Metabolic syndrome, hyperinsulinemia, and colon cancer: a review

Physical activity in the prevention and treatment of colorectal carcinoma

BACKGROUND

Colorectal carcinoma is the most common type of tumor in Western countries. The risk of developing colorectal carcinoma depends both on genetic factors (familial predisposition) and on lifestyle-related factors such as body-mass index, level of physical activity, and nutritional behavior. Regular physical activity is important in primary prevention, and there is also evidence that the prognosis after treatment of a colorectal carcinoma can be improved by exercise.

METHODS

The PubMed database was searched for relevant articles that appeared in the last 10 years, and selected articles were evaluated.

RESULTS

Cross-sectional studies have shown that regular physical activity (ca. 7 hours of brisk walking per week) lowers the risk of colon carcinoma by 40%. Physical activity also improves the outcome of patients already diagnosed with colorectal carcinoma: for example, patients with advanced disease (UICC stage II or III) have been found to survive significantly longer if they perform 4 hours of brisk walking per week, or the equivalent degree of physical exercise.

CONCLUSIONS

Cross-sectional studies show that physically active persons are less likely to develop colorectal carcinoma than physically inactive persons, and that they have better outcomes in the event that they do develop the disease. The positive findings with respect to secondary prevention still need to be confirmed in interventional trials, but in primary prevention, at least, physical activity should be actively promoted, along with other beneficial lifestyle habits and screening measures.

The association of metabolic syndrome with triple-negative breast cancer

Metabolic syndrome, a conglomerate of obesity, insulin resistance, dyslipidemia, and hypertension has been linked with an increased risk of breast cancer. We investigated the possible association of highly aggressive triple-negative breast cancer and the metabolic syndrome. Information on metabolic syndrome components and tumor characteristics were reviewed in a cohort of 176 patients (including 86 triple-negatives). Retrospective comparison was performed using Pearson Chi-square test or Student's t test for data analysis. A statistically significant association of triple-negative breast cancer with the metabolic syndrome was observed. In accordance with the NCEP (National Cholesterol Education Program) definition, 58.1% of triple-negative patients had metabolic syndrome compared to only 36.7% of non-triple-negative patients (P = 0.004). Consistently, by the AACE (American Association of Clinical Endocrinologists) criteria, 52.3% of triple-negative patients had metabolic syndrome as compared to 34.4% of non-triple-negative patients (P = 0.017). Blood glucose, triglyceride, and HDL levels but not hypertension or BMI (body mass index) showed significant independent association with triple-negative breast cancer. Additionally, triple-negative tumors displayed a significantly higher histological grade and relative paucity of ductal carcinoma in situ (DCIS) when compared to the non-triple-negative tumors (P < 0.001). Our study suggests that metabolic syndrome is significantly more prevalent in triple-negative breast cancer patients as opposed to non-triple-negative patients. Furthermore, triple-negative breast cancer showed a significantly higher histological grade and a relative absence of DCIS. Whether the presence of metabolic syndrome preferentially increases the risk of developing triple-negative-breast cancer remains to be elucidated with future prospective studies.

The diseasome of physical inactivity--and the role of myokines in muscle--fat cross talk

Type 2 diabetes, cardiovascular diseases, colon cancer, breast cancer, dementia and depression constitute a cluster of diseases, which defines 'a diseasome of physical inactivity'. Both physical inactivity and abdominal adiposity, reflecting accumulation of visceral fat mass, are associated with the occurrence of the diseases within the diseasome. Physical inactivity appears to be an independent and strong risk factor for accumulation of visceral fat, which again is a source of systemic inflammation. Chronic inflammation is involved in the pathogenesis of insulin resistance, atherosclerosis, neurodegeneration and tumour growth. Evidence suggests that the protective effect of exercise may to some extent be ascribed to the anti-inflammatory effect of regular exercise, which can be mediated via a reduction in visceral fat mass and/or by induction of an anti-inflammatory environment with each bout of exercise. The finding that muscles produce and release myokines provides a conceptual basis to understand the mechanisms whereby exercise influences metabolism and exerts anti-inflammatory effects. According to our theory, contracting skeletal muscles release myokines, which work in a hormone-like fashion, exerting specific endocrine effects on visceral fat. Other myokines work locally within the muscle via paracrine mechanisms, exerting their effects on signalling pathways involved in fat oxidation.

