This message comes through loud and clear in the cover story in the current issue of one of my favorite newsletters, Nutrition Action, published by the Center for Science in the Public Interest. The excellent article was written by Bonnie Lieman.
Who Gets Cancer?
One out of two men and one in three women. But the American Cancer Society estimates that of the 571,950 cancer deaths last year, a third would never have happened if no one smoked. And another third could have been prevented with weight loss, exercise, and healthier eating.
Here’s a rundown on the how diet, weight and exercise are linked to the risk of some of the major types of cancer:
BREAST: No other cancer strikes anywhere near as many women as breast cancer, though lung cancer claims more lives. Excess weight, even if it’s not obesity, increases the risk.
After menopause, fat cells, not ovaries, are the main source of estrogen, which promotes the growth of most breast cancers. Researchers also suspect that higher insulin levels promote tumors, and the heavier you are the more likely you’ll have higher insulin.
What’s more, breast cancer patients who are more active and less overweight have better odds of surviving the disease.
COLON and RECTUM: Thanks to better screening, the incidence of these cancers has dropped since 1985. But they still claim more lives than any cancer except lung.
Being overweight or obese is clearly associated with colorectal cancer, and a larger waist circumference also increases the risk.
In an NIH-AARP study that followed nearly half a million people over seven years, men and women who did moderate to vigorous exercise at least five times a week had an 18 percent lower risk of colon cancer than those who did little to no exercise.
What you eat also matters. Red and processed meats are associated with an increased risk.
The evidence is pretty good that calcium and dairy products are protective. But men should stay under 1,500 milligrams of calcium. More than that may increase the risk of prostate cancer.
ESOPHAGUS: This cancer take two forms. Worldwide, squamous cell carcinoma is more common. Its victims are typically heavy smokers, drinkers, or poorly nourished. My wife died of this cancer at age 50 and was a heavy smoker and drinker.
In the United States, adenocarcinoma now accounts for half of all esophagus cancers. Patients often are overweight, and many suffer from acid reflux.
In the seven-year NIH-AARP study involving 500,000 people, those who were overweight had a 70 percent higher risk of esophageal adenocarcinoma than those who were normal weight. The obese had more than double that risk.
LUNG: This cancer kills more Americans than breast, colon and prostate cancers combined. And it remains the most common cause of cancer deaths in the world today. While smokers account for 87 percent of those with lung cancer, the rest were nonsmokers.
In 2010, researchers tracking a half million Europeans were totally surprised to find that those with higher blood levels of vitamin B-6 had a 55 percent lower risk of lung cancer. This finding was so surprising that a large international consortium is now measuring B vitamins in ongoing studies and pooling the results.
But don’t rush out to the drugstore to buy vitamin B-6 pills. Something else about the people who eat foods rich in vitamin B may account for the link, researchers caution. Seafood, poultry, beans, cottage cheese, nuts, whole grains, and fortified breakfast cereals are rich in vitamin B-6.
OVARY: The five-year survival rate for ovarian cancer is 94 percent when it is diagnosed before the cancer spreads to other parts of the body; when it is diagnosed later, the five-year survival rate plummets to 28 percent. Unfortunately, two out of three ovarian cancers aren’t diagnosed until after the cancer has spread.
Studies on the impact of diet, weight, and exercise in lowering the risk of ovarian cancer are inconclusive.
PANCREAS: Less than 20 percent of patients with this cancer are candidates for surgery, because the cancer has already spread before it is diagnosed. Even when the doctors catch the cancer before it spreads, the five-year survival rate is only 24 percent. Steve Jobs lived longer than most people with pancreatic cancer.
In a study that pooled data on nearly a million men and women, nonsmokers who were overweight had a 15 percent higher risk than normal weight nonsmokers, while the obese had a 28 percent higher risk.
PROSTATE; The number of prostate cases jumped between the mid-1980s and the mid-1990s, largely because PSA (prostate specific antigen) tests were detecting cases sooner. Last fall, the U.S. Preventive Services Task Force recommended that men over 50 no longer get routine PSA tests. The treatment that follows elevated PSA test results doesn’t save lives, according to the task force, and often leads to impotence, incontinence and other complications. See earlier blog post on this.
Most older men have prostate cancer and for most of them, it’s the indolent type of prostate cancer that’s not going to kill them. The risk comes from the more advanced or lethal disease.
In a 2005 study, older men who regularly engaged in vigorous exercise like jogging, biking, swimming, or tennis had a 70 percent lower risk of advanced or lethal cancer.
What is even more interesting to someone like me who already has prostate cancer is a study finding that men with local prostate cancer, those who walked briskly for at least three hours per week were about 40 percent less likely to have their cancers progress to need further treatment, to metastasize, or to cause death. Vigorous activity really made the difference, the researchers said.
A healthy body weight at or before diagnosis also is a strong predictor for survival.
UTERUS: It’s been known for some time that excess weight is a risk factor for this cancer. But recent studies indicate that the earlier a woman puts on the excess weight, the greater the risk. Long, sustained weight gain is a predictor of much earlier onset of endometrial cancer, a fact that makes the current epidemic of childhood obesity particularly scary.