Insulin resistance, insulin-like growth factor I and breast cancer: a hypothesis

Association Between Metabolic Syndrome and Mortality: Prospective Cohort Study

BACKGROUND

Metabolic syndrome (MetS) is a common metabolic disorder that results from the increasing prevalence of obesity, which has been an increasing concern in recent years. Previous evidence indicated that MetS was associated with mortality; however, different definitions of MetS were used. In 2005, the National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III updated the definition of MetS, which has since been widely adopted. Therefore, it is necessary to conduct a novel study among other populations and countries with a larger sample size using the updated definition of MetS and death code to examine the association of MetS with all-cause and cause-specific mortality.

OBJECTIVE

We aimed to examine the associations of MetS with all-cause and cause-specific mortality.

METHODS

A total of 36,414 adults were included in this study, using data from the National Health and Nutrition Examination Survey (NHANES) III (1988-1994) and the continuous NHANES (1999-2014) in the United States. Death outcomes were ascertained by linkage to National Death Index records through December 31, 2015. MetS was defined by the NCEP ATP III-2005 criterion. Complex survey design factors including sample weights, clustering, and stratification were considered for all analyses with instructions for using NHANES data. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% CIs for mortality from all causes, heart disease, diabetes, and cancer.

RESULTS

We observed 8494 deaths during the 16.71 years of follow-up. Compared with those without MetS, individuals with MetS were associated with a significantly elevated multiadjusted HR of 1.24 (95% CI 1.16-1.33), 1.44 (95% CI 1.25-1.66), and 5.15 (95% CI 3.15-8.43) for all cause, heart diseases, and diabetes mellitus, respectively, whereas no significant association was found for cancer mortality (HR 1.17, 95% CI 0.95-1.43).

CONCLUSIONS

Our study provides additional evidence that MetS and its components are significantly associated with all-cause, heart disease, and diabetes mortality, but not with cancer mortality. Health care professionals should pay more attention to MetS and its individual component.

Diabetes Mellitus as Cancer Risk: A 14-year, Cross-Sectional Analysis

Diabetes mellitus is widely thought to be a risk factors of cancers, but evidence of the association remains inconclusive, especially in Asian countries where few relevant studies have been conducted. Our study aimed to estimate overall and specific types of cancer risks among diabetes patients in Southern Thailand. Patients diagnosed with diabetes who visited the outpatient clinic of Songklanagarind Hospital during 2004 to 2018 were included. Newly diagnosed cancer patients were identified using the hospital-based cancer registry. Age-standardized incidence ratios (ASRs) and standardized incidence ratios (SIRs) were used to estimate and compare the cancer risks among diabetes patients and the general population in Southern Thailand. Of 29,314 diabetes patients identified during the study period, 1,113 patients had developed cancer. An increased risk for overall cancer was observed in both genders, with SIRs [95% CI] of 2.99 [2.65, 3.39] in men and 3.51 [3.12, 3.96] in women. Increases in the risk of several site-specific cancers including liver cancer, non-melanoma skin cancer, colon cancer and lung cancer in both sexes; prostate cancer, lymphoid leukemia, and multiple myeloma in men; and endometrial, breast, and thyroid cancer in women were observed. Our study found that diabetes generally increased the risk of both overall and site-specific cancers.

Investigation of Causal Effect of Type 2 Diabetes Mellitus on Lung Cancer: A Mendelian Randomization Study

Background

Although several observational studies have attempted to investigate the association between type 2 diabetes mellitus (T2DM) and lung cancer risk, the results are controversial. Here, we intend to examine whether there is a causal association between T2DM and lung cancer risk.

Materials and Methods

We conducted a Mendelian randomization (MR) study to systematically investigate the effect of T2DM on lung cancer among 13,327 cases and 13,328 controls. A weighted genetic risk score (wGRS) was constructed as a proxy instrument by using 82 previously reported T2DM-related single nucleotide polymorphisms (SNPs). The logistic regression model was utilized to estimate associations of T2DM-related SNPs and wGRS with lung cancer risk. Sensitivity analyses were also performed to assess the robustness of the observed associations.

Results

We found no evidence for a causal relationship between T2DM and lung cancer risk (odds ratio, OR = 0.96, 95% confidence interval: 0.91–1.01, p = 0.96), and the association did not vary among populations of different age, sex, smoking status, and histological type. Sensitivity analyses (e.g., MR-Egger test) suggest that pleiotropic effects did not bias the result.

Conclusion

In this MR study with a large number of lung cancer cases, we found no evidence to support the causal role of T2DM in lung cancer risk. Further large-scale prospective studies are warranted to replicate our findings.

Does Nutrition Affect Endometriosis?

Endometriosis is a hormone-related, chronic inflammation in women of childbearing age. The aetiology and pathogenesis of endometriosis are not yet fully understood. For other illnesses classed as lifestyle diseases, the link between nutrition and pathogenesis has already been researched and proven. With regard to these findings, the question continues to arise as to whether and how a specific diet and lifestyle could also influence pathogenesis and the progression of endometriosis. The aim of this review is to examine the data and determine what influence nutrition has on the development of endometriosis or on existing disease. The study results currently available do not permit a clear, scientific recommendation or indicate a detailed diet. In summary, it can be said that fish oil capsules in combination with vitamin B ₁₂ have been associated with a positive effect on endometriosis symptoms (particularly of dysmenorrhoea). Alcohol and increased consumption of red meat and trans fats are associated with a negative effect. The results of the studies listed with regard to fruit and vegetables, dairy products, unsaturated fats, fibre, soy products and coffee are not clear. Therefore, the general recommendations for a balanced and varied diet in line with the guidelines of the Deutsche Gesellschaft für Ernährung e. V. [German Nutrition Society] apply, along with the recommendation to cut out alcohol. In order to be able to derive more concrete recommendations, we require further studies to investigate the influence of nutrition on endometriosis.

Relationship between Diabetes and Diabetes Medications and Risk of Different Molecular Subtypes of Breast Cancer

BACKGROUND

Type II diabetes and certain diabetes treatments have been observed to impact breast cancer risk. However, their associations with different breast cancer molecular subtype defined by estrogen receptor (ER)/progesterone receptor (PR)/HER2 status are unclear.

METHODS

We conducted a retrospective multi-center population-based case-case study consisting of 4,557 breast cancer cases to evaluate the impact of type II diabetes and diabetes medications on the risk of different breast cancer molecular subtypes [ER⁺/HER2^-, ER⁺/HER2⁺, triple negative (ER^-/PR^-/HER2^-), and HER2 overexpressing (H2E, ER^-/PR^-/HER2⁺)]. Using ER⁺/HER2^- cases as the reference group, we estimated ORs and corresponding 95% confidence intervals (CI) for each subtype using polytomous logistic regression.

RESULTS

Compared with those without a diabetes history, women with type II diabetes had a 38% (95% CI, 1.01-1.89) increased odds of triple-negative breast cancer (TNBC). Current and longer term recent metformin use (13-24 months of treatment within the 24-month period prior to breast cancer diagnosis) was associated with elevated odds of TNBC (OR = 1.54; 95% CI, 1.07-2.22 and OR = 1.80; 95% CI, 1.13-2.85, respectively).

CONCLUSIONS

The odds of having a triple-negative rather than ER⁺/HER2^- breast cancer is greater for women with type II diabetes, and particularly for those who were users of metformin. This finding is supported by some preclinical data suggesting that diabetes may be more strongly associated with risk of triple-negative disease.

IMPACT

Our study provides novel evidence regarding potential differential effects of type II diabetes and metformin use on risk of different molecular subtypes of breast cancer.

