Metabolic syndrome predicts prostate cancer in a cohort of middle-aged Norwegian men followed for 27 years

Insulin resistance and hyperinsulinaemia in the development and progression of cancer

Experimental, epidemiological and clinical evidence implicates insulin resistance and its accompanying hyperinsulinaemia in the development of cancer, but the relative importance of these disturbances in cancer remains unclear. There are, however, theoretical mechanisms by which hyperinsulinaemia could amplify such growth-promoting effects as insulin may have, as well as the growth-promoting effects of other, more potent, growth factors. Hyperinsulinaemia may also induce other changes, particularly in the IGF (insulin-like growth factor) system, that could promote cell proliferation and survival. Several factors can independently modify both cancer risk and insulin resistance, including subclinical inflammation and obesity. The possibility that some of the effects of hyperinsulinaemia might then augment pro-carcinogenic changes associated with disturbances in these factors emphasizes how, rather than being a single causative factor, insulin resistance may be most usefully viewed as one strand in a network of interacting disturbances that promote the development and progression of cancer.

Serum triglyceride concentrations and cancer risk in a large cohort study in Austria

Background:

Blood lipid levels as part of the metabolic syndrome are thought to be linked to cancer risk. Few epidemiological studies have addressed the association between serum triglyceride (STG) concentrations and cancer risk.

Methods:

Serum triglyceride concentrations were collected in a health investigation (1988–2003). The analyses included 156 153 subjects (71 693 men and 84 460 women), with 5079 incident cancers in men and 4738 cancers in women, and an average of 10.6 years of follow-up. All malignancies were ascertained from the population cancer registry. Multivariate Cox proportional hazard models stratified by age and sex were used to determine adjusted cancer risk estimates and 95% confidence interval (95% CI).

Results:

In men and women combined, higher STG concentrations were associated with increased risk of lung (4th vs 1st quartile: HR, 1.94; 95% CI, 1.47–2.54), rectal (HR, 1.56; 95% CI, 1.00–2.44), and thyroid cancer (HR, 1.96; 95% CI, 1.00–3.84). Serum triglyceride concentrations were inversely associated with non-Hodgkin's lymphoma. In men, STG concentrations were inversely associated with prostate cancer and positively with renal cancer. In women, STG concentrations were positively associated with gynaecological cancers. Stratification by BMI revealed a higher risk of gynaecological cancers in overweight than in normal weight women. No other associations were found.

Conclusions:

Our findings support the hypothesis that STG concentrations are involved in the pathogenesis of lung, rectal, thyroid, prostate, and gynaecological cancers.

Impact of metabolic factors on subsequent cancer risk: results from a large-scale population-based cohort study in Japan

The impact of metabolic factors, which are major risk factors for cardiovascular disease, on total cancer risk has not been clarified. We prospectively examined whether metabolic factors and their aggregates predict the subsequent occurrence of total and major sites of cancer in the Japan Public Health Center-based Prospective Study. A total of 27 724 participants (9548 men and 18 176 women) aged 40-69 years participating in a questionnaire and health checkup survey in 1993-1995 were followed for total cancer incidence through 2004. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated for metabolic factors and for two criteria of their aggregates (three or more than three factors and two or more than two additional factors in addition to being overweight) with a Cox proportional hazards model to control for potential confounding factors. In both sexes, the presence of metabolic factors in the aggregate did not predict subsequent occurrence of cancer as a whole. By site, a significant increase in risk was observed for male liver cancer [HR = 1.73, CI = 1.03-2.91 (three or more than three factors); HR = 1.99, CI = 1.11-3.58 (two or more than two additional factors in addition to being overweight)], and female pancreatic cancer [HR = 1.99, CI = 1.00-3.96 (two or more than two additional factors in addition to being overweight)]. For other sites, positive associations were observed only for specific metabolic factors, that is, high triglycerides and male colon cancer (HR = 1.71, CI = 1.11-2.62), and obesity and female breast cancer (HR = 1.75, CI = 1.21-2.55). Metabolic factors in the aggregate may have little impact on total cancer risk in the Japanese population, although the association between specific components and specific cancers suggests an etiologic link between them.

