The role of activity in preventing cancer isn't all about going to the gym, says Christine Friedenreich, PhD, Senior Research Epidemiologist at Alberta Health Services-Cancer Care in Canada. Friedenreich, one of the leading experts in the field of physical activity and cancer, explains how activity throughout life may help in prevention and survivorship.
Q: You were one of the early researchers looking at physical activity and cancer risk: how did you become interested in the area?
A: I had done a lot of work on diet and breast cancer risk and I had also worked on smoking. When I came to Calgary, I wanted to stay with the theme of modifiable lifestyle factors and physical activity was a logical transition. We've known for a long time that physical activity reduced the risk for chronic diseases but the literature on cancer was nascent. I started to look at physical activity and breast cancer.
Q: What has your research shown overall?
A: We have found that physical activity reduces the risk of colon, breast and endometrial cancers by 25 to 30 percent. And it reduces prostate, lung and ovarian cancers by about 10 to 30 percent. We see benefits from both moderate and vigorous activity. Cancer risk is reduced more with lifelong activity, but even late life activity is beneficial. The take home message is that it's never too late to start and you can benefit from doing moderate activity, such as brisk walking.
Q: Are you also looking at the mechanisms?
A: We published a paper in 2009 where we proposed a biological model to explain how physical activity influences the risk of postmenopausal breast cancer. The main pathways are through an effect on body fat, sex steroid hormones, chronic inflammation and insulin resistance. What we're doing now is putting healthy post-menopausal women on an exercise program and seeing how it influences biomarkers.
"[W]e had one group of women exercising 225 minutes per week and the control group not asked to do any activity. After a year, we found that exercise had a strong effect on body fat, endogenous estrogens, insulin resistance and inflammation.
Our first trial – the ALPHA Trial – had one group of women exercising 225 minutes per week and the control group not asked to do any activity. After a year, we found that exercise had a strong effect on body fat, endogenous estrogens, insulin resistance and inflammation. Now, in the BETA Trial, every woman is getting randomized to 150 or 300 minutes per week and we're looking at what has the most effect on these biomarkers.
Q: Have you looked at the role of exercise post-diagnoses?
A: Yes, we're doing studies of cancer patients – putting them on exercise trials and seeing how that helps with their coping and rehabilitation, their quality of life and their survival after cancer.
Q: The session you're co-chairing for the AICR conference features sedentary behavior. Why did you want to include this?
A: Now there's a big focus on sedentary behavior as a separate entity from physical activity. The research started in the areas of cardiovascular disease and diabetes. Now the research is also in cancer risk and survival. We are examining how being inactive by sitting or lying down too much is related to cancer risk. There is also research examining the biologic mechanisms that explain how sedentary behavior affects cancer risk.
A: When I speak with our participants in exercise trials, we hear some remarkable testimonials. They just feel so fantastic about themselves. For cancer patients, exercise is often a way for them to regain some control over the disease. For both women free of cancer and patients, physical activity is very empowering. It's such a positive area to work in. There are so many benefits to be physically active – we are just adding cancer prevention to that list.
Excerpted from ScienceNow.
The study, published in Health Affairs, examined the financial costs of meeting selected elements of the 2010 Dietary Guidelines: consuming more potassium, dietary fiber, vitamin D, and calcium; decreasing calorie intake from saturated fat and added sugar.
Researchers gathered nutrient and cost estimates from questionnaires completed by 1,123 residents of a Washington state county. Consistent with national statistics, the average intake of the four highlighted nutrients fell below recommended levels.
Increasing the amount of potassium to recommended levels was the most expensive, adding $380 per year to the average consumer's food bill. And each time consumers took in 1 percent more of their daily calories from saturated fat and added sugar, their food costs declined.
The study analyzed the cost of increasing consumption of each recommended nutrient separately, rather than in combination. As the authors note, many vegetables and fruits contain more than one of the recommended nutrients.
Source: Monsivais P, Aggarwal A, Drewnowski A. "Following federal guidelines to increase nutrient consumption may lead to higher food costs for consumers." Health Aff. 2011 Aug 3.
