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

Copper homeostasis and cuproptosis in gynecological disorders: Pathogenic insights and therapeutic implications

This review comprehensively explores the complex role of copper homeostasis in female reproductive system diseases. As an essential trace element, copper plays a crucial role in various biological functions. Its dysregulation is increasingly recognized as a pivotal factor in the pathogenesis of gynecological disorders. We investigate how copper impacts these diseases, focusing on aspects like oxidative stress, inflammatory responses, immune function, estrogen levels, and angiogenesis. The review highlights significant changes in copper levels in diseases such as cervical, ovarian, endometrial cancer, and endometriosis, underscoring their potential roles in disease mechanisms and therapeutic exploration. The recent discovery of 'cuproptosis,' a novel cell death mechanism induced by copper ions, offers a fresh molecular perspective in understanding these diseases. The review also examines genes associated with cuproptosis, particularly those related to drug resistance, suggesting new strategies to enhance traditional therapy effectiveness. Additionally, we critically evaluate current therapeutic approaches targeting copper homeostasis, including copper ionophores, chelators, and nanoparticles, emphasizing their emerging potential in gynecological disease treatment. This article aims to provide a comprehensive overview of copper's role in female reproductive health, setting the stage for future research to elucidate its mechanisms and develop targeted therapeutic strategies.

Age at Menopause and Risk of Developing Endometrial Cancer: A Meta-Analysis

Object

The association of age at menopause with endometrial cancer remains controversial. Therefore, we quantitatively summarized the evidence from observational studies with a meta-analysis.

Methods

We searched PubMed, Web of Science, Embase, Medline, Chinese National Knowledge Infrastructure (CNKI), and Wan Fang Med online up to March 2019, and all eligible case-control and cohort studies were included in the study. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using the random-effects model. The dose-response relationship was assessed by restricted cubic spline model. The heterogeneity among studies was evaluated by I². Metaregression was used to explore the potential sources of between-study heterogeneity. Egger's test was used to estimate publication bias.

Results

Eighteen articles including 957242 subjects with 4781 cases were included in the meta-analysis. The pooled RR (95%CI) of endometrial cancer for the highest versus the lowest age at menopause was 1.89 (95%CI: 1.58-2.26). For dose-response analysis, a nonlinear relationship was found between age at menopause and endometrial cancer, and the positive association became statistically significant when age at menopause was greater than 46.5 years old.

Conclusions

This meta-analysis suggested that age at menopause was positively associated with endometrial cancer. For women whose menopausal age over 46.5 years old, the risk of endometrial cancer increased with the age at menopause.

Lifetime number of years of menstruation as a risk index for postmenopausal endometrial cancer in the Norwegian Women and Cancer Study

INTRODUCTION

Lifetime number of years of menstruation (LNYM) reflects a woman's cumulative exposure to endogenous estrogen and can be used as a measure of the combined effect of reproductive factors related to endometrial cancer (EC) risk.

MATERIAL AND METHODS

We aimed to study the association between LNYM and EC risk among postmenopausal women and calculate the population attributable fraction of EC for different LNYM categories. Our study sample consisted of 117 589 women from the Norwegian Women and Cancer (NOWAC) Study. All women were aged 30-70 years at enrollment and completed a baseline questionnaire between 1991 and 2006. Women were followed up for EC to December 2014 through linkages to national registries. We used Cox proportional hazards models to estimate hazard ratios with 95% confidence intervals (95% CIs), adjusted for potential confounders.

RESULTS

In all, 720 women developed EC. We found a statistically significant, positive dose-response relationship between LNYM and EC, with a 9.1% higher risk for each additional year of LNYM (P for trend < .001). Using the LNYM category ≥40 as a reference, the hazard ratios for LNYM <25, 25-29, 30-34, 35-39 were 0.17 (95% CI 0.22-0.27), 0.25 (95% CI 0.17-0.36), 0.43 (95% CI 0.32-0.58), and 0.68 (95% CI 0.51-0.92), respectively. The association between LNYM and EC was independent of incomplete pregnancies, menopausal hormone therapy, diabetes, and body mass index. When considering the population attributable fraction, 67% of EC was estimated to be attributable to LNYM ≥25 years.

CONCLUSIONS

Our study supports that increasing LNYM is an important and independent predictor of EC risk.

Breastfeeding and Endometrial Cancer Risk: An Analysis From the Epidemiology of Endometrial Cancer Consortium

OBJECTIVE

To investigate the association between breastfeeding and endometrial cancer risk using pooled data from 17 studies participating in the Epidemiology of Endometrial Cancer Consortium.

METHODS

We conducted a meta-analysis with individual-level data from three cohort and 14 case-control studies. Study-specific odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for the association between breastfeeding and risk of endometrial cancer using multivariable logistic regression and pooled using random-effects meta-analysis. We investigated between-study heterogeneity with I  and Q statistics and metaregression.

RESULTS

After excluding nulliparous women, the analyses included 8,981 women with endometrial cancer and 17,241 women in a control group. Ever breastfeeding was associated with an 11% reduction in risk of endometrial cancer (pooled OR 0.89, 95% CI 0.81-0.98). Longer average duration of breastfeeding per child was associated with lower risk of endometrial cancer, although there appeared to be some leveling of this effect beyond 6-9 months. The association with ever breastfeeding was not explained by greater parity and did not vary notably by body mass index or histologic subtype (grouped as endometrioid and mucinous compared with serous and clear cell).

CONCLUSION

Our findings suggest that reducing endometrial cancer risk can be added to the list of maternal benefits associated with breastfeeding. Ongoing promotion, support, and facilitation of this safe and beneficial behavior might therefore contribute to the prevention of this increasingly common cancer.

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.

Intrauterine devices and endometrial cancer risk: a pooled analysis of the Epidemiology of Endometrial Cancer Consortium

Intrauterine devices (IUDs), long-acting and reversible contraceptives, induce a number of immunological and biochemical changes in the uterine environment that could affect endometrial cancer (EC) risk. We addressed this relationship through a pooled analysis of data collected in the Epidemiology of Endometrial Cancer Consortium. We combined individual-level data from 4 cohort and 14 case-control studies, in total 8,801 EC cases and 15,357 controls. Using multivariable logistic regression, we estimated pooled odds ratios (pooled-ORs) and 95% confidence intervals (CIs) for EC risk associated with ever use, type of device, ages at first and last use, duration of use and time since last use, stratified by study and adjusted for confounders. Ever use of IUDs was inversely related to EC risk (pooled-OR = 0.81, 95% CI = 0.74-0.90). Compared with never use, reduced risk of EC was observed for inert IUDs (pooled-OR = 0.69, 95% CI = 0.58-0.82), older age at first use (≥ 35 years pooled-OR = 0.53, 95% CI = 0.43-0.67), older age at last use (≥ 45 years pooled-OR = 0.60, 95% CI = 0.50-0.72), longer duration of use (≥ 10 years pooled-OR = 0.61, 95% CI = 0.52-0.71) and recent use (within 1 year of study entry pooled-OR = 0.39, 95% CI = 0.30-0.49). Future studies are needed to assess the respective roles of detection biases and biologic effects related to foreign body responses in the endometrium, heavier bleeding (and increased clearance of carcinogenic cells) and localized hormonal changes.

