BÀI VIẾT GỐC CỦA GS IAN OLVER

Alcohol and reducing the risk of colorectal cancer

Professor Ian Olver

Director, Sansom Institute for Health Research

University of South Australia

Although colorectal cancer is common it is estimated that up to two thirds of bowel colorectal cancers could be prevented by lifestyle changes. Modifiable risk factors include being overweight or obese, a high consumption of red meat and especially processed meats, smoking, and alcohol consumption.

The link between alcohol and colorectal cancer is not well publically known but in some populations up to 17% of colorectal cancers have been attributed to drinking alcohol. The risk starts with any alcohol consumption and increases with the amount consumed. It does not matter what type of alcohol, it is the cumulative amount consumed that determines the risk. To show how drinking alcohol increases a man’s risk of colorectal cancer, men in developed countries have a 10% lifetime risk of being diagnosed with colorectal cancer. Just drinking one standard drink (10 gm of alcohol) every day would make that risk 10% higher than that of a man who doesn’t drink.

It can be difficult to separate the impact of weight, diet and exercise of the risk of developing colorectal cancer, however it has been estimated that 11% of colorectal cancers can be attributable to being overweight or obese. This association is greater in men where being obese increases the risk by 50% and does not depend on being obese in younger as compared to older adult life.

The consumption of red meat and processed meats although associated with a small absolute risk of bowel cancer has been definitely linked to the development of colorectal cancer by the International Agency for Research on Cancer. It was estimated that for each 50 gm of processed meat eaten each day, the risk of colon cancer increases by 18%. An ideal diet for reducing colorectal cancer risk would contain a variety of fresh fruit and vegetables with usually five servings of vegetables and two of fruit recommended.

Up to 14% of colon cancers are attributed to doing too little exercise, independent of weight. Exercise will also help reduce obesity. Sixty minutes each day of moderate to intense exercise is recommended reduce the cancer risk. The more exercise you do the more you lower your cancer risk.

Smoking has been linked to 12% of bowel cancers. Smoking would increase an individual man’s risk of bowel cancer by 20% over that of a non-smoker.

Symptoms such as altered bowel habits, blood in the bowel motions or pain in the abdomen with bloating and weight loss should trigger a search for bowel cancer. However, routine screening for bowel cancer before symptoms occur, using a faecal occult blood test (FOBT) which tests for blood in the bowel motions, can detect polyps before they become cancerous or detect very early cancers when they can be cured surgically. If the test is positive a colonoscopy to look for the cause of the bleeding follows. Screening with a FOBT is recommended every second year between the ages of 50 and 74. Younger people can be diagnosed with bowel cancer so people in a high risk group can be tested earlier. Included in this group are people with a strong family history, or genetic diseases such as Lynch Syndrome known to predispose, those with chronic inflammatory bowel disease or those who have a past history of polyps or bowel cancer.

Finally there are emerging trials showing that taking small doses of aspirin each day can reduce the risk of developing bowel cancer, particularly for those people at high risk.

Bibliography

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