Endocrine Effects of Tamoxifen in Postmenopausal Breast Cancer Patients

Identifying molecular mediators of the relationship between body mass index and endometrial cancer risk: a Mendelian randomization analysis

BACKGROUND

Endometrial cancer is the most common gynaecological cancer in high-income countries. Elevated body mass index (BMI) is an established modifiable risk factor for this condition and is estimated to confer a larger effect on endometrial cancer risk than any other cancer site. However, the molecular mechanisms underpinning this association remain unclear. We used Mendelian randomization (MR) to evaluate the causal role of 14 molecular risk factors (hormonal, metabolic and inflammatory markers) in endometrial cancer risk. We then evaluated and quantified the potential mediating role of these molecular traits in the relationship between BMI and endometrial cancer using multivariable MR.

METHODS

Genetic instruments to proxy 14 molecular risk factors and BMI were constructed by identifying single-nucleotide polymorphisms (SNPs) reliably associated (P < 5.0 × 10-8) with each respective risk factor in previous genome-wide association studies (GWAS). Summary statistics for the association of these SNPs with overall and subtype-specific endometrial cancer risk (12,906 cases and 108,979 controls) were obtained from a GWAS meta-analysis of the Endometrial Cancer Association Consortium (ECAC), Epidemiology of Endometrial Cancer Consortium (E2C2) and UK Biobank. SNPs were combined into multi-allelic models and odds ratios (ORs) and 95% confidence intervals (95% CIs) were generated using inverse-variance weighted random-effects models. The mediating roles of the molecular risk factors in the relationship between BMI and endometrial cancer were then estimated using multivariable MR.

RESULTS

In MR analyses, there was strong evidence that BMI (OR per standard deviation (SD) increase 1.88, 95% CI 1.69 to 2.09, P = 3.87 × 10-31), total testosterone (OR per inverse-normal transformed nmol/L increase 1.64, 95% CI 1.43 to 1.88, P = 1.71 × 10-12), bioavailable testosterone (OR per natural log transformed nmol/L increase: 1.46, 95% CI 1.29 to 1.65, P = 3.48 × 10-9), fasting insulin (OR per natural log transformed pmol/L increase: 3.93, 95% CI 2.29 to 6.74, P = 7.18 × 10-7) and sex hormone-binding globulin (SHBG, OR per inverse-normal transformed nmol/L increase 0.71, 95% CI 0.59 to 0.85, P = 2.07 × 10-4) had a causal effect on endometrial cancer risk. Additionally, there was suggestive evidence that total serum cholesterol (OR per mg/dL increase 0.90, 95% CI 0.81 to 1.00, P = 4.01 × 10-2) had an effect on endometrial cancer risk. In mediation analysis, we found evidence for a mediating role of fasting insulin (19% total effect mediated, 95% CI 5 to 34%, P = 9.17 × 10-3), bioavailable testosterone (15% mediated, 95% CI 10 to 20%, P = 1.43 × 10-8) and SHBG (7% mediated, 95% CI 1 to 12%, P = 1.81 × 10-2) in the relationship between BMI and endometrial cancer risk.

CONCLUSIONS

Our comprehensive MR analysis provides insight into potential causal mechanisms linking BMI with endometrial cancer risk and suggests targeting of insulinemic and hormonal traits as a potential strategy for the prevention of endometrial cancer.

Long-term comparisons of the efficacy, safety, and pregnancy outcomes of adjuvant tamoxifen plus ovarian function suppression in premenopausal Han and Zhuang Chinese patients with hormone receptor-positive early breast cancer

Objective

To compare the efficacy, safety, and pregnancy outcomes of tamoxifen plus ovarian function suppression (OFS) between Han and Zhuang women with hormone receptor-positive breast cancer.

Methods

A total of 236 Han and 101 Zhuang women with hormone receptor-positive breast cancer who received tamoxifen plus OFS were analyzed retrospectively. Long-term disease-free survival (DFS) and overall survival (OS) were evaluated by Kaplan–Meier analysis, and adverse events and pregnancy outcomes were assessed by χ² and Fisher’s exact-probability tests.

Results

There was no significant difference in DFS or OS between Han and Zhuang women (5-year DFS 74.57% and 77.23%, OS 85.59% and 90.01%, respectively). The incidences of endometrial hyperplasia, ovarian cysts, nausea and vomiting, fatty liver, retinitis, and thrombocytopenic purpura were similar in both groups, but Zhuang women had significantly more allergic reactions (6.93% vs. 2.12%). Pregnancy rates among women who attempted pregnancy were similar (Han, 7/138, 5.07%; Zhuang, 2/46, 4.35%).

Conclusions

OFS plus tamoxifen resulted in similar DFS and OS among premenopausal Han and Zhuang women with hormone receptor-positive breast cancer. However, Zhuang women were more likely to experience an allergic reaction. For women with fertility concerns, OFS plus tamoxifen was associated with similar pregnancy rates in Zhuang and Han women.

