Don’t Sit and Stay Active to Reduce Cancer Risk

November 12, 2012

Don’t Sit and Stay Active to Reduce Cancer Risk

A recent report has indicated that sitting too long may increase the risk of developing cancer. The report was presented to the American Institute for Cancer Research annual conference in Washington, D.C. along with a prediction that if people were more active then about 100,000 cases of breast and colon cancer could be avoided annually in the United States.

The report was presented at a news conference by Neville Owen, PhD, of Australia’s Baker Heart and Diabetes Institute, and he says, “It seems highly likely that the longer you sit, the higher your risk”.

It has been known for a long time now that regular exercise reduces the risk of developing some cancers, along with other diseases but now experts are telling us that sitting for too long also carries an increased risk. They propose a new way forward, keep doing the exercise but in addition do not spend a long time in a sitting position.

Christine Friedenreich, PhD, is a research scientist and epidemiologist at Alberta Health Services in Canada and was involved with the study. She says the link between being sedentary and an increased risk of cancer is established but this new report links prolonged sitting to an increased risk of some cancers too.

The way forward according to Alice Bender, RD, a dietitian for the American Institute for Cancer Research, who was also at the news conference, is to find time to exercise whilst avoiding sitting for too long. She says, “We’d like Americans to think about physical activity in a different way”.

She proposes that people should be more aware of the need to find time to exercise or do an activity. She puts it as, “We would like people to think about ‘make time’ and ‘break time’ and that equals cancer protection”.

People who sit for most of their day are now being recommended by the American Institute for Cancer Research to take an activity break every hour.

Avoid Sitting Too Long to Minimize Cancer Risk

According to Owen, irrespective of body weight or the amount of exercise being taken, “Sitting time is emerging as a strong candidate for being a cancer risk factor in its own right”. In his research he identified that taking even short one or two minute breaks from sitting reduced the cancer risk. He studied markers known to increase risks of cancer and heart disease such as inflammation and waist circumference to reach these findings. The findings were part of the study which is published in the European Heart Journal.

The report investigated the association between reduced cancer risk and physical exercise in more than 200 separate studies. The researchers say, “We can now say there is convincing evidence that activity reduces the risk of colon and breast cancer and probably endometrial”. Although the researchers accept that the effectiveness of physical activity in reducing the risk of developing lung, ovarian or prostrate cancer requires further study and presently the evidence is weak.

The studies showed that compared to the least active people, the others who exercised the most reduced their risk of developing colon cancer by between 30% and 35%. This figure matched the findings relating to endometrial cancer too. When investigating breast cancer, studies indicated that the risk reduction was between 20% and 30% when comparing most active against least active.

The earlier studies being investigated did have one area of ambiguity. The actual figures, in time or calories used, were not stated for each grouping. For example what most active means in terms of how many minutes doing what exercise is unclear. However the researchers are addressing this point in studies presently being carried out.

The SEER Program (Surveillance, Epidemiology and End Results) database of the National Cancer Institute was used as the source of data for the study and it reported that 141,210 colon cancers and 230,480 breast cancers were reported for 2011. The researchers estimated that if physical activity had taken place more frequently then about 30% of the colon cancers and 21% of the breast cancers could have been prevented. That works out at 43,000 colon cancer cases and 49,000 breast cancer cases.

In the course of her work, Friedenreich identified that women who started to exercise did not have as much C-reactive protein in their bodies as sedentary women. C-reactive protein is an indicator of inflammation and may indicate the risk of developing cancer. She conducted her research, which lasted a year, by splitting the women into two groups in a random manner. The 320 women were all aged between 50 and 74 and one half did not exercise but the other half exercised five days every week for at least 45 minutes per day.

The study is published in Cancer Prevention Research.

Other Research

In another study, published in the American Journal of Epidemiology in 2010 the effects of ‘sitting time’ and the increased risk of dying was investigated. The study involved Leslie Bernstein, PhD, professor and director of the division of cancer etiology at the City of Hope Comprehensive Cancer Center, Duarte, California.

She says that exercise is a good way to minimize the risks of developing cancer and generally reducing health risks, but she also makes us aware that sitting time has an affect on these risks.

Alpa Patel, PhD, an epidemiologist with the American Cancer Society was lead researcher on the study which found that the likelihood of dying depended on how long someone spent sitting. The study had a 14-year follow-up period and it was found that those who spent six or more hours a day sitting had an increased risk of death when compared to those who sat for less than three hours. The risk for the different sexes was not equal, it was 37% higher for women who sat for six or more hours and the men had an 18% increase.

The link between increased risk of dying and the number of hours sitting has caused the experts to re-evaluate the advice that they give. Previously it was all about exercise, but now as well as exercise the message is to remain active too when you are not doing exercise and avoid extended periods of time sitting. Heart disease was the highest cause of death noted.

How to Avoid Sitting

Many people work in jobs where the majority of the day the work is done sitting down, but experts give some tips to avoid excessive time sitting. Some of the tips include walking while talking. If a colleague wishes to talk through a problem then walk as you talk. Whenever you are on the phone, stand up and move around as much as possible and finally about once every hour just get up and take a short walk.

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