Cancer risk in Chinese diabetes patients: a retrospective cohort study based on management data

The excess risk of cancer observed in patients with type 2 diabetes (T2DM) may have been influenced by detection bias. The aim of this study was to examine the real association by evaluating time-varying site-specific cancer risks in newly diagnosed T2DM patients. A total of 51,324 registered cancer-free individuals newly diagnosed with T2DM between 2004 and 2014 were linked with the Shanghai Cancer Registry and the Vital Statistics through September 2015. A total of 2920 primary, invasive cancer cases were identified during 325,354 person-years period. Within 1 year following diabetes onset, participants with T2DM had higher risks of total, lung and rectal cancer in men and total, liver, pancreas, thyroid, breast and uteri cancer in women. Thereafter the incidence for overall cancer decreased and then increased along with follow-up time, with the upward trend varying by cancer, suggesting potential detection bias. After the initial 1-year period, standardized incidence ratios (SIR) and 95% CIs for overall cancer were 0.80 (95% CI 0.76-0.85) in men and 0.93 (95% CI 0.88-0.99) in women, but a higher risk of breast and thyroid cancers were observed in women, with SIR and 95% CI being 1.13 (1.01, 1.28) and 1.37 (1.11, 1.63), respectively. Our results suggest that T2DM patients are at higher risk of certain cancers; this risk particularly increases shortly after diabetes diagnosis, which is likely to be due to detection bias caused by increased ascertainment. Prevention of female breast and thyroid cancers should be paid attention in Chinese individuals with T2DM.

Evidence of a Causal Association Between Insulinemia and Endometrial Cancer: A Mendelian Randomization Analysis

BACKGROUND

Insulinemia and type 2 diabetes (T2D) have been associated with endometrial cancer risk in numerous observational studies. However, the causality of these associations is uncertain. Here we use a Mendelian randomization (MR) approach to assess whether insulinemia and T2D are causally associated with endometrial cancer.

METHODS

We used single nucleotide polymorphisms (SNPs) associated with T2D (49 variants), fasting glucose (36 variants), fasting insulin (18 variants), early insulin secretion (17 variants), and body mass index (BMI) (32 variants) as instrumental variables in MR analyses. We calculated MR estimates for each risk factor with endometrial cancer using an inverse-variance weighted method with SNP-endometrial cancer associations from 1287 case patients and 8273 control participants.

RESULTS

Genetically predicted higher fasting insulin levels were associated with greater risk of endometrial cancer (odds ratio [OR] per standard deviation = 2.34, 95% confidence internal [CI] = 1.06 to 5.14, P = .03). Consistently, genetically predicted higher 30-minute postchallenge insulin levels were also associated with endometrial cancer risk (OR = 1.40, 95% CI = 1.12 to 1.76, P = .003). We observed no associations between genetic risk of type 2 diabetes (OR = 0.91, 95% CI = 0.79 to 1.04, P = .16) or higher fasting glucose (OR = 1.00, 95% CI = 0.67 to 1.50, P = .99) and endometrial cancer. In contrast, endometrial cancer risk was higher in individuals with genetically predicted higher BMI (OR = 3.86, 95% CI = 2.24 to 6.64, P = 1.2x10(-6)).

CONCLUSION

This study provides evidence to support a causal association of higher insulin levels, independently of BMI, with endometrial cancer risk.

High coffee consumption and different brewing methods in relation to postmenopausal endometrial cancer risk in the Norwegian women and cancer study: a population-based prospective study

Background

Coffee and its compounds have been proposed to inhibit endometrial carcinogenesis. Studies in the Norwegian population can be especially interesting due to the high coffee consumption and increasing incidence of endometrial cancer in the country.

Methods

A total of 97 926 postmenopausal Norwegian women from the population-based prospective Norwegian Women and Cancer (NOWAC) Study, were included in the present analysis. We evaluated the general association between total coffee consumption and endometrial cancer risk as well as the possible impact of brewing method. Multivariate Cox regression analysis was used to estimate risks, and heterogeneity tests were performed to compare brewing methods.

Results

During an average of 10.9 years of follow-up, 462 incident endometrial cancer cases were identified. After multivariate adjustment, significant risk reduction was found among participants who drank ≥8 cups/day of coffee with a hazard ratio of 0.52 (95% confidence interval, CI 0.34-0.79). However, we did not observe a significant dose-response relationship. No significant heterogeneity in risk was found when comparing filtered and boiled coffee brewing methods. A reduction in endometrial cancer risk was observed in subgroup analyses among participants who drank ≥8 cups/day and had a body mass index ≥25 kg/m², and in current smokers.

Conclusions

These data suggest that in this population with high coffee consumption, endometrial cancer risk decreases in women consuming ≥8 cups/day, independent of brewing method.

Megestrol acetate may stimulate the production of insulin-like growth factor 1 in breast tissues of women with breast cancer

In women with breast cancer who were treated with either continuous tamoxifen alone or sequential tamoxifen followed by megestrol acetate (MA), we demonstrated significant positive associations between the breast tumor estrogen receptor (ER) and an increase in serum sex hormone-binding globulin (SHBG) during tamoxifen treatment. We interpreted this as “ER uniformity” in different tissues, e.g., breast, liver. No other associations with ER were found. In the same study, the breast tumor progesterone receptor (PR) was determined. Our aim was to see if there were any associations between PR and endocrine changes during MA treatment.

The breast tumor PR before treatment and serum insulin-like growth factor I (∂IGF-1), steroids, steroid-binding proteins, and insulin before and during treatment were measured in 17 postmenopausal women with breast cancer who were treated sequentially with tamoxifen 40 mg/day followed by MA 160 mg/day in alternating 3-month periods.

During MA treatment periods, the levels of IGF-1 and insulin increased significantly, whereas the levels of androgens, SHBG, corticosteroid-binding globulin, and cortisol decreased significantly. Significant positive correlations were found between the PR content and increments in ∂IGF-1 but not between PR and any other endocrine change.

PR expression in human liver is very weak, but malignant and normal breast tissues secrete considerable amounts of growth hormone and IGF-1 in vitro and in vivo. This activity is stimulated by progestogens. The association between PR and ∂IGF-1 may therefore reflect a direct PR-mediated action of MA on malignant and normal human breast tissues in vivo.

Percutaneous estradiol/oral micronized progesterone has less-adverse effects and different gene regulations than oral conjugated equine estrogens/medroxyprogesterone acetate in the breasts of healthy women in vivo

Gene expression analysis of healthy postmenopausal women in a prospective clinical study indicated that genes encoding for epithelial proliferation markers Ki-67 and progesterone receptor B mRNA are differentially expressed in women using hormone therapy (HT) with natural versus synthetic estrogens. Two 28-day cycles of daily estradiol (E2) gel 1.5 mg and oral micronized progesterone (P) 200 mg/day for the last 14 days of each cycle did not significantly increase breast epithelial proliferation (Ki-67 MIB-1 positive cells) at the cell level nor at the mRNA level (MKI-67 gene). A borderline significant beneficial reduction in anti-apoptotic protein bcl-2, favouring apoptosis, was also seen followed by a slight numeric decrease of its mRNA. By contrast, two 28-day cycles of daily oral conjugated equine estrogens (CEE) 0.625 mg and oral medroxyprogesterone acetate (MPA) 5 mg for the last 14 days of each cycle significantly increased proliferation at both the cell level and at the mRNA level, and significantly enhanced mammographic breast density, an important risk factor for breast cancer. In addition, CEE/MPA affected around 2,500 genes compared with just 600 affected by E2/P. These results suggest that HT with natural estrogens affects a much smaller number of genes and has less-adverse effects on the normal breast in vivo than conventional, synthetic therapy.

Skin tags and acanthosis nigricans in patients with hepatitis C infection in relation to insulin resistance and insulin like growth factor-1 levels

BACKGROUND

Skin tags (ST) are papillomas commonly found in the neck, axillae of middle-aged and elderly people

AIM

Insulin and insulin-like growth factor (IGF-1) levels are affected by hepatitis C virus (HCV) infection and both of them may be implicated in the etiopathogenesis of ST and acanthosis nigricans (AN) through their proliferative and differentiating properties. So, the aim of this work was to evaluate the impact of HCV infection on ST and AN through the estimation of insulin resistance and IGF-1.

MATERIALS AND METHODS

PARTICIPANTS WERE ARRANGED INTO FOUR GROUPS: (ST +ve / HCV +ve) 23 subjects, (ST+ / HCV -ve) 19 subjects, (HCV -ve / ST-ve) 20 subjects and (ST-ve /HCV +ve) 22 subjects. Age, ST size, color, number, AN, fasting glucose, fasting insulin, insulin resistance, IGF-1, HCV-antibodies (Ab) were recorded.

