Necropsy diagnosis of endometrial cancer and detection-bias in case/control studies

COVID-19 and Cancer Detection in Russia

Overdiagnosis, associated with mass testing in healthy populations, is a significant issue for breast, prostate, renal, and thyroid cancers. During the lockdowns caused by the COVID-19 pandemic, the intensity of cancer screening was expected to go down. In this study, we analyzed the impact of the expected reduction in screening intensity on morbidity and mortality from certain malignancies. Cumulative data from the Russian National Cancer Registry available from 2000 to 2022 were analyzed. It was noted that there has been no noticeable effect of the COVID-19 lockdowns on mortality rates from breast, prostate, renal, or thyroid cancers. At the same time, the detectable incidence decreased markedly in 2020 at the time of the lockdowns and then returned to pre-pandemic levels in 2022. At the moment, there is no sufficient reason to believe that skipping screening tests in 2020 could have any impact on breast, prostate, renal, or thyroid cancer mortality two years later (2022). The data presented further confirm that the overdiagnosis of these types of malignancies is caused by widespread screening among a generally healthy population.

Asthma and risk of glioma: a population-based case-control study

OBJECTIVES

Literature suggests an inconsistent, but largely inverse, association between asthma and risk of glioma, which is primarily due to methodological inconsistency in sampling frame and ascertainment of asthma. The objective of the study was to clarify the association between asthma and risk of glioma by minimising methodological biases (eg, recall and detection bias).

DESIGN

A population-based case-control study.

SETTING

General population in Olmsted County, Minnesota, USA.

PARTICIPANTS

All eligible biopsy-proven incident glioma cases (1995-2014) and two sets of controls among residents matched to age and sex (first set: community controls without glioma; second set: MRI-negative controls from the same community).

METHODS

The predetermined asthma criteria via medical record review were applied to ascertain asthma status of cases and controls. History of asthma prior to index date was compared between glioma cases and their matched controls using conditional logistic regression models. Propensity score for asthma status was adjusted for multivariate analysis.

RESULTS

We enrolled 135 glioma cases (median age at index date: 53 years) and 270 controls. Of the cases, 21 had a history of asthma (16%), compared with 36 of MRI controls (27%) (OR (95% CI) 0.48 (0.26 to 0.91), p=0.03). With MRI controls, an inverse association between asthma and risk of glioma persisted after adjusting for the propensity score for asthma status, but did not reach statistical significance probably due to the lack of statistical power (OR (95% CI) 0.48 (0.21 to 1.09); p=0.08). Based on comparison of characteristics of controls and cases, community controls seem to be more susceptible to a detection bias.

CONCLUSIONS

While differential detection might account for the association between asthma and risk of glioma, asthma may potentially pose a protective effect on risk of glioma. Our study results need to be replicated by a larger study.

The 4Ps of Breast Cancer Chemoprevention: Putting Proven Principles into Practice

The pioneering Royal Marsden Tamoxifen Prevention Trial recruited 2,471 eligible high-risk women to be randomized to either placebo or tamoxifen (20 mg daily) for 8 years. Breast cancer incidence was evaluated at a median of 18.4 years from the start of the study. There was a 32% reduction in estrogen/progesterone receptor (ER/PR)-positive breast cancers after tamoxifen treatment finished. Translational research, to study "the good, the bad, and the ugly of tamoxifen" in the 1980s, subsequently ensured women's safety from possible increases in osteoperosis, coronary heart disease, and endometrial cancer. Other tamoxifen chemoprevention trials followed. The result of laboratory research was the unanticipated discovery of raloxifene to prevent osteoporosis and breast cancer at the same time. A new group of medicines, now known as selective ER modulators, was established. Indeed, the ability to prevent or delay multiple diseases with a single cheap medicine has the potential to alleviate pressure on health care systems that are overwhelmed. It is a priority to educate physicians appropriately to apply recommended proven medicines as preventives. Cancer Prev Res; 10(4); 219-22. ©2017 AACRSee related article by Detre, et al., Cancer Prev Res 2017;10(3):171-6.

Current Issues in the Diagnosis and Treatment of Endometrial Carcinoma

Endometrial carcinoma is the most common carcinoma of the female genital tract. Its most important clinical sign is postmenopausal bleeding. An endometrial biopsy is essential for diagnosis. Treatment decisions are governed by tumour risk assessment and patient comorbidity, which is often present. Pelvic and paraaortic lymph node dissection is unnecessary in low risk cases (definition: pT1 a, G1/2) and adjuvant radiotherapy and systemic treatments are usually avoidable. Treatment of high-risk patients (G3 and/or pT1b) and palliative cases is difficult and not well standardised. New molecular-based subtype classification may help treatment decision making in future.

