Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0699790 (colon cancer)
 28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Selenium and vitamin E are probably 2 of the most popular dietary supplements considered for use in the reduction of prostate cancer risk. This enthusiasm is reflected in the initiation of the Selenium and Vitamin E Chemoprevention Trial (SELECT). Is there sufficient evidence to support the use of these supplements in a large-scale prospective trial for patients who want to reduce the risk of prostate cancer? Results from numerous laboratory and observational studies support the use of these supplements, and data from recent prospective trials also add partial support. However, a closer analysis of the data reveals some interesting and unique associations. Selenium supplements provided a benefit only for those individuals who had lower levels of baseline plasma selenium. Other subjects, with normal or higher levels, did not benefit and may have an increased risk for prostate cancer. The concept that supplements reduce prostate cancer risk only in those at a higher risk and/or those with lower plasma levels of these compounds is supported by trials examining beta-carotene supplements. Smokers may be the only individuals who benefit, as has also been shown with vitamin E supplementation. In 4 recent prospective studies, vitamin E was found to reduce the risk of prostate cancer in past/recent and current smokers and those with low levels of this vitamin. Vitamin E supplements in higher doses (> or =100 IU) were also associated with a higher risk of aggressive or fatal prostate cancer in nonsmokers from a past prospective study. The dose of vitamin E in the SELECT trial (400 IU/day) is 8 times higher than what has been suggested to be effective (50 IU/day) by the largest randomized prospective trial in which the incidence rate of prostate cancer was used as an endpoint. Recent research also suggests that dietary vitamin E may be associated with a lower risk of prostate cancer than the vitamin E supplement. Additionally, recent results from all past cardiovascular prospective, randomized trials suggest that vitamin E shows little benefit for cardiovascular disease risk, especially at the dose being used in the SELECT trial. Other intriguing positive findings from past prospective studies of supplements suggest that aspirin and other nonsteroidal anti-inflammatory drugs have a role in reducing the risk of prostate cancer or other types of cancer (eg, colon cancer). It may be time to conduct a large costly trial to reconsider the use of selenium and vitamin E supplements for the reduction of prostate cancer risk. Some evidence for the use of these supplements exists, but serious embellishment of study findings may be leading to an inappropriate use of these supplements in a clinical setting.
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PMID:Selenium and vitamin E supplements for prostate cancer: evidence or embellishment? 1193 32

A wide variety of plant-derived compounds, including the polyphenolic flavonoids, is present in the human diet or is consumed for medicinal reasons. Epidemiological and animal studies tend to suggest a protective effect of flavonoids against cardiovascular diseases and some types of cancer. Although flavonoids have been studied for about 50 years, the cellular mechanisms involved in their biological activity are still largely unknown. Antioxidant properties of the flavonoids have been postulated as a mechanism for putative protective effect against cardiovascular disease. Nevertheless, these properties alone are not sufficient to explain the anti-carcinogenic potential of these polyphenols. The mechanisms by which the molecules interact with cells or are absorbed by them are very important for determining the intracellular concentration and distribution of the metabolites to internal organs. With the exception of the cells lining the gastrointestinal tract, all other cells in the body are only exposed to flavonoid metabolites and degradation products. No previous studies have addressed this aspect of cellular exposure, except for some methylated metabolites. Within the last decade, reports on flavonoid activities have been largely associated with enzyme inhibition and anti-proliferative activity. From our recent work on the human colon cancer cell line HT29 and comparison with published studies, structure-function relationships demonstrate that antioxidant, enzyme inhibitor or anti-proliferative activities are dependent on particular structure motifs. The present review also presents a summary of mechanistic data on a few elected compounds.
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PMID:Evidence for consistent patterns between flavonoid structures and cellular activities. 1200 1

