A case-control study of endometrial cancer in relation to cigarette smoking, serum estrogen levels, and alcohol use

Analysis of correlation between estradiol and fracture of femur neck

Osteoporosis is a major public health challenge all over the world. Estrogen hormone was cited amongst other hormones to be an efficient hormone for the production and maintenance of bone density. This study was designed with the purpose of evaluating and analyzing the estradiol effect on fractures of femur neck in the Iranian society. This study evaluated men over 50 years of age suffering with mild trauma (falling off the same level height or lower) and with a fracture on their femur neck. Also, their serum level of estradiol was measured with an ELISA method. Using this procedure, the patients were assigned into groups with either normal estradiol serum level (10pg/ml and higher) or with lower than normal level (lower than 10 pg/ml). A control group including 50-year-old and older men without hip fracture, or its history, was chosen to access their estradiol serum level. Data collected from these two groups were statistically compared. A total of 120 patients were evaluated (60 in the control and 60 in the test group). The mean age of patients in the control and test groups were 67.9±10.22 and 69.5±8.84 years, respectively (p=0.376). Smoker patients’ percentages in the control and test groups were 35% and 31.7%, respectively (p=0.699). On the basis of the serum estradiol level, patients’ percentages with low estradiol level in control and test groups were 10% and 16.7%, respectively (p=0.283). The only significant factor in predicting serum estradiol level was smoking. In conclusion, in this study it was observed that fractures of the femoral neck following a mild trauma were not correlated to low level of serum estradiol.

Disease risk estimation by combining case-control data with aggregated information on the population at risk

We propose a novel statistical framework by supplementing case-control data with summary statistics on the population at risk for a subset of risk factors. Our approach is to first form two unbiased estimating equations, one based on the case-control data and the other on both the case data and the summary statistics, and then optimally combine them to derive another estimating equation to be used for the estimation. The proposed method is computationally simple and more efficient than standard approaches based on case-control data alone. We also establish asymptotic properties of the resulting estimator, and investigate its finite-sample performance through simulation. As a substantive application, we apply the proposed method to investigate risk factors for endometrial cancer, by using data from a recently completed population-based case-control study and summary statistics from the Behavioral Risk Factor Surveillance System, the Population Estimates Program of the US Census Bureau, and the Connecticut Department of Transportation.

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.

Case-control study of lifetime alcohol consumption and endometrial cancer risk

Purpose

Alcohol consumption is hypothesized to increase the risk of endometrial cancer by increasing circulating estrogen levels. This study sought to investigate the association between lifetime alcohol consumption and endometrial cancer risk.

Methods

We recruited 514 incident endometrial cancer cases and 962 frequency age-matched controls in this population-based case–control study in Alberta, Canada, from 2002 to 2006. Participants completed in-person interviews querying lifetime alcohol consumption and other relevant health and lifestyle factors. Participants reported the usual number of drinks of beer, wine, and liquor consumed; this information was compiled for each drinking pattern reported over the lifetime to estimate average lifetime exposure to alcohol.

Results

Lifetime average alcohol consumption was relatively low (median intake: 3.9 g/day for cases, 4.9 g/day for controls). Compared with lifetime abstainers, women consuming >2.68 and ≤8.04 g/day alcohol and >8.04 g/day alcohol on average over the lifetime showed 38 and 35 % lower risks of endometrial cancer, respectively (p trend = 0.023). In addition, average lifetime consumption of all types of alcohol was associated with decreased risks. There was no evidence for effect modification by body mass index, physical activity, menopausal status, and hormone replacement therapy use combined and effects did not differ by type of endometrial cancer (type I or II).

Conclusion

This study provides epidemiologic evidence for an inverse association between relatively modest lifetime average alcohol consumption (approximately 1/4 to 1/2 drink/day) and endometrial cancer risk. The direction of this relation is consistent with previous studies that examined similar levels of alcohol intake.

Alcohol and endometrial cancer risk in the NIH-AARP diet and health study

Previous investigations have provided conflicting results regarding whether alcohol consumption affects endometrial cancer risk, although in many of these studies the highest category of alcohol intake examined was limited. Further, most were unable to resolve how alcohol associations are affected by beverage type, the presence of other endometrial cancer risk factors, or tumor characteristics. To address these issues, we prospectively evaluated the association between alcohol intake and incident endometrial cancer (n = 1,491) in a cohort of 114,414 US women enrolled in the NIH-AARP Diet and Health Study. We calculated relative risks (RR) and 95% confidence intervals (CI) using Cox proportional hazards regression. After adjustment for age, body mass index (BMI), smoking and other potential confounders, the multivariable RRs (and 95% CIs) compared with nondrinkers were 0.97 (0.87-1.09) for >0-<12 g of alcohol/day, 1.06 (0.87-1.31) for 12-<24 g/day and 0.93 (0.71-1.20) for ≥ 24 g/day (p trend = 0.90). There was, however, some suggestion of higher risks associated with alcohol consumption among lean women (BMI, <25) and users of menopausal hormone therapy, with significant interactions with both parameters (respective interaction p-values of 0.002 and 0.005). The relationship was also enhanced, albeit nonsignificantly so, for low grade cancers. Our results do not support that alcohol is a strong contributor to endometrial cancer risk, but slight risk increases may prevail among some users or for selected tumor characteristics.