Prevalence and Associated Factors for Metabolic Syndrome in Taiwanese Hospital Employees

Metabolic syndrome (MS) is most important because of its association with subsequent development of cardiovascular diseases. However, few studies about the prevalence of MS among hospital employees had been published.The aims of our study were to examine the prevalence of MS and associated factors. The up-to-date health examination data of 1,400 hospital employees of a medical center in North Taiwan were included, and MS was defined according to the criteria that were promulgated by the National Department of Health. The overall prevalence of MS was 10.3% (21.8% males, 7.0% females). Associated factors included male gender, aging, low education, administrative employees, abnormal hemoglobin concentration, and abnormal liver function indexes. According to our study, the prevalence of MS in hospital employees was lower than the general population, and the findings could be a reference to make more efficient health-promotion programs to lower the prevalence of MS in hospital employees.

Racial differences in risk of prostate cancer associated with metabolic syndrome

OBJECTIVES

To perform a case-control study to test the association between metabolic syndrome features and prostate cancer. The metabolic syndrome refers to a cluster of conditions serving as risk factors for cardiovascular disease. The metabolic syndrome is prevalent in the United States, and the spectrum of specific features has been shown to differ by race and ethnicity. A number of recent reports have linked metabolic syndrome to prostate cancer; however, most studies have not had racially diverse populations to explore differences in risk.

METHODS

A case-control study was conducted to test the association between metabolic syndrome features and prostate cancer among 637 patients and 244 controls, with African-American men constituting 43% of the study population.

RESULTS

Metabolic syndrome, defined using a modified version of the Adult Treatment Panel III criteria, was marginally associated with an increased risk of prostate cancer in African-American men (odds ratio [OR] 1.71, 95% confidence interval [CI] 0.97-3.01), but not in white men (OR 1.02, 95% CI 0.64-1.62). After stratifying the patients by stage at diagnosis, African-American men with organ-confined disease were more likely to have a history of metabolic syndrome than were the controls (OR 1.82; 95% CI 1.02-3.23), but no association was observed among those with advanced-stage disease (OR 0.93; 95% CI 0.31-2.77). When evaluating the specific features of the metabolic syndrome, obesity was inversely related to prostate cancer among white men (OR 0.51, 95% CI 0.33-0.80) but unrelated to risk among African-American men (OR 1.15, 95% CI 0.70-1.89).

CONCLUSIONS

In the present investigation, the metabolic syndrome was associated with prostate cancer risk in African-American men, but not in white men. The prevalence of this syndrome, coupled with the racial disparity in prostate cancer incidence and outcomes after diagnosis, warrant additional investigation.

Association of metabolic syndrome with insulin-like growth factors among adults in the US

OBJECTIVE

To examine the association of insulin-like growth factors (IGFs) with metabolic syndrome in a nationally representative sample.

METHODS

We used data from the Third National Health and Nutrition Examination Survey. Analysis is based on participants who provided a fasting blood sample and were aged 20 years and older (n = 5,903). Participants were classified by a number of risk factors for metabolic syndrome and stratified by diabetes status.

RESULTS

Each of the components of metabolic syndrome (increased waist circumference, higher triglycerides, lower HDL cholesterol, higher blood pressure, higher fasting glucose and diabetes) was each associated with lower levels of IGF-I, IGF-BP3 and the Ratio IGF-I/IGF-BP3. Each of the metabolic syndrome components was also associated with higher levels of insulin. Participants with 3-5 components of metabolic syndrome had significantly lower IGF-I and higher IGF-BP3 levels compared to adults with 1-2 components or 0 components, after adjustment for potential confounders. Participants with diabetes had lower levels of IGF-I and IGF-BP3, and higher levels of insulin, regardless of the number of metabolic syndrome components.

CONCLUSION

These findings may prove useful to an understanding of the role of IGF-I in human disease, in particular its relation to metabolic syndrome, diabetes and potentially some cancers.