Intake of wholegrain products is associated with dietary, lifestyle, anthropometric and socio-economic factors in Denmark

Objective

To evaluate the association between wholegrain products intake and other dietary, lifestyle, anthropometric and socio-economic factors.

Design

Cross-sectional study, with data on diet, lifestyle and socio-economic factors obtained from questionnaires. Anthropometric measurements were collected by trained professionals. Multiple linear and principal components regression analyses were used in statistical analyses.

Setting

Part of the Diet, Cancer and Health study, a prospective cohort study to evaluate the aetiological role of diet on cancer risk, conducted in the greater Copenhagen and Aarhus area, Denmark.

Subjects

Men and women (n54 720) aged 50–64 years.

Results

In multiple linear regression analyses focusing on individual dietary factors, intake of wholegrain products was associated with intake of all dietary factors studied (fish, red meat, poultry, processed meat, dairy products, fruits, vegetables, cakes and refined-grain products). The strongest positive associations were seen for intake of vegetables and processed meat, whereas the strongest negative associations were seen for intake of red meat and refined-grain products. Regression analyses on dietary patterns identified by principal components analysis yielded similar results. Also, wholegrain products intake was positively associated with cycling, taking dietary supplements and high school education, and negatively associated with intake of alcohol, BMI and smoking.

Conclusions

Intake of wholegrain products is associated with other dietary factors, healthier lifestyle habits and higher socio-economic status. Therefore future studies need to account for the possible confounding by other dietary and lifestyle-related parameters when investigating relationships between wholegrain products intake and disease risk.

Comorbidities of obesity

Obesity, especially visceral adiposity, is associated with morbidity and mortality through endocrine and mechanical processes. Clinical manifestations due to effects of obesity on the cardiovascular, respiratory, gastrointestinal, musculoskeletal, immune, and integumentary systems have been described. Further studies are needed to understand the pathologic processes underlying these clinical manifestations to improve disease prevention.

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.

The interaction of a high-fat diet and regular moderate intensity exercise on intestinal polyp development in Apc Min/+ mice

Diet and exercise are two environmental factors that can alter colon cancer risk. The purpose of this study was to determine if regular moderate-intensity treadmill exercise training could attenuate polyp formation in Apc(Min/+) mice fed the Western-style diet. Four-week-old male Apc(Min/+) mice (n = 12 per group) were assigned to AIN-76A Control, AIN-76A Exercise, Western Control, or Western Exercise treatment groups. Mice were weaned to these diets and either subjected to regular moderate-intensity treadmill exercise (18 m/min, 60 min/d, 6 d/wk) or remained sedentary for 6 weeks. Mice fed the Western-style diet consumed approximately 14% more calories and had 42% more epididymal fat compared with mice fed the AIN-76A diet. Exercise had no effect on fat pad mass with either diet treatment. Exercise reduced total intestinal polyp number by 50% and the number of large polyps (>1 mm diameter) by 67% in AIN-76A-fed mice. The Western-style diet increased polyp number by 75% when compared with AIN-76A-fed mice, but exercise did not decrease polyp number or alter polyp size in mice fed the Western-style diet. Markers of systemic inflammation and immune system function were improved with exercise in mice fed the AIN-76A diet. Mice fed the Western-style diet showed more inflammation and immunosuppression, which were not completely ameliorated by exercise. These data suggest that the induction of adiposity, inflammation, and immunosuppression by the Western-style diet may compromise the beneficial effect of moderate-intensity exercise on the intestinal polyp burden in Apc(Min/+) mice.