Hypothalamic-Pituitary-Ovarian Axis in Women with Operable Breast Cancer Treated with Adjuvant CMF and Tamoxifen

The effect of adjuvant CMF (cyclophopshamide, methotrexate, and 5-fluorouracil) and tamoxifen (TM) on hypothalamic-pituitary-ovarian function was studied in 120 women with stage I-II operable breast cancer. Sixty patients were premenopausal, of whom 25 were treated with CMF for 9 cycles, 25 with CMF for 9 cycles + TM for 2 years, started concurrently, and 10 with TM alone for 2 years. Sixty patients were postmenopausal and they were all treated with TM alone for 2 years. In all groups treatment was started within 4 weeks of mastectomy. Plasma levels of estrone (E1), estradiol-17β (E2), follicle-stimulating hormone, luteinizing hormone (LH), prolactin (Prl), testosterone (T) and thyroid-stimulating hormone (TSH) were determined in all patients before surgery and again at 3-month intervals from initiation of the adjuvant therapy. In ten patients of each treatment group FSH-LH and Prl-TSH release was determined following stimulation with releasing hormones. CMF and CMF + TM therapy resulted in amenorrhea in 42/50 premenopausal patients with decrease of E1 + E2 (p < 0.001) and elevation of FSH (p < 0.001) and LH (p < 0.01) plasma concentration to postmenopausal levels. In premenopausal women treated with TM a marked increase of E1 + E2 (p < 0.001) was observed with unaltered FSH-LH plasma concentration. A significant fall of Prl also occurred in these patients. In postmenopausal women and premenopausal patients with CMF-induced amenorrhea TM produced a marked fall of FSH-LH and a decrease of Prl plasma level. Plasma TSH and T were not affected in any patient by any of the treatment regimens. The results of the stimulatory tests are in agreement with the hormonal changes observed under basal conditions and indicate that, whereas CMF suppresses the ovary and does not alter hypothalamic-pituitary function, TM induces profound changes of the hypothalamic-pituitary-ovarian axis.

Effects of vaginal estrogens on serum estradiol levels in postmenopausal breast cancer survivors and women at risk of breast cancer taking an aromatase inhibitor or a selective estrogen receptor modulator

BACKGROUND

Intravaginal estradiols (VE) have been proposed as safe alternatives to systemic estrogen therapy in breast cancer survivors.

PATIENTS AND METHODS

Postmenopausal women with estrogen receptor-positive breast cancer or at high risk for breast cancer (n = 24) who were taking an aromatase inhibitor (AI) or a selective estrogen receptor modulator (SERM) and VE for ≥ 90 days for atrophic vaginitis and 24 controls taking AI only participated in the study. Serum samples were drawn from VE ring patients before insertion and 30 and 60 days postinsertion, from VE tablet patients the morning before insertion and approximately 12 hours postinsertion, and once from controls. Samples were assayed for E2 concentrations by using highly sensitive radioimmunoassay after ether extraction.

RESULTS

Mean E2 levels in controls were 3.72 pmol/L (range, < 3.0-7.7 pmol/L); mean E2 levels preinsertion and 12 weeks postinsertion in the VE ring patients were significantly greater than controls (P < .001 for each comparison). Mean preinsertion E2 levels in patients using VE tablets were not significantly different than those of controls (P = .48), and postinsertion levels were 76 pmol/L higher than preinsertion (P < .001).

CONCLUSION

VE treatment increased E2 levels. Preinsertion levels for patients receiving VE tablets were not elevated compared with those of controls, suggesting that E2 elevations with this preparation may not be continuously sustained. We conclude that VE treatment, regardless of type, results in elevated circulating E2 levels in this population and should be used with caution.

Sex hormone-binding globulin gene expression in the liver: drugs and the metabolic syndrome

Sex hormone-binding globulin (SHBG) is the main transport binding protein for sex steroid hormones in plasma and regulates their accessibility to target cells. Plasma SHBG is secreted by the liver under the control of hormones and nutritional factors. In the human hepatoma cell line (HepG2), thyroid and estrogenic hormones, and a variety of drugs including the antioestrogen tamoxifen, the phytoestrogen, genistein and mitotane (Op'DDD) increase SHBG production and SHBG gene promoter activity. In contrast, monosaccharides (glucose or fructose) effectively decrease SHBG expression by inducing lipogenesis, which reduces hepatic HNF-4alpha levels, a transcription factor that play a critical role in controlling the SHBG promoter. Interestingly, diminishing hepatic lipogenesis and free fatty acid liver biosynthesis also appear to be associated with the positive effects of thyroid hormones and PPARgamma antagonists on SHBG expression. This mechanism provides a biological explanation for why SHBG is a sensitive biomarker of insulin resistance and the metabolic syndrome, and why low plasma SHBG levels are a risk factor for developing hyperglycemia and type 2 diabetes, especially in women. These important advances in our knowledge of the regulation of SHBG expression in the liver open new approaches for identifying and preventing metabolic disorder-associated diseases early in life.

Trait anxiety and tamoxifen effects on bone mineral density and sex hormone- binding globulin

OBJECTIVE

Tamoxifen therapy preserves BMD of the lumbar spine and increases levels of SHBG. We assessed whether trait anxiety, a factor linked with a reactive endocrine system, is associated with differential changes in BMD and SHBG levels in response to tamoxifen therapy.

METHODS

Postmenopausal women (N= 140) with axillary-node-negative breast cancer participated in a 2-year randomized, double-blind, placebo-controlled trial of tamoxifen (10 mg twice a day). Levels of BMD and SHBG were assessed at baseline and at 3, 6, 12, 18, and 24 months.

RESULTS

Trait anxiety predicted tamoxifen-induced changes in lumbar spine BMD; high levels of trait anxiety were associated with significantly greater lumbar spine BMD at 3, 12, and 24 months (p values <.05) for women on tamoxifen therapy. High anxiety also was associated with lower levels of SHBG for women using tamoxifen at 3, 12, 18, and 24 months (p values <.05).

