WASHINGTON — Excess body fat increases an individual's risk for six types of cancer, according to a report to be released today by two leading cancer research groups.
The American Institute for Cancer Research and the World Cancer Research Fund offer 10 recommendations for cancer prevention, including limiting consumption of red meat and alcohol, avoiding processed meats and -- most importantly -- shedding those extra pounds.
The report, the second by the two nonprofit organizations, calls on people to "be as lean as possible within the normal range of body weight" as determined by the World Health Organization or national governments, and avoid weight gain and increases in waist circumference during adulthood.
"The recommendation reflects what science is telling us today: Even small amounts of excess body fat, especially if carried at the waist, increase risk," said W. Philip T. James, chairman of the London-based International Obesity Task Force and one of the 21 members on an international panel that prepared the report.
Increased body fat, particularly in the abdominal area, affects levels of hormones and growth factors, which can influence the development of cancer cells. In addition, the report says, obesity is characterized by "a low-grade chronic inflammatory state" in the body that can promote cancer.
In their first report a decade ago, the groups linked excess weight only to cancer of the endometrium, or uterine lining. Today's report, which took five years to prepare, reviewed more than 7,000 studies published worldwide. It said it found a convincing connection between excess fat and cancers of the esophagus, pancreas, colon and rectum, endometrium and kidney, along with breast cancer in post-menopausal women.
James called the link between body fat and six types of cancers "the most striking finding" of the analysis. "That is why body weight is the focus of our first recommendation," he said.
Two recommendations focusing on weight control -- being physically active for at least 30 minutes a day and eating sparingly or completely avoiding fast food, sugary sodas and processed foods low in fiber or high in sugar or fat -- are followed by seven other healthful tips.
Among them is eating more fruits and vegetables; the report says that "people who eat various forms of vegetarian diets are at low risk of some diseases, including some cancers." Also recommended were limiting red meat consumption to 18 ounces a week and, except for very rare occasions, avoiding processed meats -- cured, smoked, salted or chemically preserved products such as ham, bacon and hot dogs.
Once an individual reaches the 18-ounce weekly limit for red meat, every additional 1.7 ounces consumed a day increases cancer risk by 15%, the report said. Every 1.7 ounces of processed meat consumed a day increases cancer risk by 21%, it added.
Alcoholic beverages are a factor in cancers of the mouth, pharynx, larynx, esophagus, colon and liver, the report says, urging that consumption be limited to two drinks a day for men and one for women.
"It doesn't matter whether you are talking about wine, beer or spirits. When it comes to cancer, even small amounts of alcohol raise your risk," James said.
The remaining recommendations include limiting salt intake and getting necessary vitamins and minerals through nourishing foods, rather than dietary supplements.
Colleen Doyle, the American Cancer Society's director of nutrition and physical activity, says the report confirms everything her organization has been promoting.
"Weight, dietary habits and physical activity have a direct effect on cancer risk," she said.
"It is important to note this means people do have a significant amount of control over their risk of developing many types of cancer," she added. "Lifestyle changes can indeed make a difference."
The 517-page report is available at www.dietandcancer report.org.