Inactivation of AMPK alters gene expression and promotes growth of prostate cancer cells

AMP-activated protein kinase (AMPK) serves as a fuel-sensing enzyme that is activated by binding of AMP and subsequent phophorylation by upstream kinases such as the tumor suppressor LKB1, when cells sense an increase in the ratio of AMP to ATP. Acute activation of AMPK stimulates fatty acid oxidation to generate more ATP and simultaneously inhibits ATP-consuming processes including fatty acid and protein syntheses, thereby preserving energy for acute cell surviving program, while the chronic activation leads to inhibition of cell growth. The goal of the present study is to explore the mechanisms by which AMPK regulates cell growth. Toward this end, we established stable cell lines by introducing a dominant negative mutant of AMPK α1 subunit or its shRNA into the prostate cancer C4-2 cells and other cells, or wild type LKB1 into the lung adenocarcinoma A549 and breast MB-MDA-231 cancer cells, both of which lack functional LKB1. Our results showed that the inhibition of AMPK accelerated cell proliferation and promoted malignant behavior such as increased cell migration and anchorage-independent growth. This was associated with decreased G1 population, downregulation of p53 and p21, and upregulation of S6K, IGF-1 and IGF1R. Conversely, treatment of the C4-2 cells with 5-aminoimidazole-4-carboxamide 1-Dribonucleoside (AICAR), a prototypical AMPK activator, caused opposite changes. In addition, our study using microarray and RT-PCR revealed that AMPK regulated gene expression involved in tumor cell growth and survival. Thus, our study provides novel insights into the mechanisms of AMPK action in cancer cells and presents AMPK as an ideal drug target for cancer therapy.

Components of the metabolic syndrome and risk of prostate cancer: the HUNT 2 cohort, Norway

BACKGROUND

The metabolic syndrome has been suggested as a unifying link between a "western" lifestyle and an increased prostate cancer risk.

METHODS

We assessed the associations of components of the metabolic syndrome with prostate cancer in a prospective cohort based on 29,364 Norwegian men followed up for prostate cancer incidence and mortality from 1995-1997 to the end of 2005 in the second Nord Trøndelag Health Study (HUNT 2).

RESULTS

During a mean 9.3 years follow-up, 687 incident prostate cancers were diagnosed, and 110 men died from prostate cancer. There was little evidence that baseline BMI, waist circumference, waist-hip ratio, total or HDL-cholesterol, triglycerides, presence of the metabolic syndrome, diabetes, antihypertensive use, or cardiovascular disease were associated with incident or fatal prostate cancer. There was weak evidence that raised blood pressure was associated with an increased risk: for each SD (12 mm) increase in diastolic blood pressure, there was an 8% (95% CI = 1-17%; p = 0.04) increased risk of incident prostate cancer.

CONCLUSIONS

We found little evidence to support the hypothesis that the metabolic syndrome or its components explains higher prostate cancer mortality rates in countries with a "western" diet and lifestyle. The positive association of blood pressure with prostate cancer warrants further investigation.

Helicobacter pylori infection is significantly associated with metabolic syndrome in the Japanese population

BACKGROUND

Metabolic syndrome comprises a cluster of metabolic abnormalities leading to insulin resistance and atherosclerosis, and Helicobacter pylori is thought to be a contributing factor.

AIM

We examined the association between H. pylori infection and metabolic syndrome in a large Japanese population.

METHOD

Consecutive asymptomatic subjects that underwent a complete medical survey in our institute between April 2006 and March 2007 were recruited, and a total of 5,488 men and 1,906 women were cross-sectionally studied. The association of H. pylori serostatus with traditional atherosclerosis risk factors was investigated by multiple linear regression analysis. Independent and significant factors affecting metabolic syndrome were determined by multiple logistic regression analysis.

RESULTS

H. pylori seropositivity significantly increased with age in both men and women. H. pylori seropositivity was significantly higher in cases with metabolic syndrome compared with those without metabolic syndrome (P < 0.001). There was a significant and independent association between H. pylori seropositivity and metabolic syndrome (OR 1.39, 95% CI 1.18-1.62, P < 0.001) by multiple logistic regression analysis. H. pylori seropositivity was significantly associated with higher systolic blood pressure (beta coefficient = 1.03, P= 0.014), lower high-density lipoprotein (HDL)-cholesterol level (beta coefficient =-2.00, P < 0.001), and higher LDL-cholesterol level (beta coefficient = 2.21, P= 0.005) by multiple linear regression analysis.

CONCLUSION

In a large Japanese population, H. pylori infection was significantly associated with metabolic syndrome.

Height and prostate cancer risk: a large nested case-control study (ProtecT) and meta-analysis

BACKGROUND

Height, a marker of childhood environmental exposures, is positively associated with prostate cancer risk, perhaps through the insulin-like growth factor system. We investigated the relationship of prostate cancer with height and its components (leg and trunk length) in a nested case-control study and with height in a dose-response meta-analysis.