The worksite is an ideal forum for cancer risk assessment. We describe here the baseline characteristics of a large cohort. Participants completed surveys that assessed a variety of risk factors and behavioral mediators. Personalized feedback letters identified cancer risks. A total of 4395 surveys were received. Cancer prevalence was 6.5% (range, 4.3% to 11.2%). The most common risk factors were lack of exercise (41%; 32% to 68%), obesity (28%; 24% to 39%), and smoking (14%; 13% to 32%). Cardiovascular risk was also common (25%; 15% to 48%). Screening was fair to good for all cancers except colon cancer. The perceived risk for cancer was less than that for cardiovascular disease (P < 0.0001). Most smokers were in the pre-contemplation phase, whereas action/maintenance phases predominated for breast and colon cancer screening. Modifiable cancer risk factors can be identified in the majority of workers. Inaccurate risk perception is an important target for future interventions.
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PMID:Implementation of a comprehensive cancer control program at the worksite: year one summary report. 1202 85

Dietary fiber consists of the structural and storage polysaccharides and lignin in plants that are not digested in the human stomach and small intestine. A wealth of information supports the American Dietetic Association position that the public should consume adequate amounts of dietary fiber from a variety of plant foods. Recommended intakes, 20-35 g/day for healthy adults and age plus 5 g/day for children, are not being met, because intakes of good sources of dietary fiber, fruits, vegetables, whole and high-fiber grain products, and legumes are low. Consumption of dietary fibers that are viscous lowers blood cholesterol levels and helps to normalize blood glucose and insulin levels, making these kinds of fibers part of the dietary plans to treat cardiovascular disease and type 2 diabetes. Fibers that are incompletely or slowly fermented by microflora in the large intestine promote normal laxation and are integral components of diet plans to treat constipation and prevent the development of diverticulosis and diverticulitis. A diet adequate in fiber-containing foods is also usually rich in micronutrients and nonnutritive ingredients that have additional health benefits. It is unclear why several recently published clinical trials with dietary fiber intervention failed to show a reduction in colon polyps. Nonetheless, a fiber-rich diet is associated with a lower risk of colon cancer. A fiber-rich meal is processed more slowly, which promotes earlier satiety, and is frequently less calorically dense and lower in fat and added sugars. All of these characteristics are features of a dietary pattern to treat and prevent obesity. Appropriate kinds and amounts of dietary fiber for the critically ill and the very old have not been clearly delineated; both may need nonfood sources of fiber. Many factors confound observations of gastrointestinal function in the critically ill, and the kinds of fiber that would promote normal small and large intestinal function are usually not in a form suitable for the critically ill. Maintenance of body weight in the inactive older adult is accomplished in part by decreasing food intake. Even with a fiber-rich diet, a supplement may be needed to bring fiber intakes into a range adequate to prevent constipation. By increasing variety in the daily food pattern, the dietetics professional can help most healthy children and adults achieve adequate dietary fiber intakes.
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PMID:Position of the American Dietetic Association: health implications of dietary fiber. 1214 67

The results of the Women's Health Initiative's (WHI) large prospective randomized controlled study on the benefits and risks of combined hormone replacement therapy (HRT) have been reported earlier than expected, due to the findings of a small excess in cases of breast cancer, myocardial infarction, cerebrovascular accident, and venous thrombosis, in conjunction with a slight diminution of the number of cases of bone fracture and colon cancer. These results were obtained in a population of women with a mean age of 63 +/- 7 years, many of whom were already presenting relative risks of diseases at randomization. The results provide the best evidence available at present on HRT for prevention of heart disease, and indicate that combined HRT is not indicated for this purpose in the studied population, thus contradicting the reported beneficial effects of HRT on coronary heart disease (CHD) in previous observational studies. Some comments need to be made, particularly with regard to the relevance of the WHI study results to the traditional use of HRT at the beginning of menopause. The results, obtained from a population having a wide age range (50 to 79 years), with only 33% being between the ages of 50 and 59, taking 0.625 mg/day conjugated equine estrogens combined with 2.5 mg/day medroxyprogesterone acetate or placebo, are presented without stratification according to the various decades. Further, 73.9% of the women never took HRT before entering the study; rather, they began HRT several years after menopause. Thus, the age distribution and late start of HRT in the women in the WHI study do not correspond to the traditional use of HRT. The studied population presented numerous risks of diseases related to aging, in particular cardiovascular disease. Except for venous thrombosis, the confidence intervals for outcomes are near the limit of statistical significance, which disappears after adjustment. The accrual of breast cancer cases appearing during the fourth year of observation is similar to that found in previous studies, and remains inferior to the increases related to lifestyle factors reported in other studies. The overall results are being applied to women aged 50 to 60 without specific data for this age group, who are usually considered to be at no or low risk for the traditional use of HRT. There are no data to compare the various formulations actually approved as class labelling (estrogens or estradiol associated or not with a progestin or natural progesterone by the oral or transdermal route) in the various outcomes of the WHI study. Results of the ongoing WHI study on estrogen alone will have to be considered when they become available. The results of the WHI study do not put into question the validity of prescribing combined HRT in early menopause. They are likely to modify somewhat the recommendations of published consensus cautioning the use of HRT. HRT remains an effective and safe intervention when it is prescribed to palliate the signs and symptoms related to estrogen deficiency, mainly in women soon after menopause, but also in women presenting risk factors for osteoporosis but without actual risk factors of cardiovascular disease and without a family history of breast cancer. New mid-term and long-term randomized studies need to be conducted on women starting various formulations of HRT before the age of 60, to evaluate their impact on risk factors and events of cardiovascular disease.
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PMID:The relevance of the Women's Health Initiative results on combined hormone replacement therapy in clinical practice. 1236 Mar 60

