Estrogen and endometrial cancer: cases and two control groups from North Carolina

Evidence-based identification of breast cancer and associated ovarian and uterus cancer risk components in source waters from high incidence area in the Pearl River Basin, China

Breast cancer, ovarian cancer, and uterus cancer are among the most common female cancers. They are suspected to associate with exposures to specific environmental pollutants, which remain unidentified in source waters. In this work, we focused on the Pearl River Basin region in China, which experienced a high incidence of breast, ovarian, and uterus cancers. Combining cancer patient data, mammalian cell cytotoxicity analyses, and exhaustive historical and current chemical assessments, we for the first time identified source water components that promoted proliferation of mammalian cells, and confirmed their association with these female cancers via the estrogen receptor mediated pathway. Therefore, the components that have previously been found to enhance the proliferation of estrogen receptor-containing cells through endocrine disruption could be the crucial factor. Based on this, components that matched with this toxicological characteristic (i.e., estrogen-like effect) were further identified in source waters, including (1) organic components: phthalates, bisphenol A, nonylphenols, and per-/polyfluoroalkyls; (2) inorganic components: Sb, Co, As, and nitrate. Moreover, these identified water components were present at levels comparable to other regions with high female cancer prevalence, suggesting that the potential risk of these components may not be exclusive to the study region. Together, multiple levels of evidence suggested that long-term co-exposures to source water estrogenic components may be important to the development of breast, ovarian, and uterus cancers.

Clinical analysis of human umbilical cord mesenchymal stem cell allotransplantation in patients with premature ovarian insufficiency

Objective

Premature ovarian insufficiency (POI) is a refractory disease that seriously affects female fertility. Growing body of evidence has indicated mesenchymal stem cells (MSCs) as promising resources in regenerative medicine. In this study, we treated POI patients with umbilical cord‐derived MSCs (UCMSCs) and then investigated the restoration of ovarian function and clinical outcomes through follow‐ups.

Materials and methods

Sixty‐one patients diagnosed with POI participated in this study. UCMSCs were isolated and cultured according to GMP standards, and then transplanted to the patients’ ovary by orthotopic injection under the guidance of vaginal ultrasound. We monitored side effects, vital signs and changes in clinical and collected haematological and imaging parameters during the follow‐ups.

Results

All patients showed normal clinical behaviour without serious side effects or complications relevant to the treatment. Transplantation of UCMSCs rescued the ovarian function of POI patients, as indicated by increased follicular development and improved egg collection. POI patients who experienced shorter amenorrhoea durations (<1 year) seemed to obtain mature follicles more easily after stem cell therapy, and patients with better ovarian conditions (pre‐operative antral follicles) were more likely to derive the better outcomes by UCMSC injection. Four successful clinical deliveries were obtained from POI patients after UCMSC transplantation, and all of these babies are developed normally.

Conclusions

The clinical trial result sugggests a possible therapy for POI by UCMSC transplantation.

Epidemiology of Endometrial Carcinoma: Etiologic Importance of Hormonal and Metabolic Influences

Endometrial carcinoma is the most common gynecologic cancer in developed nations, and the annual incidence is projected to increase, secondary to the high prevalence of obesity, a strong endometrial carcinoma risk factor. Although endometrial carcinomas are etiologically, biologically, and clinically diverse, hormonal and metabolic mechanisms are particularly strongly implicated in the pathogenesis of endometrioid carcinoma, the numerically predominant subtype. The centrality of hormonal and metabolic disturbances in the pathogenesis of endometrial carcinoma, combined with its slow development from well-characterized precursors in most cases, offers a substantial opportunity to reduce endometrial carcinoma mortality through early detection, lifestyle modification, and chemoprevention. In this chapter, we review the epidemiology of endometrial carcinoma, emphasizing theories that link risk factors for these tumors to hormonal and metabolic mechanisms. Future translational research opportunities related to prevention are discussed.

Clinical/pathologic features and patient outcome in early onset endometrial carcinoma: a population based analysis and an institutional perspective from the Detroit metropolitan area, Michigan

OBJECTIVE

Analyze tumor characteristics and outcomes in patients with endometrial carcinoma (EC)<40 years of age and compare them to the characteristics of patients ≥ 40 years of age.

METHODS

10,700 patients (305 patients <40 years of age) diagnosed between 1988 and 2007 with EC from the Metropolitan Detroit Cancer Surveillance System (MDCSS), and 884 patients (42 patients <40 years of age) diagnosed between 1996 and 2008 with EC from our institutional database were identified. Differences in clinical and demographic variables by age (<40 vs. ≥ 40) were assessed for statistical significance by chi-square tests. Cox proportional hazards models were used to calculate adjusted hazard ratios (HR) and their 95% confidence intervals (95% CI) to assess the risk of death from all causes.

RESULTS

MDCSS based analysis: Patients<40 were more likely to present with low grade tumors (p<0.0001) and endometroid histology (p=0.0004) but less likely to undergo surgery (p=0.0007) or radiotherapy (p=0.0007). A multivariate analysis confirmed the significance of age, grade, and stage in all patients, and that of histologic type, surgery, and race in patients ≥ 40 as independent prognostic factors for overall survival. Institution based analysis: Patients<40 had a higher proportion of patients with BM I ≥ 30 (p=0.04), and presented with a higher frequency of well differentiated (p=0.04) endometrioid tumors (p=0.004) that are less prone to have deep myometrial invasion (p=0.008).

CONCLUSION

This study supports the hypothesis of a disease that is biologically and genetically heterogeneous among women of different ages and ethnicities.

