How Sitting and Moving Link to Cancer Risk
Research already shows that moderate daily physical activity reduces the risk of several cancers. But at the recent AICR annual research conference, one of the highlighted areas of interest was the emerging findings on how everyday activities – independent of moderate physical activity – may help reduce cancer risk.
Here's what the latest research suggests.
Growing Evidence on Physical Activity Reducing Cancer Risk: As many as 49,000 cases of breast cancer and 43,000 cases of colon cancer occurring in the United States every year are linked to a lack of physical activity, according to new estimates presented at the conference by Christine Friedenreich, PhD, Senior Research Epidemiologist at Alberta Health Services-Cancer Care in Canada and one of the leading experts in the field of physical activity and cancer.
AICR's expert report and its continuous updates concluded that regular physical activity reduces the risk of colerectum, breast, and kidney, but these new estimates point to slightly higher decreases in risk.
"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…. "These numbers are powerful," she said. "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."
Growing Evidence on Physical Activity Reducing Cancer Risk: Findings from Dr. Friedenreich's research are providing clues as to why activity may reduce cancer risk. The latest results from her Alberta Physical Activity and Breast Cancer Prevention (ALPHA) Trial involve C-reactive protein, a marker of inflammation linked to cancer risk.
In a study appearing in this month's issue of the journal Cancer Prevention Research, moderate to vigorous daily activity reduced C-reactive protein levels among post-menopausal women. Previous studies have shown that the immune cells activated by the inflammatory response, such as macrophages and neutrophils, release reactive elements like oxygen and nitrogen that can damage DNA
"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."
Sitting Too Much Can Hurt Health: New findings from the emerging field of sedentary behavior research presented at the conference suggest that sitting for long periods of time can increase some of the same indicators of cancer risk related to exercise.
"Sitting time is emerging as a strong candidate for being a cancer risk factor in its own right," Neville Owen, PhD, Head of Behavioral Epidemiology at Australia's Baker IDI Heart and Diabetes Institute. "It seems highly likely that the longer you sit, the higher your risk. This phenomenon isn't dependent on body weight or how much exercise people do," said Dr. Owen.
"In our studies, we've measured waist circumference, insulin resistance and inflammation indicators of cancer risk common to many physical activity-cancer studies. We found that even breaks as short as one minute can lower these biomarkers," said Dr. Owen.
Sedentary time is also likely an important factor for cancer survivors, said Dr. Owen. For survivors, diabetes and cardiovascular disease are particular concerns and overweight and obesity increases the risk for both conditions. "Television viewing time, a sign of sedentary behavior, appears to increase subsequent risk of weight gain in cancer survivors."