A Pyrosequencing Assay for the Quantitative Methylation Analysis of GALR1 in Endometrial Samples: Preliminary Results

Endometrial cancer is the most common malignancy of the female genital tract while aberrant DNA methylation seems to play a critical role in endometrial carcinogenesis. Galanin's expression has been involved in many cancers. We developed a new pyrosequencing assay that quantifies DNA methylation of galanin's receptor-1 (GALR1). In this study, the preliminary results indicate that pyrosequencing methylation analysis of GALR1 promoter can be a useful ancillary marker to cytology as the histological status can successfully predict. This marker has the potential to lead towards better management of women with endometrial lesions and eventually reduce unnecessary interventions. In addition it can provide early warning for women with negative cytological result.

Transvaginal Ultrasound for Endometrial Carcinoma Screening - Current Evidence-based Data

The value of transvaginal ultrasound in gynaecological examinations is beyond dispute. But it is of particular forensic importance that the validity of this type of imaging with regard to the reliable detection of early-stage malignancy is properly understood. Vaginal ultrasound screening in asymptomatic patients for the early detection of endometrial carcinoma is not useful from a medical point of view, nor is it cost-efficient. However, even though the validity of transvaginal ultrasound for screening has currently not been proven, the method should still be an integral part of gynaecological examinations.

Asymptomatic endometrial thickening

OBJECTIVE

To formulate clinical recommendations for the assessment of endometrial thickening when it is found on ultrasound in a postmenopausal patient without bleeding.

OUTCOMES

Ensure that women with asymptomatic thickening and endometrial polyps found on ultrasound are managed appropriately.

EVIDENCE

Published literature was retrieved through searches of English language articles from the EMBASE, Cochrane, and PubMed databases for relevant peer-reviewed articles dating from 1970 to 2009, using appropriate controlled vocabulary (e.g., "asymptomatic endometrial thickness," "endometrial cancer," "postmenopausal bleeding," "transvaginal ultrasonography," "endometrial biopsy" and "endometrial polyp"). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. Searches were updated on a regular basis and incorporated in the guideline to April 2010. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The level of evidence was determined according to the criteria established by the Canadian Task Force on Preventative Health Care (Table). Recommendations are ranked according to this method.

BENEFITS, HARMS, AND COSTS

It is anticipated that the adoption of these recommendations would save postmenopausal women unnecessary anxiety, pain, and risk of procedural complication. It is also expected to decrease the cost to the health system by eliminating unnecessary interventions.

Chemoprevention of breast cancer with selective oestrogen-receptor modulators

Twenty years ago, a new therapeutic dimension was conceived that not only had the potential to treat and prevent osteoporosis, but to prevent breast and endometrial cancer at the same time. As osteoporosis was known to be caused by oestrogen withdrawal after menopause, whereas breast and endometrial cancer are caused by unopposed oestrogen action, the new tissue-selective oestrogens and anti-oestrogens, or selective oestrogen-receptor modulators (SERMs), had to recruit new networks to activate or suppress target tissues selectively. New medicines now promise to provide chemoprevention strategies for women at risk for the development of many diseases.

The endometrium on routine contrast-enhanced CT in asymptomatic postmenopausal women: avoiding errors in interpretation

We studied 54 asymptomatic postmenopausal women to characterize normal contrast-enhanced computed tomography (CT) appearance of endometrium. Endometrium was visualized in 26 out of 54 (48.1%) women, and when seen its mean short-axis thickness was 7.5 mm. The anteroposterior thickness varied directly with uterine angulation (P<.05). Endometrial attenuation was significantly less than that of the myometrium (P<.05). Endometrial thickness (short axis) and attenuation were inversely correlated to patient age and to years after menopause (P<.05). We believe that our findings will help prevent overdiagnosis of endometrial fluid or thickening in asymptomatic women.

