Colorectal cancer population studies

Ekbom, A., Helmick, C., Zack, M. and Adami H-O (1990). Ulcerative colitis and colorectal cancer a population-based study. N. Engl. J. Med. 1228-1233. 

Bradbury et al. (2004), however, recently reanalyzed the relation between tamoxifen and cataracts and described it as a null association, They used a nested, matched, case-control study design and data collected in the General Practice Research Database. They identified all women 30-79 years old who were diagnosed with breast cancer and treated with tamoxifen within 6 months, or with bladder cancer, colorectal cancer, or nonmelanoma skin cancer between January 1991 and December i999. From this population they identified all newly diagnosed cases of cataract and matched four female controls to each case on age, index date, and study entry data. They assessed the risk of cataracts for current, past, and sometime users of tamoxifen... 

There are multiple possible reasons for the wide variability in the results of these studies. Some studies only looked at heterozygous samples the population of the patients may cause discrepancies some studies used microsatellite markers to validate the presence of LOH and all studies were performed on small sample sizes. To date the extent of genotype discrepancy for TYMS TSER in colorectal cancer remains unclear. 

In the study on colorectal cancer (Table 20.4), a reduced risk was found for increasing intake of anthocyanidins (OR, 0.67 for the highest versus the lowest quintile,p-trend, 0.001), flavonols (OR, 0.64,p-trend < 0.001), flavones (OR, 0.78, p-trend, 0.004), and isoflavones (OR, 0.76, p-trend, 0.001). [Rossi et al., 2006], The estimates did not substantially differ for colon and rectal cancers. After allowance for fruit and vegetable consumption, for dietary fiber, or for micronutrients previously associated to this tumor including vitamin C, the associations with flavonoids did not change by more than 10%. A recent case-control study of 1456 pairs of cases and controls conducted in Sweden confirmed a significant decrease in risk of colorectal cancer for intake of anthocyanidins and flavonols [Theodoratou et al., 2007], but there was no relation for isoflavones and flavones. However, the results on isoflavones and flavones are questionable due to the unusually and generally low intakes of the populations studied. In the Italian population, anthocyanidins were derived mainly from wine, red fruit, and onions, and flavonols from apples or pears, wine, and mixed salads. 

Benito, E., Obrador, A., Stiggelbout, A., Bosch, F.X. Mulct, M., Munoz, N., and Kaldor, J., A population-based case-control study of colorectal cancer in Majorca. I. Dietary factors, Int. J. Cancer, 45, 69-76, 1990. 

A landmark multicenter study published by Pickhardt et al. compared CT colonography and conventional colonoscopy in asymptomatic average-risk patient population. As a screening study, comparable adenoma and colorectal cancer detection rates were reported (Pickhardt et al. 2003). In... 

Indeed, in a recent study. Van Gelder et al. showed that the median effective dose for complete (i.e., prone and supine acquisitions combined) CTC in 12 different institutions is about 8.8 mSv. CTC at 8.8 mSv may result in a risk of up to 0.02% for inducing cancer in the population over 50 years (who are currently considered the target population for colorectal cancer screening) (Van Gelder et al. 2002). Considering these factors, increasing attention has been focused on the optimization of low-dose protocols for CTC. 

Fruit and vegetable fiber has been consistently associated with a lower risk of colon cancer, but the relationship with cereal fiber is less clear. However, whole grain cereals appear to be protective—a further anomaly in the relationships between plant foods and disease risk. These discrepancies may be in the process of resolution. First, it seems that the early observational data were confounded by the analytical technologies available, and the perception that native populations consuming unrefined diets had high fiber intakes is incorrect. It seems likely that they ate relatively little fiber but had high intakes of RS. Population studies have shown a protective effect of apparent RS intake and colorectal cancer risk. The word apparent is pivotal because there is currently no accepted method for RS determination and thus, there are no reliable data on dietary intakes. There are also issues regarding the intakes of dietary fiber and cancer risk. Part of the problem inherent in the study of colonic cancer is that, in contrast to CHD (in which there are easily measurable risk markers such as plasma cholesterol that can be modified by diet), the only indices for colon cancer are not easily measurable ... 

An obvious factor for the inconsistent results of the effect of different intakes of dietary fiber on colorectal cancer is the variation in the analytical methodology used in different studies. There is also increasing evidence that total dietary complex carbohydrates may be as important as fiber. Analysis of stool weight from 20 populations in 12 countries showed that larger stools were correlated with a lower incidence of colon cancer. Intakes of starch and dietary fiber (rather than fiber alone) were the best dietary correlates with stool weight. A subsequent meta-analysis showed that greater consumption of starch (but not of NSPs) was associated with low risk of colorectal cancer in 12 populations. The examination also showed that fat and protein intakes correlated positively with risk. This meta-analysis is probably the first of its kind to... 

Cheng MH, Chiu HF, Ho SC, Tsai SS, Wu TN, Yang CY. Statin use and the risk of colorectal cancer a population-based case-control study. World J. Gastroenterol. 2011 17(47) 5197-5202. 

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