RESULTS

The mean number of ST in Group 1 was half the number of ST in Group 2 (11.0±9.3 / 22.3±14.0) (P=0.005). The difference in insulin resistance between the same groups was non-significant (13.1±10.6 / 9.0±5.5) (P=0.441) while the difference in IGF-1 was statistically significant (218.6±46.2 /285.4±32.8) (P=0.002). The multivariate logistic regression for the variables revealed that insulin resistance is the only factor affecting the occurrence of ST (OR=1.096, P=0.023). Multivariate regression analysis for the variables showed that HCV was borderline but not a significant factor affecting the number of ST (Beta=-0.409, P=0.053). The number of patients with AN was doubled in Group 2 in comparison to Group 1 but this was non significant 3(13%) / 6(32%) (P=0.2800).

CONCLUSION

HCV is associated with a significant decrease in the ST number and in the serum level of IGF-1 together with an obvious decrease in the occurrence of AN. Our results may point to the entrant effect of insulin resistance and IGF-1 in ST and AN development. The current study suggests the evaluation of IGF-1-lowering agents in the control of ST and AN especially in the females with polycystic ovary and in the prevention of the recurrence of ST after surgical removal.

Characterization of LHY-821, a novel moderately differentiated endometrial carcinoma cell line

Endometrial cancer is a major problem for women but only a small number of comprehensively characterized cell models are available for studies. Here, we established a new cell line derived from a Stage IIIc(1) Grade 2 endometrial adenocarcinoma. The cell line, designated LHY-821, was characterized using growth curve, karyotyping, immunohistochemical staining, immunoblotting, drug sensitivity assay, invasion assay, and xenografting in nude mice. LHY-821 has a doubling time of about 46 h and a colony-forming efficiency of approximately 71 %. These cells expresse high levels of progesterone receptor but not estrogen receptor and are sensitive to medroxyprogesterone acetate (MPA). LHY-821 also expresses pan-cytokeratin, PTEN, p53, β-catenin, IGF-1, and IGF-2. In addition, karyotype analysis revealed that LHY-821 possessed a near diploid karyotype including 6q-, 10p-, Xq-, 13q+, 17p+, and Triplo-12. LHY-821 showed highly tumorigenicity in nude mice (100 %) and weak invasiveness. Chemosensitivity tests showed that LHY-821 was sensitive to both carboplatin and paclitaxel. LHY-821 is an immortalized cell line which had survived more than 80 serial passages; it may provide a novel tool to study the molecular mechanism and potential treatment for endometrial cancer.

Caffeinated coffee, decaffeinated coffee and endometrial cancer risk: a prospective cohort study among US postmenopausal women

There is plausible biological evidence as well as epidemiologic evidence to suggest coffee consumption may lower endometrial cancer risk. We evaluated the associations between self-reported total coffee, caffeinated coffee and decaffeinated coffee, and endometrial cancer risk using the Women's Health Initiative Observational Study Research Materials obtained from the National Heart, Lung, and Blood Institute Biological Specimen and Data Repository Coordinating Center. Our primary analyses included 45,696 women and 427 incident endometrial cancer cases, diagnosed over a total of 342,927 person-years of follow-up. We used Cox-proportional hazard models to evaluate coffee consumption and endometrial cancer risk. Overall, we did not find an association between coffee consumption and endometrial cancer risk. Compared to non-daily drinkers (none or <1 cup/day), the multivariable adjusted hazard ratios for women who drank ≥4 cups/day were 0.86 (95% confidence interval (CI) 0.63, 1.18) for total coffee, 0.89 (95% CI 0.63, 1.27) for caffeinated coffee, and 0.51 (95% CI 0.25, 1.03) for decaf coffee. In subgroup analyses by body mass index (BMI) there were no associations among normal-weight and overweight women for total coffee and caffeinated coffee. However among obese women, compared to the referent group (none or <1 cup/day), the hazard ratios for women who drank ≥2 cups/day were: 0.72 (95% CI 0.50, 1.04) for total coffee and 0.66 (95% CI 0.45, 0.97) for caffeinated coffee. Hazard ratios for women who drank ≥2 cups/day for decaffeinated coffee drinkers were 0.67 (0.43-1.06), 0.93 (0.55-1.58) and 0.80 (0.49-1.30) for normal, overweight and obese women, respectively. Our study suggests that caffeinated coffee consumption may be associated with lower endometrial cancer risk among obese postmenopausal women, but the association with decaffeinated coffee remains unclear.

Sucrose, high-sugar foods, and risk of endometrial cancer--a population-based cohort study

BACKGROUND

Consumption of high-sugar foods stimulates insulin production, which has been associated with endometrial cancer. Although a relationship between sucrose, high-sugar food consumption, and endometrial cancer risk is biologically plausible, this hypothesis has previously been explored in very few studies.

METHODS

We used data from the Swedish Mammography Cohort, including 61,226 women aged 40 to 74 years. We examined the association between consumption of total sucrose, high-sugar foods (at baseline 1987-1990 and 1997) and endometrial cancer risk by using Cox proportional hazards models to estimate incidence rate ratios (RR) with 95% CI.

RESULTS

During 18.4 years of follow-up, 729 participants were diagnosed with incident endometrial cancer. Total sucrose intake and consumption of sweet buns and cookies was associated with increased risk of endometrial cancer. RRs (with 95% CIs) for consuming more than 35 grams of sucrose per day and consuming sweet buns and cookies more than 3 times per week were 1.36 (1.04-1.77) and 1.42 (1.15-1.75) as compared with less than 15 grams of sucrose per day and consuming sweet buns and cookies less than 0.5 times per week, respectively. RRs for consuming more than 15 grams of sucrose per day as compared with 15 grams or less were 1.97 (1.27-3.04) among obese women and 1.56 (1.20-2.04) among women with low fat intake.

CONCLUSIONS

These data indicate that sucrose intake and consumption of sweet buns and cookies may be associated with increased risk of endometrial cancer.

IMPACT

Given the high intake of sweetened foods, these results have public health implications in terms of prevention of endometrial cancer.

Growth factor signaling pathways as targets for prevention of epithelial carcinogenesis

Growth factor receptor (GFR) signaling controls epithelial cell growth by responding to various endogenous or exogenous stimuli and subsequently activating downstream signaling pathways including Stat3, PI3K/Akt/mTOR, MAPK, and c-Src. Environmental chemical toxicants and UVB irradiation cause enhanced and prolonged activation of GFR signaling and downstream pathways that contributes to epithelial cancer development including skin cancer. Recent studies, especially those with tissue-specific transgenic mouse models, have demonstrated that GFRs and their downstream signaling pathways contribute to all three stages of epithelial carcinogenesis by regulating a wide variety of biological functions including proliferation, apoptosis, angiogenesis, cell adhesion, and migration. Inhibiting these signaling pathways early in the carcinogenic process results in reduced cell proliferation and survival, leading to decreased tumor formation. Collectively, these studies suggest that GFR signaling and subsequent downstream signaling pathways are potential targets for the prevention of epithelial cancers including skin cancer.

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.

Coffee drinking and risk of endometrial cancer--a population-based cohort study

Coffee drinking has been reported to have beneficial effects on insulin resistance, which has been directly associated with endometrial cancer. Although a relationship between coffee consumption and endometrial cancer risk is biologically plausible, this hypothesis has been previously explored in only 2 prospective studies, with a small number of cases. We used data from the Swedish Mammography Cohort, a population-based prospective cohort study of 60,634 women. During 17.6 years of follow-up, 677 participants were diagnosed with incident endometrial cancer (adenocarcinoma). We examined the association between self-reported coffee consumption (at baseline 1987-90 and in 1997) and endometrial cancer risk using Cox proportional hazards models. Each additional cup (200 g) of coffee per day was associated with a rate ratio (RR) of 0.90 [95% confidence interval (CI), 0.83-0.97]. In women drinking 4 or more cups of coffee a day, the RR for the risk reduction of endometrial cancer was 0.75 (95% CI, 0.58-0.97) when compared with those who drank 1 cup or less. The association seemed largely confined to overweight and obese women, who showed a respective risk reduction of 12% (95% CI, 0-23%) and 20% (95% CI, 7-31%) for every cup of coffee, but was not observed among normal-weight women. There was a statistically significant interaction between coffee consumption and body mass index (p(interaction) < 0.001). These data indicate that coffee consumption may be associated with decreased risk of endometrial cancer, especially among women with excessive body weight. If confirmed by other prospective studies, these results are of major public health significance.