METHODS

We nested a case-control study within a population-based randomized controlled trial evaluating treatments for localized prostate cancer in British men ages 50 to 69 years, including 1,357 cases detected through prostate-specific antigen testing and 7,990 controls (matched on age, general practice, assessment date). Nine bibliographic databases were searched systematically for studies on the height-prostate cancer association that were pooled in a meta-analysis.

RESULTS

Based on the nested case-control, the odds ratio (OR) of prostate-specific antigen-detected prostate cancer per 10 cm increase in height was 1.06 [95% confidence interval (95% CI): 0.97-1.16; p(trend) = 0.2]. There was stronger evidence of an association of height with high-grade prostate cancer (OR: 1.23; 95% CI: 1.06-1.43), mainly due to the leg component, but not with low-grade disease (OR: 0.99; 95% CI: 0.90-1.10). In general, associations with leg or trunk length were similar. A meta-analysis of 58 studies found evidence that height is positively associated with prostate cancer (random-effects OR per 10 cm: 1.06; 95% CI: 1.03-1.09), with a stronger effect for prospective studies of more advanced/aggressive cancers (random-effects OR: 1.12; 95% CI: 1.05-1.19).

CONCLUSION

These data indicate a limited role for childhood environmental exposures-as indexed by adult height-on prostate cancer incidence, while suggesting a greater role for progression, through mechanisms requiring further investigation.

A genetic link between type 2 diabetes and prostate cancer

Epidemiological studies suggest that men with type 2 diabetes are less likely than non-diabetic men to develop prostate cancer. The cause of this association is not known. Recent genetic studies have highlighted a potential genetic link between the two diseases. Two studies have identified a version (allele) of a variant in the HNF1B (also known as TCF2) gene that predisposes to type 2 diabetes, and one of them showed that the same allele protects men from prostate cancer. Other, separate, studies have identified different variants in the JAZF1 gene, one associated with type 2 diabetes, another associated with prostate cancer. These findings are unlikely to completely explain the epidemiological association between the two diseases but they provide new insight into a possible direct causal link, rather than one that is confounded or biased in some way.

Testosterone, diabetes mellitus, and the metabolic syndrome

Metabolic syndrome is characterized by insulin insensitivity, central obesity dyslipidemia, and hypertension. It is recognized as a risk factor for cardiovascular disease in men; by the time metabolic syndrome is diagnosed, however, most men already have entrenched cardiovascular disease. A reliable early warning sign is needed to alert physicians to those at risk for metabolic syndrome and cardiovascular disease. Low serum testosterone level has emerged as a reliable prognosticator of metabolic syndrome in men whose testosterone deficiency is genetic (Klinefelter syndrome), iatrogenic following surgery for testicular cancer, pharmacologically induced by gonadotropin-releasing hormone during prostate cancer treatment, or a natural consequence of aging. One third of men with type 2 diabetes mellitus are now recognized as testosterone deficient. Emerging evidence suggests that testosterone therapy may be able to reverse some aspects of metabolic syndrome.

Metabolic syndrome and cancer risk

OBJECTIVE

The purpose of this population-based study is to explore for the first time the link between metabolic syndrome and cancer risk using information from the health information system of the Cancer Registry.

METHODS

Referring to all pharmaceutical prescriptions between 1 January 1999 and 31 December 2005, coded with the Anatomical Therapeutic Chemical classification, all subjects aged 40 and over resident in Milan, which were simultaneously prescribed with antihypertensive, hypolypemic and hypoglycaemic drugs, were considered affected by metabolic syndrome. New cancer cases among cohort subjects were identified trough the local Cancer Registry and standardised incidence ratios (and corresponding 95% exact confidence intervals) were computed.

RESULTS

Overall 16,677 subjects were identified corresponding to 45,828 person-years; among them 823 incidents cancers occurred. Significantly increased risks for pancreatic cancer in males--SIR 178 (114-266)--and colorectal cancer in females--SIR 133 (101-170)--were observed. Non-significantly increased risks were also observed in women for liver, gallbladder and biliary tract, breast and endometrial cancers.

CONCLUSIONS

Our study suggests that the risk for several cancers increases in subjects affected by metabolic syndrome. The pharmacological control of the syndrome seems to be inadequate for reducing cancer risk, even though both a high competitive mortality effect and short duration of follow up have to be considered.

