.34) for paired samples. The mean change in endometrial thickness +/- SD was 0.0 +/- 0.9 mm (median, 0.0). A modest number of adverse events were possibly related to treatment, but none of these were serious. Laboratory findings and vital signs were normal.

CONCLUSIONS

The findings suggest that the isopropanolic extract of black cohosh does not cause adverse effects on breast tissue. Furthermore, our data do not indicate to any endometrial or general safety concerns during 6 months of treatment.

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.

Tibolone therapy in breast cancer survivors: a retrospective study

AIM

To investigate a possible relationship between tibolone therapy and recurrence or mortality in breast cancer survivors.

METHODS

In a retrospective study, data from files of 247 patients who had been treated for breast cancer were analyzed. Twenty women were treated with tibolone because of menopausal symptoms (Group 1: mean duration of tibolone use 37.1 months). One hundred and one women who did not take tibolone were selected as the control group (Group 2). All women were followed up in our Department on our standard protocol (mean follow up: 73.4 months in Group 1, 67.4 months in Group 2). Comparison of the survival curves was applied with the Wilcoxon (Gehan) statistic. Cox regression analysis was also applied in order to identify significant coefficients in the survival curve.

RESULTS

Recurrence of breast cancer was observed in two (10%) Group 1 women versus 21 (21%) Group 2 women (P = NS). Two Group 1 women died (one from breast cancer recurrence) versus 15 Group 2 women (14 from breast cancer recurrence).

CONCLUSIONS

Despite of the inherent limitations of this small retrospective study, it seems that tibolone does not reveal an apparent negative impact on breast cancer outcome when given to breast cancer survivors.

Breast response to menopausal hormone therapy--aspects on proliferation, apoptosis and mammographic density

Breast cancer is the major malignancy among women in the Western world. The breast is clearly a target organ for sex steroid hormones and hormonal treatments have been associated with an increased risk of breast cancer. The balance between proliferation and apoptosis is important for breast cell homeostasis. Mammographic breast density has been identified as a strong and independent risk factor for breast cancer. It seems clear that there is a difference between various hormonal treatments with regard to their effects on breast density and cell proliferation. Also, not all women respond similarly to the same treatment. Combined estrogen and progestogen therapy generally will enhance density and proliferation more than treatment with estrogen alone. Certain constitutional and hormonal factors appear to be predictive of breast reactivity. Older women with a low body mass index respond more strongly to treatment. Estrogen levels have a positive and androgens a negative association to increase in density and proliferation. A combination of increased proliferation and decreased apoptosis could be one mechanism to explain the excess risk of breast cancer during combined estrogen/progestogen treatment. Tibolone seems to have less impact on breast response than conventional hormone therapy. Efforts should be made to identify those women with an adverse response to treatment as well as therapeutic principles with the least possible influence on the breast.

Tibolone and breast cancer

Tibolone is a relatively new drug for postmenopausal women, which is structurally related to 19-nortestosterone derivatives and exhibits weak oestrogenic, progestogenic and androgenic activities. The effect of tibolone on breast tissue is still obscure. In vitro studies have shown conflicting results regarding the effects of tibolone on breast cells. On the other hand, although epidemiological studies show an increase in the risk of breast cancer among women treated with tibolone, accumulation of data obtained from radiological studies presents promising results. However, the safety of tibolone with regard to breast tissue needs to be investigated further, especially through well-designed, large-scale, randomised-controlled trials.

Metabolism of exogenous sex steroids and effect on brain functions with a focus on tibolone