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.

Examining breast cancer growth and lifestyle risk factors: early life, childhood, and adolescence

The perinatal period, childhood, and adolescence are important intervals for breast cancer risk development. Endogenous estrogen exposure is thought to be highest in utero, and exposure to estrogens throughout life plays an important role in increasing breast cancer risk. Some evidence suggests that breast tissue is not fully differentiated until after the first full-term pregnancy; thus, breast tissue might be more susceptible to carcinogenic influences during early life and adolescence. Birth characteristics of the daughter, including gestational age, birth weight, and birth length are associated with maternal hormone levels during the index pregnancy, and birth size has been related to daughter's timing of puberty and adult breast cancer incidence. Furthermore, early life and adolescence are critical times for maturation of the hypothalamic pituitary ovarian axis, which regulates production of ovarian hormones including estrogen and progesterone. Childhood height, growth, diet, and body mass index (BMI) have also been associated with breast cancer risk later in life. Of the examined characteristics, we conclude that the available evidence is suggestive of a positive relationship of breast cancer risk with birth weight, birth length, and adolescent height, and an inverse relationship with gestational age and childhood BMI, although several inconsistencies exist in the literature. The best evidence for a relationship of adolescent diet and adult breast cancer risk is indirect, and the relationship of diet, weight status, and weight gain in childhood deserves further attention. The interaction of birth characteristics with established risk factors over the life course, such as age at menarche, in addition to gene-environment interactions, require more research. Further study is also needed to clarify the biologic mechanisms influencing the observed associations.

Diabetes mellitus and risk of endometrial cancer: a meta-analysis

AIMS/HYPOTHESIS

Diabetes has been associated with a statistically significantly increased risk of endometrial cancer in most, but not all studies. To provide a quantitative assessment of the association between diabetes and risk of endometrial cancer, we conducted a meta-analysis of case-control studies and cohort studies.

SUBJECTS AND METHODS

We identified studies by a literature search of PubMed and Embase through to January 2007 and by searching the reference lists of relevant articles. Summary relative risks (RRs) with 95% CIs were calculated using random-effects model.

RESULTS

The analysis of diabetes (largely type 2) and endometrial cancer is based on 16 studies (three cohort and 13 case-control studies), including 96,003 participants and 7,596 cases of endometrial cancer. Twelve of the studies showed a statistically significantly increased risk and four a non-significant increased risk of endometrial cancer. In our meta-analysis we found that diabetes was statistically significantly associated with an increased risk of endometrial cancer (summary RR 2.10, 95% CI 1.75-2.53). The risk estimates were somewhat stronger among case-control (RR 2.22, 95% CI 1.80-2.74) than among cohort studies (RR 1.62, 95% CI 1.21-2.16), stronger among studies adjusting only for age (RR 2.74, 95% CI 1.87-4.00) compared with multivariate adjustment (RR 1.92, 95% CI 1.58-2.33) and slightly lower in studies performed in the USA than in those performed Europe. The analysis of type 1 diabetes and endometrial cancer was based on three studies and found a statistically significant positive association (summary RR 3.15, 95%CI 1.07-9.29).

CONCLUSIONS/INTERPRETATION

Results from the meta-analysis support a relationship between diabetes and increased risk of endometrial cancer.

Diabetes and risk of endometrial cancer: a population-based prospective cohort study

Although there is accumulating evidence that hyperinsulinemia in the context of insulin resistance is associated with carcinogenesis, only one prospective study of endometrial cancer incidence, in relation to diabetes, addressed this issue and showed no significant positive association. No previous study has investigated whether physical activity can modify the association between diabetes and endometrial cancer. We examined the association between diabetes and incidence of endometrial cancer and the potential effect modification by obesity and physical activity in the Swedish Mammography Cohort, a prospective cohort of 36,773 women, including 225 incident endometrial adenocarcinoma cases. After adjustments, the relative risk (RR) for endometrial cancer among women with diabetes comparing with nondiabetic women was 1.94 [95% confidence interval (95% CI), 1.23-3.08]. Among obese diabetics, the RR was 6.39 (95% CI, 3.28-12.06) compared with nonobese nondiabetic women. Among diabetics with low physical activity, the RR for endometrial cancer was 2.80 (95% CI, 1.62-4.85) compared with physically active nondiabetic women. Obese diabetics with low physical activity had a RR of 9.61 (95% CI, 4.66-19.83) compared with normal weight nondiabetic women with high physical activity. Diabetes was associated with a 2-fold increased risk, and combination of diabetes with obesity and low physical activity was associated with a further increased risk for endometrial cancer. Interventions to reduce body weight and increase physical activity may have important implications in terms of prevention of endometrial cancer and future management of diabetic subjects.

Diabetes mellitus and risk of breast cancer: A meta-analysis

Diabetes mellitus has been associated with an increased risk of several types of cancers, but its relationship with breast cancer remains unclear. We conducted a meta-analysis of case-control and cohort studies to assess the evidence regarding the association between diabetes and risk of breast cancer. Studies were identified by searching MEDLINE (1966-February 2007) and the references of retrieved articles. We identified 20 studies (5 case-control and 15 cohort studies) that reported relative risk (RR) estimates (odds ratio, rate ratio/hazard ratio, or standardized incidence ratio) with 95% confidence intervals (CIs) for the relation between diabetes (largely Type II diabetes) and breast cancer incidence. Summary RRs were calculated using a random-effects model. Analysis of all 20 studies showed that women with (versus without) diabetes had a statistically significant 20% increased risk of breast cancer (RR, 1.20; 95% CI, 1.12-1.28). The summary estimates were similar for case-control studies (RR, 1.18; 95% CI, 1.05-1.32) and cohort studies (RR, 1.20; 95% CI, 1.11-1.30). Meta-analysis of 5 cohort studies on diabetes and mortality from breast cancer yielded a summary RR of 1.24 (95% CI, 0.95-1.62) for women with (versus without) diabetes. Findings from this meta-analysis indicate that diabetes is associated with an increased risk of breast cancer.

Ehrlich tumor as model to study artificial hyperthyroidism influence on breast cancer

This study used Ehrlich solid tumor as an experimental model for breast cancer to investigate the effects of thyroid hormones and castration on tumor development in adult female mice. Artificial hyperthyroidism was induced in animals, and after a 30-day-treatment, they received subcutaneous injection of neoplastic cells between left plantar cushions. We measured the growth of tumor inoculated in the paws for 10 days at necropsy. Hyperthyroidism induction led to significantly increased tumor size in non-castrated animals, and alterations were less intense in association with artificial hyperthyroidism and castration (p<0.05). Histomorphologic and histomorphometric analyses and neoplastic cell characterization were carried out by measuring nuclear diameter, by evaluating AgNORs, by mitotic count, and by measuring cell proliferation using immunohistochemical marker CDC47. At the end of the experiment, we noted metabolism and a decrease in cell proliferation in groups having received l-thyroxine, which were more evident in the non-castrated group (p<0.001).

Physical activity and risk of endometrial cancer: a population-based prospective cohort study

Physical activity is involved in the regulation of metabolic and hormonal pathways and is one of the factors important for the maintenance of body weight; obesity is a risk factor for endometrial cancer. A connection between physical activity and endometrial cancer risk through hormonal mechanisms, possibly mediated by body weight, is biologically plausible. Only one study has investigated total physical activity, and no previous study has examined leisure time inactivity directly. We investigated the association of total physical activity and different types of physical activity with risk of endometrial cancer in the Swedish Mammography Cohort, a population-based prospective cohort, including 33,723 women and 199 endometrial cancer cases. After adjustments for potential confounders (age, body mass index, parity, history of diabetes, total fruit and vegetable intake, and education), the relative risks for endometrial cancer for the second to fourth quartile of total physical activity compared with the lowest one were 0.80 [95% confidence interval (95% CI), 0.54-1.18], 0.87 (95% CI, 0.59-1.28), and 0.79 (95% CI, 0.53-1.17). High leisure time inactivity (watching TV/sitting >or=5 hours daily) compared with low was associated with increased risk of endometrial cancer (relative risk, 1.66; 95% CI, 1.05-2.61). The associations were not modified by body mass index. Findings from this study suggest that total physical activity is weakly inversely associated with endometrial cancer risk and that leisure time inactivity is statistically significantly associated with increased risk for endometrial cancer.

