Lifestyle Changes Could Prevent More Colorectal Cancer Than Screening

Zosia Chustecka

April 10, 2009

April 10, 2009 — Lifestyle changes could prevent more deaths from colorectal cancer than the implementation of screening strategies, according to a study published online April 4 in the European Journal of Cancer Prevention.

Researchers from the United Kingdom predict that "realistic" lifestyle modifications involving diet and exercise would lead to a 26% reduction in the number of cases of colorectal cancer in the British population. This would be expected to produce at least an equivalent decrease in the number of deaths, they add.

"This is considerably greater than what is likely to be achieved by the National Bowel Cancer Screening Program," they note. They previously estimated that this project, which involves 2 yearly screenings with fecal occult blood testing, would reduce colorectal cancer mortality in those screened by 13% to 15% over the next 20 years (J Med Screen. 2008:15:163-174).

An added bonus from the lifestyle-modification approach is that it would also prevent deaths from other causes, including cancers of the breast and upper gastrointestinal tract, cardiovascular diseases, and diabetes, the researchers add.

Mainly Changes in Diet, Plus Moderate Exercise

The predictions were carried out by the Cancer Research UK Center at the Wolfson Institute of Preventive Medicine, in London. A team headed by senior epidemiologist Max Parkin, MD, used results from epidemiologic studies showing the effect of diet on colorectal cancer, and then predicted the effect of lifestyle modifications on the incidence rates using a statistical method known as the Nordpred package (Stat Med 2003; 22;2751-2766).

The lifestyle modifications involved:

  • reducing consumption of red and processed meat to less than 90 g/day

  • increasing consumption of fruit and vegetables to at least 5 portions per day

  • exercising for at least 30 minutes per day on 5 or more days a week, at least at "moderate intensity" (similar to brisk walking)

  • restricting alcohol consumption to 3 units a day for men and 2 units a day for women (where 1 unit is equivalent to half a pint of beer; a single measure of spirits; 1 glass of wine; or a small glass of sherry, port, or something similar).

 

Much of this is in line with diet and exercise advice currently promulgated by the UK Department of Health, the researchers note.

The lifestyle modifications proposed in the paper are "certainly achievable," Dr. Parkin told Medscape Oncology. Proposals such as walking briskly for 30 minutes 5 times a week are "hardly difficult," he continued, "so it is hardly based on achieving miracles."

Dr. Parkin also believes that these lifestyle modifications are "realistic, especially with some energy and commitment from government, civil society, the media, etc, as in the case of tobacco smoking."

This prediction is different from those from other studies that have estimated how much cancer is due to behavior/lifestyle factors and then forecasted what would happen if no-one was overweight or drank alcohol. That sort of prediction is "totally unrealistic," he said.

In the current study, the predictions are based on the assumption that, over several years, members of the population who are in excess of the recommended guidelines with respect to alcohol and red-meat consumption and who do not meet the guidelines with respect to exercise and fruit and vegetable consumption, would modify their lifestyle to be on target — but no more than that, he explained. The model does not assume that people who are already at the recommended levels do any more — "although if they did, the beneficial effects would be bigger," he added.

At present, some of these targets are closer to being achieved than others. The researchers estimate that already 79% of men and 90% of women are within the recommendation for alcohol consumption. However, with exercise, only 30% of men and 26% of women currently achieve the recommended target of 30 minutes 5 times a week.

Obesity Rising Steadily

To achieve the 26% reduction in colorectal cancer, the model assumes that the lifestyle modifications would result in a shift of the weight profile of the population, back to what it was in 1986/87, "when the nation was already quite tubby," Dr. Parkin said.

However, the researchers also envisage another scenario, in which the lifestyle modifications would simply halt the current increasing trend to be overweight, but would not reverse the trend. In this scenario, the reduction in colorectal cancer would be a little lower, but still substantial, with estimated reductions of 28% in men and 14.7% in women (compared with reductions of 35% in men and 18.4% in women if the 1986/87 levels were achieved).

Both of these projections would require a sharp reversal of the steady increase in the weight profile of the population that has been seen over the past few decades, during which obesity has become a problem in the United Kingdom. The researchers cite figures for England that show a sharp rise in the proportion of the population classified as obese — between 1995 and 2004, there was an increase from 15% to 24% for men and from 18% to 24% for women. A health survey conducted in England in 2004 found that 43.9% of all men and 33% of all women were either obese or overweight.

A link between increasing obesity levels and a sharp rise in colorectal cancer in young people was highlighted recently by the British charity Beating Bowel Cancer. Figures released in a parliamentary question showed that the number of people younger than 30 years of age who were diagnosed with colon cancer in England and Wales has more than doubled, with an increase of 117% from 1997 to 2006. The average increase in cases across all age groups and both sexes over the same period was only 7%, the charity noted.

"This is an extraordinary rise in a group of people who virtually never got colon cancer 10 or 20 years ago," said Will Steward, MD, from the Leicester Royal Infirmary, in the United KIngdom. "My colleagues and I have definitely seen an increase in younger patients in recent years, and these worrying figures confirm our impressions. The causes must be examined by the Department of Health, but I suspect that children's changing diets, with increased fatty and high-calorie meals, are fuelling the rise in bowel cancer at such a young age," he said in a statement.

Colorectal cancer is a disease of older people, with an average age of about 72 years, Dr. Steward commented to Medscape Oncology. "We were all very surprised at the magnitude of the increase in younger people, although we suspected it would happen as we have all been seeing younger patients in our clinics."

"I think that the rise in incidence in this young age group must be related to lifestyle choices; it could not be genetic. I strongly suspect that this must be related to changes that have occurred in diet and exercise over the past 30 years or so. The World Cancer Research Fund review has shown that high fat, processed meat, high-energy drinks, fast foods, etc., are all linked to colon cancer risk, and this is just what young people have been eating and drinking. Also, exercise has been reduced . . . and [British] people are getting heavier," Dr. Steward noted.

Dr. Steward agrees with the message about lifestyle changes in the paper by Dr. Parkin and colleagues. "If diet and exercise were improved, there would be a massive reduction in colorectal cancer, as well as in other disease," he said. "It is difficult to change diet and exercise patterns . . . but not impossible," he added. "It needs better public education."

However, he notes, these messages need to be directed at the public by community doctors. "By the time patients see the oncologist, they have colon cancer and it is too late to discuss these factors."

The researchers have disclosed no relevant financial relationships.

Eur J Cancer Prev. Published online before print April 4, 2009. Abstract

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