Although many mechanisms remain unclear, a large body of evidence indicates that several dietary and lifestyle factors are likely to have a major influence on the risk of colon cancer. Physical inactivity, excess body weight, and a central deposition of adiposity are consistent risk factors. Overconsumption of energy is likely to be one of the major contributors to the high rates of colon cancer in Western countries. Beyond their influence on energy balance, the independent role of specific macronutrients remain controversial. Red meat, processed meats, and perhaps refined carbohydrates contribute to risk. Recent evidence indicate that chronic hyperinsulinemia may increase risk of colon cancer. As insulin resistance and subsequent hyperinsulinemia is induced by excess energy intake and some aspects of the Western diet (e.g., saturated fats and refined carbohydrates), insulin may be a focus of factors influencing colon cancer risk. Recent evidence also points to a role of IGF-1, but our understanding of modifiable factors that influence levels of these is poor at present. Of note is that hyperinsulinemia increases free IGF-1 exposure [25]. High alcohol consumption, probably in combination with a diet low in some micronutrients such as folate and methionine, and smoking early in life are likely to increase risk of colon cancer. Recent epidemiologic studies have tended not to support a strong influence of fiber; instead, some micronutrients or phytochemicals in fiber-rich foods may be important. Folate is one such nutrient that has received attention lately and is being studied in randomized intervention trials. Agents with chemopreventive properties, such as aspirin and postmenopausal estrogens, have potential adverse effects so a careful consideration of the risk-benefit ratio is required before general recommendations can be made. Other NSAIDs with a potential for reduced toxicity, such as celecoxib, are currently being evaluated for efficacy and toxicity. The overwhelming evidence indicates that primary prevention of colon cancer is feasible. At least 70% of colon cancers may be preventable by moderate changes in diet and lifestyle [197]. Secondary prevention, through screening by sigmoidoscopy and colonoscopy, is also critically important to prevent mortality from colon cancer; however, many of the diet and lifestyle risk factors for colon cancers are the same for cardiovascular disease and for some other cancers, so focusing on the modifiable risk factors for colon cancer is likely to have many additional benefits beyond this cancer.
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PMID:Modifiable risk factors for colon cancer. 1248 70