Long-term alcohol intake and risk of endometrial cancer in the Nurses' Health Study, 1980-2010

BACKGROUND

Previous epidemiologic studies have shown inconsistent results for the association between alcohol intake and endometrial cancer risk. Most of the studies, however, assessed alcohol intake after cancer diagnosis, or measured alcohol intake at baseline only.

METHODS

We prospectively examined the association between alcohol intake and endometrial cancer risk in the Nurses' Health Study with 68 067 female participants aged 34-59 years in 1980. Alcohol intake was measured several times with validated dietary questionnaires. We calculated cumulative average alcohol intake to represent long-term intakes of individual subjects. Using Cox proportional hazards models, we estimated incidence rate ratios (RRs) and 95% confidence intervals (CIs) for endometrial cancer risk after controlling for several risk factors simultaneously.

RESULTS

We identified a total of 794 invasive endometrial adenocarcinoma from 1980 to 2010. We found an inverse association among alcohol drinkers (multivariable RR=0.81; 95% CI: 0.68-0.96) compared with nondrinkers. Women with light alcohol intake of <5 g per day (∼half drink per day) had a 22% lower risk of endometrial cancer (multivariable RR=0.78; 95% CI: 0.66-0.94). Higher intake of alcohol, however, did not provide additional benefits against endometrial cancer: multivariable RRs for 5-14.9 g (∼1 drink), 15-29.9 g (∼2 drinks), or ≥ 30 g (≥ 2 drinks) versus 0 g per day were 0.88, 0.83, and 0.78 (95% CI: 0.49-1.25), respectively. The lower risk among drinkers (∼half drink per day) appeared to be stronger for obese women, but no significant interaction by body mass index was found.

CONCLUSIONS

This study provides prospective evidence for an inverse association between light alcohol intake (∼half drink per day) in the long term and endometrial cancer risk, but above that level no significant association was found.

Pregnancy history and risk of endometrial cancer

BACKGROUND

Epidemiologic studies are consistent in finding that women who have had at least one birth are less likely to develop endometrial cancer. Less clear is whether timing of pregnancies during reproductive life influences risk, and the degree to which incomplete pregnancies are associated with a reduced risk.

METHODS

We evaluated pregnancy history in relation to endometrial cancer risk using data from a series of 4 population-based endometrial cancer case-control studies of women 45-74 years of age (1712 cases and 2134 controls) during 1985-2005 in western Washington State. Pregnancy history and information on other potential risk factors were collected by in-person interviews.

RESULTS

Older age at first birth was associated with a reduced risk of endometrial cancer after adjustment for number of births and age at last birth (test for trend P = 0.004). The odds ratio comparing women at least 35 years of age at their first birth with those younger than 20 years was 0.34 (95% confidence interval = 0.14-0.84). Age at last birth was not associated with risk after adjustment for number of births and age at first birth (test for trend P = 0.830). Overall, a history of incomplete pregnancies was not associated with endometrial cancer risk to any appreciable degree.

CONCLUSIONS

In this study, older age at first birth was more strongly associated with endometrial cancer risk than was older age at last birth. To date, there remains some uncertainty in the literature on this issue.

Alcohol and endometrial cancer risk: a case-control study and a meta-analysis

To evaluate the association between alcohol consumption and endometrial cancer risk, we analyzed data from a hospital-based case-control study, conducted in Italy between 1992 and 2006, on 454 endometrial cancer cases and 908 controls, and performed a meta-analysis updated to October 2009. Compared to never alcohol drinkers, the odds ratio was 1.03 (95% confidence interval, CI, 0.76-1.41) for < or = 7, 1.27 (95% CI 0.86-1.87) for 8-14, and 1.19 (95% CI 0.80-1.77) for > or = 15 drinks/week, with no trend in risk. No association emerged for wine, beer, and spirit consumption analyzed separately. The meta-analysis included 20 case-control and seven cohort studies, for a total of 13,120 cases. Compared to non/low drinkers, the pooled relative risks for drinkers were 0.90 (95% CI 0.80-1.01) for case-control studies, 1.01 (95% CI 0.90-1.14) for cohort studies, and 0.95 (95% CI 0.88-1.03) overall, with no heterogeneity between study design (p = 0.156). The overall estimate for heavy versus non/low drinkers was 1.12 (95% CI 0.87-1.45). The results were consistent according to selected study characteristics, including geographic area, definition of alcohol drinkers, and type of controls in case-control studies. Our findings provide evidence that alcohol drinking is not associated with endometrial cancer risk, although a weak positive association for very high drinkers cannot be excluded.

Dietary phyto-oestrogens: molecular mechanisms, bioavailability and importance to menopausal health

Following the high-profile studies on hormone replacement therapy which provided little evidence in support of the drug therapy improving future health, there remains a growing demand for dietary solutions for maintaining health and preventing disease as women age. Although interest in the relative importance of phyto-oestrogens to human health has increased dramatically over the last decade, the effective dose for health benefits and hypothetical issues on safety remain to be resolved. Plausible mechanisms and epidemiological data are available to support the concept that phyto-oestrogen-rich diets exert physiological effects, but optimal doses and sources of these compounds have still not been elucidated for specific health benefits. In addition, much of the current mechanistic data are difficult to interpret as the experiments have incorporated levels of phyto-oestrogens that may not be achievable in vivo and have to date only used aglycones and glycosides of the pure compounds rather than examining the biological effects of gut and liver metabolites. The present review will concentrate on the isoflavone subclass of phyto-oestrogens, as, to date, these compounds have received most attention from both a commercial and research perspective.

Cancer risk among infertile women with androgen excess or menstrual disorders (including polycystic ovary syndrome)

OBJECTIVE

To define relationships of androgen excesses to cancer risk.

DESIGN

Retrospective cohort study.

SETTING

Five large infertility practices.

PATIENT(S)

Among 12,193 women evaluated for infertility during 1965-1988 and traced for cancer incidence through 1999, 2,560 had androgen excess or menstrual disorders; among these, 412 met established criteria for polycystic ovary syndrome.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Cancer incidence. Derivation of standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for cancer risk comparisons with the general population and rate ratios (RRs) for comparisons with other infertility patients.

RESULT(S)

Androgen excess/menstrual disorder patients showed significant SIRs for breast (1.31; 95% CI, 1.05-1.62) and uterine (2.02; 95% CI, 1.13-3.34) cancers and melanoma (1.96; 95% CI, 1.12-3.18). Significant associations for breast and uterine cancers were restricted to primary infertility patients (respective SIRs of 1.53 and 3.48). After adjustment for other cancer predictors, the only excess risk was for uterine cancer among primary infertility patients. Compared with women with secondary infertility and no androgen excess/menstrual disorder, those with primary infertility and a disorder had an RR of 1.88 (95% CI, 0.82-4.32). Cancer risks among the women with polycystic ovary syndrome or androgen excess disorders appeared to be similar to those in the more comprehensive group.

