Colorectal cancer: another complication of diabetes mellitus?

Evaluation of serum biomarkers in nutritional disorders: glycated apolipoprotein B, fasting serum glucose, fructosamine, stable and labile glycated hemoglobin in diabetic and non-diabetic subjects

Glycated apolipoprotein B (ApoB-G), a non enzymatically glycated protein, has recently been associated with myocardial infarction. Our aim is to evaluate, in diabetic and non diabetic subjects, the relationship of ApoB-G with serum fasting glucose, fructosamine, stable and labile fractions of glycated hemoglobin ((S)HbA(1c), (L)HbA(1c), respectively) and insulin. The subjects were recruited from a previous study on ApoB-G and myocardial infarction: 141 of them were studied, 43 with and 98 without diabetes. ApoB-G was measured using a monoclonal antibody, and linear regression and correlation were used for statistical analysis of the data. ApoB-G was higher in diabetic than in non diabetic subjects. There was a statistically significant correlation of ApoB-G with triglycerides (r = 0.38, p = 0.01) in diabetic subjects, and with total proteins (r = 0.37, p = 0.0002), triglycerides (r = 0.34, p = 0.0007), and cholesterol (r = 0.23, p = 0.02) in non diabetic subjects. In the most parsimonious multiple linear regression model of ApoB-G on all the other serum variables, there was a statistically significant association of ApoB-G with triglycerides, in both diabetic and non diabetic subjects. The main results of this study suggest that serum ApoB-G is associated with serum triglycerides in both diabetic and non diabetic subjects.

Physical activity and gastrointestinal cancer prevention

Colorectal cancer is the third most common cancer globally and is a leading cause of cancer death. Gastric cancer contributes significantly to the global cancer burden, particularly in low- and middle-income countries. We reviewed the literature for studies on physical activity or exercise and colon, rectal, and gastric cancers as well as colonic adenomatous polyps. We identified 52 studies of colon cancer, 31 studies of rectal cancer, 23 studies of colon polyps, and 16 studies of gastric cancer. Of the 52 studies of physical activity and colon cancer, 37 found a statistically significant association between increased levels of physical activity and decreased colon cancer risk in at least one comparison. Accumulated evidence suggests that physical activity is associated with a 25% reduction in colon cancer risk. In line with previous reports, we found no indication that the association was more pronounced for occupational versus recreational physical activity, with both resulting in a risk reduction of about 22%. Evidence for other domains of physical activity (i.e., transportation or household physical activity) is limited. Evidence is emerging that individuals who are consistently active across the lifetime may obtain greater risk reductions than those who are only active in recent years. Despite consistent associations with colon cancer, evidence is more limited though suggestive that physical activity reduces risk of colon adenomas or adenoma recurrence. There is clear evidence that physical activity is not associated with rectal or gastric cancers.

The effect of autonomous neuropathy on bowel preparation in type 2 diabetes mellitus

INTRODUCTION

The need for colonoscopy is common among diabetics. In this study, we aimed to evaluate the effect of autonomous neuropathy on bowel preparation in type 2 diabetes mellitus (DM) patients.

MATERIALS AND METHODS

The study population consisted of 45 patients with DM and 48 non-diabetic, age- and sex-matched subjects. All colonoscopies were performed 5 h after the last dose of sodium phosphate. Colonoscopists rated the bowel preparation quality during the procedure using the Aronchick scale. All patients underwent a detailed cardiologic examination and 24-h Holter rhythm monitoring. Orthostatic hypotension and impairment in heart rate variability were accepted as indicators of autonomous neuropathy.

RESULTS

Gender, age, blood pressure, and heart rates did not differ significantly between groups (p > 0.05). Autonomous neuropathy was detected in 14 (31.1%) patients in the DM group and in two (4.2%) in the control group (p < 0.05). Optimal bowel cleansing was achieved in 93.8% of controls and 73.3% of diabetics; bowel cleansing was suboptimal in 26.7% of diabetics and 6.2% of controls (p < 0.05). Optimal bowel cleansing was achieved in six of 14 (42.8%) diabetic patients with autonomous neuropathy; however, optimal bowel cleansing was achieved in 27 of 31 (87.1%) diabetic patients without autonomous neuropathy (p < 0.05). Although optimal bowel cleansing was more prevalent among control patients than in diabetic patients without autonomous neuropathy, the difference was not significant (87.1% vs 93.8%; p > 0.05).

CONCLUSION

These data suggest that optimal bowel cleansing is poorer in diabetics with autonomous neuropathy than in those without autonomous neuropathy and controls.

Lifestyle factors and colorectal cancer risk (2): a systematic review and meta-analysis of associations with leisure-time physical activity

OBJECTIVE

Increased physical activity may decrease the risk of colorectal cancer. As a prerequisite to the determination of lifestyle attributable risks, we performed a systematic review and meta-analysis of prospective observational studies to quantify gender-specific risk associated with increased leisure-time physical activity (LT-PA).

METHOD

We searched MEDLINE and EMBASE (to December 2007), and other sources, selecting reports based on strict inclusion criteria. We used random-effects meta-analyses to estimate summary risk ratios (RR) and 95% confidence intervals (95% CI) for uppermost vs lowermost categories of physical activity. To investigate dose-response, we explored risks ratios as a function of cumulative percentiles of physical activity distribution.

RESULTS

Fifteen datasets from 14 articles, including 7873 incident cases, were identified. For colon cancer, there were inverse associations with LT-PA for men (RR: 0.80; 95% CI: 0.67-0.96) and women (0.86; 0.76-0.98). LT-PA did not influence risk of rectal cancer. The dose-response analysis was consistent with linear pattern reductions in risk of colon cancer in both genders. There was evidence of moderate between-study heterogeneity but summary estimates were broadly consistent across potential confounding factors.

CONCLUSION

Increased LT-PA is associated with a modest reduction in colon but not rectal cancer risk; a risk reduction, which previously may have been overstated. LT-PA only interventions in public health cancer prevention strategies are unlikely to impact substantially on colorectal cancer incidences.

Association Between Rectosigmoid Adenomas and Cardiovascular Risk Factors: A Hospital-based, Cross-sectional Study

Introduction: Little was known about the association between colorectal adenomas and cardiovascular risk factors in Taiwan. The aim of this study was to assess the association between rectosigmoid adenomas and related factors. Materials and Methods: This was a hospital-based, cross-sectional study. We analysed subjects receiving self-referred health examinations at 1 medical centre in Taiwan between 2001 and 2004. In total, 4413 subjects were enrolled in this study. There were 2444 men (55.4%) and 1969 women (44.6%). The mean age was 49.3 ±12.3 years (range, 20 to 87). All subjects underwent a 60-cm flexible sigmoidoscopic examination and laboratory survey. Adjusted odds ratio (OR) and 95% confidence interval (CI) were expressed using a multivariate logistic regression analysis. Results: In the final model, increasing age (OR, 1.05; 95% CI, 1.03-1.06), hypertriglyceridemia (OR, 1.49; 95% CI, 1.07-2.07), and alcohol consumption (OR, 2.11; 95% CI, 1.47-3.04) were the risk factors for rectosigmoid adenomas in men. Increasing age was the only risk factor for rectosigmoid adenomas in women (OR, 1.03; 95% CI, 1.01-1.06). Conclusion: Age, hypertriglyceridemia and alcohol consumption are associated with rectosigmoid adenomas in men, and only age is significantly associated with rectosigmoid adenomas in women. Key words: Alcohol, Cardiovascular, Hypertriglyceridemia

Long-term all-cause mortality in cancer patients with preexisting diabetes mellitus: a systematic review and meta-analysis

CONTEXT

Diabetes mellitus appears to be a risk factor for some cancers, but the effect of preexisting diabetes on all-cause mortality in newly diagnosed cancer patients is less clear.

OBJECTIVE

To perform a systematic review and meta-analysis comparing overall survival in cancer patients with and without preexisting diabetes.

DATA SOURCES

We searched MEDLINE and EMBASE through May 15, 2008, including references of qualifying articles.

STUDY SELECTION

English-language, original investigations in humans with at least 3 months of follow-up were included. Titles, abstracts, and articles were reviewed by at least 2 independent readers. Of 7858 titles identified in our original search, 48 articles met our criteria.

DATA EXTRACTION

One reviewer performed a full abstraction and other reviewers verified accuracy. We contacted authors and obtained additional information for 3 articles with insufficient reported data.

RESULTS

Studies reporting cumulative survival rates were summarized qualitatively. Studies reporting Cox proportional hazard ratios (HRs) or Poisson relative risks were combined in a meta-analysis. A random-effects model meta-analysis of 23 articles showed that diabetes was associated with an increased mortality HR of 1.41 (95% confidence interval [CI], 1.28-1.55) compared with normoglycemic individuals across all cancer types. Subgroup analyses by type of cancer showed increased risk for cancers of the endometrium (HR, 1.76; 95% CI, 1.34-2.31), breast (HR, 1.61; 95% CI, 1.46-1.78), and colorectum (HR, 1.32; 95% CI, 1.24-1.41).

