Some of the newest cancer research is based on old-fashioned common sense. It might sound boring — eat fruits, vegetables and whole grains; stay away from animal fats; be more physically active; quit smoking — but scientists are coming closer to reaching a consensus that lifestyle choices make a significant difference in protecting against cancer.
Last month, the Harvard Center for Cancer Prevention released its second annual report. It reiterated that half of all cancer risk among Americans could be eliminated through a modified diet, increased exercise, decreased alcohol use and tobacco cessation. The report specifically linked physical activity to a potential reduction in colon cancer, which is the most common cancer for U.S. adults older than 50 and doesn’t discriminate by gender.
The Harvard findings didn’t get much media play, especially after an initial splash with its first report in 1996. But the message is powerful: If you are serious about cutting cancer risk, start with personal health habits.
“We are talking about simple steps in some ways,” said Dr. David Rosenthal, a Harvard University physician and president of the American Cancer Society. “But it is a difficult issue to persuade people to change behavior.”
Rosenthal also is director of Harvard University Health Services, which attends to some 35,000 members of the school’s community. Though the patient base figures to be an educated population, Rosenthal said it has a significant share of individuals with unhealthful tendencies, such as smoking, eating fatty meats and leading sedentary lives.
There is formidable motivation to change such habits. Research shows 30 percent of all cancer deaths are attributed to poor diet and adult obesity, matching the 30 percent linked to tobacco use. Another 5 percent is due to lack of physical activity, the same proportion associated with family history.
“One important conclusion from this report is that cancer is indeed a preventable illness,” writes Dr. Graham A. Colditz, director of education at the Harvard Center for Cancer Prevention and lead author of the report. “We believe cancer mortality in the U.S. can be substantially reduced, perhaps by as much as one-third (with the appropriate behavior modification).”
Colditz makes the point that public awareness about cancer tends to focus on treatment rather than prevention. As a society, Americans hope scientists can find a “cure for cancer” and rightfully celebrate when family members and friends achieve successful remission. But there is nothing dramatic about eating right and getting some exercise.
Another problem is people tend to give up on themselves as they get older, said Rosenthal. They tend to accept aches and illness as an inevitable part of aging.
When he speaks to groups, Rosenthal said his “first point” is that it is never too late to reform your health habits. A prime example? His father, who at age 90 participated in a landmark Tufts University study showing that even formerly sedentary subjects in their 80s and 90s can build new muscles with a weight-training program designed for their fitness levels.
The National Cancer Institute endorses new federal guidelines intended to persuade sedentary individuals to get moving, and there are many ways to kick your daily physical activity up a notch. Even moderate activity like gardening for 30 to 45 minutes, walking 20-minute miles, cycling five miles in a half-hour or snow shoveling for 15 minutes can help.
“Diet is another target for people of all ages,” said Rosenthal. “We strongly recommend eating less fat while adding more fruits, vegetables and grains. The idea is to shift many of your dietary choices from fat to fiber.”
The American Cancer Society recommends trimming fat by eating lean cuts of meat and poultry, plus fish, seafood and beans in place of too much red meat in the diet (most directly linked to colon cancer). Nutritionists suggest thinking about meat as a “condiment” or accent to dishes, rather than the main part of lunch or dinner.
A companion strategy is to change your dairy products to low- or non-fat varieties. Saturated fats, like cheese and butter, have been associated in studies with prostate cancer.
Fruits and vegetables are the key dietary addition for cancer protection. Based on a growing body of research, the National Institutes of Health has for several years urged adults and children consume five or more servings of produce each day to take advantage of numerous natural phytochemicals and vitamins.
The typical adult American’s daily consumption of fruits and vegetables averaged 3.9 servings in the years between 1989 and 1991. Federal statistics show that number increased to 4.4 by 1994.
“At the same time, two major studies show a decline in cancer mortalities and a flattening of incidence from 1989 to 1994,” noted Rosenthal. “I like to make the association that diet is part of the difference.”
While whole fruits and vegetables are best because of the fiber they put in the diet, Rosenthal and other researchers are not opposed to more convenient products. He cited studies identifying the anti-cancer properties of orange and grapefruit juices.
“You can also help yourself by routinely eating a piece of fruit at breakfast or lunch, and adding vegetables to the lettuce in your salad,” said Rosenthal. “Snacks of fruits and cut vegetables are a good idea.”
One major concern at the American Cancer Society and other health organizations is the dietary patterns of children. The latest findings show that kids average only 3.4 daily servings of produce.
“We have major education initiatives planned for schoolchildren,” Rosenthal said. “It is critical we explain healthful food choices to kids, beginning as early as the 1st grade.”