Around the menopause, changes in ovarian secretion of steroids result in changes in brain function: hot flushes and sweating later followed by changes in mood, libido and cognition. The relationship between sex steroids and brain functions are reviewed, with focus on hormonal treatments, in particular tibolone, on the postmenopausal brain and on associations between tissue levels and brain functions. Data on steroid levels in human brain are limited. Exogenous oestrogens alone or combined with progestagens reduce hot flushes and sweating, and may favourably affect anxiety, depression and mood. Testosterone alone or combined with E(2) improves libido and mood. Tibolone reduces hot flushes and sweating, and improves mood and libido, but does not stimulate endometrium or breast, like oestrogens. Tibolone is an ideal compound for studying steroid levels and metabolism in brain in view of its structural differences from endogenous steroids and its extensive metabolism required to express its endocrine effects. Brain levels of tibolone metabolites were measured in ovariectomized cynomolgus monkeys receiving tibolone for 36 days. Compared to serum, higher levels of the oestrogenic 3alpha/beta-hydroxytibolone and the androgenic/progestagenic Delta(4)-tibolone, and lower levels of sulphated metabolites are found in various brain regions. The high levels of oestrogenic metabolites in the hypothalamus explain hot flush reduction. Combined with the presence of Delta(4)-tibolone, the tibolone-induced increase in free testosterone through SHBG reduction explains androgenic effects of tibolone on mood and libido. The levels of tibolone metabolites in the monkey brain support tibolone's effects on brain functions.

Effects of Tibolone on Sulfatase Pathway of Estrogens Metabolism and on Growth of MCF-7 Human Breast Tumors Implanted in Ovariectomized Nude Mice

BACKGROUND

The benefits of estrogen plus progestin in healthy post-menopausal women remain uncertain. Tibolone, with its in vitro documented inhibitory effects on estrogens metabolism and its selective action on breast, may be an alternative that could favorably influence the health benefit of hormone replacement therapy.

METHODS

We studied the effect of tibolone on the tumor growth of MCF-7 cells implanted in 40 ovariectomized nude mice, receiving subcutaneous pellets of 17beta-estradiol, estrone, estrone-sulfate or vehicle, and daily gavages of tibolone or placebo.

RESULTS

Tibolone, although used at high dose, did not stimulate nor inhibit the estrogen-induced tumors, nor the tumors in estrogen-deprived mice. Measurements of plasma levels of estrogens indicated that tibolone potently stimulated sulfotransferase activity, but intra-tumor levels of estrogens were not significantly modified by tibolone.

CONCLUSIONS

This in vivo study performed with high dose of orally administered tibolone that allowed its hepatic conversion into active metabolites has shown no significant effect on breast tumors growth. Tibolone increased the circulating sulfated estrogens by its activity on the hepatic sulfation but not the intra-tumor levels of estrogens (free or sulfated). However, further studies of dose-response curve and molecular markers are needed to exclude definitely a stimulatory effect of tibolone on tumor growth.

Digitized assessment of mammographic breast density in patients who received low-dose intrauterine levonorgestrel in continuous combination with oral estradiol valerate: a pilot study

OBJECTIVE

To perform a pilot study of the effects on the breast by low-dose intrauterine progestogen combined with estrogen.

DESIGN

A prospective pilot study.

SETTING

University hospital.

PATIENT(S)

Twenty postmenopausal women without any previous breast disorder.

INTERVENTION(S)

Women were treated with a low-dose intrauterine system releasing 20 microg/24 hours of levonorgestrel in continuous combination with 2 mg of oral E2 valerate. The effects on mammographic breast density, breast cell proliferation, and hormonal levels were followed for 18 months.

MAIN OUTCOME MEASURE(S)

Change in mammographic breast density and breast cell proliferation. Correlations with levels of hormones, growth factors, and binding proteins.

RESULT(S)

Three women showed an apparent increase in density. For the remaining 17 women the changes were only a few percent. Digitized assessment of density showed strong correlations with visual classification scales (rs = 0.96-0.97). There was no increase in proliferation as expressed by the percentage of MIB-1-positive breast cells in fine-needle aspiration biopsies. Increase in breast density displayed a positive correlation with patients age (rs = 0.52) and an inverse relationship with levels of E2 (rs = -0.50) and free T (rs = -0.50).

CONCLUSION(S)

Low-dose intrauterine administration progestogen may develop into an attractive alternative for hormonal therapy in postmenopausal women as endometrial protection may be achieved at very low systemic levels.

Expression of p53 and markers for apoptosis in breast tissue during long-term hormone therapy in cynomolgus monkeys

OBJECTIVE

The purpose of this study was to analyze the expression of p53 and markers for apoptosis in breast tissue during long-term hormone therapy in cynomolgus monkeys.