Alcohol intake and endometrial cancer risk: a meta-analysis of prospective studies

Background:

Studies on alcohol intake in relation to endometrial cancer risk have produced inconsistent results.

Methods:

For a meta-analysis, we identified cohort studies of alcohol and endometrial cancer by a literature search of Pub-Med and Embase up to 1 March 2010 and by searching the reference lists of relevant articles.

Results:

Seven cohort studies, including 1 511 661 participants and 6086 endometrial cancer cases, were included in the dose–response random-effect meta-regression model. Compared with non-drinkers, women drinking less than 1 drink of alcohol (13 g of ethanol) per day had a lower risk for endometrial cancer; this risk was lower by 4% (95% confidence interval (95% CI): 0.93–1.00) for consumption up to 0.5 drink per day and by 7% (95% CI: 0.85–1.02) for consumption up to 1 drink. However, we found evidence of an increased risk for endometrial cancer for intakes higher than two alcoholic drinks per day: compared with non-drinkers, the risk was higher by 14% (95% CI: 0.95–1.36) for 2–2.5 drinks per day and by 25% (95% CI: 0.98–1.58) for >2.5 drinks per day.

Conclusion:

Our meta-analysis indicates a possible J-shaped relationship between alcohol intake and endometrial cancer risk.

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.

Long-term alcohol consumption and risk of endometrial cancer incidence: a prospective cohort study

Alcohol consumption has been hypothesized to increase the risk of endometrial cancer. We used data from the prospective population-based Swedish Mammography Cohort including 61,226 women to examine the association between alcohol and endometrial cancer incidence. Alcohol consumption was assessed with validated food frequency questionnaires at baseline 1987 to 1990 and at follow-up in 1997. During a mean follow-up of 17.6 years, 687 endometrial cancer cases were identified in the Swedish cancer registries. We found no association between alcohol consumption and endometrial cancer risk after adjustment for age, body mass index, and smoking. The multivariable rate ratios (95% confidence intervals) for the three upper categories of long-term alcohol consumption as compared with no consumption were 1.01 (0.84-1.22) for <3.4 g/d, 1.01 (0.80-1.27) for 3.4 to 9.9 g/d, and 1.09 (0.71-1.67) for >or=10 g/d, respectively. The association did not differ by age, body mass index, folic acid intake, or postmenopausal hormone use in stratified analysis. In conclusion, our results suggest that low alcohol consumption (up to one drink per day) is unlikely to substantially influence risk of endometrial cancer.

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.

Body mass, diabetes and smoking, and endometrial cancer risk: a follow-up study

We examined the relationship of body mass index (BMI), diabetes and smoking to endometrial cancer risk in a cohort of 36 761 Norwegian women during 15.7 years of follow-up. In multivariable analyses of 222 incident cases of endometrial cancer, identified by linkage to the Norwegian Cancer Registry, there was a strong increase in risk with increasing BMI (P-trend <0.001). Compared to the reference (BMI 20–24 kg m⁻²), the adjusted relative risk (RR) was 0.53 (95% confidence interval (CI): 0.19–1.47) for BMI<20 kg m⁻², 4.28 (95% CI: 2.58–7.09) for BMI of 35–39 kg m⁻² and 6.36 (95% CI: 3.08–13.16) for BMI⩾40 kg m⁻². Women with known diabetes at baseline were at three-fold higher risk (RR 3.13, 95% CI: 1.92–5.11) than those without diabetes; women who reported current smoking at baseline were at reduced risk compared to never smokers (RR 0.55, 95% CI: 0.35–0.86). The strong linear positive association of BMI with endometrial cancer risk and a strongly increased risk among women with diabetes suggest that any increase in body mass in the female population will increase endometrial cancer incidence.

Alcohol consumption, cigarette smoking, and endometrial cancer risk: results from the Netherlands Cohort Study

Objective

To examine the association between alcohol consumption, cigarette smoking, and endometrial cancer.

Methods

In 1986, the Netherlands Cohort Study was initiated. A self-administered questionnaire on dietary habits and other cancer risk factors was completed by 62,573 women. Follow-up for cancer was established by record linkage to the Netherlands Cancer Registry.

Results

After 11.3-years of follow-up, 280 incident endometrial cancer cases were available for analyses. In multivariate analysis, the rate ratio (RR) for alcohol users versus non-users was 1.06 (95% Confidence Interval (95% CI) = 0.78–1.43). There were neither dose-dependent trends nor associations with different types of beverages. The RR for former and current smokers versus never-smokers was 0.83 (95% CI = 0.58–1.20) and 0.59 (95% CI = 0.40–0.88), respectively. These estimates did not change significantly when body mass index (BMI) and age at menopause were added to the models.