CONCLUSIONS

Trait anxiety is associated with greater preservation of lumbar spine BMD in response to tamoxifen and with a suppression of tamoxifen-induced increases in SHBG. Trait anxiety and other affective traits may serve as indicators of underlying physiological processes that moderate the effects of estrogen receptor modulators (such as tamoxifen) in clinical trials. Such data may help to elucidate the physiological mechanisms responsible for some of the variation in individual responses to treatment.

Randomized Trial of Black Cohosh for the Treatment of Hot Flashes Among Women With a History of Breast Cancer

PURPOSE: Most breast cancer survivors experience hot flashes; many use complementary or alternative remedies for these symptoms. We undertook a randomized clinical trial of black cohosh, a widely used herbal remedy for menopausal symptoms, among breast cancer patients.

PATIENTS AND METHODS: Patients diagnosed with breast cancer who had completed their primary treatment were randomly assigned to black cohosh or placebo, stratified on tamoxifen use. At enrollment, patients completed a questionnaire about demographic factors and menopausal symptoms. Before starting to take the pills and at 30 and 60 days, they completed a 4-day hot flash diary. At the final visit, they completed another menopausal symptom questionnaire. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were measured in a subset of patients at the first and final visits.

RESULTS: Of 85 patients (59 on tamoxifen, 26 not on tamoxifen) enrolled in the study, 42 were assigned to treatment and 43 were assigned to placebo; 69 completed all three hot flash diaries. Both treatment and placebo groups reported declines in number and intensity of hot flashes; the differences between the groups were not statistically significant. Both groups also reported improvements in menopausal symptoms that were, for the most part, not significantly different. Changes in blood levels of FSH and LH also did not differ in the two groups.

CONCLUSION: Black cohosh was not significantly more efficacious than placebo against most menopausal symptoms, including number and intensity of hot flashes. Our study illustrates the feasibility and value of standard clinical trial methodology in assessing the efficacy and safety of herbal agents.

Gynecologic effects of tamoxifen: case reports and review of the literature

The literature regarding the gynecologic effects of tamoxifen contains very little data on the vagina and lower urinary tract. The authors present two patients receiving tamoxifen who had gynecologic surgery complications that could be associated with tamoxifen use. Both patients had poor healing which improved when the tamoxifen was discontinued. Possible explanations are given for this observation based on what is known about this unusual drug. Owing to the success of tamoxifen in breast cancer patients, its use is currently being extended to include groups of healthy women at risk for the development of breast cancer. Because the number of women receiving tamoxifen may be increasing the authors include a review of its effects, with which all health care providers caring for women should be familiar.

Selective oestrogen receptor modifiers (SERMs) and breast cancer therapy

Antioestrogen therapy is currently receiving renewed interest for several reasons. Tamoxifen was introduced in the treatment of metastatic breast cancer more than three decades ago. The drug significantly reduces long term mortality and also reduces the risk of contralateral tumours when administered in early breast cancer. Five years of tamoxifen is now standard in adjuvant endocrine therapy, and the drug is currently being evaluated for breast cancer prevention. Despite this, several aspects regarding the pharmacology of the drug are still unclear, and the scientific rationale for dose selection has recently been challenged. Several novel antioestrogen compounds, called selective oestrogen receptor modifiers (SERMs), express selective oestrogen agonistic or antagonistic properties depending on the organ or test system evaluated. Some of these drugs, like raloxifene, do not seem to promote the development of endometrial cancer, although they still have selected oestrogen-like beneficial effects. This paper reviews the pharmacologic and the pharmacokinetic aspects of the different SERMs with particular emphasis on their potential use in therapy and prevention of breast cancer.

Surveillance for endometrial cancer in women receiving tamoxifen

Recent studies showing a protective effect of tamoxifen in women at high risk for breast cancer have expanded the indications of the drug. While acting as an estrogen antagonist in the breast, tamoxifen can have estrogenic effects on the endometrium; consensus opinion is that tamoxifen increases the risk for endometrial cancer. Because an increasing number of women are taking tamoxifen, a strategy for gynecologic surveillance is needed. Studies examining the relation between risk for endometrial cancer and tamoxifen use have conflicting results. However, because of an overall interpretation that tamoxifen use slightly increases risk for endometrial cancer, some researchers advocate routine ultrasonography and endometrial biopsy for screening asymptomatic women receiving tamoxifen. This paper reviews the literature on endometrial cancer in women taking tamoxifen and the usefulness of various screening methods in this setting. Risk factors and screening criteria for endometrial cancer in the general population are discussed, and a strategy for surveillance of women taking tamoxifen is proposed. Patients should be screened for signs or symptoms of endometrial abnormality before taking tamoxifen. This evaluation, which should include a careful history, pelvic examination, and Papanicolaou smear, should be repeated annually while the patient is receiving tamoxifen. Although transvaginal ultrasonography is not recommended for routine screening, it is indicated if an adequate pelvic examination cannot be performed or if additional risk factors are present. The likelihood of abnormality is greater for patients who have abnormal bleeding, discharge, abnormal glandular cells on Papanicolaou smear, or an endometrial measurement on ultrasonography of more than 8 mm; these findings should prompt an aggressive evaluation of the endometrium.