CONCLUSION(S)

Previous findings linking androgen excess disorders to elevated uterine cancer risks might largely reflect underlying risk profiles.

Endometrial cancer risk among younger, overweight women

OBJECTIVE

To examine the risk for endometrial cancer among overweight women using the World Health Organization's clinical definitions of obesity based on body mass index (BMI).

METHODS

Conducted in the early 1980s, the Cancer and Steroid Hormone study was a multicenter, population-based, case-control study of breast, ovarian, and endometrial cancers among women aged 20-54 years. Participants for the case group (n=421) were identified through cancer registries and had histologically confirmed endometrial cancer. Participants for the control group (n=3,159) were chosen by random-digit dialing methods in the same regions as those in the case group. Those in the case and control groups responded to the same questions during in-person interviews. Unconditional logistic regression was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The relationship between endometrial cancer and BMI (calculated as weight [kg]/[height (m)]) was modified by age at last menstrual period (LMP). Of women who were younger than 45 years at LMP, those with BMIs of at least 35.0 had a greater risk of endometrial cancer (56%, 30/54) than did those with normal BMIs (4%, 59/1,492, adjusted OR 21.7, 95% CI 11.3-41.7). Of women age 45 or older at LMP, those with BMIs of at least 35.0 also had a greater risk (40%, 24/60) than did those with normal BMIs (14%, 168/1,235, adjusted OR 3.7, 95% CI 2.0-6.6). Women younger than 45 years at LMP and those with BMIs of at least 25.0 at 18 years and as adults (25%, 31/123) had an approximately sixfold increased risk (adjusted OR 5.8, 95% CI 3.4-9.8) compared with those with normal BMIs at 18 and as adults (4%, 58/1,460).

CONCLUSION

Very obese women aged 20-54 years have an elevated endometrial cancer risk, which appears heightened by early menopause.

LEVEL OF EVIDENCE

II.

Cigarette smoking and the risk of endometrial cancer: a meta-analysis

OBJECTIVE

Epidemiologic findings are inconsistent concerning the association of endometrial cancer risk with cigarette smoking. We conducted a meta-analysis of epidemiologic studies to examine this relation.

METHODS

A systematic literature search up to June of 2007 was performed in MEDLINE and EMBASE. Study-specific risk estimates were pooled using a random-effects model.

RESULTS

Ten prospective and 24 case-control studies were included in the analysis of the effect of ever smoking. Ever smoking was statistically significantly associated with a reduced risk of endometrial cancer among prospective studies (relative risk 0.81; 95% confidence interval [CI], 0.74-0.88) and case-control studies (odds ratio 0.72; 95% CI, 0.66-0.79). The inverse association was significant among current and former smokers. Six prospective and 6 case-control studies were included in the quantitative analysis. We noted that an increase in smoking of 20 cigarettes per day was statistically significantly associated with 16% and 27% reduced risks of endometrial cancer in prospective and case-control studies, respectively. We also found that cigarette smoking was significantly associated with a decreased risk of endometrial cancer among postmenopausal women (relative risk 0.71; 95% CI, 0.65-0.78) but not among premenopausal women. In addition, the risk reduction seemed to be stronger among hormone replacement therapy users than nonusers.

CONCLUSION

Cigarette smoking was found to be significantly associated with a reduced risk of endometrial cancer, especially among postmenopausal women.

Reduced risk of endometrial cancer from alcohol drinking in Japanese

The role of alcohol consumption in the etiology of endometrial cancer has not been clarified. To examine the association between alcohol consumption and endometrial cancer risk, we conducted a case-control study with 148 histologically diagnosed incident endometrial cancer cases and 1468 matched non-cancer controls. Median consumption of alcohol was only 19.3 g/week among cases who drank and 28.2 g/week among controls who drank. These values are lower than in Western countries. Relative risk was analyzed in subjects classified into four groups according to weekly alcohol consumption (non-drinkers, 1-24 g/week, 25-175 g/week, and >175 g/week). Confounder-adjusted odds ratios for those consuming alcohol at <25 g/week, 25-175 g/week, and >175 g/week compared to non-drinkers were 0.79 (95% confidence interval (CI), 0.49-1.28), 0.42 (95% CI, 0.23-0.79), and 0.47 (95% CI, 0.14-1.58), respectively. Further analysis was conducted concerning self-reported physical reaction to alcohol. Among women without flushing after drinking, a significant inverse association between risk and alcohol intake was seen (trend P = 0.001). In contrast, no protective effect of alcohol was seen among women who experience flushing after drinking. These results suggest the presence of an inverse association between alcohol drinking and endometrial cancer risk among Japanese women, and that this association is evident among those without flushing. Further investigation of these findings is warranted.

Aspirin, NSAID, and acetaminophen use and the risk of endometrial cancer

To date, no prospective studies have explored the relationship between the use of aspirin, other nonsteroidal anti-inflammatory medications (NSAID), and acetaminophen and endometrial adenocarcinoma. Of the 82,971 women enrolled in a prospective cohort study, 747 developed medical record-confirmed invasive endometrial cancer over a 24-year period. Use of aspirin was ascertained from 1980 to 2004, and for other NSAIDs and acetaminophen, from 1990 to 2004. Cox regression models calculated multivariate relative risks (MV RR), controlling for body mass index (BMI), postmenopausal hormone (PMH) use, and other endometrial cancer risk factors. Currency, duration, and quantity of aspirin were not associated with endometrial cancer risk overall [current use: MV RR, 1.03; 95% confidence interval (CI) 0.83-1.27; >10 years of use: MV RR, 1.01; 95% CI, 0.78-1.30; and cumulative average >7 tablets per week: (MV RR, 1.10; 95% CI, 0.84-1.44)]. However, stratified analyses showed that a lower risk of endometrial cancer among obese (BMI, >or=30 kg/m(2)) women was seen with current aspirin use (MV RR, 0.66; 95% CI, 0.46-0.95). The greatest risk reduction for current aspirin users was seen in postmenopausal obese women who had never used PMH (MV RR, 0.43; 95% CI, 0.26-0.73). The use of other NSAIDs or acetaminophen was not associated with endometrial cancer. Our data suggest that use of aspirin or other NSAIDs does not play an important role in endometrial cancer risk overall. However, risk was significantly lower for current aspirin users who were obese or who were postmenopausal and had never used PMHs; these subgroup findings require further confirmation.

Meta-analysis of intrauterine device use and risk of endometrial cancer

PURPOSE

We sought to study the association between intrauterine device (IUD) use and endometrial cancer.