Conclusions

There is no association between alcohol consumption and endometrial cancer. Current smoking is associated with a reduced risk of endometrial cancer. This association is neither mediated by BMI nor by age at menopause.

Variants in estrogen biosynthesis genes, sex steroid hormone levels, and endometrial cancer: a HuGE review

Variants in genes involved in estrogen biosynthesis are likely to be important in the etiology of endometrial cancer. This review summarizes data on variants in seven genes in the estrogen biosynthesis pathway and their relation to circulating levels of sex steroid hormones in women and to risk of endometrial cancer. Little or no association was found between genotypes of the cytochrome P-450 genes CYP11A1 (-528[TTTTA]n) or CYP17A1 (-34T/C) or the 17beta-hydroxysteroid dehydrogenase 1 gene HSD17B1 (Ser312Gly) and levels of progesterone, androgens, or estrogens. The position -34T/C variant in CYP17A1 appears to be associated with reduced risk of endometrial cancer, with those homozygous for the variant allele having about half the risk of those homozygous for the wild type. Linked variants in CYP19A1 (intron 4 [TTTA]n, intron 4 [TCT] insertion/deletion, exon 10 C/T) are related to some hormone levels and, based on two studies, to risk of endometrial cancer. For other genes (HSD3B1, HSD3B2, HSD17B2), no information is available on these associations. Results indicate the need to study other variants and haplotypes in these genes, particularly CYP17A1 and CYP19A1, as well as variants in other genes involved in hormone biosynthesis and metabolism pathways. Larger studies or combined studies that allow for investigation of gene-gene and gene-environment interactions are warranted.

Nucleotide excision repair genotype and the incidence of endometrial cancer: effect of other risk factors on the association

OBJECTIVES

Certain nucleotide excision repair (NER) genotypes appear to be associated with an altered risk of endometrial cancer. These associations could be modified by characteristics and exposures that themselves influence risk of disease.

METHODS

We conducted a population-based case-control study in western Washington State to address the role of specific NER genotypes in conjunction with relevant exposures, such as postmenopausal hormone therapy, obesity, parity, oral contraceptive use, and cigarette smoking on risk of endometrial cancer. Case women (n=371), ages 50-69 years, were diagnosed with invasive endometrial cancer between 1994 and 1999. Control women (n=420), matched to cases on age and county of residence, were selected using random-digit dialing (ages 50-65) and random selection from HCFA data files (ages 66-69).

RESULTS

Risk of endometrial cancer was not associated with ERCC1, ERCC2 (XPD), ERCC4 (XPF), or ERCC5 (XPG) genotype. A reduced risk of endometrial cancer was observed with presence of the XPA g23a variant allele, but only among women with a history of oral contraceptive use (OR 0.47, 95% CI 0.32-0.69). A decreased risk associated with carriage of at least one variant allele for both XPC A499V and XPC K939Q was restricted to women with BMI<30 kg/m2 (OR 0.45, 95% CI 0.25-0.82). The size of the association between these genotypes and risk of endometrial cancer did not differ by postmenopausal hormone use, parity, or smoking.

CONCLUSIONS

Our study provides limited evidence for interactions between NER genotypes and DNA damage-causing exposures in the etiology of endometrial cancer. Subsequent studies are needed to confirm the observed associations.

Active and passive smoking and risk of ovarian cancer

It is unclear whether smoking is a risk factor for epithelial ovarian cancer, although some studies have suggested that it may be associated with an increased risk of mucinous tumors. This study investigated the effect of smoking and environmental tobacco smoke (ETS) on ovarian cancer risk among 434 women with primary epithelial ovarian, peritoneal, or fallopian cancers and 868 age- and region-matched hospital controls with nonneoplastic conditions. All participants completed a comprehensive epidemiologic questionnaire. Results indicate that decreased risk of ovarian cancer was associated with being a nonsmoker exposed to ETS (adjusted odds ratio [aOR] 0.68, 95% confidence interval [CI] 0.46-0.99), a former smoker (aOR 0.76, 95% CI 0.53-1.10), or a current smoker (aOR 0.53, 95% CI 0.32-0.88). A similar protective effect was noted for smokers with moderate or high exposure based on smoking intensity, duration, and cumulative exposure, as well as for never smokers exposed to ETS. Results did not differ substantially by histologic subtype. Although prevailing theories of ovarian cancer etiology implicate incessant ovulation, characteristics of the study population suggest that anovulation was not the protective mechanism in this study. Immunosuppression by nicotine or upregulation of enzymes that metabolize carcinogens may be responsible for the effects observed.