Vídeo-histeroscopia da imagem endometrial alterada: uma avaliação crítica

OBJETIVO: Analisar a concordância da imagem endometrial pela vídeo-histeroscopia e pela ultra-sonografia. MÉTODO: Análise retrospectiva de 1561 laudos endoscópicos no período de 1999 a 2005. Foi avaliada a acurácia das imagens video-histeroscópicas em relação à imagens ultra-sonográficas do endométrio alterado com avaliação dicotomizada em imagens benignas e complexas. Foram também analisadas por período do menacme e pós-menopausa. RESULTADOS: Foi encontrada uma maior incidência de hipertrofias benignas: pólipos- 58,7%; hipertrofias simples - 13,3%; endometrites - 3,5%; miomatose - 6,0%; outros - 11,9%: cavidade sem alterações 0,9%: baixa incidência de hipertrofias complexas no menacme e 5,3 vezes maior na pós- menopausa. CONCLUSÃO: Há concordância entre as variáveis ultra-sonográficas do endométrio alterado com o diagnóstico histeroscópico.

Endometrial cancer risk in estrogen users after switching to estrogen-progestin therapy

OBJECTIVE

It is unknown whether postmenopausal unopposed estrogen users are better off, in terms of endometrial cancer risk, switching to a combined estrogen-progestin regimen or stopping hormone use altogether.

METHODS

We analyzed data from a series of three population-based case-control studies in western Washington state during 1985-1999, comparing proportions of "switchers" and "stoppers" in cases and controls. We also assessed whether the risk of endometrial cancer in either group of former unopposed estrogen users returned to that of never users.

RESULTS

After multivariate adjustment using unconditional logistic regression, women who switched to a combined regimen with a progestin added for at least ten days/month (37 cases, 47 controls) had half the risk of endometrial cancer of women who stopped hormone use altogether (86 cases, 78 controls) (adjusted odds ratio = 0.5, 95% confidence interval: 0.3-1.1). Most subgroups of former users, whether they switched or stopped, had some increased risk of endometrial cancer compared to never users.

CONCLUSIONS

Results from this study suggest that unopposed estrogen users may reduce their risk of endometrial cancer more by switching to a combined regimen with progestin added for at least ten days/month than by stopping hormone use altogether.

Hormone Replacement Therapy in Endometrial Cancer Survivors

OBJECTIVE

Dramatic shifts in prescription practices during the last 30 years have left physicians confused and uncertain about the use of hormone replacement therapy (HRT) in endometrial cancer survivors.

MATERIALS AND METHODS

This article reviews the published literature concerning both the safety of prescribing HRT to endometrial cancer survivors and the therapy s potential risks and benefits.

RESULTS

Prescribing HRT to endometrial cancer survivors does not seem to be contraindicated and may even confer modest protection, depending on the doses and the specific drugs used. The potential benefits of HRT are more conflicting. Although the medical community agrees on the positive effects for bone density and relief of vasomotor symptoms, the results of our review offer no clear consensus in regard to HRT's effects on coronary heart disease, health-related quality of life, cognitive functioning, and cancer incidence.

CONCLUSIONS

Until the medical community can concur on the proper prescription practices in endometrial cancer survivors, an individualized patient-based approach must be taken.

Endometrial cancer in young, normal-weight women

OBJECTIVE

To determine if young, normal-weight women with endometrial cancer have unique risk factors and clinical characteristics when compared with young, overweight and obese women with endometrial cancer.

METHODS

Between 1989 and 2003, 1531 patients were treated for endometrial cancer. 188 (12%) of these women were premenopausal and under the age of 50 at time of diagnosis. The patients were divided into three groups based on body mass index (BMI): normal weight (BMI < 25 kg/m2), overweight (BMI 25-30 kg/m2) and obese (BMI > or = 30 kg/m2). Clinical and pathologic characteristics were compared.

RESULTS

Of the 188 young endometrial cancer patients, 47 (25%) were of normal weight, 31 (17%) overweight and 106 (56%) obese. 4% of normal-weight, 12% of overweight and 0% of obese patients met criteria for Lynch syndrome/hereditary non-polyposis colorectal cancer (HNPCC). Irregular menstrual cycles were reported by 30% normal-weight, 32% of overweight and 61% of obese women (P = 0.001). 17% of normal-weight, 7% of overweight and 14% of obese women had a history of infertility (P = 0.723). Nulliparity was noted in 57% of normal-weight, 47% of overweight and 57% of obese patients (P = 0.583). Diabetes was reported in 4% of normal-weight, 13% of overweight and 35% of obese patients (P < 0.001). 28% of normal-weight, 26% of overweight and 14% of obese patients had synchronous primary tumors of the endometrium and ovary.

CONCLUSIONS

As expected, a significantly higher proportion of obese and overweight women had diabetes and irregular menstrual cycles. Among the normal-weight women, a high proportion were nulliparous, had a history of infertility, irregular menstrual cycles and synchronous tumors of the endometrium and ovary when compared with the general population. This suggests that hormonal factors, and possibly polycystic ovarian syndrome (PCOS), may contribute to the development of endometrial cancer in young normal-weight women.

Endometrial Carcinoma Risks among Menopausal Estrogen plus Progestin and Unopposed Estrogen Users in a Cohort of Postmenopausal Women

BACKGROUND

Because unopposed estrogen substantially increases endometrial carcinoma risk, estrogen plus progestin is one menopausal hormone therapy formulation for women who have not had a hysterectomy. However, endometrial carcinoma risks among estrogen plus progestin users and among former unopposed estrogen users are not firmly established.

METHODS

We evaluated endometrial carcinoma risks associated with estrogen plus progestin and unopposed estrogen therapies in 30,379 postmenopausal Breast Cancer Detection Demonstration Project follow-up study participants. We ascertained hormone therapy use and other risk factors during telephone interviews and mailed questionnaires between 1979 and 1998. We identified 541 endometrial carcinomas via self-report, medical records, the National Death Index, and state cancer registries. Poisson regression generated time-dependent rate ratios (RR) and 95% confidence intervals (95% CI).