METHODS

A comprehensive search of literature published through April 2007 was conducted, studies reviewed, and data abstracted. Data from ten studies were pooled and analyzed using both fixed- and random-effects models to examine the association of ever use of an IUD and endometrial cancer.

RESULTS

Based on the random effects model, a protective crude association between IUD use and endometrial cancer was observed (odds ratio [OR] = 0.39; 95% confidence interval [CI] = 0.29-0.51; heterogeneity p < 0.001) with a pooled adjusted risk of OR = 0.54 (95% CI, 0.47-0.63; heterogeneity p = 0.40). A decreased risk of endometrial cancer also was seen for increased years of IUD use (OR for 5 years of use 0.88; 95% CI = 0.84-0.92; n = 5; heterogeneity p = 0.14), increased years since last IUD use (OR for 5 years of use 0.91; 95% CI, 0.86-0.95; n = 4; heterogeneity p = 0.02), and increased years since first IUD use (OR for 5 years of use 0.89; 95% CI, 0.83-0.95; n = 4; heterogeneity p = 0.04).

CONCLUSIONS

Our results suggest that nonhormonal IUD use may be associated with a decreased risk for endometrial cancer; however, the exact mechanism for this association is unclear. Future investigations should address the difference in the proposed association by specific type of IUDs.

Reproductive risk factors for endometrial cancer among Polish women

We conducted a population-based case-control study of reproductive factors in Warsaw and Lódź, Poland, in 551 incident endometrial cancer cases and 1925 controls. The reproductive variable most strongly related to risk was multiparity, with subjects with three or more births having a 70% lower risk than the nulliparous women. The reduced risk was particularly strong below 55 years of age. Subjects with older ages at a first birth were also at reduced risk even after adjustment for number of births. Ages at last birth or intervals since last birth were not strongly related to risk. Spontaneous abortions were unrelated to risk, but induced abortions were associated with slight risk increases (odds ratios=1.28, 95% confidence intervals 0.8-2.1 for 3+ vs no abortions). The absence of effects on risk of later ages at, or short intervals since, a last birth fails to support the view that endometrial cancer is influenced by mechanical clearance of initiated cells. Alternative explanations for reproductive effects should be sought, including alterations in endogenous hormones.

Induced abortions and the risk of all cancers combined and site-specific cancers in Shanghai

Although some previous case-control studies found an increased risk of breast cancer in women who had an induced abortion, the evidence from prospective studies suggests that induced abortions do not cause breast cancer. We have assessed risks of 12 types of cancer in women who have had induced abortions in a prospective study in China. Female textile workers (n = 267,400) completed a baseline questionnaire (1989-1991) that ascertained information on the major risk factors for breast cancer, contraceptive use, and induced abortions and were actively followed until July 2000. Cox Proportional Hazards analysis was used to calculate incidence rate ratios for specific types of cancer in women who ever had an induced abortion and by number of induced abortions. Women who had had an abortion were not at increased risk of cancer. There was a significant reduction in risk of uterine corpus cancer in women who had ever had an induced abortion, and a significant decreasing trend in risk with increasing number of induced abortions. No convincing associations with other cancers were observed. Women who have induced abortions after a live birth are not at increased risk of cancer and induced abortions may reduce risk of cancer of the corpus uteri.

Neoplasia with use of intrauterine devices

BACKGROUND

One of the mechanisms by which intrauterine devices (IUDs) prevent pregnancy is the creation of a sterile inflammatory response in the endometrium. Additionally, hormone-releasing IUDs or intrauterine systems (IUSs) release progestins or progesterone into the uterus. Both of these mechanisms may affect users' risk for neoplasia.

STUDY DESIGN

We searched the PubMed database for studies on IUD use and risk for neoplasia conducted between 1960 and September 2006 and published in all languages. We excluded case reports and case series. For the association between ever using an IUD and risk for endometrial cancer, we conducted a meta-analysis using a Bayesian random-effects model to account for between-study heterogeneity.

RESULTS

We found no evidence of increased risk for neoplasia with IUD use. Nine case-control studies and one cohort study found reduced risks for endometrial cancer with having ever used an IUD (pooled adjusted odds ratio=0.6, 95% confidence interval=0.4-0.7). No trend in associations was observed with characteristics of IUD use, type of IUD and histologic type of cancer. Four case-control studies found no association between IUD use and risk for cervical cancer. One study found no increased incidence of breast cancer among levonorgestrel-releasing IUS users as compared with the general population in Finland. Finally, three studies found no association between IUD use and occurrence of hydatidiform moles or malignant sequelae.

CONCLUSIONS

Use of an IUD does not appear to increase the risk for neoplasia. While nearly all studies found that IUD use was associated with a decreased risk for endometrial cancer, it remains unclear whether this association is causal.

Oral contraceptive and IUD use and endometrial cancer: a population-based case-control study in Shanghai, China

Oral contraceptive (OC) and intrauterine device (IUD) use have been shown to be protective factors for endometrial cancer in several epidemiological studies; however, few studies have been conducted in Chinese populations. We evaluated the association between OC and IUD use and endometrial cancer risk in a population-based case-control study among Chinese women in Shanghai, China. The study included 1,204 newly diagnosed endometrial cancer cases and 1,212 age frequency-matched healthy controls. Logistic regression models were used to estimate adjusted odds ratios (OR) and their 95% confidence intervals (95% CI). In our study population, 18.5% cases and 24.9% controls reported having ever used OCs with an OR of 0.75 (95% CI, 0.60-0.93), after adjusting for known risk or protective factors for endometrial cancer. The risk of endometrial cancer decreased with long-term use of OCs with the OR for more than 72 months of use being 0.50 (95% CI, 0.30-0.85). The effect of OC use remained 25 or more years after cessation of use; the associated OR was 0.57 (95% CI = 0.42-0.78) as compared to nonusers. Similarly, fewer cases than controls had ever used IUD, with the multivariable adjusted OR being 0.53 (95% CI = 0.43-0.65). A reduction in risk was observed regardless the duration of use or age at first and last use. These results suggest that OC and IUD use may confer long-term protection against endometrial cancer.

Menstrual and reproductive factors in relation to risk of endometrial cancer in Chinese women

Menstrual, reproductive and contraceptive factors have been associated with risk of endometrial cancer in populations where the incidence of this tumor is high. To investigate associations between these factors in a low-risk population with a low prevalence of hormone replacement therapy, we conducted a cohort study among 267,400 women employed in the textile industry in Shanghai, China. Menstrual, reproductive and other factors were ascertained at baseline in 1989-1991, and women were followed for incident endometrial cancer through 31 December 1998 (n = 206). Cox proportional hazards modeling was used to estimate hazard ratios (HR) and 95% confidence intervals (CI). Risk of endometrial cancer decreased with increasing age at menarche (p-trend = 0.004). Among menopausal women, risk increased with age at menopause and increasing years of menstruation. Compared to women with one live birth, risk was increased in relation to nulliparity (Hazard ratio = 3.95, 95% CI 1.43-10.86). Risk was decreased with increasing age at first live birth (p-trend = 0.03). There was a decreased risk associated with ever use of an intrauterine device (HR = 0.56, 95% CI 0.35-0.88) and use of oral contraceptives for > or =2 years (HR = 0.50, 95% CI 0.23-1.07). This prospective study confirms findings from previous case-control studies relating menstrual, reproductive, and contraceptive factors and endometrial carcinoma.