Association between prostate-specific antigen and leptin, adiponectin, HbA1c or C-peptide among African-American and Caucasian men

Prior studies report slightly lower prostate-specific antigen (PSA) levels among obese men. To understand this effect, we investigated the association between PSA and blood HbA1c, C-peptide, leptin and adiponectin levels in African-American (AA) (n=121) and Caucasian (CA) (n=121) men. Among AA men, PSA levels decreased with increasing C-peptide levels (PSA=0.99, 0.93, 0.75 and 0.53 ng ml(-1) across quartiles of C-peptide, respectively; P(trend)=0.005). Among CA men, PSA levels decreased with increasing HbA1c (PSA=0.84, 0.73, 0.77 and 0.45 ng ml(-1) across quartiles of HbA1c, respectively; P(trend)=0.005). This may suggest that metabolic disturbances related to metabolic syndrome or diabetes affect the ability to detect early-stage prostate cancer.

Obesity, metabolic syndrome, and prostate cancer

Although obesity has been consistently linked to an increased risk of several malignancies, including cancers of the colon, gallbladder, kidney, and pancreas, its role in prostate cancer etiology remains elusive. Data on the association between obesity and prostate cancer incidence are inconsistent, and in some studies obesity is associated with an increase in risk of high-grade prostate cancer but with a decrease in risk of low-grade tumors. In contrast, obesity has been consistently associated with an increased risk of prostate cancer aggressiveness and mortality. The differential effects of obesity on subtypes of prostate cancer suggest etiologic heterogeneity in these tumors and complex interactions between androgen metabolism and several putative risk factors, including insulin resistance, diabetes, inflammation, and genetic susceptibility, on prostate cancer risk. Data on the role of abdominal obesity, insulin resistance, and metabolic syndrome in prostate cancer etiology are limited. Obesity has been shown to be associated with a state of low-grade chronic inflammation, and insulin resistance and the metabolic syndrome are associated with adverse metabolic profiles and with higher circulating concentrations of inflammation-related markers, including leptin, interleukin-6, and tumor necrosis factor-, many of which have been shown to enhance tumor growth. Thus, whether obesity and metabolic syndrome modulate the risk of prostate cancer through chronic inflammation needs to be investigated further. Given that the prevalence of obesity and metabolic syndrome is increasing worldwide and that the world population is aging, the roles of obesity and metabolic syndrome in prostate carcinogenesis warrant further clarification.

Symposium introduction: metabolic syndrome and the onset of cancer

Diabetes, obesity, and related metabolic disorders are among the most pressing of today's health care concerns. Recent evidence from epidemiologic and basic research studies, as well as translational, clinical, and intervention studies, supports the emerging hypothesis that metabolic syndrome may be an important etiologic factor for the onset of cancer. On March 15-16, 2006, The Harvard Medical School Division of Nutrition hosted the symposium "Metabolic Syndrome and the Onset of Cancer" as a platform to systematically evaluate the evidence in support of this hypothesis. This symposium, which gathered leaders in the fields of metabolism, nutrition, and cancer, will stimulate further research investigating the etiologic role of metabolic syndrome in cancer. Furthermore, it will help to guide the development of effective cancer prevention strategies via nutritional and lifestyle modifications to alleviate metabolic syndrome.

Metabolic syndrome and prostate cancer

Prostate cancer is a common form of cancer in men and the incidence increases with age. It is known to develop slowly but may also take an aggressive course. No conclusions have been made on the cause of prostate cancer and there is no diagnostic factor that can be used for screening purposes. Studies indicate that metabolic syndrome is associated with prostate cancer. Metabolic syndrome components are hypertension, dyslipidemia, glucose intolerance and obesity. A systematic literature search for studies on metabolic syndrome or insulin resistance and prostate cancer was performed using the OVID database manager searching the Medline and EMBASE databases. Seven studies were included, of which five were prospective cohorts and two were case-control studies. Most other studies were reviews. Four studies showed a positive association, one showed a negative association and one showed no association. One study, using two different analyses for metabolic syndrome, showed a positive association, or none, depending on the criteria used for defining metabolic syndrome. The results indicate that metabolic syndrome can be used to identify men at risk of prostate cancer. The definition of the metabolic syndrome must be taken into consideration.