CONCLUSIONS

Patients diagnosed with cancer who have preexisting diabetes are at increased risk for long-term, all-cause mortality compared with those without diabetes.

Lack of association of colonic epithelium telomere length and oxidative DNA damage in Type 2 diabetes under good metabolic control

BACKGROUND

Telomeres are DNA repeat sequences necessary for DNA replication which shorten at cell division at a rate directly related to levels of oxidative stress. Critical telomere shortening predisposes to cell senescence and to epithelial malignancies. Type 2 diabetes is characterised by increased oxidative DNA damage, telomere attrition, and an increased risk of colonic malignancy. We hypothesised that the colonic mucosa in Type 2 diabetes would be characterised by increased DNA damage and telomere shortening.

METHODS

We examined telomere length (by flow fluorescent in situ hybridization) and oxidative DNA damage (flow cytometry of 8 - oxoguanosine) in the colonic mucosal cells of subjects with type 2 diabetes (n = 10; mean age 62.2 years, mean HbA1c 6.9%) and 22 matched control subjects. No colonic pathology was apparent in these subjects at routine gastrointestinal investigations.

RESULTS

Mean colonic epithelial telomere length in the diabetes group was not significantly different from controls (10.6 [3.6] vs. 12.1 [3.4] Molecular Equivalent of Soluble Fluorochrome Units [MESF]; P = 0.5). Levels of oxidative DNA damage were similar in both T2DM and control groups (2.6 [0.6] vs. 2.5 [0.6] Mean Fluorescent Intensity [MFI]; P = 0.7). There was no significant relationship between oxidative DNA damage and telomere length in either group (both p > 0.1).

CONCLUSION

Colonic epithelium in Type 2 diabetes does not differ significantly from control colonic epithelium in oxidative DNA damage or telomere length. There is no evidence in this study for increased oxidative DNA damage or significant telomere attrition in colonic mucosa as a carcinogenic mechanism.

Elevated HbA1c is an independent predictor of aggressive clinical behavior in patients with colorectal cancer: a case-control study

AIM

The aim of this study was to seek an association between the control of type 2 diabetes mellitus (T2DM), as determined by hemoglobin A1c (HbA1c) levels, and the outcome of colorectal cancer (CRC).

METHODS

We performed a retrospective review of patients with T2DM who had CRC diagnosed between 1997 and 2001. We defined well-controlled T2DM as HbA1c < 7.5% and poorly controlled T2DM as HbA1c > or = 7.5%. A group of age- and gender-matched patients who had CRC without T2DM were used as controls. Forty clinical factors were reviewed, and those associated with poor clinical outcome in each group were examined by univariate analysis (UA) and by the maximum likelihood analysis of logistic regression to determine the independent predictors of cancer outcome.

RESULTS

We identified 155 patients with T2DM and CRC, and 114 control patients who had CRC without T2DM. We found no significant differences in any clinical factor by UA between the patients with well-controlled T2DM and the patients who had CRC without T2DM. Compared to both of those patients groups, in contrast, the patients with poorly controlled T2DM had more right-sided CRCs (P = 0.04, OR = 2, 95% CI = 1-4.1), more advanced CRCs (P = 0.02, OR = 2.1, 95% CI = 1-4.4), a younger age of presentation (P = 0.05), greater use of exogenous insulin (P = 0.002), and a poorer 5-year survival (P = 0.001) by UA. Logistic regression showed that poorly controlled T2DM independently predicted the early onset of CRC, a more advanced stage at the time of presentation, poorer 5-year survival, and an increased incidence of right-sided CRCs.

CONCLUSIONS

In patients with T2DM who have CRC, poor glycemic control is associated with a clinically aggressive course for the cancer.

Insulin therapy and colorectal adenoma risk among patients with Type 2 diabetes mellitus: a case-control study in Korea

PURPOSE

Patients with Type 2 diabetes mellitus may be at increased colorectal adenoma and cancer risk. Moreover, chronic insulin therapy may increase the risk of colorectal cancer among patients with Type 2 diabetes mellitus. We investigated to determine whether insulin therapy might increase the risk of colorectal adenoma among clinically confirmed patients with Type 2 diabetes mellitus.

METHODS

We conducted a retrospective study among patients with Type 2 diabetes mellitus who underwent total colonoscopy between January 2003 and July 2006 at Hallym University Sacred Heart Hospital. Among them (n = 325), patients with histologically confirmed colorectal adenomas (n = 100) and the same number of controls matched by age and sex were selected and analyzed.

RESULTS

Adenoma cases showed significantly higher rate of chronic insulin therapy (more than 1 year) than controls (P = 0.018). In multivariate regression analysis, patients who received chronic insulin therapy had three times the risk of colorectal adenoma compared with patients who received no insulin (odds ratio, 3; 95 percent confidence interval, 1.1-8.9; P = 0.04).

CONCLUSIONS

Chronic insulin therapy was associated with increased colorectal adenoma risk among Type 2 diabetes mellitus patients. This result may provide a need for more intensive colorectal cancer screening program in patients with Type 2 diabetes mellitus, especially those who receive chronic insulin therapy.

Diabetes mellitus affects response to neoadjuvant chemoradiotherapy in the management of rectal cancer

INTRODUCTION

Although diabetic patients with rectal cancer have poorer outcomes than their nondiabetic counterparts, few studies have looked at diabetics' response to therapy as an explanation for this disparity. This study compares the neoadjuvant chemoradiotherapy (CRT) response in diabetic and nondiabetic patients with locally advanced rectal cancers.

METHODS

This is a single-institution, retrospective review of rectal cancer patients who received CRT followed by resection from 1995 to 2006. Pretreatment tumor-node-metastasis (TNM) staging was determined using endorectal ultrasound, computed tomography (CT) scan, and magnetic resonance imaging (MRI); post-treatment staging was determined by pathological review.

RESULTS

110 patients were included; seventeen had diabetes and 93 were nondiabetics. Pretreatment staging was similar in both groups. Sixteen of the diabetics (94%) completed CRT compared to 92% (86/93) of the nondiabetics. Tumor downstaging rates were similar in the two groups (53% in diabetics, 52% in nondiabetics). Nondiabetic patients had a higher rate of nodal downstaging although not statistically significant (67% versus 27%, P = 0.80). While none of the diabetics patients achieved a pathologic complete response (pCR), 23% (21/93) of the nondiabetics did (P = 0.039). Local progression rates were higher in the diabetic group (24% versus 5%, P = 0.046).

CONCLUSION

Our study shows that neoadjuvant chemoradiotherapy in rectal cancer is less effective in diabetic patients than in nondiabetics. While minimal differences are found in the rate of downstaging, the rate of achieving a complete pathologic response was significantly higher in nondiabetic patients, and in fact was not seen in any of our diabetic patients. This may explain the poorer outcomes seen in diabetic patients with rectal cancer.

The association of elevated HbA1c on the behavior of adenomatous polyps in patients with type-II diabetes mellitus

BACKGROUND AND AIMS

The high level of circulating insulin in diabetic patients and the potential proliferative properties of insulin as a result of its cross interaction with insulin-growth factor-I (IGF-I) receptors suggest a proto-oncogenic role on the colonocyte. The aim of our study was to determine whether poor control of diabetes mellitus (DM) is associated with increased prevalence of colonic adenomatous polyps (APs), especially those that are advanced .

METHODS

A retrospective review of all patients with type-2 DM diagnosed with APs from 1996 to 2006 was performed. Hemoglobin A1c (HbA1c) levels were evaluated as an index of glycemic control over the year that preceded the diagnosis of APs. A total of 33 factors were assessed in the patients grouped as well controlled (HbA1c < 7.5%) and poorly controlled (HbA1c > or = 7.5%). Factors associated with advanced APs in each group were examined using univariate analysis (UA). Significant variables by UA were included in a stepwise logistic regression analysis to determine independent predictors of aggressive clinical behavior by the polyps. All values are presented as means +/- SE, and statistical significance was determined at P < or = 0.05.

RESULTS

Approximately 652 patients with DM type-2 and APs were identified. UA demonstrated that patients with poorly controlled DM-2 had a significantly increased incidence of right-sided APs (P = 0.001), a greater number of APs (P < 0.005), more advanced APs (P < 0.005), a younger age of presentation (P = 0.001), a history of smoking (P = 0.05), and greater use of exogenous insulin (P = 0.01). Logistic regression, as measured by HbA1c, demonstrated that poorly controlled DM-2 independently predicted a greater prevalence of right-sided AP, a more advanced lesion at the time of presentation, a greater number of polyps, and greater use of exogenous insulin.

CONCLUSIONS

Poor glycemic control in patients with DM-2 independently predicts an aggressive clinical course for patients with APs. Small differences in HbA1c elevation and, by inference, small differences in circulating insulin levels may lead to large variations in the behavior of APs.