RESULTS

Endometrial carcinoma was significantly associated with estrogen plus progestin only use (n = 68 cancers; RR, 2.6; 95% CI, 1.9-3.5), including both sequential (progestin <15 days per cycle; n = 32 cancers; RR, 3.0; 95% CI, 2.0-4.6) and continuous (progestin at least 15 days per cycle; n = 15 cancers; RR, 2.3; 95% CI, 1.3-4.0) regimens. The RR increased by 0.38 (95% CI, 0.20-0.64) per year of estrogen plus progestin use, and RRs increased with increasing duration of use for both regimens. The strong association with unopposed estrogen use declined after cessation but remained significantly elevated > or =10 years after last use (RR, 1.5; 95% CI, 1.0-2.1).

CONCLUSIONS

Both estrogen plus progestin regimens significantly increased endometrial carcinoma risk in this study. Risks among unopposed estrogen users remained elevated long after last use. The prospect that all estrogen plus progestin regimens increase endometrial carcinoma risk deserves continued research.

Compared to what? Finding controls for case-control studies

Use of control (comparison) groups is a powerful research tool. In case-control studies, controls estimate the frequency of an exposure in the population under study. Controls can be taken from known or unknown study populations. A known group consists of a defined population observed over a period, such as passengers on a cruise ship. When the study group is known, a sample of the population can be used as controls. If no population roster exists, then techniques such as random-digit dialling can be used. Sometimes, however, the study group is unknown, for example, motor-vehicle crash victims brought to an emergency department, who may come from far away. In this situation, hospital controls, neighbourhood controls, and friend, associate, or relative controls can be used. In general, one well-selected control group is better than two or more. When the number of cases is small, the ratio of controls to cases can be raised to improve the ability to find important differences. Although no ideal control group exists, readers need to think carefully about how representative the controls are. Poor choice of controls can lead to both wrong results and possible medical harm.

Hormone replacement therapy and risk of malignancy

PURPOSE OF REVIEW

The fact that today our concern is oriented towards the risks rather than the benefits of hormone replacement therapy could be the clearest message about our current position. The safety of hormone replacement therapy, an estrogen-progestin combination which has been sympathetic to and supportive of disturbing menopausal symptoms of women, is seriously challenged.

RECENT FINDINGS

Four randomized trials have now reported on the results of hormone replacement therapy in major potentially fatal conditions, in more than 20,000 women studied for about 5 years. The main concern regarding the increased risk of malignancy in healthy postmenopausal women in western countries has been breast cancer. It is estimated to cause an extra case in about six per 1000 users aged 50-59 and 12 per 1000 aged 60-69. Over the same period the estimated risk of endometrial cancer rates are not increased, with a relative risk of 0.76 per 1000 users aged 50-59. Overall, however, the increased incidence of malignancies is greater than any reduction, one per 230 users aged 50-59 and one per 150 aged 60-69. Randomized trials examining other important but rarer malignancies, like ovarian, gall bladder and urinary bladder cancer, are either nonexistent or too small to reliably describe any effects of hormone replacement therapy.

SUMMARY

Conclusively epidemiological evidence suggests that hormone replacement therapy is associated with a small but substantial increase in breast cancer risk and combined estrogen-progesterone regimens further increase this hazard. Additionally, the evidence from the recent double blind placebo controlled randomized trial on the slight increase in the incidence of adverse cardiovascular events, has turned our orientation away from hormone replacement therapy as a long term therapy in postmenopausal women. In this review, the effort is to approach comprehensively and globally the information on the risks of hormone replacement therapy on several cancer sites.

A functional polymorphism in the promoter of the progesterone receptor gene associated with endometrial cancer risk

Excessive estrogen stimulation unopposed by progesterone strongly predisposes to endometrial cancer. Because the antiproliferative effect of progesterone requires the progesterone receptor (PR), which exists in two isoforms, PR-A and -B, we reasoned that variants in the PR gene may predispose to endometrial cancer. We found six variable sites, including four polymorphisms in the hPR gene and five common haplotypes. One promoter region polymorphism, +331G/A, creates a unique transcription start site. Biochemical assays showed that the +331G/A polymorphism increases transcription of the PR gene, favoring production of hPR-B in an endometrial cancer cell line. Using a case-control study nested within the Nurses' Health Study cohort, we observed a statistically significant association between the +331G/A polymorphism and the risk of endometrial cancer, which was even greater in overweight women carriers. After including a second population of controls, these associations remained intact. Our findings suggest that the +331G/A hPR gene polymorphism may contribute to endometrial cancer risk by increasing expression of the hPR-B isoform.

Perimenopausal use of reproductive hormones effects on breast and endometrial cancer

The effect of reproductive hormone use in the form of oral contraception or HRT on endometrial cancer incidence is not caused by simply bias: the epidemiologic studies are consistent; the effect of ERT is large; the biologic rationale cited is a plausible mechanism; and the response to progestin in oral contraception or combined HRT tends to confirm the biologic mechanism. In contrast, it remains unclear whether changes in breast cancer incidence following use of oral contraception and HRT are caused by hormone exposure or to other factors: the results of epidemiologic studies are not entirely consistent, and the smaller relative effect on risk of breast cancer is susceptible to bias and other sources of error. Although the exact nature of the association between repro ductive hormone use and breast cancer incidence is not yet clear, breast cancer is a common neoplasm in older women. Prescribers and users should take this into account in weighing benefits to ensure that unnecessary risks are avoided.