Peroxisome proliferator activated receptors (PPARs) are a family of related receptors implicated in a diverse array of biological processes. There are 3 main isotypes of PPARs known as PPARalpha, PPARbeta and PPARgamma and each is organized into domains associated with a function such as ligand binding, activation and DNA binding. PPARs are activated by ligands, which can be both endogenous such as fatty acids or their derivatives, or synthetic, such as peroxisome proliferators, hypolipidaemic drugs, anti-inflammatory or insulin-sensitizing drugs. Once activated, PPARs bind to DNA and regulate gene transcription. The different isotypes differ in their expression patterns, lending clues on their function. PPARalpha is expressed mainly in liver whereas PPARgamma is expressed in fat and in some macrophages. Activation of PPARalpha in rodent liver is associated with peroxisome proliferation and with suppression of apoptosis and induction of cell proliferation. The mechanism by which activation of PPARalpha regulates apoptosis and proliferation is unclear but is likely to involve target gene transcription. Similarly, PPARgamma is involved in the induction of cell growth arrest occurring during the differentiation process of fibroblasts to adipocytes. However, it has been implicated in the regulation of cell cycle and cell proliferation in colon cancer models. Less in known concerning PPARbeta but it was identified as a downstream target gene for APC/beta-catenin/T cell factor-4 tumor suppressor pathway, which is involved in the regulation of growth promoting genes such as c-myc and cyclin D1. Marked species and tissue differences in the expression of PPARs complicate the extrapolation of pre-clinical data to humans. For example, PPARalpha ligands such as the hypolipidaemic fibrates have been used extensively in the clinic over the past 20 years to treat cardiovascular disease and side effects of clinical fibrate use are rare, despite the observation that these compounds are rodent carcinogens. Similarly, adverse clinical responses have been seen with PPARgamma ligands that were not predicted by pre-clinical models. Here, we consider the response to PPAR ligands seen in pre-clinical models of efficacy and safety in the context of human health and disease.
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PMID:Advances in understanding the regulation of apoptosis and mitosis by peroxisome-proliferator activated receptors in pre-clinical models: relevance for human health and disease. 1262 71

Until recently, observational studies suggested a decreased risk of cardiovascular disease, osteoporotic fractures, cognitive decline and colon cancer with the use of hormone replacement therapy (HRT). Recent randomized controlled trials have failed to show a protective effect of HRT in reducing the risk of coronary artery disease and instead have revealed an increased risk of heart disease, stroke, invasive breast cancer and venous thromboembolism, but a decreased risk of colorectal cancer and osteoporotic fractures. In this article we review the current evidence of the risks and benefits of HRT.
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PMID:Risks and benefits of hormone replacement therapy: the evidence speaks. 1269 85

The glycemic index (GI) has proven to be a useful nutritional concept, providing new insights into the relationship between foods and chronic disease. Observational studies suggest that diets with a high glycemic load (GI x carbohydrate content) are independently associated with increased risk of type 2 diabetes and cardiovascular disease. Postprandial hyperglycemia plays a direct pathogenic role in the disease process. Lower glucose and insulin levels are associated with improved risk profile, including high-density lipoprotein cholesterol, glycosylated proteins, oxidative status, hemostatic variables, and endothelial function. Limited evidence suggests that a low-GI diet may also protect against obesity, colon cancer, and breast cancer. Diets with a high glycemic load may affect health differently in insulin-resistant and insulin-sensitive individuals. Improvements in postprandial hyperglycemia can be brought about by manipulating either the type (i.e., GI) or amount of dietary carbohydrate, or both; at present, the GI appears to be more effective.
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PMID:Glycemic load and chronic disease. 1282 92

Insulin resistance is an important risk factor for development of type 2 diabetes as well as other chronic conditions, including hypertension, cardiovascular disease, and colon cancer. To find genes for insulin resistance it is necessary to assess insulin action in large populations. We have previously measured insulin action in a large cohort of subjects (Insulin Resistance and Atherosclerosis Study [IRAS] Family Study) using the minimal model approach. In this study, we compare sensitivity from the minimal model (insulin sensitivity index [S(I)]) with the measure of insulin resistance emanating from the homeostasis model assessment (HOMA) approach. The former measure emerges from the glycemic response to endogenous and exogenous insulin; the latter is based solely on fasting measures of glucose and insulin. A total of 112 pedigrees were represented, including 1,362 individuals with full phenotypic assessment. Heritability of S(I) was significantly greater than that for HOMA (0.310 vs. 0.163) and for fasting insulin (0.171), adjusted for age, sex, ethnicity, and BMI. In addition, correlation between S(I) and either HOMA or fasting insulin was only approximately 50% accounted for by genetic factors, with the remainder accounted for by environment. Thus S(I), a direct measure of insulin sensitivity, is determined more by genetic factors rather than measures such as HOMA, which reflect fasting insulin.
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PMID:Minimal model-based insulin sensitivity has greater heritability and a different genetic basis than homeostasis model assessment or fasting insulin. 1288 37


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