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Lifestyle and Reducing Your Risk of Bowel Cancer


Lifestyle Risk factors – how to reduce your risk of bowel cancer?

Risk factors other than family history can play a more important role in the development of bowel cancer.  The main risk factor for bowel cancer is increasing age. Only 7% of bowel cancer occurs before the age of 50 years.  However, even if you have a family history or other genetic risk of bowel cancer, this risk can be reduced by leading a healthy lifestyle.   This kind of healthy lifestyle can also reduce your risk of heart disease, stroke and other cancers.  It has been recently estimated that approximately 70% of colorectal cancer could be avoided by changes in lifestyle in Western countries.

A good further source of information about dietary and other lifestyle related risk factors is available from Cancer Research UK at http://www.cancerresearchuk.org/cancer-info/cancerstats/types/bowel/riskfactors/bowel-cancer-risk-factors

Diet 

Summary: A diet high in red meat and animal fat and low in fruit and vegetables increases your risk of bowel cancer.  So if you want to reduce your risk of bowel cancer, whether or not you have a genetic risk, eat 5 pieces of fruit or vegetables daily, plenty of fibre, and don’t eat too much processed or red meat.

Dietary Fibre

Putative anti-carcinogenic mechanisms of dietary fibre within the bowel include: the formation of short-chain fatty acids from fermentation by colonic bacteria; the reduction of secondary bile acid production; the reduction in intestinal transit time and increase of faecal bulk; and a reduction in insulin resistance. In the European Prospective Investigation into Cancer and Nutrition (EPIC) study after an average 6.2 years of follow-up, and 1,721 colorectal cancer cases, a 21% reduced risk amongst participants in the highest intake quintile was observed when compared against the lowest intake group. These results support our previous conclusion, of the potential of reducing colorectal cancer incidence by increasing fibre intake from cereal, fruit, and vegetable food sources.

Figure 5.2: The number of portions of fruit and vegetables eaten per day by adults aged 16 and over, England, 2009
Red and processed meat

In the EPIC study high intake of red or processed meat may increase risk by 71%.  The mechanisms underlying the association between colorectal cancer risk and high intake of red and processed meat are uncertain. Controlled human intervention studies have raised the possibility that the endogenous nitrosation that arises from ingestion of heme iron but not of inorganic iron or protein may account for the increased risk associated with red and processed meat consumption.  Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAH) in diet may pose a potential risk of cancer to humans, depending on the extent to which the compounds are activated in vivo by metabolic enzymes. HCAs are formed as a byproduct of reactions during the cooking of meat, poultry, and fish at high temperatures, such as pan-frying or grilling with charcoal or on a gas grill; PAHs are formed in grilled and barbecued meat and in cured, processed foods. It has been suggested that processed meat intake has a stronger association with colorectal cancer than red meat intake.

Folate and selenium

Ball-and-stick model of the folic acid molecul...

Ball-and-stick model of the folic acid molecule, a B vitamin and an important compound in cell division. This image shows it as an anion (folate). Colour code (click to show) : Black: Carbon, C : White: Hydrogen, H : Red: Oxygen, O : Blue: Nitrogen, N (Photo credit: Wikipedia)

Folate (a water-soluble B vitamin) appears to protect against bowel cancer, but it remains unclear whether the same level of benefit is derived from dietary folate (from food, particularly fruit and vegetables) and synthetic folate (folic acid supplements).  Selenium can be obtained in food (particularly brazil nuts) and supplements; evidence for its effect on bowel cancer risk is mixed. The WCRF/AICR 2010 Report concluded that “Evidence for foods containing folate… and selenium… is less consistent and no conclusion could be drawn”.

Some experts have proposed that folate plays a dual role in bowel cancer in which moderate dietary intake before development of pre-cancerous adenomas reduces risk of adenoma development, but increased folate intake once adenomas have developed increases risk of cancer. Data from interventional studies indicate that folate supplementation decreases colonic mucosal cell proliferation .  A large prospective study showing a 31% reduction in bowel cancer risk for people with the highest overall folate intake 12-16 years before diagnosis, but no effect of intakes in the more recent past.

The US Government was sufficiently convinced of the health benefits (and absence of risk) from folic acid that it introduced mandatory folic acid fortification of grain products in 1997, and a recent large cohort study found that 8.5 years on, higher total folate intake (including intake specifically from supplements) was associated with a decreased bowel cancer risk.  There is some evidence that it is better to take folic acid in its natural form rather than as supplements i.e. tablets.