Progestins and progesterone in hormone replacement therapy and the risk of breast cancer

Controlled studies and most observational studies published over the last 5 years suggest that the addition of synthetic progestins to estrogen in hormone replacement therapy (HRT), particularly in continuous-combined regimen, increases the breast cancer (BC) risk compared to estrogen alone. By contrast, a recent study suggests that the addition of natural progesterone in cyclic regimens does not affect BC risk. This finding is consistent with in vivo data suggesting that progesterone does not have a detrimental effect on breast tissue. The increased BC risk found with the addition of synthetic progestins to estrogen could be due to the regimen and/or the kind of progestin used. Continuous-combined regimen inhibits the sloughing of mammary epithelium that occurs after progesterone withdrawal in a cyclic regimen. More importantly, the progestins used (medroxyprogesterone acetate and 19-Nortestosterone-derivatives) are endowed with some non-progesterone-like effects, which can potentiate the proliferative action of estrogens. Particularly relevant seem to be the metabolic and hepatocellular effects (decreased insulin sensitivity, increased levels and activity of insulin-like growth factor-I, and decreased levels of SHBG), which contrast the opposite effects induced by oral estrogen.

Role of a critical visceral adipose tissue threshold (CVATT) in metabolic syndrome: implications for controlling dietary carbohydrates: a review

There are likely many scenarios and pathways that can lead to metabolic syndrome. This paper reviews mechanisms by which the accumulation of visceral adipose tissue (VAT) may contribute to the metabolic syndrome, and explores the paradigm of a critical VAT threshold (CVATT). Exceeding the CVATT may result in a number of metabolic disturbances such as insulin resistance to glucose uptake by cells. Metabolic profiles of patients with visceral obesity may substantially improve after only modest weight loss. This could reflect a significant reduction in the amount of VAT relative to peripheral or subcutaneous fat depots, thereby maintaining VAT below the CVATT. The CVATT may be unique for each individual. This may help explain the phenomena of apparently lean individuals with metabolic syndrome, the so-called metabolically normal weight (MONW), as well as the obese with normal metabolic profiles, i.e., metabolically normal obese (MNO), and those who are "fit and fat." The concept of CVATT may have implications for prevention and treatment of metabolic syndrome, which may include controlling dietary carbohydrates. The identification of the CVATT is admittedly difficult and its anatomical boundaries are not well-defined. Thus, the CVATT will continue to be a work in progress.

Dietary glycemic load and breast cancer risk in the Women's Health Study

A diet with a high glycemic load (GL) may contribute to a metabolic environment that enhances tumorigenesis. Little is known, however, about whether high glycemic diets increase breast cancer risk in women. We examined the associations between baseline measurements of dietary GL and overall glycemic index (GI) and subsequent breast cancer in a cohort of 39,876 women, ages 45 years or older, participating in the Women's Health Study. During a mean of 6.8 years of follow-up there were 946 confirmed cases of breast cancer. We found no association between dietary GL [multivariable-adjusted relative risk (RR), 1.01; confidence interval (CI), 0.76-1.35, comparing extreme quintiles; P for trend = 0.96] or overall GI (corresponding RR, 1.03; CI, 0.84-1.28; P for trend = 0.66) and breast cancer risk in the cohort as a whole. Exploratory analyses stratified by baseline measurements of menopausal status, physical activity, smoking history, alcohol use, and history of diabetes mellitus, hypertension, or hypercholesterolemia showed no significant associations, except in the subgroup of women who were premenopausal and reported low levels of physical activity (GL multivariable-adjusted RR, 2.35; CI, 1.03-5.37; P for trend = 0.07; GI multivariable-adjusted RR, 1.56; CI, 0.88-2.78; P for trend = 0.02, comparing extreme quintiles). Although we did not find evidence that a high glycemic diet increases overall breast cancer risk, the increase in risk in premenopausal women with low levels of physical activity suggests the possibility that the effects of a high glycemic diet may be modified by lifestyle and hormonal factors. Prospective studies of a larger sample size and longer duration are warranted to confirm our findings.

Progestins and their effects on the breast

Nowadays, when the available scientific data on the in vivo effects of progestins on mammary gland tissue remain controversial, it is of utmost importance to establish adequate criteria to evaluate their actions. One of the reasons for this situation is that a variety of progestins have been studied using a number of different study designs. In addition, data relating to the effects of progestins on breast tissue have been interpreted differently from country to country. Recent data indicate that some progestins clearly oppose the favourable effects of estrogens on a number of important metabolic processes, e.g. influencing insulin-like-growth-factor (IGF)-1 serum levels. IGF-1 is a mitogenic and antiapoptotic peptide involved in growth regulation of breast epithelial cells. Circulating IGF-1 exerts endocrine action, it regulates growth hormone secretion by a negative feedback mechanism. In the past few years, both laboratory investigations and epidemiologic studies provided strong evidence that the IGF-1/growth hormone axis is involved in human cancer risk [Maturitas 29 (1998) 61; Horm. Res. 51 (1999) 34; Eur. J. Cancer 36 (2000) 1224; Maturitas 41 (2002) 299] Some progestins also have effects on the enzymes in breast tissue that are responsible for the local synthesis of estradiol. Thus, whilst progestins without androgenic action have been found to markedly inhibit these enzymes, an equivalent degree of inhibition is not achieved with testosterone-derivatives. Therefore, special attention should be paid to the various partial actions of the different progestins and their effects on breast tissue. Furthermore, factors such as the duration of breast tissue exposure to progestin activity, the influence of different regimens on protective apoptotic mechanisms in the breasts, as well as dose levels and the degree of mammary gland tissue differentiation throughout treatment, should also be considered.

A cross-sectional investigation of breast density and insulin-like growth factor I

Our study investigated the association of breast cancer risk as assessed by mammographic density with insulin-like growth factor I (IGF-I) and one of its binding proteins (IGFBP-3) in healthy premenopausal women with different ethnic backgrounds. In a cross-sectional design, we analyzed the baseline mammograms and fasting serum samples (collected 5 days after ovulation) of premenopausal women entering a nutritional intervention. Serum concentrations of IGF-I and IGFBP-3 were measured by double-antibody ELISA. Mammographic densities were assessed using a computer-assisted method. We calculated Spearman correlation coefficients between mammographic characteristics and analytes and estimated means of mammographic characteristics by quartiles of IGF-I and IGFBP-3 while adjusting for age, body mass index (BMI) and reproductive factors. In this group of 240 women, IGF-I, IGFBP-3 and percent densities did not differ significantly by ethnicity. Whereas mammographic densities were not associated with IGF-I, we found an inverse relation with IGFBP-3 (r(s) = -0.15, p = 0.02) and a positive association with the IGF-I/IGFBP-3 ratio (r(s) = 0.13, p = 0.04). The size of the dense areas was not associated with the analytes, but the size of the nondense areas was correlated directly with IGFBP-3 (r(s) = 0.20, p = 0.002) and inversely with the molar ratio (r(s) = -0.19, p = 0.004). These associations were limited to women with a BMI of less than 25 kg/m(2). These results suggest that the balance of circulating IGF-I and IGFBP-3 levels may influence the growth of the fatty part of the breast more than the epithelial and stromal breast tissue, but the exact mechanism of action needs to be explored in more detail.

Insulin-like growth factor system gene expression in women with type 2 diabetes and breast cancer

BACKGROUND/AIMS

A twofold increased risk for breast cancer has been reported recently for women with late onset diabetes. Most studies showed that there were differences in serum concentrations of insulin-like growth factors and related proteins between women with and without diabetes who have breast cancer. This study investigated the expression of these markers at the cellular level in a cohort of women with and without type 2 diabetes who underwent biopsy because of a breast lump.

METHODS

Relative quantitative analysis of specific mRNA sequences was performed after extraction and reverse transcription polymerase chain reaction amplification from formalin fixed and paraffin wax embedded tissues. Sixty seven breast surgical specimens from women with and without diabetes who did not have cancer and from women with and without diabetes who did have cancer were studied for insulin-like growth factor I (IGF-I), the IGF-I receptor (IGF-IR), insulin-like growth factor binding protein 3 (IGFBP-3), and oestrogen receptor 1 gene expression.