Type 2 diabetes mellitus as risk factor for colorectal cancer

Colorectal cancer occurs more frequently in patients with type 2 diabetes mellitus. The hyperinsulinemia-hypothesis suggests that elevated levels of insulin and free IGF-1 promote proliferation of colon cells and lead to a survival benefit of transformed cells, ultimately resulting in colorectal cancer. In patients with type 2 diabetes mellitus, epidemiological studies show an increased risk for colorectal cancer and an even higher risk if patients are treated with sulphonylureas or insulin. Moreover, tumour progression at hyperinsulinemia is more rapid and tumour-associated mortality is increased. Colorectal cancer can be avoided by screening. Recommendations for colorectal cancer screening should employ the recent epidemiologic evidence. All patients with type 2 diabetes mellitus should be recommended to undergo colonoscopy before starting insulin therapy, and screening intervals should not exceed 5 years. For this concept, a review of the evidence is presented, and a screening algorithm for colorectal cancer in patients with type 2 diabetes mellitus is proposed.

Does biliopancreatic diversion carry increased risk for colorectal cancer? A cohort study

BACKGROUND

Because of the rearrangement of the gastrointestinal tract, biliopancreatic diversion (BPD) could lead to an increased risk of colorectal cancer caused by possible carcinogenetic action of the unabsorbed food and bile acid on colonic mucosa.

METHODS

The incidence of colorectal cancer in 1,898 obese subjects submitted to BPD from May 76 to July 2002 with a minimum follow-up of 5 years was retrospectively evaluated.

RESULTS

Among 28,811 person-years, seven cases of colorectal cancer were detected, for an overall incidence of 29.4 per 100,000, which is not different from that observed in the general Italian population, and lower than that reported for obese and type 2 diabetes patients. Logistic regression model suggests that occurrence of colorectal cancer is positively related to the time elapsed from BPD.

CONCLUSION

This study indicates that BPD does not carry any increased risk for colorectal cancer. The complete postoperative restoration of insulin sensibility could exert a valuable protective action.

The comparison of the risk factors and clinical manifestations of proximal and distal colorectal cancer

PURPOSE

Colorectal cancers in the proximal or distal site have distinct clinical characteristics. In this study, the authors compared the risk factors of proximal and distal colorectal cancer.

METHODS

A 16-page questionnaire was administered to 529 patients with colorectal cancer before operation. Cancers were classified as proximal or distal relative to the splenic flexure. Of these 529 patients, 6 patients were excluded because of the presence of synchronous colorectal cancers. Data of the 523 patients were analyzed.

RESULTS

Total numbers of proximal and distal cancers were 123 and 400. The proportion of patients with Type 2 diabetes was significantly higher for distal cancer (P = 0.034), whereas a greater proportion of patients with proximal cancer had a gallstone history (P = 0.005). Multivariate analysis revealed Type 2 diabetes to be a risk factor for distal colorectal cancer (P = 0.027) and cholelithiasis to be a risk factor for proximal cancer (P = 0.049). The odds ratio for distal colorectal cancer among males with Type 2 diabetes was 4.1 (95 percent confidence interval, 1.4-12.1). On the other hand, a gallstone history was more associated with proximal colon cancer, especially in females (odds ratio = 5.5; 95 percent confidence interval, 1.4-20.9).

CONCLUSIONS

A comparison of the risk factors of proximal and distal colorectal cancer showed that Type 2 diabetes is associated with distal colorectal cancer in males and that cholelithiasis is associated with proximal colon cancer in females.

Is metabolic syndrome a risk factor for colorectal adenoma?

BACKGROUND AND AIMS

Epidemiologic studies provide evidence for a link between obesity or diabetes and the risk for colorectal cancer. However, there is a lack of information about the relationship between metabolic syndrome and colorectal adenoma. Therefore, we investigated whether metabolic syndrome is a risk factor for colorectal adenoma.

METHODS

We did a study for consecutive subjects who underwent colonoscopy as a screening exam at the Center for Health Promotion, Samsung Medical Center, from March 2004 to December 2005. According to the modified ATP III criteria, metabolic syndrome was diagnosed. We classified a total of 2,531 subjects into the adenoma group (n = 731) and the control group (n = 1,800), including normal colonoscopic finding, nonpolyp benign lesions, or histologically confirmed hyperplastic polyp.

RESULTS

The prevalence for metabolic syndrome was 17% in the adenoma group and 11% in the control group. On the multiple logistic regression analyses, metabolic syndrome was found to be associated with an increased risk of colorectal adenoma (odds ratio, 1.51; 95% confidence interval, 1.18-1.93). Also, waist circumference among the individual components of metabolic syndrome was an independent risk factor for colorectal adenoma. An increased risk for metabolic syndrome was more evident for proximal than distal colon, for multiple (>/=3), and for advanced adenoma in the adenoma group.

CONCLUSION

Metabolic syndrome was associated with colorectal adenoma. Abdominal obesity of the individual components of metabolic syndrome was an important risk factor for colorectal adenoma.

Cancer risks in thiazolidinedione users compared to other anti-diabetic agents

PURPOSE

We conducted three nested case-control studies to evaluate the risk of breast, colon, and prostate cancers developing in patients exposed to thiazolidinediones (TZDs) compared with other anti-diabetic agents.

METHODS

Cancer cases were matched to five controls by age, gender, calendar year, and time in the database from a cohort of 1 26 971 diabetic patients taking anti-diabetic medication in the US Integrated Healthcare Information Services database. Five hundred thirteen breast cancer cases were matched with 2557 controls, 408 cases of colon cancer were matched with 2027 controls and 643 cases of prostate cancer were matched with 3176 controls. Exposure to an anti-diabetic agent within 90 days preceding the index date was defined as recent exposure and at any time during the follow-up was defined as ever exposed.

RESULTS

The adjusted odds ratios and 95%CI of cancer from ever exposure to TZDs compared to oral monotherapy, oral dual therapy, oral triple therapy, insulin monotherapy, insulin and oral therapy and all non-TZD anti-diabetic agents were, respectively for breast cancer: 0.91 (0.69-1.20), 0.80 (0.56-1.14), 0.87 (0.32-2.35), 1.27 (0.61-2.67), 0.71 (0.36-1.37), 0.89 (0.68-1.15); for colon cancer: 1.06 (0.80-1.40), 1.12 (0.77-1.63), 1.73 (0.39-7.78), 4.46 (1.05-19.00), 1.06 (0.50-2.26) 1.03 (0.80-1.32) and for prostate cancer: 1.08 (0.85-1.37), 0.89 (0.66-1.21); 0.82 (0.33-2.06); 1.80 (0.79-4.07), 1.10 (0.55-2.18), 1.04 (0.83-1.31). Results for exposure within 90 days of the date of the cancer were similar.

CONCLUSIONS

Our findings suggest that the effect of TZDs on the likelihood of development of the cancers studied (colon, prostate and breast) appears to be neutral and do not support a beneficial or deleterious effect of TZD on the cancers studied.

Metabolic syndrome, hyperinsulinemia, and colon cancer: a review

An impressive body of epidemiologic data collected over the past decade indicates that the risk of colon cancer is elevated in those with metabolic syndrome. This evidence includes studies that examined the risk of colon cancer or adenoma in relation to determinants of the metabolic syndrome (obesity, abdominal distribution of adiposity, and physical inactivity), clinical consequences of this syndrome (type 2 diabetes and hypertension), plasma or serum components of the definition of metabolic syndrome (hypertriglyceridemia, hyperglycemia, and low HDL cholesterol), and markers of hyperinsulinemia or insulin resistance (insulin and C-peptide), which is the underlying metabolic defect of the metabolic syndrome. The mechanism underlying these associations is unknown but may involve the influence of hyperinsulinemia in enhancing free or bioavailable concentrations of insulin-like growth factor-1. Future studies should also be based on better measurements of insulin resistance, beta-cell depletion, and insulin responses to better assess which aspects of insulin resistance are most closely related to the risk of colon neoplasia.

Serum C-peptide, IGFBP-1 and IGFBP-2 and risk of colon and rectal cancers in the European Prospective Investigation into Cancer and Nutrition

Western style diets and lifestyles are associated with increasing rates of obesity, diabetes and insulin resistance. Higher circulating insulin levels may modulate cell proliferation and apoptosis either directly or indirectly by increasing the bioactivity of IGF-I and decreasing the bioactivity of some of its binding proteins. The objective of this study was to determine the association of increasing levels of serum C-peptide, a biomarker of pancreatic insulin secretion, and IGF binding proteins (IGFBP) -1 and -2 with colorectal cancer risk in a case-control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC), a large cohort involving 10 Western European countries. A total of 1,078 colorectal cancer cases were matched (age, date of blood donation, fasting status, gender, study center) to an equal number of control subjects. Relative cancer risks were estimated using conditional logistic regression models. Serum C-peptide concentration was positively associated with an increased colorectal cancer risk for the highest versus the lowest quintile (OR=1.56, 95% CI=1.16-2.09, p(trend)<0.01), which was slightly attenuated after adjustment for BMI and physical activity (OR=1.37, 95% CI=1.00-1.88, p(trend)=0.10). When stratified by anatomical site, the cancer risk was stronger in the colon (OR=1.67, 95% CI=1.14-2.46, p(trend)<0.01) than in the rectum (OR=1.42, 95% CI=0.90-2.25, p(trend)=0.35). The cancer risk estimates were not heterogeneous by gender or fasting status. No clear colorectal cancer risk associations were observed for IGFBP-1 or -2. This large prospective study confirms that hyperinsulinemia, as determined by C-peptide levels, is associated with an increased colorectal cancer risk.