Smoking as a determinant for plasma levels of testosterone, androstenedione, and DHEAs in postmenopausal women

The aim of the present study was to investigate whether current smoking, ex-smoking, or amount of current smoking among postmenopausal women was associated with plasma levels of testosterone, and rostenedione, and DHEAs. About 65,000 women in Sweden have participated in two population-based prospective cohort studies where blood samples were collected at baseline, and information on life-style, reproductive history and anthropometrical measurements were available. The present study was based on 407 control subjects from a previous nested case-control study on the relation between steroid hormone levels and risk of breast cancer. A multivariate logistic regression analysis, adjusted for potential confounders, was used in order to obtain odds ratios (OR) with 95% confidence intervals. There was a high risk of high testosterone levels (above the median) in current vs. never smokers, OR: 1.85 (1.06-3.23). Risk of high testosterone levels increased by amount of daily smoking (increments of 10 cigarettes/day), OR: 1.55 (1.02-2.37). Ex-smoking was associated with high testosterone levels, OR: 1.56 (0.98-2.47). Current smoking and increasing amount of current smoking were weakly associated with high androstenedione levels. However, these associations did not reach statistical significance. No association was seen between smoking habits and DHEAs levels. We conclude that current smoking, and increasing amount of daily smoking, is associated with high testosterone levels.

Smoking and the risk of endometrial cancer: results from the Nurses' Health Study

An inverse association between smoking and endometrial cancer has generally been observed, primarily among current smokers. To assess this association, we analyzed data from the prospective Nurses' Health Study. From 1976 to 2000, 702 cases of invasive endometrial cancer were identified during 1.8 million person-years of follow-up. Smoking status was assessed in 1976 and updated every 2 years. Cox proportional hazards models were used to calculate multivariate relative risks (RRs), controlling for endometrial cancer risk factors. Compared to never smokers, the multivariate RR of endometrial cancer was significantly lower among both current smokers (RR = 0.63; 95% CI = 0.50-0.79) and past smokers (RR = 0.73; 95% CI = 0.62-0.87). When additionally adjusting for body mass index (BMI), the RR for current smokers was attenuated (RR = 0.72; 95% CI = 0.57-0.90), but the RR for past smokers did not change. Risk was lower among women who smoked 35 or more cigarettes a day (RR = 0.60; 95% CI = 0.39-0.91) and among those who smoked for 40 or more years (RR = 0.63; 95% CI = 0.45-0.87). Tests for trend, which excluded never smokers, were not statistically significant for any of the smoking variables analyzed. These data indicate that both current and past smoking are associated with a lower risk of endometrial cancer. The findings provide insight into disease etiology and suggest that the influence of smoking on endometrial cancer risk occurs even in early adulthood, is long-lasting, and may not be attributed solely to short-term hormonal modulation.

Overview of smoking and all cancers

Tobacco consumption has been clearly implicated in the causation of many cancer types, with irrefutable evidence to support the association in multiple organ systems. Tobacco cessation leads to reduced cancer risk and improved survival of those under treatment for their already established cancers. As understanding of the mechanisms by which tobacco products cause cancer increases, clinicians may be able to identify those at highest risk for tobacco-related malignancies and allow for more focused interventions toward risk reduction among current tobacco users. This article reviews the carcinogens present in tobacco products, the mechanisms by which tobacco causes cancer, and the various tumor types causally related to tobacco use.

Insulin-Like Growth Factors, Insulin-Like Growth Factor-Binding Proteins, and Endometrial Cancer in Postmenopausal Women: Results from a U.S. Case-Control Study

Objective: To assess whether circulating insulin-like growth factor-1 (IGF-1), IGF-2, insulin-like growth factor-binding protein-1 (IGFBP-1), or IGFBP-3 were associated with endometrial cancer in postmenopausal women. Study Design: Between 1987 and 1990, we conducted a case-control study of 405 women with endometrial cancer and 297 matched population-based controls. This analysis included 174 postmenopausal cases and 136 controls. Results: In logistic regression models adjusted for potential confounders, higher IGF-1 levels were not positively associated with endometrial cancer: odds ratio (OR) for the highest tertile versus the lowest tertile = 0.63, 95% confidence interval (CI) = 0.30–1.32. Endometrial cancer was inversely associated with IGF-2 (OR for the highest tertile = 0.35, 95% CI = 0.18–0.69) and IGFBP-3 (OR for the highest tertile = 0.40, 95% CI = 0.21–0.77), and not associated with IGFBP-1. Conclusion: Serum IGF-1, IGF-2, and IGFBP-3, but not IGFBP-1, were inversely associated with endometrial cancer in postmenopausal women. These associations and the potential role of the IGF system in endometrial proliferation and carcinogenesis warrant further research.

Hormone Replacement Therapy and Lung Cancer Risk

PURPOSE

To date, there are few published data regarding the use of hormone replacement therapy (HRT) and lung cancer risk. Therefore, we analyzed data regarding HRT use from a large case-control study designed to study genetic susceptibility to lung cancer to determine whether HRT affected risk of lung cancer.