Dietary soy and tea combinations for prevention of breast and prostate cancers by targeting metabolic syndrome elements in mice

BACKGROUND

The prevalence of metabolic syndrome is high and is increasing in parallel with increasing incidences of breast and prostate cancers. The combination of soy with tea was shown to have synergistic effects on preventing breast and prostate tumors, but the effects of soy and tea combinations on metabolic syndrome-related elements have not been investigated.

OBJECTIVE

We aimed to determine the effects of soy and tea components, alone and in combination, on abdominal adipose mass and serum concentrations of adipokines, growth factors, and sex hormones in male and female mice.

DESIGN

Male and female FVB/N mice were treated with soy, tea components, or both. Food intake and body weight were monitored weekly. At the end of the experiment, abdominal white adipose tissue was weighed, and serum concentrations of biomarkers were measured.

RESULTS

Whole teas, but not the tea polyphenol extracts, significantly reduced abdominal white adipose tissue by 43-60% in female mice and by 65-70% in male mice. The combination of soy phytochemical concentrate and green tea reduced serum insulin-like growth factor-I concentrations in both male and female mice in a synergistic manner. The soy phytochemical concentrate and tea combinations reduced serum estrogen concentrations in female mice in a synergistic manner. Soy phytochemical concentrate and teas also significantly reduced serum leptin concentrations in both male and female mice and testosterone concentrations in male mice.

CONCLUSION

Further research is warranted to investigate whether soy and tea combinations may prevent breast or prostate cancer in a synergistic manner in part by alleviating metabolic disorders.

The impact of obesity on prostate cancer

Increasing prevalence of obesity in many parts of the world emphasizes the importance of learning more about the relationship between obesity and prostate cancer (PC). The present paper reviews the impact of obesity on PC using knowledge obtained from the available literature. Search of published literature in PUBMED database. Adipose tissue constitutes an active endocrine and metabolic organ which may be relevant in the development and progression of PC by different potential mechanisms. Furthermore, obesity could have an impact on the outcome of different treatment modalities for PC, both functionally as anatomically. Obesity is a growing problem, however, the exact role in the development and progression of PC has not been elucidated. Regarding the optimal treatment of PC in obese patients, comparative prospective studies are needed.

Obesity and prostate cancer: epidemiology and clinical implications

OBJECTIVES

Both obesity and prostate cancer (PCa) are epidemic in Western society. Although initial epidemiological data appeared conflicting, recent studies have clarified the association between obesity and PCa. Therefore, we sought to review the epidemiological data linking obesity and PCa with an emphasis on the clinical implications and how to improve outcomes among obese men.

METHODS

A PubMed search using the keywords "prostate cancer" and "obesity" was performed. Relevant articles and references were reviewed for data on the association between obesity and PCa.

RESULTS

Recent data suggest obesity is associated with reduced risk of nonaggressive disease but increased risk of aggressive disease. This observation may be explained in part by an inherent bias in our ability to detect PCa in obese men (lower PSA values and larger sized prostates, making biopsy less accurate for finding an existent cancer), which ultimately leads to increased risk of cancer recurrence after primary therapy and increased PCa mortality. Despite this detection bias potentially contributing to more aggressive cancers, multiple biological links also exist between obesity and PCa including higher estradiol, insulin, free IGF-1, and leptin levels, and lower free testosterone and adiponectin levels, all of which may promote more aggressive cancers.

CONCLUSIONS

The association between obesity and PCa is complex. Emerging data suggest obesity increases the risk of aggressive cancer, while simultaneously decreasing the risk of more indolent disease. This is likely driven by both "biological" and "nonbiological" causes. Simple changes in clinical practice patterns can reduce the impact of nonbiological causes and may help improve PCa outcomes among obese men.

Features of the metabolic syndrome and prostate cancer in African-American men

BACKGROUND

Metabolic syndrome refers to a cluster of conditions that includes hypertension, dyslipidemia, central adiposity, and high blood glucose levels. Over the past decade, a growing body of literature suggests that metabolic syndrome may be associated with several different forms of cancer. Because prostate cancer risk is highest among African Americans, and these men, similarly, are more prone to developing specific features of the metabolic syndrome, including hypertension and type-2 diabetes, any relationships would have a significant impact on developing strategies for the primary prevention of prostate cancer.