Compliance with hormone replacement therapy among Swedish women

By means of a simple postal questionnaire, all women registered as hormone therapy patients (n = 241) at a gynaecological clinic were screened for reasons for receiving hormone therapy. They were also screened for their compliance in following the midwife's advice and information, as well as the gynaecologist's prescriptions. The majority of the women participating in this study contacted the clinic for climacteric symptoms. The time duration for using hormone therapy ranged from 1 month to 6 years. Those using a plaster or gel were asked why they should take progesterone pills. Forty per cent gave erroneous answers or did not know. Of these, 62% reported that they understood the oral information, whereas 60% reported that they understood the written information. Fifty-three per cent of the women stated that they would stop their hormone therapy if they did not feel well or increased in weight. New discoveries or information about benefits or risks were given by 22% as reasons affecting their decision. Compliance demands well-motivated and well-informed patients. The implication of the study result for practice is that there must be dialogue between the women and their midwife/ gynaecologist. It is important that the women feel they are receiving treatment which they have given their consent to, and that they feel and know that they are performing self-care. Midwives have recurrent contact with women during their life and have already established a relationship with them, which facilitates an individualized communication.

The effect of the duration of progestin use on the occurrence of endometrial cancer in postmenopausal women

OBJECTIVE

Women who have ever used estrogen replacement therapy (ERT), even at a low dose, have an increased incidence of endometrial cancer. The addition of a progestin to ERT reduces the incidence of endometrial cancer. The duration of progestin administration is more important than the dose.

DESIGN

A MEDLINE review of the literature was performed using the search terms endometrial cancer, epidemiology, and hormone replacement therapy (HRT).

RESULTS

Women who have ever used ERT have an increased incidence of endometrial cancer. The use of HRT for more than 5 years, with a progestin use of <10 days per cycle, has a relative risk = 1.8. Continuous combined HRT, or sequential or cyclic HRT with >10 days of progestin per cycle, appears to decrease the incidence of endometrial cancer to that found in nonusers of HRT.

CONCLUSIONS

The use of HRT in postmenopausal women with a uterus reduces the incidence of endometrial cancer. The duration of progestin administration should be 14 days or more per cycle based on recent epidemiologic data.

Epidemiology of endometrial cancer

Endometrial cancer is the commonest gynaecological cancer mostly affecting women in the post-menopausal age group. Rates vary worldwide and are highest in white women in Western populations. Some risk factors are related to reproduction, such as early age at menarche, late age at menopause and nulliparity, while others are more directly oestrogen-related, for example, conditions such as the polycystic ovarian syndrome. Use of unopposed oestrogen replacement therapy is associated with an increased risk, and use of the combined oral contraceptive pill is associated with a decreased risk. The relationship between tamoxifen and endometrial cancer is not established. Obesity, diabetes and hypertension increase the risk of endometrial cancer while smoking, low-fat diets and physical exercise appear to decrease the risk; all of these possibly exert their effects by various indirect influences on oestrogen levels, thus influencing the level of stimulation of the target endometrial epithelium.

Progestins suppress estrogen-induced expression of vascular endothelial growth factor (VEGF) subtypes in uterine endometrial cancer cells

Vascular endothelial growth factor (VEGF) contributes to the early advancement of uterine endometrial cancers that conserve hormone dependency via angiogenic activity. This process prompted us to study sex steroidal suppression of VEGF expression in Ishikawa cells (a line of well-differentiated uterine endometrial cancer cells). Estrogen transiently induced VEGF subtype (VEGF165 and VEGF121) secretion from Ishikawa cells. Progestins (progesterone, medroxyprogesterone acetate (MPA) and 17 alpha-hydroxyprogesterone) suppressed the estrogen-induced events. In conclusion, progestins could suppress VEGF-related angiogenic potential, which contributes to tumor growth in the early stage of uterine endometrial cancers that conserve estrogen dependency.

Expressions of vascular endothelial growth factor (VEGF) and its mRNA in uterine endometrial cancers

To know the potential of growth, invasion and metastasis of uterine endometrial cancer associated with neovascularization, the expressions of VEGF and its mRNA, especially their subtypes, in uterine endometrial cancers and normal uterine endometria as controls were determined by Western blot analyses with a sandwich enzyme immunoassay and RT-PCR-Southern blot analysis, respectively, and the relation between their expressions and histological grades, grades of myometrial invasion and clinical stages of uterine endometrial cancers was analyzed. The levels of VEGF (VEGF165 and VEGF121) protein and mRNA were in a wide range and higher in normal uterine endometria than in the malignant counterparts. The levels of VEGF protein were higher in order of histopathological differentiation (normal uterine endometrium > well-differentiated (G1) > moderately differentiated (G2) and poorly differentiated (G3)) and those of VEGF protein and VEGF121 mRNA were lower in order of the advance of clinical stages (normal uterine endometrium > stage I > stage II > stages III and IV). There was, however, no significant difference in their levels among uterine endometrial cancers classified according to grades of myometrial invasion. This suggests that VEGF is downregulated during uterine endometrial cancer progression with dedifferentiation. Namely, VEGF in some endometrial cancers might contribute to the early process of advancing of malignancy via angiogenic activity.

Estrogen- and antiestrogen-responsiveness of HEC1A endometrial adenocarcinoma cells in culture

HEC1A endometrial cancer cells express the wild-type form of the estrogen receptor (ER) and 17beta-estradiol (E2) induces proliferation of these cells. In contrast, tamoxifen only causes a minimal increase (<20%) in cell proliferation. In HEC1A cells transiently transfected with the C3-Luc plasmid derived from the complement C3 gene, both E2 and tamoxifen exhibited ER agonist activity and tamoxifen was also a partial antagonist for this response. The relative ER agonist/antagonist activities of E2, tamoxifen and ICI 182,780 were also investigated in HEC1A1 cells transiently transfected with two E2-responsive plasmids, pCATHD-CAT and pCKB-CAT which contain 5'-promoter inserts from the cathepsin D and creatine kinase B genes, respectively. The results showed that E2 and tamoxifen induced reporter gene activity in cells transiently transfected with both constructs. ICI 182,780 exhibited partial ER agonist activity only in cells transiently transfected with pCKB-CAT and antagonized E2-induced reporter gene activity using both the CKB- and CATHD-derived constructs. These results demonstrate that HEC1A endometrial cancer cells are E2-responsive and represent a useful cell culture model for understanding hormone/antihormone-induced endometrial cell responses.