Effects of experimental chemoendocrine therapy with a combination of a pure antiestrogen and 5-fluorouracil on human breast cancer cells implanted in nude mice

The antitumor effects of an experimental chemoendocrine therapy combining a new pure antiestrogen ICI 182780 and 5-fluorouracil (5-FU) were studied on MCF-7 human breast cancer cells implanted in nude mice. ICI 182780 had a dose-dependent antitumor activity, which was potentiated by the concomitant use of 5-FU. When compared with the control group, the estrogen receptor (ER) level in the ICI 182780 group was lower and that in the combination group was markedly lower. Cell cycle analysis by flow cytometry (FCM) resulted in a lower percentage of S-phase cells (%S) in the treated mice. No significant difference was observed in the 5-FU concentrations in tumor cells, while the 5-FU content in RNA was significantly higher in the combination group. The changes in free thymidylate synthetase (TS) concentration indicated TS synthesis after the administration of 5-FU to be more greatly suppressed in the combination group than in the 5-FU group. These results suggest that ICI 182780 and 5-FU exert their combination effect mainly on ER-positive cells, and that the suppression of TS synthesis in tumor cells and the potentiation of the 5-FU-induced metabolic dysfunction of RNA are thus involved in the mode of action of this combination therapy.

Behaviour of vaginal epithelial maturation and sex hormone binding globulin in post-menopausal breast cancer patients during the first year of tamoxifen therapy

To evaluate the effect of tamoxifen on vaginal epithelial maturation and on oestrogen-related hepatic synthesis, we prospectively studied the karyopyknotic index (KPI), the maturation index (MI), expressed as a percentage of parabasal (MI-1), intermediate (MI-2) and superficial (MI-3) cells, as well as the serum levels of the oestrogen-dependent sex hormone binding globulin (SHBG). Tests were performed at baseline, after 1, 3, 6 and 12 months of therapy in 64 post-menopausal breast cancer patients. Basal KPI ranged from 0 to 9 (mean 1.5 +/- 0.3) and rose 13.5-fold to 21 +/- 2.5 (P = 0.000) after the first 30 days of tamoxifen. Absence of KPI rise was observed in 23% of patients. Pretreatment MI figures 1, 2 and 3 were 56.9 +/- 5.6, 41.7 +/- 5.4 and 1.4 +/- 0.3, respectively, and sharply shifted to the right (P = 0.000) after 1 month of therapy, indicating an increase of vaginal epithelial maturation. At baselines the SHBG mean value was 62.1 +/- 3.3 nmol/l and underwent an increase of 44% (P = 0.000) after 30 days of tamoxifen. All of these observed 1-month modifications remained stable up to the studied 12 months of therapy. Present findings indicate an early and persistent oestrogenic effect of tamoxifen on the vaginal epithelium and the hepatic synthesis of SHBG.

Comparison of endometrial changes among symptomatic tamoxifen-treated and nontreated premenopausal and postmenopausal breast cancer patients

Breast cancer patients who received tamoxifen as adjuvant therapy have been reported to have more endometrial lesions such as polyps, hyperplasia, or carcinoma. We conducted a prospective study to elucidate the endometrial changes of premenopausal and postmenopausal breast cancer patients with tamoxifen. Sixty-seven symptomatic breast cancer patients who had been on tamoxifen treatment, including 34 premenopausal and 33 postmenopausal patients, and another group of 48 patients who had not been on tamoxifen, including 25 premenopausal and 23 postmenopausal patients, were recruited. Symptomatic patients were defined as having hypermenorrhea or abnormal vaginal bleeding among premenopausal patients or postmenopausal bleeding among postmenopausal patients. Endometrial thickness and uterine size determined by vaginal ultrasonography, histologic findings, and risk factors for endometrial cancer were compared. The mean endometrial thickness and uterine size showed no statistically significant difference in premenopausal patients with (n = 34) or without (n = 25) tamoxifen treatment, whereas there was a significant difference in the postmenopausal patients with (n = 33) or without (n = 23) tamoxifen treatment (12.11 +/- 12.38 mm vs 5.41 +/- 2.70 mm, P = 0.025; 234.71 +/- 76.36 cm3 vs 108.81 +/- 81.27 cm3, P = 0.0018, respectively). The frequency of endometrial histopathologic findings was 23.5% (8/34) in tamoxifen-treated women compared with 12.0% (3/25) in nontreated women (P = 0.269) in the premenopausal groups. In contrast, it was remarkably high with 66.7% (22/33) in tamoxifen-treated women compared with 30.4% (7/23) in the nontreated women in the postmenopausal groups (P = 0.025). There were four postmenopausal patients with tamoxifen, including three with atypical endometrial hyperplasia and one endometrial carcinoma, in contrast to no postmenopausal nontreated patients, although this difference did not reach statistical significance in this study (P = 0.096). There was a remarkably high prevalence of endometrial histopathologic findings in symptomatic tamoxifen-treated breast cancer patients, especially postmenopausal women. Tamoxifen might be associated with premalignant or malignant changes in postmenopausal endometrium. Thus timely, aggressive histologic assessment such as curettage or hysteroscope should be performed to detect the endometrial lesions when symptoms occur. Vaginal ultrasonography could be a useful tool to detect the endometrial lesions.