RESULTS

The expression of IGF-I and IGF-IR was significantly lower in the cancer groups, whereas there was no significant difference for IGFBP-3 between women with and without cancer. Moreover, there was a good correlation between the expression of IGF-I and IGF-IR in women without cancer: this link was still present in breast tissue from patients with diabetes and cancer, whereas it was lost in patients without diabetes but with cancer.

CONCLUSIONS

These differences in IGF-I/IGF-IR expression could contribute to the increased risk for breast cancer in women with type 2 diabetes.

Role of exogenous and endogenous hormones in endometrial cancer: review of the evidence and research perspectives

Endometrial carcinoma is the most common cancer of the female reproductive organs in the United States. International comparisons reveal that the incidence of endometrial cancer vary widely between different countries with the highest rates observed in North America and Northern Europe, intermediate rates in Eastern Europe and Latin America, and lowest rates in Asia and Africa. International variation in endometrial cancer rates may represent differences in the distribution of known risk factors, which include obesity, postmenopausal estrogen replacement, ovarian dysfunction, diabetes mellitus, infertility, nulliparity, and tamoxifen use. Most of the risk factors for endometrial cancer can be explained within the framework of the unopposed estrogen hypothesis, which proposes that exposure to estrogens unopposed by progesterone or synthetic progestins leads to increased mitotic activity of endometrial cells, increased number of DNA replication errors, and somatic mutations resulting in malignant phenotype. Although the impact of exogenous hormone replacement was intensively studied during the last two decades, less is known about the effects of endogenous hormones in endometrial cancer. A review of available experimental, clinical, and epidemiologic data suggests that in addition to estrogens, other endogenous hormones, including progesterone, androgens, gonadotropins, prolactin, insulin, and insulin-like growth factors, may play a role in the pathogenesis of different histopathologic types of endometrial cancer.

Erythrocyte membrane fatty acids and subsequent breast cancer: a prospective Italian study

BACKGROUND

The relationship between erythrocyte membrane fatty acids and postmenopausal breast cancer risk was analyzed previously only by retrospective studies, which suggested a protective effect of increased saturation index (SI), i.e., the ratio of membrane stearic to oleic acid. We investigated the relationships in a prospective study of hormones, diet, and prediagnostic breast cancer (the ORDET study) conducted in northern Italy.

METHODS

A total of 4052 postmenopausal women were followed for an average of 5.5 years; 71 cases of invasive breast cancer were identified. For each case subject, two matched control subjects were chosen randomly from among cohort members. The various fatty acids in erythrocyte membranes were measured as a percentage of total fatty acids. Conditional logistic regression analysis evaluated the association between membrane fatty acid composition and breast cancer risk. The SI, which is influenced by the activity of the enzyme delta 9 desaturase (Delta 9-d), was also investigated. All statistical tests were two-sided.

RESULTS

Oleic (highest versus lowest tertile of percentage of total fatty acids, odds ratio [OR] = 2.79; 95% confidence interval [CI] = 1.24 to 6.28) and monounsaturated fatty acids (highest to lowest tertile, OR = 5.21; 95% CI = 1.95 to 13.91) were positively associated with breast cancer risk. The SI (highest to lowest tertile, OR = 0.29; 95% CI = 0.13 to 0.64) was inversely associated with breast cancer risk. The analysis suggested an inverse association between total polyunsaturated fatty acids and breast cancer risk, but individual polyunsaturated fatty acids behaved differently. There was no association between saturated fatty acids and breast cancer risk.

CONCLUSIONS

We have found that monounsaturated fats and SI in erythrocyte membranes are predictors of postmenopausal breast cancer. Both of these variables depend on the activity of the enzyme Delta 9-d. The dietary, metabolic, and hormonal factors acting on Delta 9-d expression and activity and, therefore, on patterns of fatty acid metabolism, should be further investigated as possible determinants of breast cancer.

Susceptibility of lean and obese Zucker rats to tumorigenesis induced by N-methyl-N-nitrosourea

To address the possible involvement of hyperinsulinemia in breast cancer development, we have examined the susceptibility of lean and obese Zucker rats to N-methyl-N-nitrosourea (MNU)-induced mammary cancer. Fifty-day-old female lean or obese Zucker rats received intraperitoneal (i.p.) injections of 37.5 or 20 mg/kg MNU, respectively. We showed in separate experiments that these doses produce similar levels of DNA methylation in the mammary epithelial cells of the lean and obese animals. Over the course of 29 weeks following MNU treatment, half of the lean rats developed carcinomas of the mammary gland, demonstrating that they are of intermediate susceptibility to mammary tumorigenesis. During this period, the obese rats developed hyperinsulinemia and insulin resistance as expected. Although palpable tumors developed at a similar rate in the lean and obese rats, only 10% of the obese animals developed mammary carcinomas. The obese rats, however, developed a high incidence (63.3%) of epidermal cysts that occurred mainly in the region of the mammary glands. A 13.3% incidence of colon carcinomas was also found in the obese rats. These results suggest that the development of hyperinsulinemia does not render the obese Zucker rats more susceptible to mammary gland carcinogenesis. Our observation of colon carcinomas in obese, but not lean rats, however, is consistent with evidence that hyperinsulinemia promotes colon cancer in rodents and humans.

Suppression of dolichol synthesis with isoprenoids and statins may potentiate the cancer-retardant efficacy of IGF-I down-regulation

Agents that inhibit the synthesis of mevalonate or of downstream isoprenoids block the G1-S transition and induce apoptosis in many cell lines; these agents include statins, phenylacetate, and a range of cyclic and acyclic isoprenoids. This cytostatic effect is mediated primarily by decreased availability of dolichol; this deficit impedes the glycosylation of nascent IGF-I receptors, preventing their transfer to the cell surface. In most tissues as well as transformed cell lines, IGF-I activity is crucial for transition to S phase, and also prevents apoptosis. Thus, down-regulation of serum levels of free IGF-I - as may be achieved by caloric restriction, low-fat vegan diets, and various estrogen agonists/antagonists - may represent a useful strategy for preventing and controlling cancer; however, a compensatory up-regulation of tissue expression of IGF-I receptors limits the efficacy of such an approach. Concurrent use of agents that inhibit dolichol synthesis can be expected to prevent an increase in plasma membrane IGF-I receptors, thus potentiating the cancer-retardant efficacy of IGF-I down-regulation. Since dolichol and IGF-I appear to be essential for angiogenesis, these measures may also prove useful for control of pathogenic neovascularization.

Birth characteristics and subsequent risk for breast cancer in very young women

There is growing evidence that prenatal exposures may influence later breast cancer risk. This matched case-control study used linked New York State birth and tumor registry data to examine the association between birth characteristics and breast cancer risk among women aged 14-37 years. Cases were women diagnosed with breast cancer between 1978 and 1995 who were also born in New York after 1957 (n = 484). For each case, selected controls were the next six liveborn females with the same maternal county of residence. The authors found a J-shaped association between birth weight and breast cancer risk, and very high birth weight (> or =4,500 g) was associated with the greatest elevation in risk (adjusted odds ratio (OR) = 3.10, 95% confidence interval (CI): 1.18, 7.97). The association of maternal age with breast cancer risk was also J-shaped, with maternal age of more than 24 years showing a positive, linear association (adjusted OR = 1.94, 95% CI: 1.18, 3.18 for maternal age > or =35 vs. 20-24 years; p for trend = 0.02). In contrast, women born very preterm had a lower risk (adjusted OR = 0.11, 95% CI: 0.02, 0.79 for gestational age <33 vs. > or =37 weeks). These findings support a role for early life factors in the development of breast cancer in very young women.