Risk of endometrial cancer following cessation of menopausal hormone use (Washington, United States)

While there are a number of benefits to the health of postmenopausal women from use of unopposed estrogens, the increased risk of endometrial cancer related to these hormones has led many women to use combined estrogen-progestogen therapy instead, or not to use hormones at all. Most women who take hormones do so only in the early portion of their postmenopausal years, so the risk of endometrial cancer following cessation of use might bear heavily on the overall risk/benefit evaluation. We analyzed data from a case-control study of women in western Washington (United States) to assess the magnitude of excess risk of endometrial cancer following discontinuation of estrogen use. Cases (n = 661) consisted of women aged 45 to 74 diagnosed between 1985 and 1991 who resided in one of three countries in Washington State. Controls (n = 865) were identified by random-digit dialing. Subjects were interviewed in-person to ascertain current and prior hormone use. The analysis was restricted to women who had not received combined estrogen-progestin therapy. Among women who had used unopposed estrogens at some time, risk of endometrial cancer declined as time since last use increased. Nonetheless, even among women who used these hormones for just a few years, the risk remained elevated by 30 to 70 percent almost a decade after cessation. These results, combined with those of most (but not all) other studies of this issue, suggest that a women who has discontinued unopposed estrogen therapy may retain a small increased risk of endometrial cancer for a long period of time.

Expression of corticosteroid-binding globulin mRNA in human uterine endometrial cancers

Since it has been demonstrated that corticosteroid-binding globulin (CBG) plays a role in intracellar steroidal actions in target cells, the expression of CBG mRNA as the measure of CBG expression was investigated in human endometrial cancers in order to assess the biological implications of CBG. The level of CBG mRNA was analyzed using competitive reverse transcription-polymerase chain reaction-Southern blot analysis. While the level of CBG mRNA was significantly (P < 0.01) higher in secretory phase endometrium than in early and late proliferative phase endometrium, the level of CBG mRNA tended to decrease with advanced dedifferentiation of endometrial cancers as compared to normal endometrium. These results suggest that dedifferentiation of endometrial cancers induces a reduction in intracellular CBG synthesis.

Postmenopausal unopposed estrogens. Characteristics of use in relation to the risk of endometrial carcinoma

To determine whether treatment regimens for unopposed estrogens can be tailored so as to minimize the excess risk of endometrial cancer, results from 19 published studies of the association between unopposed estrogen use and endometrial cancer were compiled. We sought to examine the influence of duration of use, recency, dose, type of estrogen preparation, and periodic interruption of use on cancer incidence. Estrogen use for 5 years or longer was examined in 18 studies and was associated with a large increase in the risk of endometrial cancer in each one (range in relative risk, 1.8 to 36). Use for shorter durations also was observed to increase risk; however, among women who used estrogens for less than 6 months, any increased risk that may exist appears to be very small in size (six studies; range, 0.6 to 1.4). Risk consistently was seen to decrease with increasing time since cessation of use, although there is evidence from seven of eight studies that some residual excess risk remains long after estrogens have been discontinued. In each of 12 studies that examined the influence of dose, all dose levels of conjugated estrogens increased risk of endometrial cancer substantially. Four of five studies found no differences between oral synthetic estrogens and conjugated estrogens with respect to cancer risk, and all of eight studies found no difference between cyclic and continuous regimens. Based on our review, we conclude that apart from minimizing the duration of use, there is no way of taking unopposed postmenopausal estrogens that reduces their potential to cause endometrial cancer.

Sex steroids and cancer in older women

Menopause and hormone replacement therapy (HRT) continue to be controversial subjects. The main concern is the potential risk of prolonged HRT and the possible development of endometrial and breast carcinoma. There is no obvious evidence at present to suggest that HRT increases endometrial carcinoma provided the patient receives progestogen for a period of 10 or more days (usual period is 12 days) during each month. However the breast does not seem to enjoy this safety margin and there is some concern about possible increase in the incidence of breast cancer if the treatment period is longer than 5 years. The increase in the risk is higher after 15 years of estrogen use. There is no obvious adverse effect on the ovary or on the cervix following HRT.

A population-based case-control study of endometrial cancer in Shanghai, China

A case-control study of 268 patients with endometrial cancer and 268 population controls was conducted during 1988-1990 in Shanghai, China, to evaluate etiologic factors in a population whose risk had not been substantially altered by the use of exogenous estrogens. In spite of this, the major risk factors resembled those found in other studies. The risk of endometrial cancer was significantly elevated among nulligravidas (OR = 5.4, 95% CI = 2.0-14.6) and decreased with number of pregnancies (p less than 0.01). Late age at menopause was associated with increased risk, while early age at menarche was unrelated. Use of oral contraceptives for more than 2 years was associated with a reduction in endometrial cancer risk (OR = 0.4, 95% CI = 0.1-1.2), while short-term use of oral contraceptives and other methods of contraception were unrelated. Obesity was a strong predictor of risk, with women in the highest quartile of weight having 2.5 times the risk of those in the lowest quartile. In contrast to many other studies, cigarette smokers were at elevated risk (OR = 1.7, 95% CI = 0.9-3.0). Risk was also elevated among women reporting a history of gall-bladder disease, polycystic ovaries, menstrual symptoms, and non-estrogen hormone use.