The taller women are, the greater their risk for at least ten types of cancer, suggests a large new study published online in Lancet Oncology. The study adds to the evidence showing tallness heightens cancer risk and looks at how height may influence different cancers.
Study researchers pulled data on height and cancer from 1.3 million middle-aged U.K. women. The women were tracked for almost 10 years, during which almost 100,000 of the women were diagnosed with cancer.
For every 4 inch-increase in height from an average of 5 feet, the risk of cancer increased by 16 percent overall. The researchers looked at 17 cancer sites and the findings were statistically significant for 10 of them: cancers of the colon, rectum, malignant melanoma, breast, endometrium, ovary, kidney, CNS, non-Hodgkin lymphoma and leukemia.
The study took into account 12 personal characteristics, finding that such factors as socioeconomics, alcohol intake, activity level and body weight did not alter the height-cancer risk. (Smoking was the only factor that slightly altered the height-related risk of cancer. Taller women were at a lower risk for smoking-related cancers than for other cancers, but only in current smokers.)
Height is determined by genetic, environmental, hormonal and nutritional factors acting mostly in the first 20 years of life. AICR's expert report and its updates found that the taller people are the higher their risk for cancers of the colorectum, pancreas, breast and ovary. It's not tallness itself that is the culprit, note the report's authors, but the factors that influence a person's height, such as nutrition. These factors may, in turn, influence hormone levels that play a role in cancer development.
Source: Green, Jane et al. Height and cancer incidence in the Million Women Study: prospective cohort, and meta-analysis of prospective studies of height and total cancer risk. The Lancet Oncology, Volume 12, Issue 8, Pages 785 - 794, August 2011.
Restaurants, on average, post accurate calorie information but almost one in five food items may contain at least 100 calories more than posted, suggests a new study published in the Journal of the American Medical Association.
Study researchers analyzed 269 food items from 42 randomly selected chain restaurants. The restaurants, located in Massachusetts, Arkansas and Indiana, included both quick-serve and sit down.
The analysis found that 40 percent of the foods were at least 10 calories higher than the stated calories; 52 percent were at least 10 calories lower than the stated calories. But almost one in five of the food items (19 percent) contained at least 100 calories more than the posted calories.
For all foods, the discrepancy in calorie counts was found for sit-down restaurants compared with quick-serve restaurants. The largest inaccuracies of foods that contained more calories than stated were found among soups, salads, carbohydrate-rich side dishes, and desserts.
Given that almost half of U.S. residents eat out at least three meals per week, according to the study authors, having an accurate calorie count from restaurants is an important part of weight control.
Source: Urban LE, et al. "Accuracy of stated energy contents of restaurant foods." JAMA. 2011 Jul 20; 306(3): 287-93.
Sessions are now finalized for AICR's 22nd Annual Conference, in Washington, DC, on November 3 and 4. This conference remains the premier scientific forum on food, nutrition and physical activity as they relate to cancer prevention, treatment and survival. Session topics include:
The conference opens with a vigorous and analytical look at how the three main approaches to cancer research – observational studies, randomized clinical trials and animal studies – fit together in understanding the evidence.
This session delves into several novel and promising findings in the field, including new insights in fatty acids, targeting an obesity-cancer pathway and analytic techniques for dietary assessment.
With the number of U.S. cancer survivors at almost 12 million and growing, research in survivorship is also growing rapidly. Leading experts in the field will discuss the latest findings in survivorship related to diet, with talks on nutrition and cancer cachexia, the role of soy and micronutrient status during treatment.
The topic of cancer stem cells has spurred excitement and promising studies, although it is still early. This session provides an overview and highlights the research involving diet's role in affecting cancer stem cells.
If activity can reduce the risk of cancer, can too much inactivity increase the risk – even among people who are active? This session features renowned experts in the new field of the health effects of sedentary activity as they discuss its link to prevention and survivorship.
The Institute of Medicine 2011 report revealed important questions on the role of vitamin D to cancer prevention. The closing plenary presents the current state of the evidence on vitamin D and cancer, from epidemiological to laboratory, and provides insights on future needs.