Effect of melatonin and linolenic acid on mammary cancer in transgenic mice with c-neu breast cancer oncogene

Breast cancer is one of the most common cancers and is a leading cause of mortality in women. The TG.NK transgenic mouse line expresses the c-neu breast cancer oncogene under the control of a MMTV promoter and appears to be a useful animal model for evaluation of intervention strategies to delay/prevent breast cancer. Fiber-rich nonpurified diet (NTP-2000) and some retinoid analogues have been shown to significantly delay the development of mammary cancer in the TG.NK model. Four-week-old hemizygous TG.NK female mice with MMTV/c-neu oncogene fed NTP-2000 diet were gavaged with 0.05-0.2 ml of flaxseed oil as the source of omega-3 rich PUFA, or melatonin at 50-200 mg/kg or a combination of 0.10 ml flaxseed oil and 50 mg/kg melatonin in a gavage volume of 0.2 ml per mouse with corn oil as the vehicle for 30 weeks. The time course of the mammary tumor incidence pattern was advanced by flaxseed oil compared to the control. At the high dose (0.2 ml) of flaxseed oil, when the omega-6: omega-3 PUFA ratio was closer to 1, there was some delay in the growth of mammary tumors. Melatonin delayed the appearance of palpable tumors and the growth of the tumors with a dose-related statistically significant negative trend for the incidence of tumors. The combination of flaxseed oil and melatonin caused a significant decrease in the number of tumors and tumor weight per mouse compared to the control and to flaxseed oil but not to melatonin alone. Flaxseed oil may delay the growth of mammary tumors if the omega-6:omega-3 PUFA ratio of fat consumed is closer to 1. Melatonin has the potential to markedly delay the appearance of palpable mammary tumors. Studies are in progress with the TG.NK mouse model to understand the histological and molecular changes associated with the dose-response pattern of mammary tumor incidence and growth after treatment with a broad range of doses of melatonin.

Relations of insulin resistance and serum concentrations of estradiol and sex hormone-binding globulin to potential breast cancer risk factors

There is a hypothesis that hyperinsulinemia or insulin resistance may be a mediator for breast cancer risk factors. On the other hand, some, but not all, of the well-known risk factors of breast cancer have been associated with serum estrogen concentrations. We assessed the relationships of potential breast cancer risk factors to indicators of insulin resistance, fasting plasma insulin concentration and homeostasis model assessment insulin resistance (HOMA-R), in 88 postmenopausal Japanese women. We also examined whether insulin resistance would explain the association of breast cancer risk factors with serum estradiol and sex hormone-binding globulin (SHBG). Information on potential breast cancer risk factors, such as demographic characteristics, smoking and drinking habits, diet, exercise, menstrual and reproductive factors, was obtained by self-administered health questionnaire including a validated semiquantitative food frequency questionnaire. Body mass index (BMI) was significantly correlated with the ratio of estradiol to SHBG (Spearman r = 0.30, P = 0.0004), fasting plasma insulin (r = 0.45) and HOMA-R (r = 0.43, P = 0.0001) after controlling for age. The correlations were still significant between BMI and estradiol / SHBG ratio (r = 0.21, P = 0.047) after controlling for fasting plasma insulin and between BMI and fasting plasma insulin (r = 0.40, P = 0. 0001) as well as HOMA-R (r = 0.38, P = 0.0003) after controlling for estradiol / SHBG ratio. There is a possibility that effect of BMI on breast cancer risk is mediated by both insulin resistance and estrogen metabolism.

Chemoprevention of breast cancer: the Italian experience

The activity of our group is focused on the conduction of chemoprevention clinical trials of breast cancer in at-risk subjects, among which we include women on hormone replacement therapy (HRT). The role of the insulin-like growth factor (IGF) system and of mammographic breast density as surrogate biomarkers for breast cancer prevention is also being investigated. The IGF system is involved in human carcinogenesis of several solid tumors. IGF-I is a potent mitogen for breast cancer cells; elevated circulating IGF-I levels have been associated with a higher risk of premenopausal breast cancer, prostate and colorectal cancer in prospective studies. Both tamoxifen and the synthetic retinoid fenretinide (4-HPR) have been shown to decrease plasma IGF-I levels. A trial of their combination is ongoing in premenopausal women with increased risk for breast cancer. Mammographic breast density has also been associated with an increased risk of breast cancer in several prospective studies. In this article, we discuss the rationale for selection of appropriate cohorts, candidate agents, and putative surrogate biomarkers in our breast cancer prevention trials. Moreover, updated results of the secondary prevention trial of 4-H PR and of the primary prevention trial of tamoxifen are presented. Finally, the rationale for a reduction of tamoxifen dose in future prevention trials is provided.

HRT and breast cancer risk: a clue for interpreting the available data

Epidemiological and biological data on HRT and breast cancer risk are reviewed. Some aspects deserve consideration. (1) The majority of epidemiological data have been gathered from populations where high estrogen doses (> or = 1.25 mg daily of conjugated estrogens) were used as first line therapy. (2) HRT does not increase the risk in overweight women, even in the series in which a risk increase (in longterm users) is found. This could be as a result of the fact that oral estrogens, through their metabolic and hepatocellular effects, reverse some biological features of obesity (e.g. increased insulin-like growth factor I activity and decreased sex hormone binding globulin level) which potentially increase breast cancer risk, so balancing the estrogen stimulation. (3) The progestin addition seems to increase the risk when the 19 nor-testosterone derivatives are used. These androgenic compounds contrast the metabolic and hepatocellular effects of oral estrogens. To sum up, the possibility does exist that even the longterm use of oral estrogens at the right ('low') dose, with the addition of a non-androgenic progestin, will be shown to be associated with a very limited breast cancer risk increase.

Vegan proteins may reduce risk of cancer, obesity, and cardiovascular disease by promoting increased glucagon activity

Amino acids modulate the secretion of both insulin and glucagon; the composition of dietary protein therefore has the potential to influence the balance of glucagon and insulin activity. Soy protein, as well as many other vegan proteins, are higher in non-essential amino acids than most animal-derived food proteins, and as a result should preferentially favor glucagon production. Acting on hepatocytes, glucagon promotes (and insulin inhibits) cAMP-dependent mechanisms that down-regulate lipogenic enzymes and cholesterol synthesis, while up-regulating hepatic LDL receptors and production of the IGF-I antagonist IGFBP-1. The insulin-sensitizing properties of many vegan diets--high in fiber, low in saturated fat--should amplify these effects by down-regulating insulin secretion. Additionally, the relatively low essential amino acid content of some vegan diets may decrease hepatic IGF-I synthesis. Thus, diets featuring vegan proteins can be expected to lower elevated serum lipid levels, promote weight loss, and decrease circulating IGF-I activity. The latter effect should impede cancer induction (as is seen in animal studies with soy protein), lessen neutrophil-mediated inflammatory damage, and slow growth and maturation in children. In fact, vegans tend to have low serum lipids, lean physiques, shorter stature, later puberty, and decreased risk for certain prominent 'Western' cancers; a vegan diet has documented clinical efficacy in rheumatoid arthritis. Low-fat vegan diets may be especially protective in regard to cancers linked to insulin resistance--namely, breast and colon cancer--as well as prostate cancer; conversely, the high IGF-I activity associated with heavy ingestion of animal products may be largely responsible for the epidemic of 'Western' cancers in wealthy societies. Increased phytochemical intake is also likely to contribute to the reduction of cancer risk in vegans. Regression of coronary stenoses has been documented during low-fat vegan diets coupled with exercise training; such regimens also tend to markedly improve diabetic control and lower elevated blood pressure. Risk of many other degenerative disorders may be decreased in vegans, although reduced growth factor activity may be responsible for an increased risk of hemorrhagic stroke. By altering the glucagon/insulin balance, it is conceivable that supplemental intakes of key non-essential amino acids could enable omnivores to enjoy some of the health advantages of a vegan diet. An unnecessarily high intake of essential amino acids--either in the absolute sense or relative to total dietary protein--may prove to be as grave a risk factor for 'Western' degenerative diseases as is excessive fat intake.