A 2011 meta analysis found men with the highest concentrations of selenium in the blood had 32% lower bowel cancer risk compared with men with the lowest concentrations, but found no association between selenium level and bowel cancer risk in women.3A 2004 pooled analysis found a similar level of risk reduction for both sexes combined.

Body weight and Obesity

Body mass index (BMI) values

Body mass index (BMI) values (Photo credit: Wikipedia)

Obesity is associated with an increased risk of colon cancer, particularly for men. Meta analyses show the risk of colon cancer increases by an estimated 24-30% per 5kg/m2 increase in body mass index (BMI) for men. In comparison to healthy-weight men (BMI less than 25 kg/m2), overweight men (BMI 25-29.9kg/m2) have a 23% higher risk of colon cancer, and obese men (BMI 30kg/m2 or more) have a 53% higher risk. The association is weaker in women, with colon cancer risk increasing by 9-12% per 5kg/m2 BMI increase, and the association proving non-significant in one meta analysis.

Larger waist size has been associated with increases in colon cancer risk in men (33% risk increase per 10cm waist circumference increase) and women (16% risk increase per 10cm waist circumference increase), as has increasing waist-to-hip ratio in both men (43% risk increase per 0.1-unit increase in ratio) and women (20% risk increase per 0.1 unit increase in ratio).

Higher BMI is linked less strongly to higher rectal cancer risk: a 5kg/m2 BMI increase is associated with a 9-12% higher rectal cancer risk for men (obese men have a 27% higher rectal cancer risk than healthy-weight men), but with no effect on rectal cancer risk in women

Regular exercise

Regular physical activity can reduce your risk of bowel cancer, this is clearly shown in many studies.  We would recommend 2-3 30 minute sessions per week of dedicated exercise (rather than more ‘passive’ exercise such as being busy at work!).

The relationship between physical activity and a reduced risk is one of the most consistent findings in epidemiologic literature.

Other risk factors

Not smoking and drinking less than the upper recommended limit of normal (less than 21 units for men and less than 14 units for women) may also be helpful in reducing risk.

 

Poor people are at a higher risk of colorectal cancer


 

Journal of the National Cancer Institute

Journal of the National Cancer Institute (Photo credit: Wikipedia)

http://m.jnci.oxfordjournals.org/content/early/2012/09/03/jnci.djs346.abstract

September 5, 2012 — People with a relatively low socioeconomic status account for a disproportionate number of colorectal cancers in the United States. Now, for the first time, a large prospective, observational study has shed light on the degree to which behavior and body mass contribute to this disparity.

Over one third of the excess risk…could be explained by differences in…behavioral risk factors.

“This study showed that over one third of the excess risk of invasive adenocarcinoma of the colon and rectum resulting from low [socioeconomic status] could be explained by differences in…behavioral risk factors, particularly in an unhealthy diet,” conclude the authors, led by Chyke A. Doubeni, MD, MPH, from the Department of Family Medicine and Community Health at the University of Pennsylvania Perelman School of Medicine in Philadelphia.

In addition to diet, Dr. Doubeni and colleagues found that physical inactivity, smoking, and being overweight are likely contributors to this risk.

In their study, published online September 5 in the Journal of the National Cancer Institute, the authors looked at health behaviors, obesity, and colorectal cancer risk among Americans of all socioeconomic statuses.

They used the National Institutes of Health-AARP Diet and Health Study as their data source. Specifically, they looked at middle-aged and elderly people from 6 states (California, Florida, Louisiana, New Jersey, North Carolina, and Pennsylvania) and 2 metropolitan areas (Atlanta, Georgia and Detroit, Michigan). All of the participants enrolled in the study in 1995/96 and were followed through 2006. Health behaviors of the participants were determined using questionnaires.

Of the 506,488 study participants, 7676 developed colorectal cancer during the 10-year follow-up period.

How Class and Behavior/Body Mass Are Related

The authors evaluated the socioeconomic status of the participants in 2 ways: by census-tract data, which revealed “neighborhood socioeconomic status,” and by self-reported educational level (less than high school vs high school and more than high school).

On the basis of data from other studies on colorectal cancer and behavior, Dr. Doubeni and his team used statistical modeling to estimate the likely percentage of colorectal cancers mediated by behavioral risk factors.

They found that differences in socioeconomic status in the reported levels of physical inactivity, unhealthy diet, smoking, and unhealthy weight each explained between 11.3% and 21.6% of the association between education and risk for colorectal cancer, and between 8.6% and 15.3% of the association between neighborhood status and risk for colorectal cancer. Diet was found to have the biggest impact of all the health behaviors.