Anthropometry, physical activity, and endometrial cancer risk: results from the Netherlands Cohort Study

Although obesity is an established risk factor for endometrial cancer, evidence linking risk to height, weight change since age 20, and physical activity is limited. In this case-cohort study, 62 573 women from The Netherlands Cohort Study on Diet and Cancer were followed up from 1986 to 1995, and 226 endometrial cancer case patients were identified. In Cox proportional hazards analyses, women 175 cm or taller had an increased risk of endometrial cancer compared with those less than 160 cm (rate ratio [RR] = 2.57, 95% confidence interval [CI] = 1.32 to 4.99). Compared with women with a body mass index (BMI; kg/m2) between 20 and 22.9, women with a BMI of 30 or greater had a higher risk (RR = 4.50, 95% CI = 2.62 to 7.72; P(trend)<.001). Moreover, BMI at age 20 and BMI gain since age 20 were positively associated with endometrial cancer risk (P(trend) = .02 and <.001, respectively). Women who spent 90 minutes per day or more doing nonoccupational physical activities had a lower risk (RR = 0.54, 95% CI = 0.34 to 0.85; P(trend) = .002) compared with those who spent less than 30 minutes per day. High BMI and low physical activity were strong and independent risk factors for endometrial cancer.

FFPRHC Guidance (January 2004) The Copper Intrauterine Device as Long-term Contraception

This Guidance provides information for clinicians providing women with copper-bearing intrauterine devices as long-term contraception. A key to the grades of recommendations, based on levels of evidence, is given at the end of this document. Details of the methods used by the Clinical Effectiveness Unit (CEU) in developing this Guidance and evidence tables summarising the research basis of the recommendations are available on the Faculty website (www.ffprhc.org.uk). Abbreviations (in alphabetical order) used include: acquired immune deficiency syndrome (AIDS); actinomyces-like organisms (ALOs); automated external defibrillator (AED); blood pressure (BP); British National Formulary (BNF); confidence interval (CI); copper-bearing intrauterine contraceptive device (IUD); emergency contraception (EC); Faculty Aid to Continuing Professional Development Topic (FACT); levonorgestrel-releasing intrauterine system (IUS); human immunodeficiency virus (HIV); Medicines and Healthcare products Regulatory Agency (MHRA); non-steroidal antiinflammatory drugs (NSAIDs); odds ratio (OR); pelvic inflammatory disease (PID); relative risk (RR); Royal College of Obstetricians and Gynaecologists (RCOG); Scottish Intercollegiate Guidelines Network (SIGN); sexually transmitted infection (STI); termination of pregnancy (TOP); World Health Organization (WHO); WHO Medical Eligibility Criteria (WHOMEC); WHO Selected Practice Recommendations (WHOSPR).

Menstrual and reproductive factors and endometrial cancer risk: Results from a population-based case-control study in urban Shanghai

The purpose of our study was to evaluate the association of menstrual and reproductive factors with the risk of endometrial cancer. In a population-based case-control study conducted in urban Shanghai, in-person interviews were completed for 833 women aged 30-69 years and an equal number of controls frequency-matched to cases by age. All cases were newly diagnosed with endometrial cancer between January 1, 1997 and December 31, 2001. The unconditional logistic regression model was employed to derive the adjusted odds ratios (ORs) of endometrial cancer and 95% confidence intervals (CIs) in relation to menstrual and reproductive factors. Earlier menarche age, particularly among premenopausal women, and later menopausal age were associated with an elevated risk of endometrial cancer. A clear dose-response relation between endometrial cancer risk and years of menstruation was observed (p for trend < 0.01). Compared to women ever having a pregnancy and women ever having had a live birth, respectively, nulligravity and nulliparity were both associated with a more than one-fold elevated risk of endometrial cancer. Both completed (OR = 3.02, 95% CI 1.10-8.32 for women never having a complete pregnancy) and incomplete pregnancy (OR = 0.69, 95%CI 0.55-0.87) conferred a protective effect against endometrial cancer, and the protective effect appeared to increase with total number of pregnancies (p for trend = 0.01). The effect of pregnancy on endometrial cancer remained unchanged with increasing time since the last pregnancy. Stillbirth and age at first pregnancy was unrelated to endometrial cancer risk. Our study suggests that prolonged menstruation was related to an increased risk of endometrial cancer while pregnancy, including induced abortion, reduced the risk of endometrial cancer.

Effects of weight control and physical activity in cancer prevention: role of endogenous hormone metabolism

Excess body weight and/or lack of physical activity are increasingly recognized as major risk factors for cancer of the colon, breast, endometrium, and prostate. This paper reviews the effects of excess body weight and physical inactivity on endogenous hormone metabolism (insulin, the IGF-I/IGFBP system, and sex steroids) and of endocrine alterations with risk of cancer of the endometrium, breast, prostate, and colon.

Current opinion: consensus statement on intrauterine contraception

Forty-five experts from around the world attended a 1-day seminar in September 2001 in Chapel Hill, North Carolina, USA, to identify ways that they might collaborate to overcome unnecessary barriers to the use of intrauterine devices (IUDs). Seminar participants formed working groups that produced at least three specific recommendations relating to: training/performance improvement; service delivery improvement; general public information; and clinical and programmatic research. Key recommendations included: integrating reproductive health knowledge and skills into curricula for all healthcare professionals; reviewing and reinforcing with providers evidence-based guidelines for IUD use; encouraging evidence-based review of the IUD label and package insert; and conducting further research about IUD client eligibility, potential health benefits, acceptability among clients and providers, and use by HIV-infected women. At the meeting's conclusion, a number of participants, representing the fields of research, policy, communications, donors, women's advocacy, and medicine, expressed an interest in refining and acting upon the recommendations. Hosted by Family Health International, the meeting was supported by the Mellon Foundation.

Noncontraceptive health benefits of intrauterine devices: a systematic review

Most women and their clinicians are unaware that IUDs confer important noncontraceptive health benefits. This review summarizes the evidence from published articles on this topic. We conducted a series of systematic literature searches to identify articles on the noncontraceptive health benefits of IUD use. We reviewed the potentially pertinent ones for content, grouped them according to type of IUD, and evaluated them using the U.S. Preventive Services Task Force rating system. Over 500 titles were identified and several hundred abstracts were reviewed. Use of nonhormonal IUDs (plastic and copper) was associated with a decrease in endometrial cancer. The levonorgestrel intrauterine system can treat a variety of gynecological disorders, including menorrhagia and anemia. The levonorgestrel system has also been used successfully as part of hormone replacement therapy, as adjuvant therapy with tamoxifen, and as an alternative to hysterectomy for women with bleeding problems. Like oral contraceptives, intrauterine contraceptives confer important noncontraceptive health benefits.