The epidemiology of endometrial cancer

The descriptive and analytical epidemiology of endometrial cancer is reviewed. Over the last few decades, age-standardized incidence rates have been rising in several countries. The rise has been even greater in terms of absolute numbers of cases, and hence public health implications, due to the aging of the population. Although endometrial cancer rates were found to be higher in richer countries and urban populations, there is now evidence of some changes in the socioeconomic determinants of the disease in developed countries. In etiological terms, any factor that increases exposure to unopposed estrogens (such as menopausal replacement treatment, obesity, and irregular menstrual cycles) tends to increase the risk of the disease, while factors that decrease exposure to estrogens or increase progesterone levels (such as oral contraceptives or smoking) tend to be protective. Less well defined, or more difficult to explain in biological terms, is the role of other factors, such as births, miscarriages, or diabetes and hypertension, and only suggestive evidence is available on diet from analytical epidemiology. The data reviewed herein are discussed in terms of models of carcinogenesis, as well as attributable risks and public health implications.

Oral contraceptives and the risk of endometrial cancer

The relationship between the use of combination oral contraceptives (OCs) and the risk of endometrial cancer was assessed in a case-control study conducted in the Swiss Canton of Vaud between 1 January 1988 and 31 July 1990. Subjects included 122 women aged 75 or less with histologically confirmed endometrial cancer, and 309 control women in hospital for acute conditions unrelated to OC use. Overall, 14 percent of cases and 27 percent of controls had ever used OCs, corresponding to a multivariate relative risk (RR) of 0.5 (95 percent confidence interval [CI]: 0.3, 0.8). The risk of endometrial cancer was found to be related inversely to duration of OC use: RR = 1.0 for less than two years of OC use; 0.5 for two to five years; and 0.3 (95 percent CI: 0.1, 0.7) for more than five years. The protection appeared greater within 20 years since last use, and the RR rose to 0.8 after 20 or more years since last use; numbers are too small, however, for reliable inference from these subanalyses. No significant interaction or modifying effect was observed with other major factors related to endometrial cancer, including parity, body mass index, estrogen replacement therapy, and cigarette smoking. While this study provides further evidence for the protective effect of OCs against risk of endometrial cancer, the relationship requires continued evaluation to assess the long-term implications and public health impact of OC use.

Recent time trends in uterine cancer

Recent trends in corpus uterine cancer incidence rates were explored using 1979-86 data from the Surveillance and End Results Program (SEER); recent trends in hospitalizations for corpus uterine cancer were explored using 1979-86 data from National Hospital Discharge Surveys (NHDS); and recent trends in exogenous hormone use were delineated using data from the 1980, 1981, and 1985 National Ambulatory Medical Care Surveys (NAMCS). Uterine cancer incidence rates using SEER data have continued to decline since 1979. An acceleration in the decline since 1983-84 is suggested in all women and in women with intact uteri ages 45-64. Hospitalizations for uterine cancer have also declined since 1979, with a marked acceleration in the decline since 1983-84 for all women and for women ages 40-79 has increased 22 percent and use of unopposed exogenous estrogens in women of similar age has increased 7 percent, while use of exogenous progesterones have shown much more substantial increases of approximately 700 percent. Possible relationships between trends in exogenous hormone use and incidence rates of corpus uterine cancer are discussed.

The histochemistry of isocitric and oestradiol-17 beta dehydrogenases in the endometrium of postmenopausal women treated with oestrogens and progestogens

Endometrium was obtained from postmenopausal women during treatment with either oestrogen alone or on the third, sixth, tenth or twelfth day of combined therapy with oestrogens and progestogens. The activities of oestradiol-17 beta and isocitric dehydrogenases were measured in homogenates of the whole tissue and the enzymes were also located histochemically. Oestradiol dehydrogenase was located exclusively within the epithelium, whilst isocitric dehydrogenase was found in both epithelium and stroma, and also in stromal arterioles. Histochemically, oestradiol dehydrogenase was found in all the specimens which exhibited biochemical activity but in none of those from which it was absent. Isocitric dehydrogenase however, was seen in all tissue sections despite widely varying levels of biochemical activity in the homogenate. The method for measuring isocitric dehydrogenase activity was therefore nonspecific, whilst that for oestradiol dehydrogenase was reliable and low levels of enzyme activity could be detected. The latter technique may therefore be useful to predict the sensitivity of endometrial carcinomata to progestogens.

Estrogen replacement therapy and the risk of endometrial cancer: remaining controversies

To examine the relationship between exogenous estrogen administration and endometrial cancer, we used data from the Cancer and Steroid Hormone Study, a multicenter, population-based case-control study. Estrogen replacement therapy for greater than or equal to 2 years was associated with an increased risk of both localized and extrauterine cancer (relative risk = 2.8, 95% confidence limits 1.6, 4.6; relative risk = 2.9, 95% confidence limits 0.9, 9.4, respectively). However, the latter finding was based on a small number of cases in which estrogen was used. Women who underwent estrogen replacement therapy for greater than or equal to 2 years had significantly elevated risks of endometrial cancer (2.1 for 2 to 5 years and 3.5 for greater than or equal to 6 years). An elevated risk persisted for greater than or equal to 6 years after discontinuation of therapy. Women who exclusively used conjugated equine estrogen preparations less than or equal to 0.625 mg had no increased risk of endometrial cancer. A history of oral contraceptive use appeared to reduce the risk of endometrial cancer associated with estrogen replacement therapy. However, these latter two potentially important findings were based on a small number of cases in which hormones were used.