Overall, the combination of health behaviors and body mass index (BMI) explained approximately 43.9% (95% confidence interval [CI], 35.1% to 57.9%) of the association between risk for colorectal cancer and education and 36.2% (95% CI, 28.0% to 51.2%) of the association between the risk and neighborhood socioeconomic status.

In short, somewhere between one third and nearly one half of colorectal cancers among either low-income or less-than-high-school-educated Americans might be attributable to obesity and unhealthy behaviors.

However, a pair of experts not involved with the study do not find these results to be a cause for despair.

Instead, the study “demonstrates the intricate interplay” of socioeconomic and behavioral factors affecting colorectal cancer risk, write John Z. Ayanian, MD, and John M. Carethers, MD, in an accompanying editorial. Dr. Ayanian is from the Department of Health Care Policy at Harvard Medical School in Boston, Massachusetts, and Dr. Carethers is from the Department of Internal Medicine at the University of Michigan in Ann Arbor.

Public health practitioners can learn from these results, they believe. The study “underscores the need for more effective public health strategies to improve nutrition and physical activity in the United States and thereby curb the rising tide of obesity, particularly for those with less education and in disadvantaged communities,” the editorialists write.

Colon Cancer by Location

The study accounted for the anatomic location of the participants’ cancers (proximal colon, distal colon, or rectum), which resulted in one of the study’s “key findings,” according to the editorialists.

The health behaviors and BMI explained 95% of the association between education and the incidence of proximal colon cancer, but only 38% of the association between education and distal cancer and 24% of that between education and rectal cancer, Dr. Ayanian and Dr. Carethers point out.

That is a dramatic difference, they note. However, the editorialists think that these contrasting results for proximal and more distal cancers might “reflect the impact of an important omitted variable — colorectal cancer screening by socioeconomic status.”

Colorectal cancer screening has been shown to be more effective in reducing cancer incidence and mortality in the distal colon and rectum than in the proximal colon, the editorialists explain. Thus, this finding might have an easy explanation, they note.

“Because adults who are less educated and from less affluent communities are less likely to be screened, the greater effectiveness of screening for distal colorectal cancer may explain why socioeconomic gradients were much steeper for these anatomic sites than for proximal cancer,” they write.

The study was funded in part by the National Cancer Institute. The study authors and editorialists have disclosed no relevant financial relationships.

Logo of the United States National Cancer Inst...

Logo of the United States National Cancer Institute, part of the National Institutes of Health. (Photo credit: Wikipedia)

J Natl Cancer Inst. Published online September 5, 2012. Abstract, Editorial

 

Lifestyle and Reducing your Risk


 

Lifestyle Risk factors – how to reduce your risk of bowel cancer?

Risk factors other than family history can play a more important role in the development of bowel cancer.  The main risk factor for bowel cancer is increasing age. Only 7% of bowel cancer occurs before the age of 50 years.  However, even if you have a family history or other genetic risk of bowel cancer, this risk can be reduced by leading a healthy lifestyle.   This kind of healthy lifestyle can also reduce your risk of heart disease, stroke and other cancers.  It has been recently estimated that approximately 70% of colorectal cancer could be avoided by changes in lifestyle in Western countries.

A good further source of information about dietary and other lifestyle related risk factors is available from Cancer Research UK at http://www.cancerresearchuk.org/cancer-info/cancerstats/types/bowel/riskfactors/bowel-cancer-risk-factors

Diet 

Summary: A diet high in red meat and animal fat and low in fruit and vegetables increases your risk of bowel cancer.  So if you want to reduce your risk of bowel cancer, whether or not you have a genetic risk, eat 5 pieces of fruit or vegetables daily, plenty of fibre, and don’t eat too much processed or red meat.

Dietary Fibre

Putative anti-carcinogenic mechanisms of dietary fibre within the bowel include: the formation of short-chain fatty acids from fermentation by colonic bacteria; the reduction of secondary bile acid production; the reduction in intestinal transit time and increase of faecal bulk; and a reduction in insulin resistance. In the European Prospective Investigation into Cancer and Nutrition (EPIC) study after an average 6.2 years of follow-up, and 1,721 colorectal cancer cases, a 21% reduced risk amongst participants in the highest intake quintile was observed when compared against the lowest intake group. These results support our previous conclusion, of the potential of reducing colorectal cancer incidence by increasing fibre intake from cereal, fruit, and vegetable food sources.