Endometrial safety of hormone replacement therapy: review of literature

Unopposed estrogens for treating menopausal symptoms were extensively used when epidemiological findings associated them with an increased endometrial cancer risk. Adding progestogens reverse this side effect efficiently but patient, dose, type and especially time during which the progestogen is administered are important. Long-term uterine safety of the long cycle HRT with administration of the progestogen every 3 months remains unclear. Because regular bleeding lowers compliance, continuous combined estrogen-progestogen treatment has become popular. Many different regimens are now available using oral, transdermal, subcutaneous, intravaginal or intra-uterine application of the estrogen and/or progestogen. Available but inadequate studies seem to point towards a slightly decreased endometrial cancer risk with continuous combined preparations compared with non-HRT-users and an increased risk with long-term oral but not vaginal treatment with low-potency estrogen formulations such as estriol. Newer compounds for menopausal health such as tibolone and raloxifene seem to be safe. As for any women with abnormal vaginal bleeding, those on HRT must have an intra-uterine evaluation. Transvaginal ultrasound (TVU) is very accurate in predicting a normal uterine cavity but inaccurate in predicting endometrial pathology because of a low specificity and positive predictive value of a thick echogenic endometrium. In all such cases a three-dimensional visualisation of intra-uterine lesions is more accurate. Periodic examination with TVU and/or endometrial biopsy of HRT exposed endometrium in asymptomatic women is not cost-effective. The available limited data on the use of HRT in hysterectomised women for early stage endometrial cancer show little evidence in terms of recurrence.

Regulation of estrogen target genes and growth by selective estrogen-receptor modulators in endometrial cancer cells

OBJECTIVE

Tamoxifen has mixed agonist/antagonist activities, leading to tissue-specific estrogen-like actions and endometrial cancer. The purpose of this study was to evaluate the effects of antiestrogens on the growth of estrogen receptor (ER)-positive ECC-1 endometrial cancer cells in vitro and in vivo.

METHODS

We performed growth studies and luciferase assays using ERE-tK and AP-1 reporters. ERalpha protein expression was measured by Western blot after antiestrogen treatments. We investigated the actions of antiestrogens on the transcription of the pS2 gene in situ measured by Northern blot and the actions of antiestrogens on the VEGF protein secreted by ELISA. ERalpha, ERbeta, EGFR, and HER2/neu mRNAs were determined by RT-PCR. Last, ECC-1 tumors were developed by inoculation of cells into ovariectomized athymic mice and treated with estradiol (E2), tamoxifen, raloxifene, and a combination.

RESULTS

E2 induced cell proliferation while antiestrogens did not. E2 and raloxifene down regulated ERalpha protein; in contrast, 4OHT did not. ICI182,780 completely degraded the receptor. ECC-1 cells express ERbeta at insignificant levels. Luciferase assays did not show any induction in ERE- nor AP-1-mediated transcription by antiestrogens. E2 caused a concentration-dependent increase in pS2 mRNA but antiestrogens did not. E2 increased VEGF expression in a dose-dependent manner and antiestrogens blocked E2 action. E2 down regulated HER2/neu while 4OHT and raloxifene did not change HER2/neu levels compared to control. In addition, EGFR mRNA was down regulated by E2 but raloxifene did not change it. Tamoxifen and raloxifene did not promote tumor growth in vivo. However, raloxifene (1.5 mg daily) only partially blocked E2-stimulated growth.

CONCLUSION

Tamoxifen and raloxifene are antiproliferative agents and antiestrogens in ECC-1 endometrial cells in vitro and in vivo. The observation that selective estrogen-receptor modulators do not down regulate EGFR and HER2/neu mRNA may provide a potential role for these oncogenes in the development of raloxifene- or tamoxifen-stimulated endometrial cancer. The ECC-1 cell line could provide important new clues about the evolution of drug resistance to tamoxifen and raloxifene.

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.

An assessment of the value of ultrasonographic screening for endometrial disease in postmenopausal women without symptoms

OBJECTIVE

Our purpose was to evaluate the use of transvaginal ultrasonography for the detection of endometrial disease in a population of postmenopausal women who were without symptoms.

STUDY DESIGN

Postmenopausal women were screened for potential inclusion in 2 multicenter, double-blind, placebo-controlled studies of 2 years' duration to evaluate the safety and efficacy of idoxifene in the prevention of osteoporosis. Baseline endometrial evaluation was performed by transvaginal ultrasonography and aspiration biopsy of the endometrium.