Alcoholism and risk for endometrial cancer

Endogenous estrogens increase the risk of endometrial cancer and are also elevated among women with high alcoholic intake. It is incompletely known, however, whether alcohol intake in general and alcohol abuse in particular increases risk for endometrial cancer. We thus analyzed prospectively the risk for endometrial cancer among 36,856 women hospitalized with alcoholism between 1965 and 1994 through linkages between several national Swedish registers. Compared with the general population, women who were alcoholics had an overall 24% lower risk of developing endometrial cancer, a finding challenging our a priori hypothesis. However, among women below the age of 50 years at follow-up, the mean age of menopause among Swedish women, the risk was 70% higher, whereas the risk among women aged 50 years or more at follow-up was 40% lower compared with the general population. Hence, the effect of alcoholism on endometrial cancer appears to be age dependent.

Energy balance and cancer: the role of insulin and insulin-like growth factor-I

Recent theories propose that a Western lifestyle may increase cancer risk through alterations in the metabolism of insulin and insulin-like growth factors (IGF: McKeown-Eyssen, 1994; Giovannucci, 1995; Kaaks, 19%; Werner & LeRoith, 1996). Insulin regulates energy metabolism, and increases the bioactivity of IGF-I, by enhancing its synthesis. and by decreasing several of its binding proteins (IGFBP; IGFBP-1 and -2). Insulin and IGF-I both stimulate anabolic processes as a function of available energy and elementary substrates (e.g. amino acids). The anabolic signals by insulin or IGF-I can promote tumour development by inhibiting apoptosis, and by stimulating cell proliferation. Furthermore, both insulin and IGF-I stimulate the synthesis of sex steroids, and inhibit the synthesis of sex hormone-binding globulin (SFIBG), a binding protein that regulates the bioavailability of circulating sex steroids to tissues. The present paper reviews epidemiological findings relating the risk of cancers of the colo-rectum, pancreas, breast, endometrium and prostate to body size (obesity, height) and physical activity, and discusses the relationships between obesity and physical activity and plasma levels of insulin, IGF-I and IGFBP. Subsequent sections review epidemiological findings relating cancer risk to indices of chronic hyperinsulinaemia, and to plasma levels of IGF-I and IGFBP. Conclusions are that chronic hyperinsulinaemia may be a cause of cancers of the colon, pancreas and endometrium, and also possibly of the breast. On the other hand, elevated plasma IGF-I, as total concentrations or relative to levels of IGFBP-3, appears to be related to an increased risk of prostate cancer, breast cancer in young women, and possibly cob-rectal cancer. For cancers of the endometrium, breast and prostate, these findings are discussed in the context of relationships between insulin and IGF-I and levels of bioavailable sex steroids.

Intrauterine device and upper-genital-tract infection

Concern about upper-genital-tract infection related to intrauterine devices (IUDs) limits their wider use. In this systematic review I summarise the evidence concerning IUD-associated infection and infertility. Choice of an inappropriate comparison group, overdiagnosis of salpingitis in IUD users, and inability to control for the confounding effects of sexual behaviour have exaggerated the apparent risk. Women with symptomless gonorrhoea or chlamydial infection having an IUD inserted have a higher risk of salpingitis than do uninfected women having an IUD inserted; however, the risk appears similar to that of infected women not having an IUD inserted. A cohort study of HIV-positive women using a copper IUD suggests that there is no significant increase in the risk of complications or viral shedding. Similarly, fair evidence indicates no important effect of IUD use on tubal infertility. Contemporary IUDs rival tubal sterilisation in efficacy and are much safer than previously thought.

Cancer incidence trends in urban shanghai, 1972-1994: an update

Incidence rates for a number of cancers in urban Shanghai, China, have been changing markedly. Herein we update the trends using population-based data from the Shanghai Cancer Registry for 1972-1994. During 1993-1994, cancers of the lung, stomach, and liver were the 3 leading forms among men, with age-adjusted (world standard) incidence rates of 50.9, 39.2, and 26.5 per 100,000 person-years, respectively, followed by cancers of the colon (12.4) and esophagus (10.0). Among women, cancers of the breast (27.5), stomach (19.1), and lung (17.7) were the most common tumors, followed by cancers of the colon (11.3) and liver (9.4). Over the 23-year period, the rate for all cancers combined, excluding non-melanoma skin cancer, decreased from 247.5 to 215.2 among men and from 173.6 to 154.0 among women. However, trends for individual forms of cancer varied considerably. Rates doubled for cancers of the colon and biliary tract in both sexes, and they increased substantially for cancers of the brain and nervous system, kidney, pancreas, prostate, corpus uteri, female breast, and ovary, and for non-Hodgkin's lymphoma. Rates for cancers of the lung and rectum changed little. Rates declined by at least one-half for cancers of the esophagus and cervix, with notable decreases also for cancers of the stomach and liver. Some of these trends may reflect variations in diagnostic or screening practices, although changes in lifestyle and other environmental exposures are likely to play important roles. Further epidemiologic research in China is needed to identify risk factors influencing the cancer incidence trends.

Rising incidence of biliary tract cancers in Shanghai, China

Cancers of the biliary tract, including cancers of the gallbladder, extra-hepatic bile ducts, and ampulla of Vater, are relatively uncommon malignancies. From 1972 to 1994, biliary tract cancer was the most rapidly rising malignancy in Shanghai, China, with a 119% increase in men and 124% in women. The increase in incidence was seen for all 3 subsites, both sexes, and all age groups. Future studies are needed to identify reasons for the large increases in these rates.

A study of the influence of a gestodene-containing triphasic oral contraceptive on endometrial morphology

The objective of the study was to investigate histological changes in the endometrium in 20 volunteers treated with a low-dose, gestodene-containing triphasic oral contraceptive. Endometrial biopsy specimens were taken before, during a 6-month period of oral contraceptive use and in a post-treatment period. These specimens were evaluated using light microscopy, scanning and transmission electron microscopy. In addition, ultrasound examinations of the uterus, endometrial thickness and ovaries were performed. The low-dose, gestodene-containing triphasic oral contraceptive had no adverse effects on the endometrium (e.g. no proliferation, no polyps, no inflammatory processes), was well tolerated and showed a low side-effect profile. The inhibition of endometrial transformation was demonstrated both by endometrial morphology as well as by endometrial thickness, as measured by transvaginal ultrasound examination.

Childbearing and mortality from cancer of the corpus uteri

BACKGROUND

To investigate the mortality from cancer of the corpus uteri in relation to parity and age at first and last birth.

METHODS

A cohort of 431,604 married women aged 45-74 years at the Norwegian Census in 1970 was followed over 15 years. A total of 752 deaths from cancer of the corpus uteri were diagnosed during follow-up.