[Obesity and cancer]

Obesity which is now well recognized as a public health problem increases the risk of developing cancers. Some systematic review and meta-analyses assessed the strength of associations between body mass index and common cancers such as breast, endometrial, colon and adenocarcinoma of oesophagus. The causal mechanisms remain unexplained. However, epidemiological data and animal models have provided some evidence that hormonal alteration linked to obesity, such as hyperinsulinism, high insulin-like growth factor (IGF-1) levels or biodisponibility, low adiponectin serum level and high oestradiol serum level resulting from an enhanced aromatase activity may have mitogenic and antiapoptotic effects. The inflammation associated with visceral adiposity is another factor which promotes cancer. To date, there are no convincing data that weight loss could improve the prognosis of treated neoplasia. However, a regular physical activity and a limited caloric intake are probably safe in healthy subject to prevent cancer and also in cancer survivors.

Risk factors for sporadic colorectal cancer in southern Chinese

AIM: To investigate the role of smoking, alcohol drinking, family history of cancer, and body mass index (BMI) in sporadic colorectal cancer in southern Chinese.

METHODS: A hospital-based case-control study was conducted from July 2002 to December 2008. There were 706 cases and 723 controls with their sex and age (within 5 years) matched. An unconditional logistic regression model was used to analyze the association between smoking, alcohol drinking, family history of cancer, BMI and sporadic colorectal cancer.

RESULTS: No positive association was observed between smoking status and sporadic colorectal cancer risk. Compared with the non alcohol drinkers, the current and former alcohol drinkers had an increased risk of developing sporadic colorectal cancer (CRC) (adjusted OR = 8.61 and 95% CI = 6.15-12.05; adjusted OR = 2.30, 95% CI = 1.27-4.17). Moreover, the increased risk of developing sporadic CRC was significant in those with a positive family history of cancer (adjusted OR = 1.62, 95% CI = 1.12-3.34) and in those with their BMI ≥ 24.0 kg/m² (adjusted OR = 1.39, 95% CI = 1.10-1.75). Stratification analysis showed that the risk of developing both colon and rectal cancers was increased in current alcohol drinkers (adjusted OR = 7.60 and 95% CI = 5.13-11.25; adjusted OR = 7.52 and 95% CI = 5.13-11.01) and in those with their BMI ≥ 24.0 kg/m² (adjusted OR = 1.38 and 95% CI = 1.04-1.83; adjusted OR = 1.35 and 95% CI = 1.02-1.79). The risk of developing colon cancer, but not rectal cancer, was found in former alcohol drinkers and in those with a positive family history of cancer (adjusted OR = 2.51 and 95% CI = 1.24-5.07; adjusted OR = 1.82 and 95% CI = 1.17-2.82).

CONCLUSION: Alcohol drinking, high BMI (≥ 24.0 kg/m²) and positive family history of cancer are the independent risk factors for colorectal cancer in southern Chinese.

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.

Physical activity as a determinant of fecal bile acid levels

Physical activity is protective against colon cancer, whereas colonic bile acid exposure is a suspected risk factor. Although likely related, the association between physical activity and bile acid levels has not been well-studied. Furthermore, the effect of triglycerides, which are known to modify bile acid levels, on this relationship has not been investigated. We conducted a cross-sectional analysis of baseline fecal bile acid levels for 735 colorectal adenoma formers obtained from participants in a phase III ursodeoxycholic acid chemoprevention trial. Compared with the lowest quartile of recreational physical activity duration, the highest quartile was associated with a 17% lower fecal bile acid concentration, adjusted for age, sex, dietary fiber intake, and body mass index (P = 0.042). Furthermore, consistent with a previously established relationship between serum triglyceride levels and bile acid metabolism, we stratified by triglyceride level and observed a 34% lower fecal bile acid concentration (highest versus lowest quartiles of physical activity) in individuals with low triglycerides (<136 mg/dL; P = 0.002). In contrast, no association between physical activity and fecal bile acid concentration was observed for subjects with high triglycerides (> or =136 mg/dL). Our results suggest that the biological mechanism responsible for the protective effect of physical activity on the incidence of colon cancer may be partially mediated by decreasing colonic bile acid exposure. However, this effect may be limited to individuals with lower triglyceride levels.

