Reducing cancer risk

Does lifestyle really make a difference?
Absolutely. Experts now estimate that nearly half of all cancer cases are directly related to the everyday choices we make—from what we put into our bodies to how often we move them. Some 595,930 people died of cancer in the U.S. in 2015, according to government statistics, making it America’s second-biggest killer after heart disease. While some of those cases involved cancers driven by genetic mutations, the majority of sufferers were diagnosed with common cancers directly linked to Westerners’ sedentary lifestyles, high-fat diets, and tobacco and alcohol consumption. “The real key here is that most cancers are not just a result of bad luck or chance,” says public health expert Graham Colditz. “The majority are preventable.”

Where can people begin?
Keep an eye on the scales. Body weight has a huge bearing on a person’s likelihood of getting cancer: For every five points that a person goes above the “normal” Body Mass Index (BMI) range of 18.5 to 24.9, his or her risk of colorectal cancer or post-menopausal breast cancer doubles. People who fall into the “obese” category—a BMI of 30 or above—face an increased risk for 13 different types of cancer. Excess body fat produces chemicals that promote chronic inflammation and increase levels of insulin and hormones—creating an environment in which cancer cells can thrive. Body fat “is not just sitting there,” says Emma Shields, of Cancer Research UK. “It’s sending messages to the rest of your body.”

What’s the best way to lose weight?
By getting a sweat on. Exercise doesn’t just help us maintain a healthy weight; it has its own cancer-fighting benefits—including boosting the immune system and speeding up digestion, thereby reducing the amount of time that the gastrointestinal tract is exposed to possible carcinogens. The average American adult should aim for at least 30 minutes of moderate exercise—like a brisk walk—every day. “It doesn’t require marathon training,” says James Lacey Jr., associate professor at City of Hope’s Division of Cancer Etiology in California.

What about diet?
Try to avoid processed meats, such as bacon or hot dogs, and red meat. Both seem to cause inflammation in the body, increasing a person’s risk of colorectal cancer. In general, it’s best to go Mediterranean or Japanese: diets that incorporate lots of fruit and vegetables and are high in fiber. But opt for brown rice rather than white, which can cause a spike in blood sugar. The American Institute for Cancer Research recommends that you avoid sugary drinks, eat no more than 18 ounces of red meat a week, and fill at least two-thirds of your plate with vegetables, fruits, whole grains, and beans.

How harmful are alcoholic drinks?
“Alcohol is a recognized carcinogen,” says Alice Bender, head of nutrition programs for the American Institute for Cancer Research. “It can damage DNA. It can increase hormones in your body, like estrogen, that can fuel cancer.” Women should aim to drink no more than 5 ounces of wine or 12 ounces of beer a day; men can have double that limit. Throw away the cigarettes too. Smoking is linked to 81 percent of lung cancers, and raises the risk of 12 other cancers, including those of the larynx and mouth. Fortunately, quitting has immediate benefits. Just 20 minutes after doing so, a smoker’s heart rate and blood pressure drops; within 12 hours, the body’s carbon monoxide levels are back to normal.

What else can we do?
About 86 percent of skin cancers are linked to sun exposure, so avoid spending long periods in the sun. And try to get eight hours of sleep. “After just one night of only four or five hours’ sleep, your natural killer cells—the ones that attack the cancer cells that appear in your body every day—drop by 70 percent,” warns Professor Matthew Walker, director of the Center for Human Sleep Science. Another tip: It’s never too late to change. Someone who quits smoking before the age of 50 is half as likely to die of cancer in the subsequent 15 years as a result. The most important step in making a change is the first one, says Wilson Mertens, medical director of Cancer Services for the Baystate Regional Cancer Program. “Even small changes can make a difference.”

Anti-cancer fads and myths

Asparagus extract. Essiac tea. Herbal blends. None of these has been scientifically proven to prevent cancer, despite what many wellness gurus argue. “Alkaline diet” superfans would have you believe that an acid-heavy diet leads to cancer formation, and that people should rigorously avoid “acid-promoting” foods like dairy, eggs, meat, and most grains. Yet nutritionists have never found any evidence that food affects body tissue acidity. Countless experiments have shown that avoiding antiperspirants, artificial sweeteners, microwaves, and cell­phones won’t lower your risk of cancer. Nor will consuming a $45 ­bottle of Revivin herbal blend, despite its claim to “attack” cancer at the DNA level. “Snake oil salesmen have been around medicine for hundreds of years,” says oncologist Ian Haines. “I don’t think it’s necessarily changed that much.”

The Week