RESULTS

All age groups showed significant trends of decreasing mortality rates with increasing number of children. The age-adjusted reduction in mortality was 9.2% (95% CI 5.2-13.0) for each child. Women with 8-11 children had a relative risk of 0.35 (95% CI 0.14-0.85) compared to nulliparous women. For first birth at age > = 35 years versus < = 19 years, the relative risk was 0.53 (95% CI 0.34-0.83). No significant effect of age at last birth was found.

CONCLUSIONS

This study supports the notion that high parity and postponing the first delivery may reduce the risk of uterine cancer death.

Endometrial cancer in relation to intra-uterine device use

Data from a population-based case-control study were used to evaluate the risk of endometrial cancer among women who have used an intra-uterine device (IUD). Incident cases were identified between 1985 and 1991 among women aged 45-74 years who were residents of one of 3 counties in Washington State. Controls were selected by random digit dialing, and both groups of subjects received an in-person detailed interview. In this study population, women who had ever used an IUD were estimated to have a risk of endometrial cancer that was 0.61 times that of other women (95% CI 0.41-0.89). The reduction in cancer risk was not found to be dependent on duration of IUD use. There was a suggestion that women who had used intra-uterine contraception relatively late in reproductive life experienced a greater reduction in risk than those whose use was more distant or at a younger age. The relative risk among the small number of women who were currently using an IUD was 0.49 (95% CI 0.12-2.80). These results apply to the use of inert and copper IUDs as there was no use of progestin-releasing IUDs among women in the study population. The data from this and several other studies of the question support the hypothesis that use of an IUD has a favorable effect on the subsequent risk of endometrial cancer. The reason(s) for such a reduced risk is unclear.

Smoking habits and risk of cancers other than lung cancer: 28 years' follow-up of 26,000 Norwegian men and women

The impact of tobacco smoking on lung cancer risk has been investigated thoroughly since the 1950s, but other types of cancer also have been associated with smoking. In the present study, the aim was to explore the variation in risk connected with cigarette, cigar, and pipe smoking of suspected smoking-associated cancers other than lung cancer. Data were obtained from a survey of a random sample of the Norwegian population. A self-administered mailed questionnaire, which included questions about smoking habits, was completed by 26,000 men and women in 1965 (response rate: 76 percent). The cohort was followed from 1966 through 1993, including registration of all incident cancer cases. A dose-response relationship of cigarette smoking to the risk of urinary bladder cancer and cancers of the upper digestive and respiratory tract was observed. For the latter forms of cancer, a dose-response relationship of pipe smoking also was observed. In cancer of the pancreas, a stronger association between cigarette smoking and cancer risk was observed when the analysis was confined to histologically confirmed cases only. Current cigarette smokers at baseline had a significantly higher risk of cervical cancer than those who never smoked cigarettes. In cancers of the stomach, colon, rectum, breast, corpus uteri, ovary, and prostate, and in leukemia, no association between smoking and cancer risk was observed.

Oral contraceptives and cancer. A review of the evidence

The following review considers epidemiological data published from 1990 onwards on oral contraceptives (OCs) and the risk of cancers of the breast, cervix uteri, endometrium, ovary, liver and skin. In several studies, breast cancer risk was seen to be elevated among women who were current users of an OC, or had recently stopped using an OC, whereas there was no residual risk 5 or more years after stopping OC use. No interaction was observed between type of OC, or with any recognised risk factor for breast cancer, or time-factor, except for some potential excess risk for women who started OC use at a young age. Most studies have confirmed that OCs moderately increase the risk of cervical cancer, particularly in human papilloma virus (HPV)-positive women, thus suggesting that OCs may act as a promoter for HPV-induced carcinogenesis. Recent epidemiological studies have confirmed that combined OCs provide substantial protection against endometrial and ovarian cancers, and results suggest that such protection is long-lasting, and may persist for 15 years or more after stopping OC use. Most case-control studies have shown a relationship between OC use and hepatocellular carcinoma. However, data from cohort studies or analysis of vital statistics indicate that the public health impact of such an association is modest, if not negligible. No association was observed between combined OC use and the incidence of skin melanoma, or any other common skin neoplasm. In terms of clinical and public health implications, the most relevant points regarding OC use are: (i) recent data confirm that OCs confer presistent protection against ovarian cancer; and (ii) any increased risk of breast cancer in OC users is moderate and is restricted to current/recent users. This is reassuring for younger women, whose baseline risk of this disease is extremely low.

Is the risk of cancer of the corpus uteri reduced by a recent pregnancy? A prospective study of 765,756 Norwegian women

We have examined the relations between the incidence of cancer of the corpus uteri and pregnancies in a cohort of 765,756 Norwegian women, contributing a total of 9,307,118 person-years in the age interval 30-56 years. Incidence rate ratios (IRR) were calculated by Poisson regression analyses of person-years at risk. Separate analyses were carried out for the 2 main histological subtypes, endometrial carcinomas (554 cases) and sarcomas (112 cases). We observed a decrease in risk of endometrial carcinoma with an increasing number of full-term pregnancies (p < 0.001). The reduction in risk associated with the first pregnancy was more pronounced than that observed for any subsequent pregnancy. The risk of endometrial carcinoma increased with increasing time since last birth (IRR = 1.20, 95% CI = 1.08-1.34 per 5-year time interval). The reduction in risk among parous women compared to nulliparous women diminished with increasing time since last birth. For endometrial carcinoma, the decrease in risk with increasing age at first and last birth disappeared after adjustment for time since last birth. For sarcomas, however, the relation with age at births remained in analyses adjusted for time since birth, and time since birth seemed to be of minor importance as an independent risk factor. Our results support the hypothesis that the reduction in risk of endometrial carcinoma associated with a pregnancy is related to a mechanical shed of malignant or pre-malignant cells at each delivery.

Incidence trends for cancers of the breast, ovary, and corpus uteri in urban Shanghai, 1972-89

Incidence data from the Shanghai (People's Republic of China) Cancer Registry were used to assess the temporal trends of three major female cancers during 1972-89. Rates for cancers of the breast, corpus uteri and, to a lesser extent, ovary rose over the study period. The increases in breast and ovarian cancer were most pronounced among women under age 50, whereas those for corpus uteri cancer were restricted generally to those aged 55 to 69 years. When considered by cohort year of birth, risk of breast and ovarian cancers rose among women born since 1925 and 1935, respectively, but little evidence of cohort effect was apparent for corpus uteri cancer. Potential explanations for these patterns are explored.