Components of metabolic syndrome and metachronous colorectal neoplasia

BACKGROUND

The consistent association between obesity and colorectal cancer is thought to be explained by metabolic disturbances common, but not exclusive, to the obese.

METHODS

We assessed the relation between metachronous neoplasia and the components of metabolic syndrome (MetS) as defined by the National Cholesterol Education Program's Adult Treatment Panel III in 2,392 participants of two previously conducted chemoprevention trials. Waist circumference, fasting plasma glucose, trigylcerides, high-density lipoprotein, and systolic and diastolic blood pressure were measured at baseline.

RESULTS

MetS classification was associated with increased odds of metachronous neoplasia among women [odds ratio (OR), 1.37; 95% confidence interval (95% CI), 1.01-1.85] but not among men (OR, 0.99; 95% CI, 0.81-1.21). High waist circumference in men (OR, 1.41; 95% CI, 1.15-1.72) and women (OR, 1.41; 95% CI, 1.05-1.90) and elevated fasting glucose in women (OR, 1.46; 95% CI, 1.09-1.96), as defined by Adult Treatment Panel III cutpoints, were associated with increased odds, whereas none of the other criteria were independently associated with metachronous neoplasia. When each trait was evaluated using quartiles, elevated glucose among women and large waist circumference among men were significantly associated with metachronous lesions. Exploratory analysis of waist circumference and fasting glucose suggested an interaction, where only the combination of large waist circumference and elevated glucose conferred significant increased odds of metachronous neoplasia among both men (OR, 1.36; 95% CI, 1.04-1.78; P(interaction) = 0.08) and women (OR, 1.83; 95% CI, 1.26-2.67; P(interaction) = 0.12).

CONCLUSIONS

These results suggest that, of the specific components of MetS, those that capture impaired glucose uptake increased the odds of metachronous neoplasia.

Association between body mass index and colorectal neoplasia at follow-up colonoscopy: a pooling study

A direct relation between body mass index (BMI) and risk of colorectal adenomas and cancer has been reported, but few studies have had adequate sample size for conducting stratified analyses by sex, family history, colorectal subsite, or features of metachronous lesions. Data from 8,213 participants in 7 prospective studies of metachronous colorectal adenomas were pooled to assess whether the association between BMI and metachronous neoplasia varied by these factors. A statistically significant direct association between BMI and the odds of nonadvanced adenomas (P(trend) < 0.001) was observed, while the relation for advanced adenomas was of marginal significance (P(trend) < 0.07). In sex-stratified analyses, obesity was statistically significantly associated with the odds of any metachronous lesion among men (odds ratio = 1.36, 95% confidence interval: 1.17, 1.58) but not among women (odds ratio = 1.10, 95% confidence interval: 0.89, 1.37). The associations with BMI appeared to be limited to proximal neoplasia, with statistically significant results for BMI and proximal (P(trend) < 0.001), but not distal (P(trend) < 0.85), neoplasia. Exploratory analyses indicated that BMI was significantly related to most histologic characteristics of metachronous adenomas among men but not among women. Our results provide further support for the association between BMI and metachronous colorectal adenomas, particularly among men, thereby indicating that body size may affect colorectal carcinogenesis at comparatively early stages.

[Review of the association between obesity and gastroesophageal reflux and its complications]

Esophageal adenocarcinoma and its precursor Barrett's esophagus are increasing in incidence in western populations. Gastroesophageal reflux and high body mass index (BMI) are known risk factors. Studies about Barrett's esophagus in obese patients have emphasised the role of central adiposity as a stronger risk factor than BMI in the development of specialized intestinal metaplasia and subsequently esophagus adenocarcinoma. The proinflammatory impact of adipocytokines of the abdominal fat associated with the metabolic syndrome is also relevant. Except cardiovascular diseases, type 2 diabetes and non alcoholic steatohepatitis, abdominal obesity and metabolic syndrome are responsible of an increase of prevalence of esophageal adenocarcinoma, but also other cancer sites. In this review, we study the up to date main epidemiologic and physiopathologic data concerning this association that could be important in future for a preventive action in obese patients, especially when metabolic syndrome is present.