METHODS

The Flint Men's Health Study is a community-based, case-control study of prostate cancer conducted exclusively among African Americans. Prostate cancer cases and controls completed an interviewer-administered questionnaire that asked about the respondent's history of high blood pressure and diabetes. All men also participated in a physical examination in which several measures of body composition, including waist circumference, were collected.

RESULTS

Hypertension was reported more commonly among men with prostate cancer (cases) compared with men in the control group (odds ratio [OR]. 2.4; 95% confidence interval [95% CI], 1.5-3.7), and cases were more likely to have a waist circumference >102 cm (OR, 1.8; 95% CI, 1.2-2.9). However, self-reported diabetes was not associated with prostate cancer risk. The men with prostate cancer also were more likely than controls to exhibit multiple syndrome characteristics (OR, 1.9; 95% CI, 1.2-3.0).

CONCLUSIONS

The current results indicated that features of the metabolic syndrome, specifically abdominal obesity and hypertension, are associated with prostate cancer in African-American men. This relationship, if it is proved causal, suggests that prevention or control of these conditions eventually may lead to a reduction in the incidence of prostate cancer in this high-risk minority group.

The role of obesity and related metabolic disturbances in cancers of the colon, prostate, and pancreas

Recent evidence indicates that obesity and related metabolic abnormalities are associated with increased incidence or mortality for a number of cancers, including those of the colon, prostate, and pancreas. Obesity, physical inactivity, visceral adiposity, hyperglycemia, and hyperinsulinemia are relatively consistent risk factors for colon cancer and adenoma. Also, patients with type 2 diabetes mellitus have a higher risk of colon cancer. For prostate cancer, the relationship to obesity appears more complex. Obesity seems to contribute to a greater risk of aggressive or fatal prostate cancer but perhaps to a lower risk of nonaggressive prostate cancer. Furthermore, men with type 2 diabetes mellitus are at lower risk of developing prostate cancer. Long-standing type 2 diabetes increases the risk of pancreatic cancer by approximately 50%. Furthermore, over the past 6 years, a large number of cohort studies have reported positive associations between obesity and pancreatic cancer. Together with data from prediagnostic blood specimens showing positive associations between glucose levels and pancreatic cancer up to 25 years later, sufficient evidence now supports a strong role for diabetes and obesity in pancreatic cancer etiology. The mechanisms for these associations, however, remain speculative and deserve further study. Hyperinsulinemia may be important, but the role of oxidative stress initiated by hyperglycemia also deserves further attention.

Interaction of factors related to the metabolic syndrome and vitamin D on risk of prostate cancer

BACKGROUND

Factors related to the metabolic syndrome and low levels of vitamin D have been implicated as risk factors for prostate cancer. Insofar, no studies have assessed their joint effects on prostate cancer risk.

METHODS

We studied (a) the associations of vitamin D with the metabolic syndrome factors body mass index, systolic and diastolic blood pressure, and high-density lipoprotein cholesterol (HDL-C) and (b) the prostate cancer risk associated with these factors and especially their joint effects with vitamin D on risk of prostate cancer. We did a longitudinal nested case-control study on 132 prostate cancer cases and 456 matched controls from a cohort of 18,939 Finnish middle-aged men from the Helsinki Heart Study. The odds ratios (OR) of prostate cancer were assessed via conditional logistic regression analysis.

RESULTS

Apart from HDL-C, there was no linear association between the metabolic syndrome factors and vitamin D levels. In univariate analysis, men in the highest quartiles of body mass index (>28 kg/m(2)) and systolic blood pressure (>150 mmHg) showed a modest increase in risks of prostate cancer, with ORs of 1.37 (P = 0.16) and 1.53 (P = 0.05) when compared with the three lower quartiles, but low HDL-C entailed no prostate cancer risk. However, with all three factors present, the OR was 3.36 (P = 0.02), and jointly with low vitamin D (<or=40 nmol/L), the OR was 8.03 (P = 0.005) compared with those with no metabolic syndrome factors and intermediate levels of vitamin D. There was an interaction between vitamin D and the metabolic syndrome factors so that a clustering of these factors entailed high risk of prostate cancer but only if vitamin D level was low (<or=40 nmol/L). If it was at intermediate levels, the metabolic syndrome factors entailed no prostate cancer risk.

CONCLUSIONS

We conclude that the prostate cancer risk associated with factors related to the metabolic syndrome is strongly conditioned by levels of vitamin D.