Figure 5.2: The number of portions of fruit and vegetables eaten per day by adults aged 16 and over, England, 2009
Red and processed meat

In the EPIC study high intake of red or processed meat may increase risk by 71%.  The mechanisms underlying the association between colorectal cancer risk and high intake of red and processed meat are uncertain. Controlled human intervention studies have raised the possibility that the endogenous nitrosation that arises from ingestion of heme iron but not of inorganic iron or protein may account for the increased risk associated with red and processed meat consumption.  Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAH) in diet may pose a potential risk of cancer to humans, depending on the extent to which the compounds are activated in vivo by metabolic enzymes. HCAs are formed as a byproduct of reactions during the cooking of meat, poultry, and fish at high temperatures, such as pan-frying or grilling with charcoal or on a gas grill; PAHs are formed in grilled and barbecued meat and in cured, processed foods. It has been suggested that processed meat intake has a stronger association with colorectal cancer than red meat intake.

Folate and selenium

Ball-and-stick model of the folic acid molecul...

Ball-and-stick model of the folic acid molecule, a B vitamin and an important compound in cell division. This image shows it as an anion (folate). Colour code (click to show) : Black: Carbon, C : White: Hydrogen, H : Red: Oxygen, O : Blue: Nitrogen, N (Photo credit: Wikipedia)

Folate (a water-soluble B vitamin) appears to protect against bowel cancer, but it remains unclear whether the same level of benefit is derived from dietary folate (from food, particularly fruit and vegetables) and synthetic folate (folic acid supplements).  Selenium can be obtained in food (particularly brazil nuts) and supplements; evidence for its effect on bowel cancer risk is mixed. The WCRF/AICR 2010 Report concluded that “Evidence for foods containing folate… and selenium… is less consistent and no conclusion could be drawn”.

Some experts have proposed that folate plays a dual role in bowel cancer in which moderate dietary intake before development of pre-cancerous adenomas reduces risk of adenoma development, but increased folate intake once adenomas have developed increases risk of cancer. Data from interventional studies indicate that folate supplementation decreases colonic mucosal cell proliferation .  A large prospective study showing a 31% reduction in bowel cancer risk for people with the highest overall folate intake 12-16 years before diagnosis, but no effect of intakes in the more recent past.

The US Government was sufficiently convinced of the health benefits (and absence of risk) from folic acid that it introduced mandatory folic acid fortification of grain products in 1997, and a recent large cohort study found that 8.5 years on, higher total folate intake (including intake specifically from supplements) was associated with a decreased bowel cancer risk.  There is some evidence that it is better to take folic acid in its natural form rather than as supplements i.e. tablets.

A 2011 meta analysis found men with the highest concentrations of selenium in the blood had 32% lower bowel cancer risk compared with men with the lowest concentrations, but found no association between selenium level and bowel cancer risk in women.3A 2004 pooled analysis found a similar level of risk reduction for both sexes combined.

Body weight and Obesity

Body mass index (BMI) values

Body mass index (BMI) values (Photo credit: Wikipedia)

Obesity is associated with an increased risk of colon cancer, particularly for men. Meta analyses show the risk of colon cancer increases by an estimated 24-30% per 5kg/m2 increase in body mass index (BMI) for men. In comparison to healthy-weight men (BMI less than 25 kg/m2), overweight men (BMI 25-29.9kg/m2) have a 23% higher risk of colon cancer, and obese men (BMI 30kg/m2 or more) have a 53% higher risk. The association is weaker in women, with colon cancer risk increasing by 9-12% per 5kg/m2 BMI increase, and the association proving non-significant in one meta analysis.

Larger waist size has been associated with increases in colon cancer risk in men (33% risk increase per 10cm waist circumference increase) and women (16% risk increase per 10cm waist circumference increase), as has increasing waist-to-hip ratio in both men (43% risk increase per 0.1-unit increase in ratio) and women (20% risk increase per 0.1 unit increase in ratio).

Higher BMI is linked less strongly to higher rectal cancer risk: a 5kg/m2 BMI increase is associated with a 9-12% higher rectal cancer risk for men (obese men have a 27% higher rectal cancer risk than healthy-weight men), but with no effect on rectal cancer risk in women

Regular exercise

Regular physical activity can reduce your risk of bowel cancer, this is clearly shown in many studies.  We would recommend 2-3 30 minute sessions per week of dedicated exercise (rather than more ‘passive’ exercise such as being busy at work!).

The relationship between physical activity and a reduced risk is one of the most consistent findings in epidemiologic literature.

Other risk factors

Not smoking and drinking less than the upper recommended limit of normal (less than 21 units for men and less than 14 units for women) may also be helpful.

 

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