Estrogen dermatitis

The aim of the present study was to evaluate the estrogen dermatitis of women who have chronic skin disorders with exacerbations or premenstrual dermatitis in a cyclic pattern. Twenty-three women exhibiting skin disorders of pruritus, urticaria, eczema, papulovesicular eruption, hirsutism-acne with hyperpigmentation (hirsutism and/or its related disorders such as acne) and 18 healthy control subjects were included in the study. Sensitivity to estrogen was described in 14 of 23 women. Of the 14 estrogen sensitive women, nine had a premenstrual flare of their skin lesions and five had a chronic dermatitis with exacerbations. In the evaluation of endocrine profile, mean serum testosterone and LH levels of the patient group were significantly higher than controls (2.814 +/- 0.839 vs. 1.561 +/- 0.645 nm/l, P < 0.001; 10.843 +/- 2.538 vs. 4.539 +/- 1.215 IU/l, P < 0.0001). The LH/FSH ratio of the patient group was also significantly higher than controls (1.765 +/- 0.329 vs. 0.810 +/- 0.0116, P < 0.0001). Mean serum progesterone level of the patient group was significantly lower than the control group (0.499 +/- 0.201 vs. 0.977 +/- 0.396 ng/ml, P < 0.001). Hyperandrogenism and anovulation were the two more common outcomes in the patient group. Skin lesions of estrogen sensitive women were all cured with the administration of tamoxifen 20 mg daily for 7 days premenstrually.

A realistic clinical perspective of tamoxifen and endometrial carcinogenesis

Tamoxifen has been the endocrine treatment of choice for all stages of breast cancer for nearly a decade. Millions of women are currently receiving tamoxifen worldwide, while large-scale randomised trials have been launched aiming to investigate the drug's merit as a preventive agent. However, there are now concerns about tamoxifen's potential carcinogenicity. The goal of this review is to address these concerns, re-evaluate the available data from laboratory biological models and those from clinical reports and put the whole issue into perspective. Our focus is the association between tamoxifen and the increased frequency of endometrial tumours, while key issues, such as the role of duration of tamoxifen therapy, are also addressed. Finally, we discuss the various monitoring strategies for early detection of endometrial lesions and pertinent problems most likely to be encountered by clinicians taking care of patients who are receiving tamoxifen.

Suppression of Estrogenic Activity by Medroxyprogesterone Acetate in Tamoxifen-treated Patients after Surgery for Breast Cancer to Reduce the Risk of Endometrial Cancer Development

BACKGROUND: Postoperative adjuvant tamoxifen (TAM) therapy in breast cancer patients may lead, albeit rarely, to endometrial cancer. Preventive measures are urgently needed. METHODS: The study subjects were postmenopausal women who had undergone surgery for breast cancer. The control group (n=10) received no further therapy. Patients who had completed adjuvant TAM therapy were assigned to a medroxyprogesterone acetate (MPA;400 mg/day orally for 4 weeks) group (n =15) or no MPA treatment group (no MPA group)(n=15). Uterine cervix cytodiagnosis was performed after completing the TAM therapy(initial), and 4(4-week)and 16(16-week)weeks later. The serum 17beta-estradiol (E2) and progesterone concentrations were measured initially and at 4 weeks. The karyopyknotic index (KPI), eosinophilic index (EI) and maturation index (MI) were calculated from Papanicolaou-stained specimens. RESULTS: The background parameters showed no biases. There were no differences in the PKI or El between the no MPA and MPA groups. However, regarding the MI, after 4 weeks in the MPA group, the intermediate cells were significantly increased, while the superficial cells tended to be significantly decreased. Regarding the percent change from the initial value, after 4 weeks in the MPA group, the KPI and superficial cells were significantly decreased, and the intermediate cells were significantly increased. The estrogen activity level and the progesterone concentration were significantly lower in the MPA group compared with the no MPA group. CONCKLUSIONS: The MPA administration clearly lowered the estrogenic activity, indicating that MPA therapy should be effective in reducing the risk of TAM-associated endometrial cancer.

Estrogen receptor (ER) and its messenger ribonucleic acid expression in the genital tract of female mice exposed neonatally to tamoxifen and diethylstilbestrol

BACKGROUND

Tamoxifen (Tx) is known as an antiestrogen because of its competitive inhibition of estrogen binding to estrogen receptor (ER), and it is used as an estrogen antagonist in the human breast. However, Tx is known to have estrogen agonist activity in the human fetal reproductive tracts and vaginal epithelium and endometrium of postmenopausal women as has been known in the mouse uterus. Therefore, we examined estrogenic potency of Tx on the uterus and vagina in newborn mice and adult ovariectomized mice.

METHODS

Using immunohistochemistry and in situ hybridization, we studied changes in expression of ER protein and ER mRNA in the uterus and vagina of C57BL/Tw mice exposed neonatally to 100 micrograms Tx and 0.03-3 micrograms diethylstilbestrol (DES), and changes in expression of ER mRNA in the ovariectomized adult mice given injections of 100 micrograms Tx and 3 micrograms DES.

RESULTS

Nuclei of the epithelial and stromal cells in the vagina and of the stromal cells in the uterus showed strong ER immunostaining on the day of birth (= day 0), whereas nuclei of the epithelial cells in the uterus exhibited the ER immunostaining by day 5. In uterine epithelial cells, however, ER was induced by DES, 17 beta-estradiol, testosterone or Tx 24 h after a single injection on day 0, but not by the injection of 5 alpha-dihydrotestosterone, progesterone, or epidermal growth factor. ER in uterine epithelial cells was detected even 12 h after a single injection of 3 micrograms DES on day 0. ER mRNA expression of uterine and vaginal epithelial cells of newborn mice increased 4 h after a single injection of 3 micrograms DES. ER mRNA expression of uterine and vaginal stromal cells in neonatal mice increased 4 h after a single injection of 100 micrograms Tx. In uterine epithelial and stromal cells and vaginal epithelial cells of ovariectomized adult mice, ER mRNA expression increased 12 h after a single injection of 3 micrograms DES and 100 micrograms Tx.