The underuse of screening services among elderly women with diabetes

OBJECTIVE

To determine whether the use of nondiabetes-related preventive services (mammography, colorectal cancer screening, and bone density testing) among elderly diabetic women is different from the use among nondiabetic women.

RESEARCH DESIGN AND METHODS

Using a representative sample of the U.S. elderly female population and the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare files, we identified women with or without diabetes who were > or =67 years of age on 1 January 1999. All women with a prior history of cancer were excluded. Bivariate and multivariate analyses were used to compare the rates of preventive service use and to understand the factors influencing their use in the next 2-4 years.

RESULTS

Women with diabetes were less likely to have a mammogram (odds ratio [OR] 0.83 [95% CI 0.78-0.88]), colorectal cancer screening (0.79 [0.70-0.88]), and bone density testing (0.63 [0.58-0.69]). Women with diabetes seen by endocrinologists had significantly higher rates of bone density testing than women seen by primary care physicians. Women seen by obstetrician/gynecologists had the highest rates of use of all three services.

CONCLUSIONS

Elderly women with diabetes are less likely to receive cancer and osteoporosis screening than women without diabetes. Physicians treating these patients need to assure that they receive all recommended preventive services appropriate for their age. Additional national guidelines, practice-based improvements, and patient education targeting those at greatest risk of not receiving these services may be needed to achieve parity.

Change in body size and the risk of colorectal adenomas

Adiposity has been recognized as a risk factor for colorectal adenoma, but the influence of weight gain, adipose tissue distribution, and possible differences between ethnic/racial and gender groups remains unanswered. The aim of this prospective study was to examine the association between adiposity and weight change and colorectal adenoma risk. Over approximately 10-year period, anthropometric measures and other risk factors were measured at three time points in the multicenter multiethnic Insulin Resistance Atherosclerosis Study cohort. Colonoscopies were then conducted on 600 cohort participants regardless of symptoms whose mean age at colonoscopy was 64 years. Multivariate logistic regression analyses were used to assess the association between colorectal adenomas and measures of adiposity and weight change over the approximately 10-year period before colonoscopy. Obesity was positively associated with risk of colorectal adenomas at the time of colonoscopy [adjusted odds ratio (OR(adj)), 2.16; 95% confidence interval (95% CI), 1.13-4.14] and was stronger in women (OR(adj), 4.42; 95% CI, 1.53-12.78) than in men (OR(adj), 1.26; 95% CI, 0.52-3.07). The risk of adenomas increased among participants who gained weight compared with those who maintained weight over the approximately 5 years (OR(adj), 2.30; 95% CI, 1.25-4.22) and approximately 10 years (OR(adj), 2.12; 95% CI, 1.25-3.62). These associations were similar for both advanced and nonadvanced adenomas. These results suggest a positive association between obesity, weight gain, and colorectal adenoma risk. Stronger associations were observed when obesity was measured at the time of colonoscopy, suggesting that obesity may be a promoting factor in the growth of colorectal adenomas.

Physical activity and risk of colon and rectal cancers: the European prospective investigation into cancer and nutrition

We investigated several aspects of the role of physical activity in colon and rectal cancer etiology that remain unclear in the European Prospective Investigation into Nutrition and Cancer. This cohort of 413,044 men and women had 1,094 cases of colon and 599 cases of rectal cancer diagnosed during an average of 6.4 years of follow-up. We analyzed baseline data on occupational, household, and recreational activity to examine associations by type of activity, tumor subsite, body mass index (BMI), and energy intake. The multivariate hazard ratio for colon cancer was 0.78 [95% confidence interval (95% CI), 0.59-1.03] among the most active participants when compared with the inactive, with evidence of a dose-response effect (P(trend) = 0.04). For right-sided colon tumors, the risk was 0.65 (95% CI, 0.43-1.00) in the highest quartile of activity with evidence of a linear trend (P(trend) = 0.004). Active participants with a BMI under 25 had a risk of 0.63 (95% CI, 0.39-1.01) for colon cancer compared with the inactive. Finally, an interaction between BMI and activity (P(interaction) = 0.03) was observed for right-sided colon cancers; among moderately active and active participants with a BMI under 25, a risk of 0.38 (95% CI, 0.21-0.68) was found as compared with inactive participants with BMI >30. No comparable decreased risks were observed for rectal cancer for any type of physical activity for any subgroup analyses or interactions considered. We found that physical activity reduced colon cancer risk, specifically for right-sided tumors and for lean participants, but not rectal cancer.

Effect of diabetes mellitus on the epidemiology and outcomes of colon cancer

OBJECTIVES

To assess the effect of diabetes mellitus (DM) on the pathogenesis and outcomes from colon cancer.

METHODS

A retrospective chart review was conducted on 1853 patients with colon cancer.

RESULTS

A higher percentage of males than females with colon cancer had DM (16.2% vs 11.3%; p < 0.01). Males had a slightly lower risk of dying from colon cancer (RR - 0.88; p=0.08). There was no difference in the median age of diagnosis of colon cancer in patients with and without DM, but a larger proportion of patients with diabetes mellitus were >or=70 yr at diagnosis (50% vs 43%) (p=0.0004). No significant relationship was noted between stage of colon cancer or survival and presence of DM.

CONCLUSIONS

DM did not affect either the stage at diagnosis, or outcomes from colon cancer. More males with colon cancer tended to have DM and a larger proportion of patients with DM were >or=70 yr at the time of diagnosis.

Effect of diabetes mellitus on the epidemiology and outcomes of colon cancer

OBJECTIVES

To assess the effect of diabetes mellitus (DM) on the pathogenesis and outcomes from colon cancer.

METHODS

A retrospective chart review was conducted on 1853 patients with colon cancer.

RESULTS

A higher percentage of males than females with colon cancer had DM (16.2% vs 11.3%; p < 0.01). Males had a slightly lower risk of dying from colon cancer (RR - 0.88; p=0.08). There was no difference in the median age of diagnosis of colon cancer in patients with and without DM, but a larger proportion of patients with diabetes mellitus were >or=70 yr at diagnosis (50% vs 43%) (p=0.0004). No significant relationship was noted between stage of colon cancer or survival and presence of DM.

CONCLUSIONS

DM did not affect either the stage at diagnosis, or outcomes from colon cancer. More males with colon cancer tended to have DM and a larger proportion of patients with DM were >or=70 yr at the time of diagnosis.

Diet supplemented with citrus unshiu segment membrane suppresses chemically induced colonic preneoplastic lesions and fatty liver in male db/db mice

The modulatory effects of dietary citrus unshiu segment membrane (CUSM) on the occurrence of aberrant crypt foci (ACF) and beta-catenin accumulated crypts (BCACs) were determined in male C57BL/KsJ-db/db (db/db) mice initiated with azoxymethane (AOM). Male db/db, db/+ and +/+ mice were given 5 weekly subcutaneous injections of AOM (15 mg/kg body weight), and then they were fed the diet containing 0.02%, 0.1% or 0.5% CUSM for 7 weeks. At Week 12, a significant increase in the numbers of ACF and BCAC was noted in the db/db mice in comparison with the db/+ and +/+ mice. Feeding with CUSM caused reduction in the frequency of ACF in all genotypes of mice and the potency was high in order of the db/db mice, db/+ mice and +/+ mice. The number of BCACs was also reduced by feeding with CUSM, thus resulting in a 28-61% reduction in the db/db mice, possibly due to suppression of cell proliferation activity in the lesions by feeding with CUSM-containing diet. Clinical chemistry revealed a low serum level of triglyceride in mice fed CUSM. In addition, CUSM feeding inhibited fatty metamorphosis and fibrosis in the liver of db/db mice. Our findings show that CUSM in the diet has a chemopreventive ability against the early phase of AOM-induced colon carcinogenesis in the db/db as well as db/+ and +/+ mice, indicating potential use of CUSM in cancer chemoprevention in obese people.

Investigation on the risks of colorectal cancer in patients with diabetes mellitus

AIM: To investigate the influences of DM-associated factors on the pathogenesis of colorectal cancer (CRC), and clarify whether diabetes mellitus (DM) is a risk factor of CRC.