RESULTS

A total of 1926 women were screened by transvaginal ultrasonography, and 1833 of them had endometrial thickness < or =6 mm. Five cases of endometrial abnormality (adenocarcinoma [n = 1] and atypical hyperplasia [n = 4]) were detected in the 1750 women from this cohort who underwent biopsy. The negative predictive value was >99%. One case of adenocarcinoma was detected in the 42 women who had endometrial thickness >6 mm and underwent biopsy. However, the sampling rate (45%) of women with endometrial thickness >6 mm was too low for confidence in the positive predictive value of 2%.

CONCLUSIONS

Despite a high negative predictive value, transvaginal ultrasonography may not be an effective screening procedure for detection of endometrial abnormality in untreated postmenopausal women who are without symptoms.

Performance characteristics of the Indiana University Medical Center endometrial sampler (Tao Brush) in an outpatient office setting, first year's outcomes: recognizing histological patterns in cytology preparations of endometrial brushings

Following successful hysterectomy-controlled trials, Tao brush endometrial cytology with liquid fixation was offered to clinicians for office use. This report recounts our first year's cytology and correlative histology outcomes. One hundred thirteen cases were accrued. Correlative tissue examinations comprising Pipelle (Prodimed, Neuilly-en-Thelle, France) biopsy, hysteroscopy and biopsy, dilatation and curettage, and hysterectomy were available at this institution for 59 cases. In 42 cases, cytology diagnoses could be compared to histology diagnoses. Twenty-five of 63 normal brushings were followed up. Fourteen were normal. Eleven Pipelle biopsies of cytologically atrophic endometrium were quantitatively limited and insufficient for diagnosis. Thirty-seven cases were abnormal, and 15 of these showed nuclear anaplasia. Twenty-eight of the abnormal cases were followed up. All correlative tissue examinations confirmed an abnormality. All 15 cases with nuclear anaplasia showed significant histopathology comprising atypical endometrial hyperplasia, endometrial intraepithelial neoplasia (EIN), endometrial intraepithelial carcinoma (EIC), and invasive adenocarcinoma. There were 13 inadequate endometrial brushings. Three cases had insufficient cellular material. The remaining 10 cases were cellular but were chiefly cervical/endocervical samples. Two of the cellular cases resulted from clinicians failing to replace the protective sheath over the brush bristles before removing the Tao brush from the endometrial cavity. The remaining 11 cases resulted from inaccessibility of the uterine cavity due to a tight or stenotic cervix. The Tao brush is a reliable uterine sampling device that performs well as a diagnostic tool for outpatient assessment of the endometrium of women with patent cervices. An advantage of endometrial cytology is that it accurately represents atrophic endometrium, and it is an effective case-finding tool for EIN and EIC. Women with tight or stenotic cervices are poor candidates for endometrial brushing, and may experience pain if the procedure is attempted. Diagn. Cytopathol. 2000;22:186-195.

Rare epithelial sheets with "cancer-like" nuclei presenting against a background of cytologically normal-appearing endometrial epithelium in endometrial brush samplings: establishing a differential diagnosis

Liquid-fixed Tao brush samples showing small quantities (less than 10%) of endometrial epithelial sheets with cancer-like nuclei that are admixed with benign endometrium raise a concern about false-positive cytology interpretations. This paper details 7 cases along with the outcomes of three prior papers that touch on the differential diagnosis of "small amounts of atypical epithelium with cancer-like nuclei." Liquid-fixed, cytocentrifuge-processed Tao brush endometrial samples from 7 women showing "small amounts of atypical epithelium with cancer-like nuclei" were followed up by hysterectomy. Clinical presentations, diagnostic tests, surgical procedures, and tissue outcomes are detailed. Four women had hyperplastic polyps (three with focal atypical complex hyperplasia, and one with focal atypical simple hyperplasia). One had endometrial microcarcinoma. One had p53-positive endometrial intraepithelial carcinoma (EIC). One had endometrial intraepithelial neoplasia (EIN). The differential diagnosis of the index cytological finding, "small quantities of endometrial epithelial sheets with cancer-like nuclei admixed with benign endometrium," includes hyperplastic polyp, EIC, microcarcinoma/EIN, and carcinoma metastatic to the endometrium. Combining endometrial brushing, endovaginal sonography/sonohysterography, and selective immunostaining may be useful for both detecting and sorting out these lesions. Diagn. Cytopathol. 1999;21:378-386.

