The Collison Newsletter June 2012

 

                    COLORECTAL CANCER*

LIFESTYLE and RISK    FIGHTING CANCER with LIFESTYLE  

Colon, or colorectal, cancer is cancer that starts in the large intestine (colon) or the rectum (end of the colon). It is commonly referred to as 'bowel cancer'. Other types of malignancy (cancer) can affect the colon. These include lymphoma, carcinoid tumours, melanoma and sarcoma. These are rare and, in this newsletter, the use of the term "colon cancer or colorectal cancer" does not refer to these malignancies.

 

Colorectal cancer is predominantly a disease of Westernized countries, indicating that components of Western lifestyle may contribute to risk.

 

Colorectal cancer is the second most common cancer in both men and women in Australia when non-melanoma skin cancer is excluded. Eighty percent of cases have no known hereditary genetic associations.

 

In Australia, there are more than 14,000 new cases each year. The risk of being diagnosed with colon cancer by age 85 is 1 in 10 for men and 1 in 14 for women. In 2007, there were 4,047 deaths from colorectal cancer (Cancer Council of Australia).

 

The American Cancer Society says that colorectal cancers are one of the leading causes of cancer-related deaths in the United States.

 

Almost all colon cancer starts in the glands in the lining of the colon and rectum. Nearly all colon cancers begin as non-malignant or non-cancerous (benign) polyps, which slowly develop into cancer. There is no single cause of colon cancer.

Risk Factors 

There is a higher risk of colorectal cancer if you:

  • Are 60 years of age or older 
  • Have colorectal polyps 
  • Have inflammatory bowel disease such as ulcerative colitis 
  • Have a family history of colon cancer 
  • Eat a diet high in red meats and processed meats 
  • Are African American or eastern European descent 
  • Eat a diet that is high in fat and low in fibre 
  • Smoke tobacco 
  • Drink excess alcohol 
  • Have little physical activity and low exercise. 

Symptoms of Colorectal Cancer 

Symptoms of colorectal cancer include:

  • Change in bowel habit with diarrhoea, constipation or the feeling of incomplete emptying 
  • Blood in the faeces 
  • Abnormal bloating or cramping 
  • Pain and tenderness in the lower abdomen
  • Thin, ribbon-like faeces. 

More general symptoms include:

  • Weight loss 
  • Tiredness and fatigue 
  • Unexplained anaemia. 

Diagnosis 

The diagnosis is made by colonoscopy.

Screening for Colorectal Cancer 

With proper screening, colon cancer may be able to be detected before symptoms develop.

 

Screening includes:

  • Physical examination with palpating of the abdomen when a lump may be felt (rarely). 
  • Rectal examination. This will only detect rectal cancer, not cancer in the colon. 
  • Faecal occult blood test. This may detect small amounts of blood in the faeces, which could suggest colon cancer. This test may be negative in patients with colon cancer. 
  • Colonoscopy and sigmoidoscopy. Polyps can be detected and treated (removed) before cancer develops. 

The earlier the diagnosis, the better the outcome.

Treatment 

At diagnosis, the cancer can by 'staged'. Stage 0 is very early cancer with stages up to stage IV, where the cancer has spread beyond the colon to other organs.

 

The orthodox treatment depends partly on the stage of the cancer. In general, treatments may include (and they will not be discussed further in this newsletter):

  • Surgery, most often colonectomy (removal of part of the colon), to remove the cancer cells 
  • Chemotherapy, aiming to kill the cancer cells 
  • Radiation therapy, to destroy cancerous tissue. 

Prognosis 

Colorectal cancer, in many cases, is a treatable disease. If it is diagnosed early, treatment may result in a cure.

 

It is much better to prevent colorectal cancer. Is this possible?

  

PREVENTING COLORECTAL CANCER 

When the risk factors are considered, there are a number that cannot be changed. Age, race and genetics are facts.

 

Polyps if shown to be present should be removed, preferably at the time of diagnosis.

 

Diseases like ulcerative colitis should be treated energetically.

 

Smoking should be stopped, and alcohol restricted.

 

Diet is another important aspect of lifestyle that can be changed. From the risk factors listed, an appropriate diet for the prevention of colorectal cancer would appear to be one which is low-fat, high-fibre and low in animal products, especially the red meats. Correct diet becomes increasingly important if you are over 60 years old, have a positive family history, or are of one of the races at greater risk.