METHODS: A case-control study was performed to compare 364 colorectal cancer patients (198 colon cancer patients and 166 rectal cancer patients) with 733 controls (patients without cancer), with respect to their family history of CRC and DM, personal DM history, habits of smoking and drinking, cholesterol and triglyceride levels.

RESULTS: The value of odds ratio (OR) in patients with DM history was 1.72 and that in patients with family DM history was 1.64. The value of OR in DM patients with family CRC history was 3.23, significantly higher in DM patients without family CRC history (OR = 1.57). After further analysis, the rate of DM patients with/without family CRC history was always higher than that in the controls. Logistic analysis showed that the age, gender, DM history, coronary heart disease, hypertension, smoking, drinking, and blood lipid had no marked relationship with colorectal cancer, but DM and family CRC history were correlated with the occurrence of colorectal cancer (OR = 2.99, P < 0.01; OR = 1.79, P < 0.01).

CONCLUSION: DM is an independent risk factor of CRC. Routine examination for CRC is recommended for DM patients to make earlier diagnosis of CRC and improve the prognosis of patients.

Physical activity and risk of colorectal cancer in Japanese men and women: the Japan Public Health Center-based prospective Study

OBJECTIVE

To prospectively examine the association between physical activity and the risk of developing colorectal cancer in a large population-based cohort study of Japanese men and women, and to investigate whether the effects of physical activity on colorectal cancer risk differ by sex and subsite.

METHODS

We analyzed data from a population-based cohort of 65,022 subjects. A total of 486 incident colorectal cancers (154 proximal colon, 166 distal colon and 149 rectal cancers) was identified during 6 years of follow-up.

RESULTS

We observed a significant inverse association between physical activity and the risk of developing colorectal cancer, particularly colon cancer, among men. Relative to men in the lowest level of metabolic equivalent (MET) hours per day, those in the highest level had a RR of 0.69 (95% CI = 0.49-0.97). A significant decrease in risk of colorectal cancer was associated with increasing MET hours per day among men. This inverse association was essentially limited to colon cancer. A significant decrease in risk with increasing MET-hour score was observed predominantly for proximal colon cancer among men. In contrast, no significant decrease was seen among women.

CONCLUSION

These findings suggest that physical activity may prevent colon cancer among Japanese men.

Greater development of 1,2-dimethylhydrazine-induced colon cancer in a rat model of type 2 diabetes mellitus

Several clinical cohort and case-control studies have suggested a link between diabetes and colon cancer. Otsuka Long-Evans Tokushima Fat (OLETF) rats spontaneously develop type 2 diabetes mellitus and Long-Evans Tokushima Otsuka (LETO) rats are non-diabetic. The relationship between type 2 diabetes mellitus and colon cancer was examined in these rats. The carcinogen 1,2-dimethylhydrazine was administered subcutaneously once weekly for 10 weeks, and the animals were killed and necropsied in week 29. All OLETF rats and 80% of the LETO rats developed cancer. The number of colon cancers per rat was significantly greater in the diabetic than in the non-diabetic rats. Although the tumours tended to be larger in diabetic rats, the difference was not statistically significant. No significant differences were observed in the depth of invasion or histological type of cancer in the two groups. Type 2 diabetes mellitus may enhance the generation and growth of colon cancer.

A prospective study of anthropometric and clinical measurements associated with insulin resistance syndrome and colorectal cancer in male smokers

Type 2 diabetes mellitus shares risk factors for and has shown a positive association with colorectal cancer. Anthropometric measures (height, weight, and body mass index (weight (kg)/height (m)(2)) and metabolic abnormalities associated with insulin resistance syndrome (IRS) (abnormalities in measured blood pressure, high density lipoprotein (HDL) cholesterol, and total cholesterol) were prospectively evaluated for associations with incident colon (n = 227), rectal (n = 183), and colorectal (n = 410) cancers diagnosed between 1985 and 2002 in 28,983 Finnish male smokers from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Cox proportional hazards models were used to calculate hazard ratios and 95% confidence intervals. In comparison with the lowest quintile, the highest quintile of body mass index was significantly associated with colorectal cancer (hazard ratio (HR) = 1.70, 95% confidence interval (CI): 1.01, 2.85; p-trend = 0.01), particularly colon cancer. Subjects with a cluster of three IRS-related conditions (hypertension, body mass index >/=25 kg/m(2), and HDL cholesterol level <40 mg/dl (<1.55 mmol/liter)), compared with those with fewer conditions, had a significantly increased risk of colorectal cancer (HR = 1.40, 95% CI: 1.12, 1.74), particularly colon cancer (HR = 1.58, 95% CI: 1.18, 2.10), but not rectal cancer. These results support the hypothesis that the significant association observed between IRS-defining metabolic abnormalities and colorectal cancer is determined primarily by adiposity.

Impaired glucose metabolism in colorectal cancer

OBJECTIVE

Some studies have found that people with type 2 diabetes mellitus are at increased risk of neoplasms, especially colorectal cancer (CRC). In other studies it is also suggested that there is a higher incidence of diabetes mellitus in patients with CRC. The aims of this study were to assess whether the incidence of type 2 diabetes mellitus and impaired glucose tolerance (IGT) are higher in subjects with CRC and to determine the difference between diabetic subjects and healthy controls regarding glucose metabolism (glycaemia, insulinaemia, serum levels of C-peptide) as well as insulin resistance and sensitivity.

MATERIAL AND METHODS

The study included a total of 80 subjects: 40 enrolled patients (20 M, 20 F) with newly diagnosed sporadic colorectal cancer and 40 subjects with endoscopically excluded CRC or adenomas serving as controls. Subjects were matched for gender, age and body mass index (BMI) (age +/- 5 years BMI +/- 1 kg/m2). A 75-g oral glucose tolerance test was performed after an overnight fast. Samples for glycaemia, serum levels of C-peptide and insulin were taken at 0, 30, 60, 90, 120 and 150 min of the study. HOMA-IR, EIR, EIR/HOMA-IR indexes were calculated.

RESULTS

There was a significantly higher incidence of impaired glucose metabolism (IGM-diabetes mellitus or IGT) in CRC subjects. No differences were found in levels of glucose, insulin or C-peptide. Insulinaemia and C-peptide curves showed a shift typical of diabetes, in the form of a delayed insulin release peak. The HOMA-IR, EIR as well as the EIR/HOMA-IR indexes showed no differences between groups.

CONCLUSIONS

A significantly higher incidence of IGM appears to occur in CRC patients than in the healthy population. This phenomenon is not dependent on age and body-weight, which may suggest that it is cancer that predisposes to diabetes rather than the other way round. The neoplastic process in the colon is not associated with hyperinsulinaemia or insulin resistance, but in CRC patients, pancreatic B-cell dysfunction typical of the early stages of diabetes is seen.

Association of obesity, serum glucose and lipids with the risk of advanced colorectal adenoma and cancer: a case-control study in Korea

BACKGROUND

Previous studies on colorectal cancer risk suggest that obesity, serum lipids and glucose might be related to colorectal carcinogenesis. This case-control study was conducted to investigate the association between obesity, serum lipids and glucose, and the risk of advanced colorectal adenoma and cancer.

METHODS

Patients with histologically confirmed colorectal cancers (n=105), same number of patients with advanced colorectal adenomas matched by age and sex, and the same number of controls matched by age and sex were selected in Hanyang University Guri Hospital between January 2002 and June 2004.

RESULTS

Adenoma and cancer group showed significantly higher levels of mean body mass index and serum glucose. Cancer group also showed significantly lower mean serum lipids levels than controls. We used an unordered polytomous logistic model to calculate multivariate odds ratios for advanced adenoma and cancer relative to controls. Higher serum glucose level was more strongly associated with increased risk of cancer relative to controls (odds ratio, 3.0; 95% confidence interval, 0.9-9.8) than with increased risk of advanced adenoma (odds ratio, 2.1; 95% confidence interval, 0.9-5.4). Higher body mass index was strongly associated with increased risk of advanced adenoma (odds ratio, 10.8; 95% confidence interval, 4.6-25.3), but associated with attenuated risk of cancer (odds ratio, 2.3; 95% confidence interval, 0.9-5.8). Serum triglycerides and cholesterol levels were strongly associated with reduced risk of cancer (odds ratio, 0.3; 95% confidence interval, 0.1-0.8 and odds ratio, 0.2; 95% confidence interval, 0.1-0.6, respectively).

CONCLUSIONS

Obesity and hyperglycaemia are positively related to advanced colorectal adenoma formation. Furthermore, hyperglycaemia plays an important role in progression to cancer. Findings on an inverse relationship between serum triglyceride and cholesterol levels and the risk of colorectal cancer may be the secondary results from metabolic or nutritional changes in advanced colorectal cancer patients and should be clarified in further studies.

Type 2 diabetes mellitus: the impact on colorectal adenoma risk in women

OBJECTIVES

Increased risk for colorectal cancer (CRC) has been associated with type 2 diabetes. Despite several studies linking insulin resistance to increased CRC risk, there are limited data on colorectal adenoma risk in diabetic women. We hypothesized that diabetic women would have increased rates of colorectal adenomas relative to a group of nondiabetic women.