The role of exogenous hormones in the epidemiology of breast, ovarian and endometrial cancer

This review focuses on the effects of oral contraceptives (OC) and estrogen replacement therapy (ERT) on the risk of breast, ovarian and endometrial cancer. The relationship between OC and cancer risk is first placed in a historical perspective. Since 1960, when OC were introduced, the hormonal composition of OC as well as the characteristics of the OC user have changed considerably. Studies conducted in the 1970s were generally reassuring, but it was not until the 1980s that studies could evaluate the effect of prolonged OC use after an extended follow-up period. Although the relationship between breast cancer and OC has been investigated in about 40 studies, the issue still remains essentially unresolved. Most studies report no association between ever use of OC and breast cancer risk. Several studies find increased risk for prolonged use and other studies report elevated risks for women who used OC very early in their reproductive years. The inconsistent results of recent studies are attributed to bias or to geographical variation in latency period elapsed, types of OC preparations, or prevalence of other risk factors. In contrast, the use of combined OC has consistently been shown to reduce the risk of ovarian and endometrial cancer. The risk further decreases with increasing duration of use and the protective effect seems to persist in ex-users for at least 5 years. Some evidence indicates that higher parity reduces the protective effect. Though studies relating ERT to breast cancer are far from consistent, overall, there is evidence for a moderately increased risk with high dose and/or long duration. The effect seems to be modified by mode of administration (injections vs. pills) and by type of ERT, but this needs confirmation. The number of adequate studies on the relationship between ERT and ovarian cancer is too small to draw firm conclusions. The positive relationship between ERT and endometrial cancer is now well established. The ERT effect is dose- and duration-dependent and is characterized by a short latency period. The cyclic addition of progesterone (greater than 10 days/cycle) may reduce the risk increase.

Endometrial cancer and patterns of use of oestrogen replacement therapy: a cohort study

5,160 non-hysterectomised women aged 44-100 years completed a health survey questionnaire as part of a longitudinal study of a southern California retirement community begun in June 1981. As of 1 January 1987, 50 incident cancers of the endometrium had occurred among these women, who had contributed 23,786 years of follow-up. Women who had used oestrogen replacement therapy had a relative risk of endometrial cancer of 10 compared to women who had never used oestrogens (P less than 0.0001). Risk increased with increasing duration of use (chi 2 test for trend = 50.60, P less than 0.0001); women who had used oestrogens for 15 or more years had a relative risk of 20 (95% C.I. = 7.2, 54) compared to non-users. While current and recent users (i.e. those who had used oestrogen within one year of the initial survey) had the greatest risk (RR = 25, 95% C.I. = 9.2, 69), women who had last used oestrogens 15 or more years ago still had a significantly increased risk (RR = 5.8, 95% C.I. = 2.0, 17). No other variable studied had a major effect on risk, except smoking. Women who smoked at the time of menopause had a significantly reduced risk of disease (RR = 0.38, P = 0.005), which was essentially unchanged after adjustment for oestrogen use.

Advanced-stage endometrial cancer: contributions of estrogen use, smoking, and other risk factors

The contributions of estrogen replacement therapy, smoking, and other risk factors to the development of advanced-stage (2-4) endometrial cancer were evaluated in a case-control study of women 40-69 years old from upstate New York. Eighty-four cases and 168 matched community controls were interviewed in person about estrogen exposure and other risk factors. Despite a statistically significant increase in risk with longer use of estrogen pills (P less than 0.05), estrogen exposure actually contributed little to the overall risk of advanced-stage endometrial cancer. Other physical conditions (increased weight, lower parity, diabetes) and socioeconomic factors (education, access to medical services) largely accounted for advanced-stage disease. The evidence in this study does not support the hypothesis that women who smoke have a lower risk than nonsmokers of developing advanced-stage endometrial cancer.

Gynecologic consequences of long-term, unopposed estrogen replacement therapy

We evaluated the gynecologic risks of unopposed, long-term estrogen use in postmenopausal women. Our medical record review showed that unopposed estrogen users (mean dose, 0.9 mg of conjugated estrogens) had a significantly higher (P less than 0.001) incidence of abnormal vaginal bleeding, curettage, hysterectomy, and endometrial cancer. The ratios of occurrence of these events among users compared with non-users were 7.8, 4.9, 6.6 and 7.7. The prevalence of hysterectomy reached 28.2% of users compared with 5.3% of non-users, and endometrial carcinoma developed in 9.9% of users compared with 1.4% of non-users.

Biological markers in epidemiologic research

This paper identifies some of the issues relevant to the use of biological markers in epidemiologic research. Foremost among these are clarity of definitions and marker classification. Illustrations of markers in the categories of internal dose, biological effective dose, biological response, disease, and susceptibility are presented with a theoretical model for the interrelationship among these. Issues faced by epidemiologists in selecting markers for specific studies concern exposure complexity, marker specificity, marker persistence, time to appearance, and the use of target vs. surrogate biological media. Feasibility issues concern sample collection, transport, storage, and characteristics of the laboratory assay. The rationale for biological markers in epidemiologic research is strong in that markers have the potential for (1.) improving the accuracy of our "exposure variables," (2.) permitting the identification of preclinical disease and providing opportunities for prevention, (3.) allowing for more homogeneous and etiologically relevant classifications of disease, and (4.) enhancing our understanding of the biological processes leading to disease occurrence, thereby strengthening the interpretation of epidemiologic data and the theoretical framework from which we formulate research questions.

Benefits and risks of menopausal estrogen and/or progestin hormone use

Current evidence is reviewed here on risks and benefits of estrogen and progestin use by peri- and postmenopausal women in relation to the following conditions: endometrial cancer, breast cancer, osteoporosis, and coronary artery disease (CAD). On balance, estrogen therapy appears to be beneficial for menopausal women, as it probably reduces the risks of CAD and osteoporosis, two of the major causes of mortality and morbidity. Although unopposed estrogen therapy increases the risk of endometrial cancer, that cancer is relatively rare and is not fatal in the vast majority of cases associated with estrogen use. Definitive conclusions about the relation of menopausal estrogens to breast cancer cannot be drawn due to inconsistent evidence to date. Although evidence from randomized controlled trials is lacking, biochemical and clinical evidence suggest that progestin supplementation is associated with a reduction in endometrial cancer risk in women taking menopausal estrogens. Progestin supplementation also may augment the beneficial effects of estrogens in providing protection against osteoporosis, although this effect is not yet well established. There is little direct evidence bearing on the relation of menopausal progestins to breast cancer. Although studies of CAD per se are lacking at present, progestins probably unfavorably alter lipoprotein profiles, thereby increasing a user's risk of CAD. Given the relatively high incidence and mortality of CAD in postmenopausal women, any negative effects on CAD risk could potentially counterbalance beneficial effects on other causes. We conclude that estrogen replacement therapy is of potential benefit to postmenopausal women, but that the question of progestin supplementation requires further study, particularly for CAD risk.