Metabolic syndrome and risk of cancer mortality in men

BACKGROUND

Metabolic syndrome (MetS) has been linked with an increased risk of developing cancer; however, the association between MetS and cancer mortality remains less clear. Little research has focused on pre-cancer risk factors that may affect the outcome of treatment. The purpose of this study was to examine the association between MetS and all-cancer mortality in men.

METHODS

The participants included 33,230 men aged 20-88 years who were enrolled in the Aerobics Centre Longitudinal Study and who were free of known cancer at the baseline.

RESULTS

At baseline 28% of all the participants had MetS. During an average of 14 years follow-up, there were a total of 685 deaths due to cancer. MetS at baseline was associated with a 56% greater age-adjusted risk in cancer mortality.

CONCLUSION

These data show that MetS is associated with an increased risk of all-cause cancer mortality in men. Based on these findings, it is evident that successful interventions should be identified to attenuate the negative effects of MetS.

Impact of somatostatin analogs versus surgery on glucose metabolism in acromegaly: results of a 5-year observational, open, prospective study

OBJECTIVE

The aim of the study was to investigate the 5-yr impact of surgery and somatostatin analogs (SSA) on glucose metabolism in acromegaly.

DESIGN

We conducted an observational, prospective, comparative, nonrandomized study.

PATIENTS

The 100 patients (48 women, 52 men; median age, 49 yr) in the study were grouped as follows for treatment: SSA only (group A; n = 34); SSA followed by surgery (group B; n = 20); surgery only (group C; n = 30); and surgery followed by SSA (group D; n = 16).

RESULTS

At diagnosis, 28% had impaired glucose tolerance, and 22% had diabetes mellitus; fasting glucose levels (4.13-10.60 mmol/liter) were best predicted by age (t = 2.88; P = 0.0049) and disease duration (t = 1.99; P = 0.049). After 60 months, fasting glucose levels reduced (-4.9 +/- 19.7%) in group A only, whereas they did not change in the other groups. In the 68 nondiabetic patients at baseline, fasting glucose levels increased by 0.7 +/- 11.2%, 7.5 +/- 10.3%, 4.3 +/- 10.4%, and 4.3 +/- 14.8% (P = 0.28), from groups A to D, respectively. Percentage change of fasting glucose in all patients receiving SSA was 1.9 +/- 12.3%, and in those not receiving SSA it was 6.4 +/- 10.8% (P = 0.13). Overall, prevalence of new onset of diabetes during SSA treatment was nine of 55 (16.4%) vs. three of 23 after surgery (13.0%, P = 0.98). Deterioration of glucose tolerance was correlated with increased body mass index (r = 0.49, P < 0.0001) and not with use of SSA or surgery (r = 0.06; P = 0.53), control or not of GH (r = -0.10, P = 0.31) and IGF-I (r = -0.12; P = 0.22).

CONCLUSIONS

The results of this study demonstrate a similar deterioration of glucose tolerance after 60 months in patients receiving SSA or cured with surgery. Increase in body mass index was the major predictor of deterioration of glucose tolerance.

Risk of cholecystitis in patients with cancer: a population-based cohort study in Denmark

BACKGROUND

To the authors' knowledge, little information is available regarding the incidence of cholecystitis among patients with cancer.

METHODS

The authors conducted a population-based historical cohort study of 51,228 patients with incident cancer, identified in medical databases of western Denmark between 1995 and 2003. A general population comparison cohort of 512,280 persons was assembled using the Danish Civil Registration System. The occurrence of cholecystitis in the 2 groups was determined by linkage to the regional Hospital Discharge Registry.