 

The ‘game’ of Russian roulette involves having one bullet in the revolver, spinning the cylinder, putting the muzzle against the head, pulling the trigger ...  and hoping! The best way not to put a bullet into the head is .... not to pull the trigger. Age, genetics etc are like the bullet in the revolver. How do you not pull the trigger? The following study looked at five lifestyle factors and their link to colorectal cancer and its prevention.

A Study Assessing Lifestyle and Risk 

This study was published in the British Medical Journal, October 2010 (BMJ 2010; 341:c5504). The title was Association of adherence to lifestyle recommendations and risk of colorectal cancer: a prospective Danish cohort study.

 

The objective of the study was "to evaluate the association between a simple lifestyle index based on the recommendations of five lifestyle factors and the incidence of colorectal cancer, and to estimate the proportion of colorectal cancer cases attributable to lack of adherence to the recommendation".

 

It was a prospective cohort study with the subjects from the general population of Copenhagen and Aarhus, Denmark. 55,487 men and women aged 50-64 years at baseline (1993-1997), not previously diagnosed with cancer, took part in the study.

 

The lifestyle index was based on the following five lifestyle factors:

  • Physical activity 
  • Waist circumference 
  • Smoking 
  • Alcohol intake 
  • Diet (dietary fibre, energy percentage from fat, red and processed meat, and fruits and vegetables). 

This lifestyle index resulted from known risk factors for colorectal cancer and recommendations of the World Health Organization and the World Cancer Research Fund.  Participants scored one point for each of the following recommendations they met at baseline:

  • Physically active at least 30 minutes a day, or had a job with light manual activity, or heavy manual activity 
  • Waist circumference of 88 cm or less for women and 102 cm or less for men 
  • Not smoking 
  • Alcohol intake of 7 or less standard drinks per week for women and 14 or less standard drinks per day for men 
  • Consumed a healthy diet. 

This fifth lifestyle factor, diet, was based on a dietary index including four recommendations: 

  • a minimum of 600 grams of fruit and vegetables a day 
  • less than 500 grams of red meats and processed meats per week 
  • more than 3 grams of dietary fibre per MJ of dietary energy 
  • less than 30% of the total energy from fat. 

These four would reflect a healthy dietary pattern. Study participants who followed all four dietary recommendations received one point for the dietary factor in the lifestyle index. 

The results: "During a median follow-up of 9.9 years, 678 men and women had colorectal cancer diagnosed. After adjustment for potential confounders, each additional point achieved on the lifestyle index, corresponding to one additional recommendation that was met, was associated with a lower risk of colorectal cancer. In this population an estimated total of 13% of the colorectal cancer cases were attributable to lack of adherence to merely one additional recommendation among all participants except the healthiest. If all participants had followed the five recommendations 23% of the colorectal cancer cases might have been prevented."

 

In conclusion, the authors (Helene Kirkegaard et al) state:  "Adherence to the recommendations for physical activity, waist circumference, smoking, alcohol intake, and diet may reduce colorectal cancer risk considerably."

Comments 

Cancer can, to a significant extent, be prevented or at least protected against.

 

Prevention is like not pulling the trigger in the example given above. The study showed clearly that adherence to the five controllable lifestyle patterns can reduce risk of colorectal cancer, a deadly disease.

 

The lifestyle index used in the above study is very similar to the recommendations in the 537 page report of the massive meta-analysis of the causes of cancer by the World Cancer Research Fund (WCRF) International, in collaboration with the American Institute for Cancer Research (AICR), that were reproduced in my March 2008 newsletter Prevention of Cancer. Food, Nutrition, Physical Activity and the Prevention of Cancer. In brief summary it was recommended that, to prevent cancer, we should be thin (body mass index of 20 or less - this is closely linked to the waist circumference in the above study), we should exercise, and from a dietary point of view, we should consume little in the way of animal products, avoid all processed and refined foods, especially meats, eat liberal amounts of fruits and vegetables, and limit alcohol intake. The link between smoking and lung cancer is clear cut and well known and accepted. Smoking as a contributing factor to colorectal cancer is a new addition to the adverse effects of this habit.

 

These recommendations were again summarized and set out in my January 2011 newsletter Preventing Cancer – Global Report Recommendations.

 

It is recommended that the above two newsletters be read in conjunction with this present one.

Finally, the last recommendation by the committee who did the meta-analysis looking at the prevention of cancer was what to do if you have cancer. The simple answer was to follow all the recommendations already set out in their report. 

 

*Copyright 2012: The Huntly Centre.

Disclaimer: All material in the huntlycentre.com.au website is provided for informational or educational purposes only. Consult a health professional regarding the applicability of any opinions or recommendations expressed herein, with respect to your symptoms or medical condition.

 

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