EXPERIMENTAL DESIGN

In a secondary analysis, we compared self-reported HRT use among 499 women with lung cancer and 519 healthy age-matched controls.

RESULTS

HRT use was associated with an overall reduced risk of 34% [odds ratio (OR), 0.66; 95% confidence interval (CI), 0.51-0.89] of lung cancer, after adjusting for age, ethnicity, smoking status, education, body mass index, and menopausal status. The use of estrogen replacement therapy alone was associated with a 35% reduction in lung cancer risk (OR, 0.65; 95% CI, 0.47-0.89) and the use of combination therapy (estrogen and progestin) was associated with a 39% reduction in lung cancer risk (OR, 0.61; 95% CI, 0.40-0.92). HRT use was also associated with a statistically significantly reduced risk of lung cancer in current smokers (OR, 0.59; 95% CI, 0.38-0.92), but the risk estimates were not statistically significant in never (OR, 0.72; 95% CI, 0.37-1.40) or former smokers (OR, 0.73; 95% CI, 0.46-1.15). In addition, as the cigarette pack-years increased among ever smokers, the protective effect diminished, so that light smokers appeared to benefit the most from HRT use. Decreased lung cancer risks were also evident when the data were stratified by age, ethnicity, and body mass index. The joint effects of HRT use and mutagen sensitivity suggest that HRT use modifies lung cancer risk for genetically susceptible women. HRT use was also associated with a lower risk of death and improved survival compared with the women not taking HRT. To provide a possible biological mechanism to explain our findings, we compared plasma levels of insulin-like growth factor I in users and nonusers, and demonstrated that HRT use was associated with statistically significantly lower insulin-like growth factor I levels for both cases and controls compared with non-HRT users.

CONCLUSIONS

These data suggest an association of HRT use with a decrease in lung cancer risk. However, there are several limitations to this secondary analysis, requiring that the data be viewed with caution, and confirmation is required in well-designed hypothesis driven studies. The biological role of HRT in lung cancer remains understudied, and only extensive research can yield new insights into the mechanisms underlying a protective effect of HRT for lung cancer.

Alcohol consumption and endometrial cancer: some unresolved issues

The role of hormonal factors, in particular unopposed estrogens, on endometrial cancer occurrence is well established. Progesterone deficiency has also been suggested as a possible risk factor. Alcohol use has been shown to be associated with elevated estrogen levels and reduced progesterone. Epidemiologic studies, however, have not offered much support for a positive association between alcohol intake and endometrial cancer, with results generally indicating no association or suggesting an inverse relationship with endometrial cancer. However, certain methodologic limitations, such as small sample size, limited range of alcohol intake, and confounding may have explained those findings. Moreover, there are some unexplored aspects of the possible effect of alcohol, such as the possible interaction with use of exogenous estrogens, and other factors, that need clarification.

Dietary factors in relation to endometrial cancer: a nationwide case-control study in Sweden

The incidence of endometrial cancer varies up to 10-fold between high- and low-incidence regions, suggesting the importance of environmental factors, including diet, in the etiology of this disease. However, few studies have examined the role of diet in the etiology of endometrial cancer. Using unconditional logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI), we analyzed data from a large, case-control study of Swedish-born postmenopausal women aged 50-74 yr (709 cases and 2,887 controls) residing in Sweden between 1994 and 1995. We found no clear association between foods or food groups and endometrial cancer risk, although high consumption of certain foods, such as Brassica vegetables, coffee, and legumes, might be associated with small-to-moderate reduced risks of endometrial cancer, while red meat consumption might be associated with a small-to-moderate increased risk. Daily use of calcium supplements appeared to lower endometrial cancer risk (OR = 0.5, 95% CI = 0.3-0.9, P for trend = 0.04), especially among women with low calcium intake from dairy products. On the other hand, the use of iron supplements appeared to increase the risk (OR = 1.7, 95% CI = 0.9-3.3, P for trend = 0.03). The findings are discussed with respect to previous studies and the possible underlying mechanisms.

Tobacco use and cancer causation: association by tumour type

In the second part of our review we describe the association between tobacco use and risk of specific cancer types. There is evidence for an established association of tobacco use with cancer of the lung and larynx, head and neck, bladder, oesophagus, pancreas, stomach and kidney. In contrast, endometrial cancer is less common in women who smoke cigarettes. There are some data suggesting that tobacco use increases the risk for myeloid leukaemia, squamous cell sinonasal cancer, liver cancer, cervical cancer, colorectal cancer after an extended latency, childhood cancers and cancer of the gall bladder, adrenal gland and small intestine. Other forms of cancer, including breast, ovarian and prostate cancer, are unlikely to be linked to tobacco use.