Changes associated with delay of mammary cancer by retinoid analogues in transgenic mice bearing c-neu oncogene

Breast cancer is one of the common cancers and is a leading cause of cancer mortality in women. The TG.NK transgenic mouse line on FVB strain background expresses the c-neu oncogene under the control of a MMTV promoter in mammary tissue and appears to be a useful animal model for evaluation of strategies to delay or prevent mammary cancer. Fiber-rich nonpurified diet (NTP-2000) and some retinoid analogues have delayed mammary cancer in the TG.NK model. Four week old hemizygous TG.NK female mice with MMTV/c-neu (erbB2) activated oncogene were fed NTP-2000 diet containing the retinoid analogue 4-hydroxyphenylretinamide (4-HPR) at 7 mmol/kg or the arotinoid Ro 40-8757 at 1.5 and 2.5 mmol/kg for 26 weeks. The 4-HPR at 7 mmol/kg diet delayed the development of palpable tumors up to 24 weeks, but by 26 weeks, the incidence markedly increased and was closer to the NTP-2000 diet control group. However, the 4-HPR diet markedly decreased the average weight of the tumors at 26 weeks with no decrease in multiplicity. The 4-HPR also caused significant increase in liver weights without an effect on body weight. Arotinoid Ro 40-8757 caused marked decrease in the number and branching of mammary ducts, and inhibited mammary tumor development with significant decrease in the incidence, multiplicity, and tumor weights compared to the NTP-2000 diet control. Arotinoid also caused a significant dose-related increase in liver weights without a significant effect on body weights. At the doses tested, the arotinoid but not 4-HPR decreased the circulating levels of IGF-1. However, there was no association between the IGF-1 levels and the size, incidence, or absence of tumors when evaluated for any treatment group or for all mice in the study irrespective of treatment. The oncogene erbB2 (c-neu) and the growth factor EGF expression were more prominent in the small tumors of the mice treated with arotinoid than in the larger tumors of the control group. PCNA staining was observed in areas where there was high erbB2 and EGF staining. The delay in onset of mammary tumors by the above retinoid analogues may be related to the delay in development of mammary glands.

Obesity, weight change, fasting insulin, proinsulin, C-peptide, and insulin-like growth factor-1 levels in women with and without breast cancer: the Rancho Bernardo Study

Postmenopausal overweight women have an increased risk of breast cancer. The link between obesity and breast cancer could be mediated through hyperinsulinemia. Insulin and insulin-like growth factor-1 (IGF-1) stimulate mammary cell proliferation in vitro, and cell proliferation is directly linked to the risk of breast cancer. Our objective was to investigate the relationship between breast cancer and body composition, IGF-1, proinsulin, C-peptide, and fasting insulin. A case-control study was conducted of 438 community-dwelling women aged 53-90 years in 1992-1994 who had no history of cancer at the baseline visit in 1972-1974. Women were excluded who were using estrogen replacement therapy (ERT) or tamoxifen at the 1992-1994 visit, when IGF-1, proinsulin, fasting insulin, and C-peptide levels were measured. Prior ERT, alcohol and tobacco use, exercise, and reproductive history were recorded. Weight, height, and waist/hip ratio were measured. The 45 women with breast cancer had similar baseline body mass indices to the 393 women without breast cancer but had gained significantly more weight between the baseline visit in 1972-1974 and 1992-1994, (age-adjusted relative risk [RR] 1.05/kg, 95% confidence interval [CI] 1.01-1.09, p = 0.016). Proinsulin, fasting insulin, and C-peptide were each significantly positively correlated with both current weight and weight gain. However, levels of these hormones and IGF-1 did not differ significantly between women with and without breast cancer (all 95% CI within 0.996-1.004). Past ERT was significantly more common among women with breast cancer (p = 0.015), and duration of use was significantly longer (age-adjusted RR 1.13 per year of use, 95% CI 1.08-1.18, p = 0.000). The risk of breast cancer was significantly increased in women who had gained weight or used ERT. This increased risk was not associated with circulating levels of IGF-1, fasting insulin, proinsulin, or C-peptide.

Expression of sex steroid receptors and IGF-1 mRNA in breast tissue--effects of hormonal treatment

The mechanisms behind increased breast tissue proliferation and a possibly increased breast cancer risk in women using hormonal contraception (HC) and hormonal replacement therapy (HRT) are incompletely understood. We analyzed breast tissue from 20 premenopausal and seven postmenopausal women undergoing reduction mammoplasties for estrogen receptor (ER) and progesterone receptor (PR) content as well as mRNA levels for ER, PR and insulin-like growth factor-1 (IGF-1). The receptor values were correlated to IGF-1 mRNA concentrations and levels of steroid and peptide hormones and SHBG. In women using HC, we found significantly lower ER values (p = 0.02) but non-significantly lower ER mRNA levels compared to those in naturally cycling women. PR and PR mRNA were no different. Women on HC displayed a higher breast tissue proliferation (p = 0.05) expressed as Ki-67, MIB-1 positivity, which was correlated with IGF-1 mRNA (r(s) = 0.82, p = 0.04). Since the concentration of sex steroid receptors in breast tissue is comparatively low and steroid receptors are down-regulated during hormonal treatment, mechanisms other than direct sex steroid receptor action are likely to be present. Our results suggest a role for IGF-1 in the proliferative response of breast tissue during exogenous hormonal treatment.

Diabetes and endometrial cancer: an Italian case-control study

We considered the association between diabetes and risk of endometrial cancer using data from a large case-control study conducted in Italy. Cases were 752 women with incident, histologically confirmed endometrial cancer < 75 years of age (median age 60 years, range 28-74) admitted to a network of hospitals in Milan. Controls were 2,606 patients (median age 54 years, range 25-74) aged < 75 years, admitted for acute non-neoplastic, non-gynecological, non-hormone-related conditions to the same network of hospitals where cases had been identified. A total of 132 (17.6%) cases and 116 controls (4.5%) reported a history of diabetes. The corresponding multivariate odds ratio (OR) was 2.9 [95% confidence interval (CI) 2.2-3.9]. No association emerged with diabetes diagnosed under age 40 (likely to be insulin-dependent diabetes), whereas the OR of endometrial cancer was 3.1 (95% CI 2.3-4.2) for diabetes diagnosed at age > or = 40 years. The OR of endometrial cancer in women with history of diabetes was 3.0 for women with a body mass index (BMI) (QI) kg/m2 < 25, 3.6 for those with a BMI of 25-29, and 3.3 for those with a BMI > or = 30. No consistent interaction or modifying effect was observed for any other covariate. Our results confirm that non-insulin-dependent diabetes is associated with the risk of endometrial cancer. The association may be mediated through elevated oestrogen levels in diabetic women, hyperinsulinemia or insulin-like growth factor-I (IGF-I).

Insulin and polycystic ovary syndrome: a new look at an old subject

In recent years the metabolic implications of polycystic ovary syndrome (PCOS) have received a great deal of attention; in fact 50% of women with PCOS are obese and a similar percentage of subjects was found to show exaggerated insulin secretion and reduced insulin-stimulated glucose uptake. The presence of these features in women with PCOS has profound clinical implications in terms of morbidity due to diabetes mellitus, dyslipidemia, hypertension and cardiovascular disease. Moreover, hyperinsulinemia has recently been proposed as a possible independent risk factor for endometrial and breast cancer. In the light of these considerations, the importance of metabolic screening in patients with PCOS in order to improve their quality of life cannot be underestimated. In this review we analyze all the clinical pathologies in which hyperinsulinemia of PCOS could be involved. Furthermore, in order to clarify the possible mechanisms leading to the insulin disorders of the syndrome, we review the available data about the insulin receptor abnormalities, as well as those concerning the insulin resistance and the exaggerated insulin secretion. Finally, we examine the main therapeutic strategies to ameliorate the insulinemic status of PCOS patients in order to potentially be able to prevent the long-term consequences of this syndrome.

Insulin-like growth factor I (IGF-I) serum level modifications during transdermal estradiol treatment in postmenopausal women: a possible bimodal effect depending on basal IGF-I values

The objective of this study was to determine the influence of transdermal estradiol administration on insulin-like growth factor I (IGF-I) serum level in a series larger than those published to date. Thirty-nine postmenopausal women with vasomotor symptoms were studied; blood samples (after overnight fast) were obtained just before and at the 6th month of treatment with transdermal estradiol 0.05 mg/day, and serum levels of IGF-I, growth hormone and sex hormone binding globulin (SHBG) were evaluated. Sixteen of the 39 women did not show variations of IGF-I values (group A), while 11 showed an increase (group B) and 12 showed a decrease (group C) by at least 20% with transdermal estradiol treatment. IGF-I basal levels were higher in group C as compared to group A (p < 0.05) and to group B (p < 0.01), intermediate in group A, and lower in group B. Group C showed a significant increase of SHBG values with transdermal estradiol treatment. Transdermal estradiol seems to induce a bimodal effect on IGF-I serum levels, depending on IGF-I basal values. This could be caused by a different responsivity to estrogen action on the liver (the major site of circulating IGF-I production) and also, possibly, by a different degree in insulin sensitivity changes caused by estrogen.