STUDY DESIGN

Sixty oophorectomized macaques were randomized to receive tibolone, conjugated equine estrogens (CEE), CEE+medroxyprogesterone acetate (MPA), or no hormonal treatment. Breast tissue was collected at necropsy after 2 years, and stained for p53, p21, and cleaved caspase-3.

RESULTS

Differences were seen between treatment groups. The expression of p53 and caspase-3 was significantly lower in tibolone-treated animals (P<.01). Levels of p53 and caspase-3 were lower in the combined treatment group (CEE+MPA) when compared to both estrogen only and control groups.

CONCLUSION

Alternative regimens for hormonal therapy seem to have different effects on p53 expression and apoptotic activity within the breast. A combined effect of increased proliferation and decreased apoptosis could be one possible mechanism to explain an increased risk for breast cancer.

Conjugated estrogen/progestagen versus tibolone hormone replacement therapy in postmenopausal women: Effects on carbohydrate metabolism and serum sex hormone-binding globulin

OBJECTIVE

To study the effects of different types of continuous hormone replacement therapy on carbohydrate metabolism.

METHOD

Postmenopausal women were treated with conjugated estrogens, 0.625 mg/medroxyprogesterone acetate, 2.5 or 5 mg (CEE/MPA) or tibolone 2.5 mg daily for 13 28-day cycles. Serum glucose and insulin were measured before and during a 75 g oral glucose tolerance test (OGTT) at baseline and after 3, 6 and 13 cycles and areas under the curve (AUC) were calculated. Sex hormone-binding globulin (SHBG) was measured as an additional marker of nutritional and insulin status.

RESULTS

Neither CEE/MPA 2.5mg nor tibolone had any effects on carbohydrate metabolism while AUC(insulin), AUC(glucose) and also body mass index (BMI) increased after 13 cycles of treatment in the CEE/MPA 5 mg group. SHBG increased significantly during CEE/MPA treatment and decreased significantly during treatment with tibolone. The effects on SHBG were less pronounced in the CEE/MPA 5mg group. Pretreatment SHBG showed significant negative correlations to BMI and to variables that may reflect a certain degree of insulin resistance, the most pronounced being fasting glucose. Changes in SHBG during treatment with tibolone were negatively correlated to pretreatment SHBG and positively to BMI, AUC(insulin) and fasting insulin resistance index, while no such correlations were found in the CEE/MPA groups. There were no correlations between changes in AUC(insulin) and AUC(glucose) on one hand and basal variables or treatment SHBG on the other in the CEE/MPA groups.

CONCLUSION

The effects of tibolone and CEE/MPA on carbohydrate metabolism were considered to have clinical significance only for CEE/MPA 5mg, indicating a less favourable role of the higher progestagen dose. The results further support the important role of metabolic and insulin status in the physiological regulation of SHBG and also indicate that the suppressive effect of tibolone on circulating SHBG is mainly depends on pretreatment SHBG levels. SHBG does not reflect changes in carbohydrate metabolism during CEE/MPA treatment.

Tibolone: Clinical recommendations and practical guidelines

An international multidisciplinary panel of experts in the management of the menopause met at the 4th Amsterdam Menopause Symposium in October 2004 to determine the specific place of tibolone, a synthetic steroid with a unique clinical profile, within the wide range of currently available postmenopausal therapy options. The consensus was that tibolone is a valuable treatment option for women with climacteric complaints. As well as relieving vasomotor symptoms, tibolone has positive effects on sexual well-being and mood, and improves vaginal atrophy and urogenital symptoms. Prevention of bone loss with tibolone is comparable to that seen with estrogen therapy (ET) and estrogen/progestogen therapy (EPT). As tibolone rarely causes endometrial proliferation, no additional progestogen is required. It also has good tolerability, being associated with a low incidence of vaginal bleeding and of breast pain. Tibolone does not increase mammographic density. Absolute numbers of women at increased risk for breast cancer are estimated to be low or absent with both tibolone and ET, and the risk with tibolone should be significantly lower than that with EPT. Tibolone might therefore be preferable to EPT in certain women who have not been hysterectomised. Based on the evidence available, the panel proposed a number of subgroups of postmenopausal women with vasomotor symptoms in whom tibolone might have added value; these included women with sexual dysfunction, mood disorders, fibroids and urogenital complaints, as well as those with breast tenderness or high mammographic breast density with EPT use.