The joint effect of risk factors on endometrial cancer

The joint effect of risk factors on endometrial cancer was examined by applying general statistical models to the data of a hospital-based case-control study conducted in Copenhagen, Denmark. The analysis included 149 cases of histologically confirmed adenocarcinoma of the endometrium and 154 age-matched controls with cervical cancer. Information on risk factors derived from the medical records. Estrogen use and body mass were found to be the main predictors of endometrial cancer risk. In the model proposed, women who ever used non-contraceptive estrogens had a 10-fold increased risk irrespective of their weight and height. Among non-users of estrogen, the risk of endometrial cancer rose with increasing body mass, the largest showing a five-fold increased risk. These data provide further evidence of the significant role that excess estrogens play, whether exogenous from replacement therapy or endogenous from enhanced androgen conversion, in the etiology of endometrial cancer.

Replacement estrogens and risk of gynecologic cancers and breast cancer

The two cancers specific to women for which substantial research on their relationship to exogenous estrogens has been reported are endometrial cancer and breast cancer. With the former, the link to estrogen use is well established. The estrogen use patterns associated with increased risk of endometrial cancer are characteristic of a promotional agent. The example serves as a prototype model for the study of an adverse health effect subsequent to a prescribed medication. However, modification in estrogen prescribing patterns have lowered significantly the endometrial cancer risk for patients. A relationship between estrogen replacement therapy and breast cancer is difficult to assess. Despite biologic plausibility, large epidemiologic studies have shown no association between estrogen use and breast cancer occurrence. Those studies suggesting a relationship find it concentrated in the high dose estrogen products and possibly among women who have had a prior bilateral oophorectomy. A convincing resolution to the current uncertainty is likely to require new approaches in laboratory, clinical, and epidemiologic research. Larger studies investigating more refined hypotheses within the same conceptual confines are unlikely to be productive.

Smoking, body weight, and early-stage endometrial cancer

The effect of cigarette smoking on the risk of early-stage endometrial cancer was evaluated in a population-based case-control study of women aged 40 to 69 years from upstate New York. Two hundred women with early-stage endometrial cancer diagnosed between 1979 and 1981, and 200 matched community controls were interviewed in person and asked about smoking habits and other risk factors. Statistical analysis revealed a significant decline in relative risk with increased smoking (P less than 0.05). This effect strongly modified the well-known increase in risk with body weight. Among smokers risk did not increase with body weight, whereas among nonsmokers risk increased rapidly with body weight, especially among nonsmokers in whom the peripheral conversion of androgens was the primary source of serum estrogen. Despite this apparent reduced risk for endometrial cancer, smoking remains a major health hazard for women as well as men.

Nude mouse system in the study of tumor biology, treatment strategies and progesterone receptor physiology in human endometrial carcinoma

A nude mouse system where the biological, morphological and biochemical characteristics of human endometrial carcinoma are maintained during serial transplantation has been previously described. Applications of this system to the study of (a) hormonal sensitivity (b) treatment strategies and (c) progesterone receptor physiology of human endometrial carcinomas are presented here.

The immune system during the pre-cancer and the early cancer period. IL-2 production by PBL from post-menopausal women with and without endometrial carcinoma

We report on alterations in IL-2 production and cell proliferation following PHA stimulation of peripheral blood lymphocytes (PBL) from stage-I endometrial carcinoma (EC) patients, and on mechanisms involved in these alterations. Our study includes 3 groups: EC patients, post-menopausal women at high risk of developing EC, and age-matched healthy women. IL-2 production was markedly lower in most EC patients than in healthy controls. Varying levels of IL-2 were produced by PBL from women in the high-risk group. The proliferative response of PBL to PHA appeared to correlate with levels of IL-2 production. Our results suggest that macrophages are involved, in part, in the modulation of T-cell functions of EC patients.

Risk of localized and widespread endometrial cancer in relation to recent and discontinued use of conjugated estrogens

In a case-control study of the risk of adenocarcinoma of the endometrium in relation to conjugated-estrogen use, we found that 31 per cent of 425 women with endometrial cancer and 15 per cent of 792 controls reported having used conjugated estrogens; the rate-ratio estimate was 3.5 with a 95 per cent confidence interval of 2.6 to 4.7. For use that lasted at least one year, the rate-ratio estimate for Stage I or II cancer was 5.2 (95 per cent confidence interval, 3.7 to 7.2), and for Stages III and IV combined it was 3.1 (1.5 to 6.4). Among women who had used estrogen for at least one year and then discontinued it, the risk of endometrial cancer remained significantly elevated even after estrogen-free intervals of over 10 years. The findings suggest that long-term use of conjugated estrogen increases the risk of both localized and widespread endometrial cancer. The data also suggest that women who have taken conjugated estrogen for one or more years remain at increased risk for at least 10 years after they discontinue use. Such women should be considered for long-term gynecologic surveillance.

Endometrial carcinogenesis and its relation to oestrogens

The epidemiological evidence suggesting an association between the administration of exogenous oestrogens and an increased risk of developing endometrial adenocarcinoma is critically reviewed and it is concluded that the case for oestrogens being a cause of endometrial cancer is proven. The benefits flowing from preventing postmenopausal osteoporosis by oestrogen replacement therapy are assessed and contrasted with the danger to life posed by endometrial adenocarcinoma: it is pointed out that the type of neoplasm developing in patients taking oestrogens is well differentiated, nonaggressive and easily cured, the survival rate being very high. The addition of progestational agents to the therapeutic regime may prevent the development of endometrial carcinoma but could introduce a risk of cardiovascular disease.