Dr. June Stevens, AICR/WCRF Distinguished Professor at UNC/Chapel Hill, led off this morning’s session on obesity and cancer by noting some troubling global trends. She shared data showing that, around the world, obesity is on the rise. Yet in country after country, the same phenomenon is observed: First, obesity rates increase among all income groups. Then, rates start to level off — but only among higher-income people. Among the lowest income groups, obesity continues to surge unabated.
Dr. Juan Rivera, of Mexico’s National Institute of Public Health, was a member of the expert panel who authored the AICR/WCRF report, Food, Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective. He presented data on the growing obesity epidemic among Mexican children, and mentioned that AICR/WCRF expert report’s recommendations are being used by the Mexican government in its efforts to prevent obesity and lower cancer rates.
Today’s (early) morning session of the AICR Research Conference featured a lot of interesting charts and graphs illustrating how major population studies are helping us understand the link between diet and cancer risk. The two prominent speakers – Dr. Teresa Norat at Imperial College London and Dr. Laurence N. Kolonel of the University of Hawaii – talked about cohort studies and what they are telling us.
In cohort studies, researchers follow a (large) group of healthy people and link it with certain risk factors. The two major cohorts Dr. Norat and Dr. Kolonel discussed ask the study population lots of questions about their diets repeatedly, take blood and other biological samples, and then follow their cancer incidence in the coming years.
Both cohorts feature diverse populations in different ways. Dr. Norat spoke about The European Prospective Investigation into Cancer and Nutrition (EPIC) study, a cohort that includes 10 European countries and over half a million people. Dr. Kolonel’s cohort includes over 200,000 participants of five ethnicities living in Hawaii and Los Angeles.
As the researchers pointed out, the diverse populations allows them to see confirmations among certain risk factors – such as high intake of soy compound with decreased prostate cancer risk – and look for unique differences among populations.
These cohort studies, among many others, provide the evidence for which diet/lifestyle factors link to what cancers, and that’s where Dr. Norat’s work on AICR/WCRF’s Continuous Update Project enters the picture. The project is a follow-up to AICR/WCRF’s second expert report, and Dr. Norat is leading the project. Last year, the Continuous Update Project released an update on the report’s findings on breast cancer. Colon and prostate cancer are in the works, along with an analysis of the findngs on breast cancer survivorship.
You can read more about the project here and look for updates here on our blog.
At the Diet, Physical Activity and Survivorship session of AICR’s annual meeting, leading researchers pointed to the latest developments in lifestyle changes that might affect risk and death from major cancers. Catherine M. Alfano of the National Cancer Institute stressed the desire of cancer survivors, now numbering more than 12 million in the US, to “take control and actively participate” in beating cancer.
In breast cancer, physical activity has been studied most and found to have an impact on preventing recurrence and improving quality of life, as well as reducing negative side-effects of treatment.
Human trials looking at the impact of physical activity, diet and obesity on other kinds of cancers are sorely needed — as borne out by evidence presented by Jeffrey Meyerhardt, Ph.D, of Dana-Farber Cancer Institute in Boston, who noted that studies linking physical activity with preventing colon cancer have shown clear results, but design of studies on survivors have varied.
Finding evidence on recurrence and mortality is more complex, Dr. Meyerhardt said, such as in looking into the various stages of colon cancer diagnosis, so these studies must be large and long-term, accumulating data over decades.
Prostate cancer and physical activity also has not been adequately studied, although presenter Edward Giovanucci, MD, of Harvard University said that being active before diagnosis is best, and that vigorous activity seemed to help survivors in the later stages of prostate cancer. He noted that brisk walking (3 miles an hour or more) for at least 7 hours per week did seem to have a positive effect in a small study of prostate cancer survivors. As for obesity, studies so far do not show an effect on survival from prostate cancer, but they may affect screening and treatment effectiveness, which may in turn affect survival of this cancer. A low-fat diet also seems to help survival rates.
The presenters emphasized the many health benefits of a physically active and prudent-diet lifestyle besides the likely cancer prevention and survival benefits, including lower risk for diabetes, heart disease and other chronic health problems — in other words it’s smart to make healthy changes while we are still healthy so that even after a cancer diagnosis, we are more likely to survive.
We fund cutting-edge research and give people practical tools and information to help them prevent–and survive–cancer.
American Institute for Cancer Research
P: (800) 843-8114 | Fax: (202) 328-7226