CONCLUSIONS

The present study indicates that Tx acts as ER inducer in the uterus and vagina of neonatal and ovariectomized adult mice. However, responsiveness of reproductive tracts to Tx is different between newborn and adult mice.

Mechanisms of action of endocrine treatment in breast cancer

Endocrine treatment plays an important role in the therapy of breast cancer. While the basic mechanisms are understood, additional mechanisms may be of importance to their action and they may also contribute to the mechanism(s) of acquired resistance. Currently, several novel drugs are entering into clinical trials. Observations of the absence or presence of cross resistance to novel 'pure' steroidal antiestrogens and the non-steroidal tamoxifen may add important information to our understanding of the mechanisms of action of both classes of drugs. Similarly, exploration of different aromatase inhibitors in sequence or concert, as well as the combining of different endocrine treatment options may be warranted. Additionally, alterations in different biochemical parameters such as growth factors should not only be carefully explored in relation to treatment options but should also be followed during the course of treatment to asess alterations over time and in relation to the development of drug resistance.

Influence of tamoxifen on sex hormones, gonadotrophins and sex hormone binding globulin in postmenopausal breast cancer patients

Estrone sulphate (E1S) may be an important estrogen source in breast cancers, particularly in postmenopausal women. Recent studies have shown that tamoxifen inhibits the uptake and metabolism of E1S to estradiol (E2) in cell cultures. To evaluate a possible influence of tamoxifen on E1S disposition in vivo, we measured plasma levels of E1S together with unconjugated estrogens (E1 and E2), androgens (T, A, DHEA and DHEAS), SHBG, FSH and LH in 32 postmenopausal breast cancer patients before and during tamoxifen treatment. In a subgroup of 10 patients, we measured 24 h urinary excretion of estrogen metabolites to evaluate the influence of tamoxifen treatment on estrogen metabolism and total estrogen production. Tamoxifen increased plasma levels of E1S (mean increase of 18.1%, P < 0.05) and the ratio of E1S/E1 (mean increase of 25.7%, P < 0.01) and E1S/E2 (mean increase of 34.7%, P < 0.0005). No significant change in plasma E1 was seen, but plasma E2 was reduced (mean reduction of 12.1%, P < 0.005). The fall in plasma E2 was probably secondary to a fall in plasma T (mean reduction of 11.9%, P < 0.05) due to a reduced ovarian excretion of this androgen. The mechanisms may be a reduced gonadotrophin stimulation of the ovary, as plasma FSH and LH fell by mean values of 45.5 and 48.1%, respectively (P < 0.0001 for both). The increase in plasma E1S was accompanied by a reduced ratio of 2OHE1/E1 in urine (mean reduction of 38.2%, P < 0.025) indicating reduced 2-hydroxylation. Possible mechanisms for these alterations are discussed.

PCNA-immunoreactivity in the uterus of rats after treatment with the antiestrogen tamoxifen

We used an antibody to the proliferating cell nuclear antigen (PCNA) to investigate the effect of the long-term administration of tamoxifen on proliferative activity in the uterus of mature rats. Untreated cycling and ovariectomized rats served as controls. The PCNA labelling indices (PI) and the mitotic indices (MI) were estimated for the luminal and glandular epithelium and for the stromal fibroblasts. A strong correlation was found for PI and MI in the luminal and in the glandular epithelium, and a lower, but also significant correlation, for the endometrial stroma cells. Tamoxifen treatment decreased the PI of the luminal epithelial cells and of the stroma as much as ovariectomy. In both of these groups, the proportion of anti-PCNA positive cells in the glandular epithelium was significantly higher than in the luminal epithelium. These data indicate that tamoxifen has a strong antiproliferative effect on the uterus of mature rats, and that this antiestrogenic action is cell type specific.

Pathology of endometrium treated with tamoxifen

AIMS

To determine the type of endometrial abnormalities associated with prolonged tamoxifen treatment and to investigate the correlation between tamoxifen dose and any abnormalities detected.

METHODS

Endometria from 19 prospectively collected breast cancer patients treated with tamoxifen were ascribed a pathological diagnosis and the findings compared with those in a control group matched for age and presentation. The abnormalities were related to cumulative tamoxifen dose.

RESULTS

The two asymptomatic treated patients had generalised simple endometrial hyperplasia at necropsy. No endometrial abnormalities were seen at necropsy in the two control cases. Of the 17 patients treated with tamoxifen who underwent surgery for gynaecological symptoms, 11 had hyperplastic endometrial polyps characterised by epithelial metaplasias and patchy periglandular condensation of stroma. Two women had primary endometrial malignancies with myometrial invasion, and three women, one of whom had previously presented with a benign polyp, had an endometrial polyp-cancer on a background of hyperplasia. Endometrial malignancies were confined to women who had taken more than 35 g of tamoxifen. The control group included no endometrial polyp-cancers, only one patient with an endometrial polyp, four women with endometrial hyperplasia and four with primary endometrial malignancy.

CONCLUSIONS

These findings support a link between prolonged tamoxifen treatment and endometrial malignancy and identify a subgroup of patients--that is, those who have taken more than 35 g of tamoxifen, who may be at increased risk of endometrial cancer. The spectrum of pathological findings in patients treated with tamoxifen suggests that the drug promotes endometrial growth and that endometrial polyps may be an important intermediate step in endometrial carcinogenesis.