Therapy for Menopausal Symptoms During and After Treatment for Breast Cancer

Breast cancer is the most common newly diagnosed cancer in women. Life-time risk in the US is 1 in 8 (13.2%), in the UK it is 1 in 9 and in Australia it affects 1 in 11 women, of whom approximately 27% will be premenopausal at the time of their diagnosis. Many of these women will experience a sudden menopause as a result of chemotherapy, endocrine therapy or surgical interventions. For these women, the onset of menopausal symptoms is often sudden and severe. The management of such symptoms remains controversial. Women experiencing menopausal symptoms after breast cancer should be encouraged to avoid identifiable triggers for their symptoms and to consider lifestyle modification as a means of controlling those symptoms. When such measures fail, non-hormonal treatments may also be considered. These include clonidine, gabapentin and some antidepressants. Randomised trials have shown a significant difference in the symptom relief associated with various selective serotonin reuptake inhibitors and selective serotonin and noradrenaline (norepinephrine) reuptake inhibitors compared with placebo. Many women elect to use non-prescription complementary therapies to alleviate their menopausal symptoms. Systematic reviews of phytoestrogens have, however, failed to demonstrate significant relief of menopausal symptoms. More than 20 clinical trials have been conducted examining the relationship between postmenopausal hormone replacement therapy and breast cancer recurrence. The majority of these have been observational and have shown no increased risk of recurrence. However, the largest randomised trial that has thus far been conducted was recently halted because of a reported increase in the risk of recurrence amongst users of hormone replacement therapy. Tibolone, a selective tissue estrogen activity regulator, is a compound that exerts clinical effects both by receptor-mediated actions and tissue selective enzyme inhibition, and has been shown in preclinical studies to have different effects to estrogen on the breast. Although tibolone may prove safer than estrogen for long-term use in breast cancer survivors, the results of a large randomised trial are awaited to confirm this.The decision on how best to manage menopausal symptoms must thus be made on an individual basis and after thorough discussion and evaluation of the risks and benefits of each potential intervention.

The effects of tibolone and oestrogen-based HT on breast cell proliferation and mammographic density

Tibolone is a tissue-selective compound used for the treatment of climacteric symptoms and the prevention of osteoporosis in post-menopausal women. In this review some in vitro data and clinical studies indicating that the effects of tibolone on breast tissue are different from those seen with oestrogen-based hormone therapy (HT) are briefly discussed. From a clinical perspective, an increase in mammographic density and breast cell proliferation should be regarded as an unwanted side-effect of HT. Efforts should therefore be made to define treatment regimens for post-menopausal women that have minimal effects on the breast but still maintain the many advantages of HT. Data suggest that tibolone may be such an alternative.

Mammographic breast density, hormones, and growth factors during continuous combined hormone therapy

OBJECTIVE

To study the effect on mammographic breast density of two different continuous combined regimens for hormone therapy.

DESIGN

Randomized clinical study.

SETTING

University hospital.

PATIENT(S)

Postmenopausal women without any previous history of breast disorder.

INTERVENTION(S)

The women received either estradiol valerate/dienogest or estradiol/norethisterone acetate. Mammograms and venous blood samples were obtained at baseline and after 6 months.

MAIN OUTCOME MEASURE(S)

Change in mammographic breast density. Correlations with levels of hormones, growth factors, and binding proteins.

RESULT(S)

An increase in mammographic density was recorded in approximately 50% of the women, and there were no differences between treatments. Increased density showed a positive correlation with estradiol, estrone, and sex hormone-binding globulin and showed a negative association to free T. Among hormonal factors, levels of free T were the most important for predicting increased density.

CONCLUSION(S)

Continuous combined hormone therapy with different progestogens has a marked impact on the breast.