METHODS

Colorectal adenoma rates were determined in 100 estrogen-negative women with type 2 diabetes mellitus and compared with 500 nondiabetic, estrogen-negative controls. Adenomas were defined as any adenoma or advanced adenoma (villous or tubulovillous features, size >1 cm or high-grade dysplasia). A multivariate model including age, race, diabetes, hypertension, hypercholesterolemia, body mass index, and nonsteroidal anti-inflammatory drug status was used to determine the independent effects of diabetes on colorectal adenoma incidence.

RESULTS

Diabetics as compared with nondiabetics had greater rates of any adenoma (37%vs 24%, p= 0.009) and advanced adenomas (14%vs 6%, p= 0.009). Two hundred forty-five obese subjects compared with 355 nonobese subjects had a higher rate of any adenoma (32%vs 22%, p= 0.001). Obese diabetics compared with nonobese, nondiabetics had greater rates of any adenoma (42%vs 23%, p< or = 0.001) and advanced adenomas (19%vs 7%, p< or = 0.001). Multivariate analysis showed that adenomas and advanced adenomas were independently predicted by diabetes (p < 0.05) and adenomas by age.

DISCUSSION

Women with type 2 diabetes mellitus had higher rates of colorectal adenomas as compared with lean and nondiabetic women. This finding adds to the evidence that type 2 diabetes is an important factor in the progression of the adenoma-carcinoma sequence.

Clinically confirmed type 2 diabetes mellitus and colorectal cancer risk: a population-based, retrospective cohort study

OBJECTIVES

Patients with type 2 diabetes mellitus (DM) may be at increased colorectal cancer (CRC) risk. However, existing data are inconsistent. We investigated CRC risks, overall and by anatomic subsite, within a population-based inception cohort of clinically confirmed type 2 DM subjects.

METHODS

All residents of Rochester, Minnesota who first met standardized criteria for type 2 DM from 1970 to 1994 (997 men and 978 women) were identified and followed forward in time until emigration, death, or December 31, 1999. Incident CRC cases were identified by review of inpatient and outpatient medical records. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were estimated to compare CRC incidence within the type 2 DM inception cohort with previously published rates for the Rochester general population.

RESULTS

Over 19,158 person-years of follow-up, 51 incident CRC cases were identified within the type 2 DM cohort, while only 36.8 cases were expected (SIR = 1.39, 95% CI 1.03-1.82). Among men, type 2 DM was associated with increased overall (SIR = 1.67, 95% CI 1.16-2.33) and proximal (SIR = 1.96, 95% CI 1.16-3.10) CRC risks; distal CRC risk was also increased, but the point estimate was not statistically significant (SIR = 1.43, 95% CI 0.82-2.32). Among women, type 2 DM was not a risk factor for overall, proximal, or distal CRC (SIR = 1.03, 95% CI 0.60-1.66; SIR = 1.17, 95% CI 0.58-2.09; and SIR = 0.74, 95% CI 0.24-1.72, respectively). Within the type 2 DM cohort, current and former cigarette smokers were at higher CRC risk (SIR = 1.77, 95% CI 1.24-2.47) than never smokers (SIR = 0.99, 95% CI 0.57-1.61) and the interaction between type 2 DM and cigarette smoking status was statistically significant (p= 0.05).

CONCLUSIONS

In this population-based, retrospective cohort study, clinically confirmed type 2 DM was associated with increased CRC risk, predominantly among men. Cigarette smoking appeared to positively modify DM-associated CRC risk, which to our knowledge has not been previously reported. These data suggest that further investigation of potential interactions between endogenous and exogenous factors involved in colorectal carcinogenesis may help to clarify the magnitude and extent of CRC risk experienced by persons with type 2 DM.

Visceral fat analysis at CT colonography

RATIONALE AND OBJECTIVES

Obesity is associated with increased risks for colorectal neoplasia. Few studies have examined quantitative body fat measurements as predictors of colorectal polyps. The objective is to determine whether visceral fat is associated with colorectal polyps at computed tomography (CT) colonography.

MATERIALS AND METHODS

Case (n = 25) and control (n = 25) subjects with proven large (>1 cm) colorectal adenomas or normal colons respectively were randomly selected from among an established CT colonography research study cohort. Using supine CT colonography data, the body wall was traced at three levels: top of the right kidney, iliac crest, and superior acetabulum. Total area from the three slices and each slice area were determined within the visceral fat range (-170 to -45 Hounsfield units) and recorded within the selected region. Visceral fat measures were compared between patient groups with and without polyps.

RESULTS

None of the single slice visceral fat area measures or summed measures predicted case or control status. The most informative visceral fat measure was obtained at the top of the right kidney with a maximum area under the received operator characteristic curve of 0.77 (0.05 SE). For a selected sensitivity of 75%, the maximum specificity for a large (>or=1 cm) polyp was 64%.

CONCLUSION

In this pilot study, visceral fat measures at CT colonography were not significantly associated with the presence of large colorectal adenomas. However, odd ratios were elevated by a factor of 2. This suggests that a larger study may be justified.

Physical activity and the risk of colon cancer among women: a prospective cohort study (United States)

Physical activity has frequently been reported to decrease the risk of colon cancer in men, but data on the relation of physical activity to colon cancer risk in women have generally been less consistent. To further investigate the relationship of physical activity with colon cancer risk in women, we studied a cohort of 31,783 US women participating in the Breast Cancer Detection Demonstration Project Follow-up Study. Information on daily physical activity over the past year was ascertained using a self-administered questionnaire at study baseline. The Cox proportional hazards model was used to estimate relative risks (RRs) relating physical activity to the risk of incident colon cancer. During 270,325 person-years of follow-up, 243 colon cancer cases were identified. No association was observed between physical activity and the subsequent risk of colon cancer. The multivariable RRs of colon cancer across increasing quintiles of total physical activity were 1.0, 1.45, 1.16, 1.27 and 1.15 (95% CI: 0.76, 1.75; p(trend) = 0.77). The multivariable RRs comparing women at the extremes of moderate and vigorous physical activity, respectively, were 1.07 (95% CI: 0.70, 1.62) and 1.10 (95% CI: 0.78, 1.55). The relationship between physical activity and colon cancer risk did not vary by anatomic subsite or across subgroups defined by age, body mass, dietary fiber intake, menopausal status, menopausal hormone use or aspirin use. The results of this large prospective cohort study among women do not support the hypothesis that physical activity is related to a lower incidence of colon cancer.

Fasting blood glucose and cancer risk in a cohort of more than 140,000 adults in Austria

AIMS/HYPOTHESIS

We investigated relations between fasting blood glucose and the incidence of cancer.

METHODS

A population-based cohort of more than 140,000 Austrian adults (63,585 men, 77,228 women) was followed over an average of 8.4 years. Incident cancer (other than non-melanoma skin cancers) was ascertained by a population-based cancer registry (n=5,212). Cox proportional-hazards models were used to estimate hazard rate ratios (HR) stratified for age and adjusted for smoking, occupational group and body mass index.

RESULTS

The highest fasting blood glucose category (> or =7.0 mmol/l) was weakly associated with all cancers combined (HR 1.20; 95% CI, 1.03-1.39 in men and 1.28; 95% CI, 1.08-1.53 in women) relative to the reference level (4.2-5.2 mmol/l). The strongest association was found for liver cancer in men (HR 4.58; 95% CI, 1.81-11.62). Positive associations between fasting hyperglycaemia (6.1-6.9 or > or =7.0 mmol/l) and cancer incidence were also observed for non-Hodgkin's lymphoma in men, and for colorectal and bladder cancer in women. Breast cancer in women diagnosed at or after age 65 was also associated with fasting blood glucose > or =7.0 mmol/l. Positive associations with glucose values >5.3 mmol/l were noted for thyroid cancer, gallbladder/bile duct cancer and multiple myeloma in men and women combined.

CONCLUSIONS/INTERPRETATION

These findings provide further evidence that elevated blood glucose is associated with the incidence of several types of cancer in men and women.

Measures of familial aggregation depend on definition of family history: meta-analysis for colorectal cancer

OBJECTIVE

Familial aggregation, a primary theme in genetic epidemiology, can be estimated from family studies based on an index person. The excess risk due to the presence of affected family members can be classified according to whether disease in the relatives is considered a risk factor for the index person (type I relative risk) or whether the disease status of the index person is considered a risk factor for the relatives (type II relative risk).

STUDY DESIGN AND SETTING

A meta-analysis of published colorectal cancer studies reporting a measure of familial association was performed and application of multilevel linear regression to model age-specific relative risks presented.

RESULTS

The pooled type I relative risk of colorectal cancer given any affected first-degree relative (based on 20 studies) was 2.26 (95% confidence interval CI = 1.86, 2.73) and decreased with the age of the consultand. The pooled type II estimate (based on seven studies) was 2.81 (95% CI = 2.05, 3.85).