Uterine leiomyomata and endometrial proliferation in postmenopausal women treated with the anti-oestrogen tamoxifen

Two cases of fibroid growth and endometrial proliferation in postmenopausal women on tamoxifen (anti-oestrogen) therapy for breast cancer are described. Oestrogen in association with growth factors may control fibroid growth and differentiation. The possible mechanisms and consequences of tamoxifen-induced fibroid growth are discussed. Oestrogen responsive tissues demonstrate a differential and contrasting response to tamoxifen and caution should be exercised in the expansion of its clinical application. Women on long-term tamoxifen therapy may benefit from ultrasound surveillance of their uterus and endometrium, with biopsy in suspicious cases, as there is a paucity of data on malignant transformation of these benign lesions induced by tamoxifen therapy.

Risk of endometrial cancer after tamoxifen treatment of breast cancer

Since large trials have been set up to assess whether tamoxifen decreases the risk of breast cancer in healthy women, it has become important to investigate the drug's potential adverse effects, including occurrence of endometrial cancer. We undertook a case-control study in the Netherlands to assess the effect of tamoxifen on the risk of endometrial cancer after breast cancer. Through the population-based Netherlands Cancer Registry and two older, hospital-based, registries, we identified 98 patients who had endometrial cancer diagnosed at least 3 months after a diagnosis of primary breast cancer. Detailed information about treatment was obtained for all these patients, and for 285 controls, who were matched to the cases for age, year of breast cancer diagnosis, and survival time with intact uterus. Tamoxifen had been used by 24% of patients with subsequent endometrial cancer and 20% of controls (relative risk 1.3 [95% CI 0.7-2.4]). Women who had used tamoxifen for more than 2 years had a 2.3 (0.9-5.9) times greater risk of endometrial cancer than never users. There was a significant trend of increasing risk of endometrial cancer with duration of tamoxifen use (p = 0.049), and also with cumulative dose (p = 0.046). The duration-response trends were similar with daily doses of 40 mg or 30 mg and less. These findings support the hypothesis that tamoxifen use increases the risk of endometrial cancer. This oestrogenic effect on the endometrium was not related to the dose intensity. Physicians should be aware of the higher risk of endometrial cancer in tamoxifen users.

Influence of toremifene on the endocrine regulation in breast cancer patients

In a combined phase I-II study, the hormonal effects of toremifene (TOR) were investigated in 30 patients. Half of the patients received continuous therapy of TOR 60 mg and half 300 mg of TOR orally daily. Serum concentrations of oestradiol (E2), progesterone (PROG), testosterone (TE), follicle stimulating hormone (FSH), luteinising hormone (LH), prolactin (PRL), human growth hormone (hGH) and sex hormone binding globulin (SHBG) were monitored prior to the treatment and at the second, sixth, eighth and twelfth weeks. The influence of TOR upon the hypothalamo-hypophyseal axis was investigated by the TRH (thyroid-stimulating hormone releasing hormone) functional test using 400 micrograms intravenous injection of TRH for stimulation of PRL secretion. The concentration of E2 decreased during the TOR therapy with 60 mg and 300 mg causing 82 and 71% decreases, respectively (non-significant). PRL was significantly (P < 0.001) suppressed. Both these effects reflect the anti-oestrogenic action of TOR. SHBG increased significantly at both doses of TOR, probably due to a direct oestrogen-like effect of TOR in the liver. TE decreased as a consequence of the elevated SHBG. The TRH-induced PRL release was suppressed by both doses of TOR. There were 17 and 27% reductions at 12 weeks in the 60 and 300 mg groups, respectively. Other hormones measured were not significantly affected by TOR. The hormonal effects of 60 and 300 mg doses of TOR did not differ significantly. Anti-oestrogenic (i.e. decrease of E2), and partially oestrogenic (i.e. increase of SHBG) properties as well as the antiprolactinic effects of TOR may have an overall beneficial effect in the clinical management of breast cancer patients.

Tamoxifen reduces bone turnover and prevents lumbar spine and proximal femoral bone loss in early postmenopausal women

Although widely used for its anti-estrogen properties tamoxifen has estrogen like effects on a number of tissues including bone and liver. Previous studies suggest a preservation of lumbar spine density in postmenopausal women but the effect on the hip had not been addressed. To determine whether tamoxifen prevents bone loss in the early postmenopausal period bone mineral density at the lumbar spine and femoral neck was measured using dual energy X-ray absorptiometry at presentation and 6 monthly thereafter for 1 year in a prospective controlled study. Also indices of bone turnover, serum osteocalcin and urinary hydroxyproline excretion, were assessed. Fifteen early postmenopausal women with Stage I or II breast cancer treated with tamoxifen and 21 normal postmenopausal women were studied. Sex hormone binding globulin and antithrombin III levels in serum were also measured as indices of the hepatic estrogenic activity. Tamoxifen (20 mg daily) prevented bone loss at the femoral neck and lumbar spine. Median rates of change in bone mineral density (%/year) for the tamoxifen group were +0.09%/year in the lumbar spine and 1.4%/year in the femoral neck compared with -2.3%/year and -1.8%/year for the control group (P = 0.04 and 0.03, respectively). Tamoxifen resulted in a significant decrease in both serum osteocalcin and urinary hydroxyproline by 6 months of treatment and this effect persisted for the 12 months of observation. An increase in sex hormone binding globulin and a decline in antithrombin III levels was also observed. These data indicate that, in recently, postmenopausal women tamoxifen prevented bone loss at both the lumbar spine and femur and reduced bone turnover.