Cigarette smoking and the risk of endometrial cancer

Epidemiological studies have shown that cigarette smoking is associated with a reduced risk of endometrial cancer, in contrast to the increased risks observed with many other non-respiratory-tract cancers, including those of the bladder, pancreas, and cervix uteri. Some studies of endometrial cancer suggest that the inverse association with smoking is limited to certain groups of women, such as those who are postmenopausal or those taking hormone-replacement therapy. The biological mechanisms that might underlie this association remain unclear, although several have been proposed, including an antioestrogenic effect of cigarette smoking on circulating oestrogen concentrations, a reduction in relative bodyweight, and an earlier age at menopause. We have examined the evidence for an association between cigarette smoking and risk of endometrial cancer, including studies related to the proposed biological mechanisms.

A prospective cohort study of cigarette smoking and the risk of endometrial cancer

Case-control studies have shown inverse associations between cigarette smoking and endometrial cancer risk. However, two small prospective cohort studies have not clearly supported an association. Moreover, quantitative measures of smoking have been examined infrequently. Our aim was to study the association between smoking and endometrial cancer risk in a large prospective cohort. We used proportional hazards models to estimate hazard ratios relating cigarette smoking to endometrial cancer risk among 70 591 women aged 40-59 years at recruitment into a randomised controlled trial of mammography screening for breast cancer. During an average of 10.6 years of follow-up (751 833 person-years), a total of 403 women were diagnosed with incident endometrial cancer. We found that a reduced endometrial cancer risk was evident only among women who currently smoked 20 cigarettes per day or more (hazard ratio=0.62, 95% CI=0.42-0.92, P for trend=0.03). There was some suggestion of an inverse association with smoking duration, but this was less clear. The association did not vary with menopausal status, relative body weight, or the use of hormone replacement therapy, but it appeared to be stronger among parous than nulliparous women. The underlying biological mechanisms of this association remain unclear.

A cohort study of nutritional factors and endometrial cancer

To evaluate the role of nutritional factors in the etiology of endometrial cancer, we performed a case-cohort analysis using data from women enrolled in the National Breast Screening Study in Canada from 1980 to 1985. For this analysis, a subcohort was constructed by selecting a 10% random sample from the 56,837 women in the dietary cohort. Cases were the 221 women diagnosed with incident adenocarcinoma of the endometrium during follow-up to December 31, 1993 and ascertained by record linkage to the Canadian Cancer Database. Information on usual diet at enrollment and other epidemiological variables was collected by means of self-administered questionnaires. Hazard ratios were obtained from proportional hazards regression models, with estimation of robust standard errors. We found a strong association of endometrial cancer with body mass index > 25 kg/m2 (hazard ratio 2.72, 95% CI: 2.06-3.50). Endometrial cancer risk was not associated significantly with intakes of total energy, carbohydrates, proteins, total fat and major fatty acids, total dietary fiber and various types of fibers, vitamin C, E and A, folic acid, beta-carotene, lutein, or cryptoxanthin. Some decrease in risk was noted with relatively high intakes of saturated fat, animal fat or lycopene. The associations observed in the study were independent of total energy intake and most non-dietary risk factors. The study suggests that dietary intakes of energy and most major nutrients are not related to the risk of endometrial cancer among Canadian women.

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.

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.

Breast cancer incidence in relation to smoking cessation

High plasma levels of oestrogens are associated with increased breast cancer risk. If smoking, as has been suggested, have both a tumour initiating mutagenic effect and a protective anti-oestrogenic effect, one would assume that smokers who give up smoking have the highest incidence of breast cancer. This was evaluated in the follow-up of a cohort of 10,902 women of whom 4,359 were premenopausal. Record-linkage with official cancer registries yielded 416 incident cases during an average follow-up of 13.6 years. The adjusted relative risk in all ex-smokers was 1.31 (1.02-1.69), as compared to never smokers, and in premenopausal ex-smokers it was 1.57 (1.07-2.30). Breast cancer incidence in premenopausal ex-smokers was inversely related to time since cessation, (p for trend = 0.01), and was highest among the women who had given-up smoking less than 12 months before screening: 2.76 (1.55-4.91). There was no significant association between current smoking and breast cancer risk. We conclude that incidence of breast cancer in premenopausal women who have given up smoking is higher than it is in smokers and never smokers. To what extent this may be related to endocrine effects associated with smoking cessation remains to be evaluated.

Risk factors for hyperplasia-associated versus atrophy-associated endometrial carcinoma

OBJECTIVE

Endometrial cancer can be divided into atrophy-associated and hyperplasia-associated subtypes. It has been suggested that these subtypes have different pathologic features and prognoses. This preliminary study explores whether these subtypes are associated with different risk factors.

STUDY DESIGN

Hysterectomies performed in cases of endometrial carcinoma with evaluable benign endometrium on routine processing were reviewed, and clinical data were abstracted from medical records. Forty-eight subjects with atrophy-associated and 28 subjects with hyperplasia-associated cancers were studied.