CONCLUSION

Type I relative risks are useful in clinical counseling settings when a consultand wants to know his/her disease risk given his or her family history. Type II relative risks can be used to quantify the risk of disease to relatives of an affected individual and then identify subjects eligible for screening.

Increased cancer-related mortality for patients with type 2 diabetes who use sulfonylureas or insulin

OBJECTIVE

Numerous studies have identified an increased risk of cancer in type 2 diabetes. We explored the association between antidiabetic therapies and cancer-related mortality in patients with type 2 diabetes, postulating that agents that increase insulin levels might promote cancer.

RESEARCH DESIGN AND METHODS

This was a population-based cohort study using administrative databases from Saskatchewan Health. Cancer-related mortality was compared among inception cohorts of metformin users and sulfonylurea monotherapy users. Multivariate Cox regression was used to estimate the hazard ratio (HR) of cancer-related mortality, after adjusting for age, sex, insulin use, and chronic disease score. All statistical tests were two-sided.

RESULTS

We identified 10,309 new users of metformin or sulfonylureas with an average follow-up of 5.4 +/- 1.9 years (means +/- SD). The mean age for the cohort was 63.4 +/- 13.3 years, and 55% were men. Cancer mortality over follow-up was 4.9% (162 of 3,340) for sulfonylurea monotherapy users, 3.5% (245 of 6,969) for metformin users, and 5.8% (84 of 1,443) for subjects who used insulin. After multivariate adjustment, the sulfonylurea cohort had greater cancer-related mortality compared with the metformin cohort (adjusted HR 1.3 [95% CI 1.1-1.6]; P = 0.012). Insulin use was associated with an adjusted HR of cancer-related mortality of 1.9 (95% CI 1.5-2.4; P < 0.0001).

CONCLUSIONS

Patients with type 2 diabetes exposed to sulfonylureas and exogenous insulin had a significantly increased risk of cancer-related mortality compared with patients exposed to metformin. It is uncertain whether this increased risk is related to a deleterious effect of sulfonylurea and insulin or a protective effect of metformin or due to some unmeasured effect related to both choice of therapy and cancer risk.

Diabetes Mellitus and Risk of Colorectal Cancer in the Singapore Chinese Health Study

The incidence of colorectal cancer is highest in populations that consume an energy-dense diet, have low intakes of vegetables and fruit, or lead a sedentary lifestyle. These factors may influence colorectal carcinogenesis via insulin pathways. We examined whether diabetes mellitus was associated with colorectal cancer in Singapore Chinese, whose body type and lifestyle profiles are distinct from those of Western populations. Between April 1993 and December 1998, 63,257 Singapore Chinese men and women aged 45 to 74 years were enrolled in a prospective study of diet and cancer. Each subject provided dietary, medical, and lifestyle information through an in-person interview. As of December 31, 2002, 636 incident colorectal cancer cases had been diagnosed. A history of physician-diagnosed diabetes was statistically significantly associated with colorectal cancer risk in both men (relative risk [RR] = 1.5, 95% confidence interval [CI] = 1.2 to 2.1) and women (RR = 1.4, 95% CI = 1.0 to 1.9). In stratified analyses, this association remained statistically significant among the subset of diabetics with high total calorie intake and low physical activity levels. Our results support the hypothesis that hyperinsulinemia may play a role in colorectal carcinogenesis, even in a relatively lean population.

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

BACKGROUND

Diabetes has been associated with an increased risk of colorectal cancer in most, but not all, studies. Findings have also been inconclusive with regard to sex and subsite in the colorectum. To resolve these inconsistencies, we conducted a meta-analysis of published data on the association between diabetes and the incidence and mortality of colorectal cancer.

METHODS

We identified studies by a literature search of Medline from January 1, 1966, through July 31, 2005, and by searching the reference lists of pertinent articles. Summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated with a random-effects model. All statistical tests were two-sided.

RESULTS

Analysis of 15 studies (six case-control and nine cohort studies), including 2 593 935 participants, found that diabetes was associated with an increased risk of colorectal cancer, compared with no diabetes (summary RR of colorectal cancer incidence = 1.30, 95% CI = 1.20 to 1.40), without heterogeneity between studies (P(heterogeneity) = .21). These results were consistent between case-control and cohort studies and between studies conducted in the United States and in Europe. The association between diabetes and colorectal cancer incidence did not differ statistically significantly by sex (summary RR among women = 1.33, 95% CI = 1.23 to 1.44; summary RR among men = 1.29, 95% CI = 1.15 to 1.44; P(heterogeneity) = .26) or by cancer subsite (summary RR for colon = 1.43, 95% CI = 1.28 to 1.60; summary RR for rectum = 1.33, 95% CI = 1.14 to 1.54; P(heterogeneity) = .42). Diabetes was positively associated with colorectal cancer mortality (summary RR = 1.26, 95% CI = 1.05 to 1.50), but there was evidence for heterogeneity between studies (P(heterogeneity) = .04).

CONCLUSIONS

Our findings strongly support a relationship between diabetes and increased risk of colon and rectal cancer in both women and men.

Therapy insight: Influence of type 2 diabetes on the development, treatment and outcomes of cancer

Although type 2 diabetes and cancer are major health concerns among the adult population, few studies have directly addressed the relationship between the two, or the impact of diabetes on cancer outcomes. Diabetes and hyperglycemia are associated with an elevated risk of developing pancreatic, liver, colon, breast, and endometrial cancer. When treating cancer patients who have diabetes, clinicians must consider the cardiac, renal, and neurologic complications commonly associated with diabetes. Chemotherapeutic choices and, ultimately, the outcome for cancers may be affected by the avoidance of agents that have been shown to provide the best clinical response and survival in cancer patients without other disease complications. Evidence from population-based studies and clinical trials indicate that hyperglycemic and diabetic patients experience higher mortality and recurrence rates after diagnosis with, and treatment for, cancer. Evidence from the intensive care literature indicates that achieving glucose control leads to better clinical outcomes. If so, continued improvement of cancer outcomes may depend upon improved diabetes control. The association between diabetes and cancer is complex and warrants further study as the general population ages and the magnitude of both health problems continues to grow. Here we consider the influence of diabetes and hyperglycemia on the development, treatment, and long-term outcomes of cancer.

Possible participation of advanced glycation end products in the pathogenesis of colorectal cancer in diabetic patients

Colorectal cancer is a major public health problem, being the second most common cause of cancer in developed countries. Several epidemiological studies have reported moderately increased risks of colorectal cancer in diabetic patients compared with general population. However, the underlying molecular link between diabetes and colorectal cancer remains to be elucidated. In diabetes mellitus, the formation and accumulation of advanced glycation end products (AGEs) progress. There is a growing body of evidence to show that AGEs-their receptor (RAGE) interactions are involved in the development of atherosclerosis and diabetic microangiopathy. AGEs-RAGE interactions stimulated the growth of human pancreatic cancer cells through the autocrine induction of platelet-derived growth factor-B. Furthermore, we have recently found that AGEs stimulated the growth and migration of cultured human melanoma cells and that anti-RAGE antibodies inhibited tumor formation and lung metastasis of melanoma cell xenografts and subsequently improved survival in athymic mice. These observations let us to hypothesize that AGEs could explain the molecular link between diabetes and colorectal cancer. In this paper, we would like to propose the possible ways of testing our hypotheses. Is elevation of serum AGE levels a risk factor for colorectal cancer in patients with diabetes? Does treatment with metformin, which has a potential effect on the inhibition of glycation reactions in vivo, decrease the risk for colorecetal cancer in diabetic patients? If the answer is yes, is this beneficial effect of metformin superior to that of other anti-diabetic agents with equihypoglycemic properties? Does treatment with pyridoxamine, a post-Amadori inhibitor (so-called Amadorins) of AGE formation, reduce the risk for colorectal cancer as well? Furthermore, are increased levels of AGEs and RAGE in colorectal cancer associated with poor prognosis in patients with diabetes? These clinical studies could clarify whether the AGEs-RAGE interactions serve as a causal link between diabetes and colorectal cancer.

Insulin-like growth factor-I and insulin are associated with the presence and advancement of adenomatous polyps

BACKGROUND & AIMS

Insulin and insulin-like growth factor-I (IGF-I) affect proliferation, differentiation, and apoptosis and are potential risk factors for colorectal cancer (CRC). Visceral obesity, possibly via hyperinsulinemia, has also been linked to CRC risk. We evaluated the relationship of insulin, IGF-I, insulin-like growth factor binding protein (IGFBP) 3, and visceral adipose tissue (VAT) in subjects with adenomatous polyps, the precursor lesion of colorectal cancer.

METHODS

Participants were asymptomatic subjects who underwent screening flexible sigmoidoscopy (FSG) within the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Subjects underwent single-slice, computerized tomography scanning to measure VAT and serum fasting insulin, IGF-I, and IGFBP-3 measurements.