Impact of contraception on gynecologic cancers

In considering the appropriate contraceptive method for a particular woman, the potential effect of that method on her risk of developing cancer of the breast, cervix, endometrium, or ovary is crucial. Among the most closely studied of the risk factors for gynecologic neoplasm has been the potential role of contraceptives, especially oral contraceptives, intrauterine devices, and injectable progestins. Physicians need to consider the potential impact of these agents on the disease process, therapy for the disease, future fertility, and the health of the fetus. Although much of the epidemiologic data is inconsistent and difficult to interpret, most studies find no association between oral contraceptive use and increased risk of breast cancer, except possibly in younger women (< 45 years of age) with prolonged use. Oral contraceptive use may also protect against benign breast disease. Data concerning oral contraceptive use and cervical neoplasm are confounded by several interacting variables, the most important of which is that oral contraceptive users tend to have more Papanicolaou smears than nonusers. Some studies have indicated an increased risk of two- to fourfold after 10 years of use. Oral contraceptive use provides clear protection against endometrial and ovarian cancer, an effect that persists for years after discontinuation. Less data have been collected regarding the relationship between intrauterine devices and injectable hormonal preparations and various types of cancer. No evidence suggests that the intrauterine device predisposes to the development of preneoplastic conditions of the cervix, nor to endometrial or ovarian cancer. A reliable form of contraception is indicated in women with cancer of any kind that may require chemotherapy or radiation, because these treatments can have adverse effects on the fetus, especially if given during the first trimester.

Occupational physical activity and the incidence of cancer of the breast, corpus uteri, and ovary in Shanghai

BACKGROUND

A sedentary life style has been consistently associated with an increased risk of colon cancer, but the evidence for its association with breast and other gynecologic cancers is limited.

METHODS

Occupational information for 3783 incident patients with cancer (breast, 2736; corpus uteri, 452; and ovary, 595) whose disease was diagnosed during the period 1980-1984 was compared with 1982 census data on employment in Shanghai urban areas. The standardized incidence ratios (SIR) of these cancers were estimated for each occupational group classified by job titles and physical activity levels.

RESULTS

A significantly increased incidence of breast cancer was found among professionals (SIR = 158), government officials (SIR = 131), and clerical workers (SIR = 143); the incidence was reduced among service workers (SIR = 87) and craftsmen (SIR = 91). Occupational physical activity, as measured by sitting time and energy expenditure, was inversely related to breast cancer incidence, with SIR of 127-131 for inactive jobs (sedentary or low-energy expenditure) and 79-93 for active jobs (long periods of standing or high energy expenditure). Similar associations, although to a lesser extent, were also seen for cancer of the corpus uteri and ovary.

CONCLUSIONS

Women with low physical activity occupations had an increased incidence of cancer of the breast, corpus uteri, and ovary; the incidence was reduced among women with high-activity jobs. These findings were consistent with observations from earlier studies and provided further evidence that physical activity may lower the risk of these female hormone-dependent cancers.

Oral contraceptives and endometrial cancer: do other risk factors modify the association?

The joint effect of use of combination-type oral contraceptives and other exposure factors on risk of endometrial cancer was examined in data from a multicenter case-control study conducted in 5 areas of the United States. Cases were 405 women with histologically confirmed invasive epithelial endometrial cancer first treated at one of 7 participating hospitals. A total of 297 population-based controls of similar age, race, and geographic area were selected as a comparison group. Information on exposure factors was derived from in-person interviews. Combination-type oral contraceptive (COC) use was associated with a significant reduction in risk of endometrial cancer, with an adjusted odds ratio (OR) of 0.4 (95% confidence interval 0.3 to 0.7) for ever compared to never use. Long-term (> or = 10 years) users experienced a markedly lower risk (OR = 0.2). Women who discontinued COC use > or = 20 years earlier remained at reduced risk (OR = 0.7) compared with non-users. The negative association with COC use was apparent regardless of the presence or level of several other risk factors for endometrial cancer, including age, menopausal status, parity, obesity, ever-use of menopausal estrogens, smoking history, or history of infertility. The magnitude of the negative association observed in COC users, however, was considerably diminished in women with no full-term births and in women who subsequently used replacement estrogens for 3 or more years. These results provide new evidence that the protective effect of COC use lasts for 20 or more years after use is discontinued, and highlight several sub-groups of users in whom the level of protection is attenuated by the presence of other risk factors for this disease.

Cancer incidence trends in urban Shanghai, 1972-1989

Incidence data pertaining to more than 250,000 cancer cases diagnosed during the years 1972-1989 among residents of urban Shanghai, China, were analyzed to determine the relative importance of the various malignancies and to discover changes over time. In the most recent 3-year period, lung cancer was the most frequent cancer among men (57.0 per 100,000 person-years, age-adjusted world standard), followed by cancers of the stomach (50.1), liver (29.6), esophagus (13.3), colon (11.2) and rectum (9.4). Among women, breast cancer leads (25.1), followed by cancers of the stomach (23.2), lung (18.8), liver (10.9), colon (10.2) and rectum (7.3). The most impressive increases in incidence rates from 1972-74 to 1987-89 were observed for cancers of the gallbladder (119% and 101% among men and women, respectively), colon (85% and 78%), and brain and other nervous system (71% and 60%). In addition, increases of 20-50% occurred for cancers of the pancreas, male lung, female breast, corpus uteri, kidney, and for non-Hodgkin's lymphoma. Rates declined notably for cancers of the esophagus (-54% and -53%), cervix uteri (-86%), and to a lesser extent (10-20%) cancers of the male stomach and liver. These observed trends can be explained only partly by improvements in cancer diagnosis and completeness of the cancer registry, and most likely reflect changes in the prevalence of risk factors in this population.

Reproductive, menstrual, and medical risk factors for endometrial cancer: results from a case-control study

OBJECTIVE

Our objective was to evaluate the risk for endometrial cancer in relation to reproductive, menstrual, and medical factors.

STUDY DESIGN

A case-control study of 405 endometrial cancer cases and 297 population controls in five areas of the United States enabled risk to be evaluated.

RESULTS

A major risk factor was the absence of a prior pregnancy (relative risk 2.8, 95% confidence interval 1.7 to 4.6). The protective effect of pregnancy appeared to reflect the influence of term births, because spontaneous and induced abortions were unrelated to risk. Among nulliparous women infertility was a significant risk factor, with women having sought medical advice having nearly eight times the risk of those without difficulty conceiving. After adjustment for other reproductive characteristics, age at first birth and duration of breast-feeding were not related to risk.

CONCLUSIONS

Elevated risks were found for subjects reporting early ages at menarche (relative risk 2.4 for ages < 12 vs > or = 15) and longer days of flow (relative risk 1.9 for > or = 7 vs < 4 days), but there was no relationship with late ages at natural menopause. Height was not associated with risk, but there was a significant relation to weight, with the risk for 200 versus < 125 pounds being 7.2 (95% confidence interval 3.9 to 13.3). After adjustment for weight and other factors, histories of hypertension and gallbladder disease were not significantly related to risk, but an effect of diabetes persisted (relative risk 2.0, 95% confidence interval 1.1 to 3.6). Hirsutism developing at older ages was also significantly related (relative risk 2.0, 95% confidence interval 1.2 to 3.4).