Too much time on your behind may increase your risk for breast and colon cancer, scientists say.
A new study linked inactivity and prolonged periods of sitting to new cases of cancer in the United States. The analysis presented by the American Institute for Cancer Research this week cited about 49,000 new cases of breast cancer and about 43,000 new cases of colon cancer per year.
The study, which was also released on the AICR website, also found that a brisk daily walk helps to reduce certain indicators of cancer risk, including sex hormone levels, insulin resistance, inflammation and body fatness.
"These numbers are powerful," Senior Research Epidemiologist Christine Friedenreich, PhD, said in a statement. "The bottom line: For many of the most common cancers, it seems like something as simple as a brisk walk for 30 minutes a day can help reduce cancer risk."
Friedenreich presented results from the Alberta Physical Activity and Breast Cancer Prevention (ALPHA) Trial at the annual AICR conference in Washington, D.C. The trial looked at activity in women and levels of inflammation, a known cancer risk. Friedenreich reported that engaging in moderate activity, like brisk walking, can significantly reduce the risk of certain cancers.
"In breast and colon cancers, for example, we're seeing overall risk reductions of about 25 to 30 percent associated with higher levels of physical activity. With prostate cancer the evidence isn't as strong but it's still there – about 10 to 20 percent lower risk. For endometrial cancer, we are finding about 30 to 35 percent risk reduction with more physical activity,” she said in a statement.
Another study, presented to the conference by Neville Owen of Australia's Baker IDI Heart and Diabetes Institute, showed that sitting for prolonged amounts of time is associated with health risks, even in physically active people.
"Sitting time is emerging as a strong candidate for being a cancer risk factor in its own right. It seems highly likely that the longer you sit, the higher your risk,” Owen said in a statement, regardless of body weight or how much exercise a person gets.
His research also showed that a sedentary lifestyle is common among Americans. One study showed that people spent 60 percent of their waking hours in sedentary activities and 35 percent doing only light activity, such as walking through a grocery store. Office workers spent more than 75 percent of their waking hours in sedentary activities and prolonged sitting.
The American Cancer Society urges Americans to make time for breaks from sitting and inactivity, by taking a walk, lifting light hand weights or standing when talking on the phone.
Charles Matthews, an epidemiologist at the National Cancer Institute suggested ways to take breaks at home.
“For instance, you can take the time to stand and prepare a meal from scratch rather than buying fully prepared or convenience foods. Other easy ways to increase activity is to do other things while watching TV, like standing and sorting laundry. Get up during commercials and take a walk around the house,” he said at the conference.
"Taken together, this research suggests that every day, we're each given numerous opportunities to be active and protect ourselves from cancer, not one," said AICR spokesperson Dr. Alice Bender in a statement. "We need to start thinking in terms of make time and break time."