RESULTS

Four hundred fifty-eight subjects were enrolled, of which 202 subjects had an adenoma, 70 of which were an advanced adenoma. IGF-I (P = .02), IGF-I/IGFBP-3 ratio (P = .003), and insulin (P = .02) were significantly increased in subjects with adenomas compared with controls. In an unadjusted logistic regression analysis using sex-specific quartile cut points, subjects in quartile 4 in comparison with quartile 1 of IGF-I (odds ratio [OR] = 1.7; [95% CI: 1.0-2.9], Ptrend = .03), IGF-I/IGFBP-3 ratio (OR = 1.9 [95% CI: 1.1-3.3], Ptrend = .01), and insulin (OR = 2.1 [95% CI: 1.2-3.6], Ptrend = .04) were at increased risk of adenoma. When limiting the case group to advanced adenomas, the effect was more pronounced: IGF-I (OR = 2.8 [95% CI: 1.3-6.2], Ptrend = .006), IGF-I/IGFBP-3 ratio (OR = 2.3, [95% CI: 1.0-5.2], Ptrend = .04), and insulin (OR = 2.3 [95% CI: 1.1-4.9], Ptrend = .14). Visceral adipose tissue was not associated with adenoma risk.

CONCLUSIONS

Levels of IGF-I, ratio of IGF-I/IGFBP-3, and insulin are associated with adenomas and even more so with advanced adenomas. These data support the hypothesis that insulin and IGF-I may contribute to the development and advancement of adenomatous polyps.

Association between adenomas of rectosigmoid colon and metabolic syndrome features in a Chinese population

BACKGROUND AND AIMS

Metabolic syndrome (MS) consists of a cluster of diseases, including obesity, dyslipidemia, hyperglycemia and high blood pressure. The purpose of the present study was to assess the association of MS with adenomas of the rectosigmoid colon, a well-established precancerous lesion.

METHODS

A total of 4938 Taiwanese patients (2891 men and 2047 women with a mean age of 50.1 years), who had a physical examination at our hospital between January 2001 and October 2002, were enrolled in this study. All patients underwent a sigmoidoscopic examination to 60 cm from the anus. A modified National Cholesterol Education Program (NCEP) definition of MS was used in this study, in which body mass index (BMI) was substituted for the waist circumference measurement.

RESULTS

Overall, 14% of patients had an elevated fasting glucose, 27% had high blood pressure, 14% had an increased triglyceride (TG) level, 8% had low high density lipoprotein (HDL) cholesterol, and 18% were obese. Rectosigmoid polyps were present in 17% of patients, among whom 568 received polypectomy. Pathological findings were hyperplastic in 138 subjects, adenomas in 341, carcinomas in 10, and other benign lesions in 79. In patients without polyps, the adjusted mean TG level and calculated BMI level were lower than those in patients with adenomas. No such difference existed, however, between patients without polyps and those with hyperplastic polyps. The odds ratio of adenomas in situ as compared to either a polyp-free state or the presence of hyperplastic polyps increased significantly with the number of MS diagnostic criteria the patient exhibited.

CONCLUSION

Our study shows that MS is associated with rectosigmoid adenomas in a Chinese population. In patients with rectosigmoid polyps, the coexistence of MS may portend an increased risk of adenomas.

Obesity, insulin resistance and cancer risk

Obesity is a known cause of metabolic syndrome which includes Type II diabetes, hypertension, and dyslipidemia. It is well documented that insulin resistance contributes to the mortality and the incidence of metabolic syndromes including central obesity, dyslipidemia, hyperglycemia and hypertension. Both obesity and diabetes are emerging topics for researchers to consider as having a possible causal association with cancer since the two factors have been viewed as risk factors for cancer. The present paper introduced the hypothesis of a possible causal relationship between obesity, insulin resistance and cancer and reviews relevant existing studies in this area. More efforts and studies are needed to clarify the mechanisms and the common risk factors which might be incorporated into interventions to prevent cancer and cardiovascular diseases as top causes of death.

Decreased intestinal polyp multiplicity is related to exercise mode and gender in ApcMin/+ mice

Moderate-intensity treadmill running can alter male Apc(Min/+) mouse polyp formation. This purpose of this study was to examine whether exercise mode differentially affects Apc(Min/+) mouse intestinal polyp development in male and female mice. Male and female Apc(Min/+) mice were randomly assigned to control, treadmill (18 m/min; 60 min/day; 6 days/wk), or voluntary wheel running (24-h access) groups. Nine weeks of training decreased total intestinal polyps by 29% in male treadmill runners (66 +/- 9; P = 0.038) compared with male controls (93 +/- 7). The number of large polyps (>/=1-mm diameter) were also reduced by 38% in male treadmill runners (49 +/- 6; P = 0.005) compared with male controls (79 +/- 6). Treadmill running in female Apc(Min/+) mice and wheel running in both genders did not affect polyp number or size. Spleen weight decreased in male treadmill runners (91 +/- 9 mg; P = 0.011) and wheel runners (75 +/- 6 mg; P = 0.004) compared with controls (141 +/- 13 mg). Plasma IL-6 was reduced by 96% in male treadmill runners (1.2 +/- 0.6 pg/ml) and 78% in male wheel runners (6.6 +/- 3.3 pg/ml) compared with control mice (27.9 +/- 2.8 pg/ml; P < 0.05). Female mice responded similarly with an 86% decrease in plasma IL-6 with treadmill running (3.2 +/- 1.2 pg/ml) and 90% decrease with wheel running (2.9 +/- 2.0 pg/ml) compared with control mice (21.1 +/- 5.3 pg/ml; P < 0.05). The crypt depth-to-villus height ratio in the intestine, an indirect marker of intestinal inflammation, decreased by 21 (P = 0.024) and 24% (P = 0.029), respectively, in male and female treadmill runners but not wheel runners. Physical activity-induced attenuation of intestinal polyp number and size is dependent on exercise mode and differs between genders. The modulation of systemic and intestinal inflammation may also depend on exercise mode.

Cancer incidence and mortality in patients with insulin-treated diabetes: a UK cohort study

Raised risks of several cancers have been found in patients with type II diabetes, but there are few data on cancer risk in type I diabetes. We conducted a cohort study of 28 900 UK patients with insulin-treated diabetes followed for 520 517 person-years, and compared their cancer incidence and mortality with national expectations. To analyse by diabetes type, we examined risks separately in 23 834 patients diagnosed with diabetes under the age of 30 years, who will almost all have had type I diabetes, and 5066 patients diagnosed at ages 30–49 years, who probably mainly had type II. Relative risks of cancer overall were close to unity, but ovarian cancer risk was highly significantly raised in patients with diabetes diagnosed under age 30 years (standardised incidence ratio (SIR)=2.14; 95% confidence interval (CI) 1.22–3.48; standardised mortality ratio (SMR)=2.90; 95% CI 1.45–5.19), with greatest risks for those with diabetes diagnosed at ages 10–19 years. Risks of cancer at other major sites were not substantially raised for type I patients. The excesses of obesity- and alcohol-related cancers in type II diabetes may be due to confounding rather than diabetes per se.

A prospective study of C-peptide, insulin-like growth factor-I, insulin-like growth factor binding protein-1, and the risk of colorectal cancer in women

Hyperinsulinemia, hyperglycemia, and elevated insulin-like growth factor (IGF)-1 levels have been implicated in the etiology of colorectal cancer. However, the joint effects of insulin and IGF-I have not been considered, and whether hyperinsulinemia or hyperglycemia is more etiologically relevant is unclear. IGF binding protein-1 (IGFBP-1) has been hypothesized to mediate the effects of insulin, but epidemiologic data on IGFBP-1 are sparse. We conducted a nested case-control study among the 32,826 women of the Nurses' Health Study who provided a blood sample in 1989 to 1990. After excluding diabetics, we confirmed 182 incident colorectal cancer cases over 10 years of follow-up and 350 controls. Cases were matched to two controls on year of birth, date of blood draw, and fasting status. C-peptide levels were weakly associated with risk of colon cancer [top quartile (Q4) versus bottom quartile (Q1): multivariable relative risk (MVRR), 1.76; 95% confidence interval (95% CI), 0.85-3.63]. Fasting IGFBP-1 was inversely associated with risk of colon cancer (MVRR, 0.28; 95% CI, 0.11-0.75). We observed no clear association between glycosylated hemoglobin and risk for colorectal cancer. The IGF-I to IGFBP-3 molar ratio was associated with colon cancer risk (MVRR, 2.82; 95% CI, 1.35-5.88), and women with low levels of both IGF-I/IGFBP-3 and C-peptide (or high IGFBP-1) were at low risk, and elevation of either was sufficient to increase risk. Although altering IGF-I levels may not be practical, the growing burden of obesity and consequently hyperinsulinemia, which seems increasingly important for colon cancer, may be a target for effective prevention.