Endometrial changes in postmenopausal women treated with tamoxifen for breast cancer

OBJECTIVE

To evaluate whether risk factors, other than tamoxifen, can be identified for the development of endometrial pathologies in postmenopausal breast cancer patients treated with tamoxifen.

DESIGN

A cross-sectional study.

SETTING

Department of Obstetrics and Gynaecology and Oncology Clinic, Sapir Medical Center, Kfar Saba, Israel.

SUBJECTS

77 asymptomatic postmenopausal women, treated with tamoxifen for breast cancer. Of these, 55 had no endometrial tissue and 22 had endometrial tissue obtained by biopsy.

MAIN OUTCOME MEASURES

Demographic characteristics, health habits, risk factors, vaginal ultrasonographic evaluations of endometrial thickness and texture, and histologic evaluations of endometrial biopsies.

RESULTS

Overall, there was a high rate (29%) of endometrial pathological change among the 77 asymptomatic postmenopausal women. There were no significant statistical differences in the features tested between the two groups.

CONCLUSION

It is impossible to predict which postmenopausal women will develop pathological endometrial changes after treatment with tamoxifen and thus a routine periodic endometrial sampling-follow up is suggested for all postmenopausal women being treated with this agent.

Endometrial carcinoma in tamoxifen-treated breast cancer patients

Tamoxifen is an important agent for the treatment of breast cancer. Occasionally the drug, which is an antiestrogen, has agonistic estrogenic activity. The authors describe three new cases of endometrial carcinoma developing in breast cancer patients taking tamoxifen and stress the necessity of carefully monitoring the uterine cavity under tamoxifen treatment.

Effects of tamoxifen on the female genital tract

Tamoxifen is a widely used drug in medical oncology, mainly for treatment of breast cancer, but also for second line treatment of endometrial cancer. We recently reported an increased incidence of endometrial cancer associated with long-term adjuvant tamoxifen. This observation, previous reports of stimulatory effects of tamoxifen in the female genital tract, and experimental data are in accordance with a mainly estrogenic effect of tamoxifen in these tissues. An increased incidence of endometrial cancer may limit the usefulness of tamoxifen for benign indications. For adjuvant treatment of early breast cancer, however, the improvement of both recurrence-free survival and overall survival probably outweighs the increased frequency of uterine tumors. However, the possibility of growth stimulation of tumor subclones should be considered when tamoxifen is used in the treatment of endometrial cancer.

Tamoxifen-associated endometrial carcinoma in postmenopausal breast cancer patients

Tamoxifen citrate, a nonsteroidal antiestrogen with agonistic properties, is prescribed as an adjuvant to surgery in the treatment of breast cancer. Recent reports have suggested that tamoxifen has an estrogenic property and may be implicated in the development of endometrial carcinomas. Seven new cases are reported to the existing literature in which endometrial carcinomas developed in postmenopausal women on tamoxifen therapy for breast carcinomas.

Hormonal effects of toremifene in breast cancer patients

The effect of toremifene treatment on the serum levels of sex steroids (estradiol, progesterone, testosterone), FSH, LH, prolactin, TSH, T3, T4 and SHBG was investigated. Basal prolactin level and the "prolactin reserve capacity" of the hypophysis was also studied by the TRH functional test. Steroid hormone receptors were detected in the patients where a tumor biopsy could be obtained. In a randomized trial patients were treated by 60 and 300 mg of toremifene per os, daily. Hormone levels were assayed prior to treatment and at the 2nd, 6th, 8th and 12th week of tormifene therapy. The hormonal effects of toremifene were the most marked at the 2nd and at the 8th week. Estradiol decreased continuously, SHBG increased slightly and the high initial value of basal prolactin level decreased. The TRH-induced prolactin release was suppressed by tormifene after an 8-week period. No clinical response-related tendency was found.

Four case reports presenting new acquisitions on the association between breast and endometrial carcinoma

In recent years, the association between breast and endometrial cancer has been the subject of many studies. The present report describes four cases of this association in which tamoxifen had been administered to all of the patients. Data have been published regarding the possibility that tamoxifen may be responsible for the subsequent development of carcinoma of the corpus uteri in these patients. The authors intend to carry out a case-control study on patients treated with tamoxifen for breast carcinoma to reveal the possible presence of endometrial carcinoma.

Alternating tamoxifen and medroxyprogesterone acetate in postmenopausal advanced breast cancer patients--short and long term endocrine effects

The endocrine effects of alternating tamoxifen and medroxyprogesterone acetate have been evaluated in 26 post-menopausal patients with metastatic breast cancer. Endocrine evaluations included the RIA determination of plasma levels of sex-hormone binding globulin, follicle-stimulating hormone, luteinizing hormone, estradiol, prolactin, cortisol, and testosterone. The evaluation of the study parameters at different intervals during therapy indicates that with this schedule an alternate sequential effect on the endocrine system is achievable because each drug exerts its own endocrine activity that is completely reversed when the other drug is administered. We can hypothesize that the same alternate activity as seen on the endocrine system could be obtained also on other tissues and organs including tumors.

Modulation of natural killer cell activity by tamoxifen in stage I post-menopausal breast cancer

Tamoxifen, an antiestrogen which competes for the estrogen receptor, modulates natural killer cell activity in vivo. Seventeen post-menopausal stage I breast cancer patients received tamoxifen for 1 month and a statistically significant increase in NK activity was demonstrated (P = 0.0005). There was a small incremental shift in the number of Leu-11b positive cells. These data demonstrate that tamoxifen functions as a biological response modifier.