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."
Teens may purchase fewer sugary drinks and more water when faced with easily visible signs stating calories and its physical activity equivalent – jogging for almost an hour – according to a recent study published in the American Journal of Public Health.
Researchers conducted the study at four stores in low-income Black neighborhoods where they collected data among purchasers who appeared aged 12-18. For the test cases, researchers posted one of three signs near the soda and fruit juice: the item's total calories (about 250); the percent of daily calories (about 10 percent); and the amount of activity needed to work off their calories (about 50 minutes of running).
Over the next six months, researchers collected data on 400 beverage sales for each calorie intervention and one control, for a total of 1,600.
The study found that providing any calorie information reduced the odds youths would purchase a sugar-sweetened beverage by 44 percent. Of the three interventions, stating the physical activity equivalent was most effective, reducing the odds teens purchased sugary beverages by almost 50 percent.
Source: Sara N. Bleich, Bradley J. Herring, Desmond D. Flagg, and Tiffany L. Gary-Webb. "Reduction in Purchases of Sugar-Sweetened Beverages Among Low-Income, Black Adolescents After Exposure to Caloric Information." American Journal of Public Health. e-View Ahead of Print.
Coffee drinkers may have a modestly reduced risk of endometrial cancer, finds a new analysis of the literature published last month in the online early edition of the International Journal of Cancer.
The review evaluated all relevant population studies on endometrial cancer and coffee intake, ending with a total of 16 studies from around the world. When taken together, participants who consumed the most coffee had a 29 percent reduced risk of endometrial cancer compared to those who drank the least. Each cup of coffee consumed daily resulted in a 8 percent decrease in risk.
Results varied by geographic region, but all regions showed a protective effect. For example, the Japanese coffee drinkers who drank the most versus least coffee (from three studies) had a 60 percent reduced risk; the Americans/Canadians (five studies) had a 31 percent reduced risk.
In another analysis of the literature on coffee, researchers found that coffee (and tea) had no link to pancreatic cancer. The study, published in Cancer Epidemiology, Biomarkers & Prevention, confirms the findings of AICR's expert report, which judged coffee unlikely to have any effect on the risk of pancreatic – or kidney cancer – the two cancers for which there was enough evidence to make a conclusion.
A new analysis on vitamin D confirms earlier research in finding that there is insufficient evidence to conclude whether vitamin D supplements reduce cancer risk.
The review of research by the U.S. Preventive Services Task Force (USPSTF) also concluded that combined vitamin D and calcium supplementation may reduce fracture risk among some populations.
The USPSTF review of the literature, published in Annals of Internal Medicine, comes about a year after an extensive review of the vitamin D research by the Institute of Medicine (IOM). The USPTF review took 47 studies into account; the IOM report's recommendations examined nearly 1,000 studies.
The review of nearly 50 studies on vitamin D – present in a small number of foods and produced naturally in the skin with sun exposure – by the U.S. Preventive Services Task Force (USPSTF) also indicates that it's too soon to tell if vitamin D supplements can help prevent cancer.
A new laboratory study published in the Journal of Nutritional Biochemistry indicates how resveratrol, a phytochemical found in red grapes and peanuts, may counteract the effects of a carcinogen that appears to play a role in breast cancer.
The study focused on the effects of resveratrol on the expression of BRCA-1, a protein in breast tissue needed for DNA repair. First, the researchers showed that breast cancer cells treated with the toxin did not express BRCA-1. Then the researchers treated the cancer cells with resveratrol before adding the toxin, and the effects on BRCA-1 were reversed.
Resveratrol appears to activate BRCA-1 expression via a protein called AhR for short (the aryl hydrocarbon receptor). Previous research by the scientists suggested that the toxin activated AhR, and it was this protein that suppressed BRCA-1. The current study found that resveratrol-treated cells inactivated AhR, thereby leading to BRCA-1 expression.
Source: Papoutsis AJ, Borg JL, Selmin OI, Romagnolo DF. "BRCA-1 promoter hypermethylation and silencing induced by the aromatic hydrocarbon receptor-ligand TCDD are prevented by resveratrol in MCF-7 Cells." J Nutr Biochem. 2011 Dec 22. [Epub ahead of print]