RESULTS

We found younger age, higher weight, absence of cigarette smoking, and earlier menarche in subjects with hyperplasia-related cancers.

CONCLUSIONS

Our findings support the idea that hyperplasia-associated endometrial cancer is estrogen-related but also suggest that atrophy-associated cases may result from a different causal pathway. Epidemiologic studies may yield more precise and accurate measures of association if atrophy-associated and hyperplasia-associated endometrial cancers are considered separately.

Lifestyle and endometrial cancer risk: a cohort study from the Swedish Twin Registry

Case-control studies of lifestyle factors have been inconclusive in the study of endometrial cancer, and prospective data are scarce. Our aim was to examine the associations of physical activity, weight and weight change, fruit, vegetable, and alcohol consumption, socio-economic status, parity and presence of diabetes mellitus with the risk of endometrial cancer in a cohort study. In 1967, 11,659 women in the Swedish Twin Registry, born 1886-1925, answered a 107-item questionnaire, including questions about diet, physical activity and other lifestyle factors. Complete follow-up through 1992 was attained through record linkage to the Swedish Cancer and Death Registers. The relative risks for endometrial cancer were estimated in proportional hazards models that adjusted confidence limits for correlated outcomes. We observed 133 incident cases of endometrial cancer in the cohort. There was no clear pattern of risk over strata of alcohol or fruit and vegetable intake, although the data suggest an increased risk with very low fruit and vegetable intake. Increasing physical activity markedly decreased the risk of endometrial cancer (p for trend < 0.01), independently of weight and parity; the risk in the highest quartile, relative to the sedentary category, was 0.2 (95% CI 0.3-0.8). As expected, higher weight in middle age increased the risk (p for trend < 0.01), as did higher weight in early adulthood. Contrary to previous findings, weight gain did not have an effect independent of weight at enrollment. We did not find a genetic component to endometrial cancer. Our results confirm that environmental factors are the most important, especially physical activity, parity, and weight in young and middle age.

Medical risks for women who drink alcohol

OBJECTIVE

To summarize for clinicians recent epidemiologic evidence regarding medical risks of alcohol use for women.

METHODS

MEDLINE and PsychINFO, 1990 through 1996, were searched using key words "women" or "woman," and "alcohol." MEDLINE was also searched for other specific topics and authors from 1980 through 1996. Data were extracted and reviewed regarding levels of alcohol consumption associated with mortality, cardiovascular disease, alcohol-related liver disease, injury, osteoporosis, neurologic symptoms, psychiatric comorbidity, fetal alcohol syndrome, spontaneous abortion, infertility, menstrual symptoms, breast cancer, and gynecologic malignancies. Gender-specific data from cohort studies of general population or large clinical samples are primarily reviewed.

MAIN RESULTS

Women develop many alcohol-related medical problems at lower levels of consumption than men, probably reflecting women's lower total body water, gender differences in alcohol metabolism, and effects of alcohol on postmenopausal estrogen levels. Mortality and breast cancer are increased in women who report drinking more than two drinks daily. Higher levels of alcohol consumption by women are associated with increased menstrual symptoms, hypertension, and stroke. Women who drink heavily also appear to have increased infertility and spontaneous abortion. Adverse fetal effects occur after variable amounts of alcohol consumption, making any alcohol use during pregnancy potentially harmful.

CONCLUSIONS

In general, advising nonpregnant women who drink alcohol to have fewer than two drinks daily is strongly supported by the epidemiologic literature, although specific recommendations for a particular woman should depend on her medical history and risk factors.

Cigarette smoking, sex hormones and bone density in women

It is known that among women over the age of 65, bone mineral density is lower, and the risk of hip fracture higher, in smokers than non-smokers. We report a study in 1334 health pre- and post-menopausal women aged 35-64 years, to determine whether this effect can be attributed to lower oestrogen levels in smokers. Among 676 premenopausal women forearm bone density was no lower in smokers (95% confidence interval 1% lower, 4% higher). Among 543 postmenopausal women who had not used hormone replacement therapy (HRT) for more than a year there was no statistically significant difference, but the lower confidence interval was consistent with a lower bone density in older smokers (by 8% at age 55-59, 16% at age 60-64). Measurements in 194 postmenopausal women not taking HRT showed that oestrone and oestradiol were similar in smokers and non-smokers, as were cortisol and FSH, LH and prolactin. Meta-analysis of the present study and previous studies confirmed significantly higher levels in smokers of the androgens DHEAS (by 37%) and androstenedione (by 34%). Oestrogens were no lower in smokers, and the lower confidence limit excluded more than a trivial effect of smoking in lowering oestrogen. These results indicate that the recognised lower bone density in elderly smokers cannot be explained by an effect of smoking on oestrogen, since in premenopausal women bone density is no lower in smokers and in postmenopausal women oestrogens are no lower in smokers. The data suggest a balance between higher androgen levels but lower rates of conversion of androgens to oestrogens in smokers. The effect of smoking on bone may be due to impaired response of bone and other target organs to oestrogen, or to actions independent of oestrogen.