RESULTS

In all, 230 incident diagnoses of cholecystitis were identified in the cancer cohort during 130,185 person-years (median follow-up time: 1.6 years), corresponding to an incidence rate of 1.8 of 1000 person-years. After adjustment for confounders, the relative risk (RR) for cholecystitis among cancer patients compared with the general population cohort was 1.38 (95% confidence interval [95% CI], 1.20-1.58). Overall, the RR for cholecystitis was doubled during the first 6 months after cancer diagnosis (RR = 1.95; 95% CI, 1.50-2.54), after which the RR declined but remained greater than 1 throughout the rest of the follow-up period (RR = 1.23; 95% CI, 1.05-1.45). Cancer patients between the ages of 51 and 70 years had the highest risk increase for cholecystitis compared with other age groups. During the first 6 months after a cancer diagnosis, pancreatic cancers (12 cholecystitis events; RR = 9.44 [95% CI, 5.18-17.18]) and colorectal cancers (10 cholecystitis events; RR = 4.98 [95% CI, 2.65-9.34]) were found to be associated with the greatest cholecystitis risk increase compared with other tumor types. After 6 months, most cancers were associated with a relatively small increased risk, although there was an RR of 4.72 (95% CI, 1.99-11.21) based on 5 cholecystitis events among thyroid cancer patients.

CONCLUSIONS

The results of the current study indicate that cholecystitis occurs more frequently among cancer patients than in the general population, particularly within the first 6 months after a cancer diagnosis. Clinicians who treat cancer patients should remain vigilant about this type of infection.

Immunological, Hematological, and Glycemia Effects of Dietary Supplementation withAgaricus sylvaticuson Patients’ Colorectal Cancer

Objective: The aim of this study was to evaluate the effects of dietary supplementation with Agaricus sylvaticus fungus on hematological, immunological, and glycemia levels of postsurgical patients with colorectal cancer. Methods: A randomized, placebo-controlled, clinical trial was conducted at the General Hospital of Brazil for 6 months. Fifty-six patients with colorectal cancer (stages I, II, and III) were divided into 2 groups: A. sylvaticus (30 mg/kg/day) and placebo. Complete hemogram, serum iron, and fasting glycemia evaluations were carried out throughout the treatment course. Subjects were divided according to body mass index (BMI), sex, and stage of colorectal cancer. Data were analyzed using SPSS 14.0 programs, Student’s t test, and F statistical test, with P ≤ 0.05 considered significant. Results: After 6 months of supplementation, the group that received A. sylvaticus showed significant increases in hemoglobin ( P = 0.0001), hematocrit ( P = 0.0001), erythrocytes ( P = 0.01), mean cell volume ( P = 0.01), mean cell hemoglobin ( P = 0.0001), mean cell hemoglobin concentration ( P = 0.0001), and neutrophil levels ( P = 0.0001). The platelet count was significantly reduced ( P = 0.03), but remained within normal levels. No significant alterations were observed in the placebo group. The study group was composed of 32 women (57.1%) and 24 men (42.9%). Mean BMI was 24.65 kg/m2. Glycemia levels in the placebo group (average age 59.14 ± 12.95 years) were: initial, 94.36 ± 15.34 mg/dl; 3 months, 98.12 ± 15.54 mg/dl ( P = 0.03); and 6 months, 98.52 ± 9.03 mg/dl ( P = 0.01). Glycemia levels in the supplemented group (average age 56.34 ± 15.53 years) were: initial, 95.92 ± 11.64 mg/dl, 3 months, 94.88 ± 12.24 mg/dl ( P = 0.65); and 6 months, 92.86 ± 6.82 mg/dl ( P = 0.01). Conclusions: The results of this study suggest that supplementation with A. sylvaticus produces benefits in hematological and immunological parameters and can reduce glycemia levels in patients with colorectal cancer.

Modifiable risk factors for colorectal neoplasms and hyperplastic polyps

PURPOSE

Obesity, smoking and alcohol are modifiable putative risk factors for colorectal neoplasms (CRN) and hyperplastic polyps (HP). The aim of this study was to evaluate the strength of association between these modifiable risk factors and colorectal polyps.

METHODS

These risk factors were assessed by using a questionnaire completed by the patient prior to colonoscopy. Eight hundred-seventy consecutive patients satisfying inclusion criteria who had undergone a complete colonoscopy were divided into 4 groups: CRN (n=194), HP (n=132), CRN and HP (n=42) and control (neither CRN nor HP; n=586). Multiple logistic regression was performed.