Antecedent therapy versus detection bias as causes of neoplastic multimorbidity

Neoplastic multimorbidity occurs when a patient is found to have a second primary cancer after the occurrence of a first. The phenomenon may be the result of aging, chance, or other specific causes, but in recent years, the radio- or chemotherapy administered for the first cancer has regularly been suspected as a possible cause of the second. A commonly disregarded alternative explanation, however, is that the second cancers were clinically "silent" discoveries found because of increased diagnostic detection procedures in patients known to have a first cancer. Such patients are more likely to receive intensive surveillance and technologic testing than the general population often used as a control group. In 43 recent reports of neoplastic multimorbidity, however, only five mentioned the problem of detection bias, and only one tried to eliminate it by using a suitable analytic comparison. Unless adequate analytic precautions are taken, antineoplastic therapy may be falsely accused of being carcinogenic.

Effects of the antiestrogens tamoxifen, toremifene, and ICI 182,780 on endometrial cancer growth

BACKGROUND

Tamoxifen has been shown to promote the growth of human endometrial tumors implanted in athymic mice, and it has been associated with a twofold to threefold increase in endometrial cancer. Toremifene, a chlorinated derivative of tamoxifen, and ICI 182,780, a pure antiestrogen, are two new antiestrogens being developed for the treatment of breast cancer. The effects of these drugs on endometrial cancer are currently unknown. Our objective was to evaluate the effects of toremifene and ICI 182,780 on the growth of human endometrial cancer in athymic mice.

METHODS

Athymic, ovariectomized mice were implanted with human endometrial tumors and treated with estrogen, tamoxifen, or the new antiestrogens.

RESULTS

The effects of tamoxifen and toremifene on the growth of either tamoxifen-stimulated or tamoxifen-naive endometrial tumors in athymic mice were not substantially different. ICI 182,780 inhibited the growth of tamoxifen-stimulated endometrial cancer, in both the presence and the absence of estrogen.

CONCLUSIONS

Toremifene and tamoxifen produce identical effects in our endometrial cancer models. Therefore, it is possible that toremifene, like tamoxifen, may be associated with an increased incidence of endometrial cancer. In contrast, ICI 182,780 inhibited tamoxifen-stimulated endometrial cancer, both in the presence and in the absence of estrogen, suggesting that this drug may be safe with regard to the endometrium, even if it is used following tamoxifen, and that it may not result in an increased incidence of endometrial cancer. Indeed, it is even possible that ICI 182,780 may prove useful as an adjuvant agent in early stage endometrial cancer.

Detection of occult endometrial carcinoma

Endometrial carcinoma is commonly diagnosed as a consequence of abnormal uterine bleeding. In a study published in 1962, it was documented that endometrial cancer may be detected by vaginal pool smears in asymptomatic postmenopausal women. As a consequence of these observation, a systematic search for occult endometrial carcinoma was initiated in 1979, supported by a contract from the National Cancer Institute. The techniques used in this study and the problems encountered in the diagnosis of occult endometrial carcinoma will be discussed. Within 3-1/2 years of this study encompassing 2,586 peri- or postmenopausal women 16 occult endometrial carcinomas were discovered by direct endometrial sampling. Two carcinomas, missed on initial screening, were subsequently documented in this cohort, for a prevalence rate of 6.96 per 1,000. The incidence data based on follow-up examination of 1,754 women was 1.71 per 1,000 woman-years. An elaborate epidemiologic questionnaire was evaluated. Contrary to some prevailing views, obesity, hypertension, and diabetes failed to reach statistical significance as risk factors. The only risk factor of statistical value was delay in the onset of menopause past age 49, observed in about 50% of the cohort. It was noted that the administration of estrogens to women in Quetelet Index groups below means was more likely to be associated with carcinoma than in women in higher Quetelet groups but, again, the difference was not statistically significant. It was noted that in spite of an active search for endometrial hyperplasias, the rate of these lesions was nearly identical to the prevalence and incidence rates for carcinoma. It was postulated that some or perhaps most, endometrial carcinomas in postmenopausal women are not preceded by hyperplasia but originate ab initio in the endometrium.