Environmental toxins and endometriosis

The effect of natural, environmental, or manufactured substances on endocrine organs is a current topic of discussion. Recently, some toxicants have been suggested to promote endometriosis; therefore, attention has turned to the role of environmental factors as a stimulant for endometriosis growth and maintenance. This article reviews the influence of various toxicants on endometriosis.

Epidemiologic data on alcoholic beverage consumption and risk of cancer

Recent epidemiologic data confirm the results of earlier studies in supporting that alcoholic beverage consumption is a cause of cancer of the mouth, pharynx, larynx, esophagus, and liver. The effect of a specified level of alcohol intake on absolute risk of cancers of the head, neck, and esophagus depends on the presence of other risk factors, especially smoking. Whether alcoholic beverage consumption is a cause of cancer of the breast or large bowel is unclear. Alcohol intake appears not to increase risk of cancer of the lung, bladder, prostate, stomach, ovary, endometrium, or of melanoma. Indirect epidemiologic evidence suggests that alcohol may be a weak causal factor for pancreatic cancer. Although heavy alcohol consumption increases risk of cancer of the head, neck, esophagus, and liver, whether moderate alcohol consumption increases risk at these sites is unclear.

Nutrition and endometrial cancer

Epidemiologic evidence on the relation between nutrition and endometrial cancer (EC) is reviewed. Obesity is an important determinant of EC, probably because of its effect on the hormonal milieu of both pre- and postmenopausal women. However, epidemiologic studies of body fat distribution and EC are inconsistent, as are the data pertaining to the relation between body fat distribution and sex hormones. Randomized and observational studies of diet and sex hormones indicate that low fat diets may be associated weakly with decreased estrogen levels, and thus a lowering of EC risk. Only ecologic and case-control studies of diet and EC have been reported. These findings as well as the methodologic limitations of these study designs are discussed. Both types of studies implicate fat as a potential risk factor, while the case-control studies suggest that carotene may lower risk of EC. Epidemiologic studies of alcohol and EC also are inconsistent, but generally indicate no association, or a weak protective effect. The role of diet in the etiology of EC is unresolved. The conduct of cohort and intervention studies, which can avoid many of the methodologic shortcomings of ecologic and case-control studies, would improve our understanding of diet and EC.

Alcohol consumption and risk of cancer in humans: an overview

Recent epidemiologic data continue to support alcoholic beverage consumption as a cause of cancer of the mouth, pharynx, larynx, esophagus, and liver. The effect of a given alcohol intake on absolute risk of these cancers depends on the prevalence of other risk factors. Whether alcoholic beverage consumption is a cause of cancer of the breast or large bowel is unclear. Alcohol intake appears not to increase risk of cancer of the lung, bladder, prostate, stomach, ovary, endometrium, or of melanoma. Indirect epidemiologic evidence suggests that alcohol may be a weak causal factor for pancreatic cancer. Additional research is needed to determine whether middle-aged women who drink moderately may experience a slight increase in longevity if they decrease alcohol intake. A number of biologically plausible mechanisms exist by which alcohol may cause cancer.

Alcohol and endometrial cancer risk: findings from an Italian case-control study

Using data from a case-control study conducted in Northern Italy, we analyzed the relation between alcohol drinking and risk of endometrial cancer. Cases were 726 patients, < 75 years of age, admitted to the Ospedale Maggiore (including the 4 largest teaching and general hospitals in the Greater Milan area), the University Obstetrics and Gynecology Clinics, and the National Cancer Institute of Milan with histologically confirmed endometrial cancer. Controls were 2,123 nonhysterectomized patients, < 75 years of age, admitted for acute nongynecological non-hormone-related nonneoplastic conditions to the same network of hospitals where cases had been identified. When total consumption of all alcoholic beverages was considered, 68.2% of cases and 63.9% of controls were drinkers and 12% of cases and 9.3% of controls reported > or = 2 drinks/day. Considering total alcohol drinking, the relative risk for alcohol drinkers vs. nondrinkers was 1.3 (95% confidence interval 1.1-1.5), and the RR estimates for subsequent levels of intake were 1.1, 1.4, and 1.6 for women drinking > 0 < or = 1, > 1 < or = 2 drinks/day (chi 2(1) trend 11.33, p < 0.001). The estimates were similar when wine only (which represents the large majority of all alcohol intake in Italy) was considered, whereas data were less informative for beer and spirits intake only. No relation emerged between duration of alcohol consumption and risk of endometrial cancer. These findings suggest a potential link between alcohol drinking and endometrial cancer risk and are, in any case, inconsistent with a protective role of alcohol in endometrial carcinogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)