RESULTS

The ORs [95%CI] of both CRN and HP for incremental body mass index expressed in 2 categories (>or=22, >or=25) were 2.12 [1.00, 4.50] and 1.41 [0.53, 3.77], respectively. The ORs [95%CI] of CRN and HP for heavy smoking of over 20 pack-years were 1.66 [1.05, 2.64] and 1.67 [1.01, 2.77], respectively. The ORs of CRN and HP for habitual alcohol drinking (median ethanol intake 32 g/day and interquartile range 18-40 g/day) were 1.31 [0.86, 1.98] and 1.91 [1.06, 3.47], respectively. CRN and HP were correlated with each other (p=0.0043, chi-square test). Aging was a significant risk factor for all three groups of colorectal polyps.

CONCLUSION

These findings are especially important since smoking and alcohol consumption are modifiable risk factors. Heavy smokers should be encouraged to quit to reduce their risk of CRN and HP. Habitual drinkers should be warned of the risk of HP. HP can be a marker of coincidence of CRN.

Insulin and insulin-like growth factor signalling in neoplasia

Insulin and insulin-like growth factors (IGFs) are well known as key regulators of energy metabolism and growth. There is now considerable evidence that these hormones and the signal transduction networks they regulate have important roles in neoplasia. Epidermiological, clinical and laboratory research methods are being used to investigate novel cancer prevention and treatment strategies related to insulin and IGF signalling. Pharmacological strategies under study include the use of novel receptor-specific antibodies, receptor kinase inhibitors and AMP-activated protein kinase activators such as metformin. There is evidence that insulin and IGF signalling may also be relevant to dietary and lifestyle factors that influence cancer risk and cancer prognosis. Recent results are encouraging and have justified the expansion of many translational research programmes.

Insulin resistance: a proinflammatory state mediated by lipid-induced signaling dysfunction and involved in atherosclerotic plaque instability

The dysregulation of the insulin-glucose axis represents the crucial event in insulin resistance syndrome. Insulin resistance increases atherogenesis and atherosclerotic plaque instability by inducing proinflammatory activities on vascular and immune cells. This condition characterizes several diseases, such as type 2 diabetes, impaired glucose tolerance (IGT), impaired fasting glucose (IFG), obesity, hypertension, dyslipidemia, and other endocrinopathies, but also cancer. Recent studies suggest that the pathophysiology of insulin resistance is closely related to interferences with insulin-mediated intracellular signaling on skeletal muscle cells, hepatocytes, and adipocytes. Strong evidence supports the role of free fatty acids (FFAs) in promoting insulin resistance. The FFA-induced activation of protein kinase C (PKC) delta, inhibitor kappaB kinase (IKK), or c-Jun N-terminal kinase (JNK) modulates insulin-triggered intracellular pathway (classically known as PI3-K-dependent). Therefore, reduction of FFA levels represents a selective target for modulating insulin resistance.

Insulin, insulin-like growth factors and neoplasia

Over the past decade, dozens of epidemiological studies and laboratory experiments have provided evidence for relationships between insulin-like growth factor (IGF) physiology and neoplasia. Population studies provide evidence for a modestly increased risk of a subsequent cancer diagnosis in subjects with IGF-I levels at the high end of the broad normal range, as compared to those at the low end of the normal range. At the cellular level, IGF-I receptor signalling has been shown to play an important role in facilitating the transforming action of a variety of oncogenes. Reducing receptor function with anti-receptor antibodies or specific tyrosine kinase inhibitors reduces the proliferation of many cancers in vitro and in vivo. At present, clinical relevance of the relationship between circulating IGF-I level and cancer risk is limited, but in terms of experimental therapeutics, many clinical trials have been initiated to investigate the possibility that the paradigm of hormonal treatment of cancer may be extended from targeting gonadal steroids to targeting the growth hormone-IGF-I axis.

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.