What do we know and what don't we know about tamoxifen in the human uterus

Since its introduction in the early seventies, the list of indications for the use of the antiestrogen tamoxifen has been continuously expanded. Tamoxifen is now used for the treatment of metastatic breast cancer and for long-term and often indefinite administration as an adjuvant therapy. Large clinical trials in three countries are now evaluating the efficacy of tamoxifen as a preventive agent. However, tamoxifen therapy has been associated with an increased incidence of endometrial carcinoma. Laboratory and clinical data available to date on this controversial issue can be summarized as follows: a) Tamoxifen can have an estrogenic effect on endometrium in the presence of low estrogen levels. b) Tamoxifen treatment is probably associated with an increased incidence of endometrial cancer; however, this association appears to be linked to higher tamoxifen doses (40 mg/d). d) It is not known whether tamoxifen causes or allows the identification of occult endometrial carcinoma. e) At the present time there is evidence for a tumor promoting effect of tamoxifen on endometrial cancer at a dose of 20 mg per day. f) Replacement of tamoxifen by 'pure' antiestrogens or coadministration of progestins with tamoxifen do not appear to offer benefit unless clinical trials demonstrate a reduced incidence of endometrial problems. g) Patients must be evaluated for pre-existing endometrical carcinoma before starting tamoxifen therapy. f) Close followup of long-term tamoxifen patients with endometrial biopsies is recommended with individuals who experience symptoms.

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 mathematic analysis of the "epidemiologic necropsy"

There has been much debate regarding the validity and implications of the "epidemiologic necropsy." Two opposing mathematic analyses have previously appeared--one by Flanders and O'Brien and one by Feinstein and colleagues. Because these analyses omitted discussion of certain key parameters and assumptions, I provide a more detailed analysis. I show that under the assumptions used by earlier authors, the observed ("registry") disease rates will equal the true disease rates, even if there is differential disease detection and large pool of undetected cases. Under realistic violations of assumptions, both the observed rates and the necropsy estimates will be biased. In any case, the data offered thus far are insufficient to accurately assess the impact of undetected disease on epidemiologic studies.

Inappropriate comparisons of incidence and prevalence in epidemiologic research

Several epidemiologists have published papers in major medical journals in which they compare incidence rates and prevalence and use these comparisons to support conclusions regarding questions of major public health importance. Although these papers have been criticized in published correspondence, we believe that continued use and advocacy of such comparisons by some epidemiologists has created the need for a full discussion of this practice. In this commentary, we review basic differences between incidence and prevalence and show that direct comparison of these two measures is inappropriate for conceptual, theoretical, and practical reasons.

Oestrogen replacement therapy: physiological considerations and new applications

The total impact of the menopause on the health of women and the ultimate benefit/risk ratio of oestrogen replacement therapy are yet to be defined completely. Until these are accomplished, broad general guidelines for the use of oestrogen replacement therapy in all patients cannot be given. Treatment should be individualized to the patient's specific needs. Use of appropriate dosages of oestrogen in combination with progestin administration should reduce risk and enhance benefits for those subjects requiring its use. The development of new non-oral methods of administration should also help.

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.

Hormones, medications, and cancer

Hormones have been shown experimentally to act as cocarcinogens or promoters, i.e., they facilitate the carcinogenic event. In the cases of breast and endometrium, those hormones that facilitate growth may also favor carcinogenesis in the human. There is good epidemiologic evidence that use of estrogens after the menopause increases the incidence of breast and endometrial cancer, the risk increasing with increasing duration of use. Periodic progestin-induced withdrawal will probably mitigate the risk of endometrial cancer after the menopause. Prolactin is the important promoter of mammary cancer in the rat and mouse, but its significance in women is still under study. Intermittently elevated prolactin levels have been noted in some women who subsequently developed breast cancer, but epidemiologic studies of women who have received prolactin-releasing drugs such as reserpine and perphenazine have not disclosed increased risk. Diethylstilbestrol is listed as a carcinogen but any estrogen can induce mammary cancer in the rodent or vaginal adenosis in the neonatal mouse (an experimental model of human vaginal adenocarcinoma).

Actions of progestins on the morphology and biochemistry of the endometrium of postmenopausal women receiving low-dose estrogen therapy

Endometrial biopsies were obtained from postmenopausal women receiving 0.625 mg Premarin daily and either 2.5 or 5 mg norethindrone daily or 150 or 500 microgram dl-norgestrel daily for 10 days each month. Sample were taken during the estrogen-only phase of treatment and on the sixth day of combined estrogen/progestin administration. Progestin exposure caused marked morphologic and biochemical changes as well as features comparable with the premenopausal luteal phase. Thus, progestins oppose the stimulation of premarin to the postmenopausal endometrium. However, the currently recommended dosage of norethindrone and dl-norgestrel greatly exceed those necessary to suppress endometrial proliferation effectively. The recommended daily dosage may be lowered without losing protective effect. This reduction will probably minimize the risk of dose-dependent progestin side effects.