美国:与肥胖相关的癌症案例上升

The American Cancer Society says in its annual report that fewer Americans are dying of cancer, but doctors are seeing more patients with cancers linked to obesity, including pancreatic and kidney cancers. And while breast cancer patients are living longer, the risks of developing this type of tumor are rising along with the growing rates of obesity.

For many people, a cancer diagnosis is no longer a death sentence.

Former U.S. presidential candidate Herman Cain was diagnosed six years ago with stage-four colon cancer. Tumors had already spread to his liver. Cain was given a 30 percent chance of survival. But after having surgery and undergoing chemotherapy, Cain says his cancer went into remission.

The American Cancer Society's annual report shows that death rates from cancer in the U.S. have continued to fall. Between 2004 and 2008, cancer death rates for men went down nearly two percent a year; for women they declined about one-and-a-half percent each year.

Over a longer period of time, from 1990 through 2008, cancer death rates plunged almost 23 percent for men and just over 15 percent for women. That translates to a million lives saved.

But doctors are reporting more cases of esophageal, pancreatic, liver and kidney cancer. Obesity is a risk factor for these types of cancers and for breast cancer as well. It's also a risk factor for a number of chronic diseases, including Type 2 diabetes. 

At the Harvard School of Public Health, Dr. Dariush Mozaffarian focuses on the connection between diet and chronic diseases.

"Most of my focus has been on diet, because the bang for your buck for changing your diet is really profound," Mozaffarian noted.

And Dr. Mozafarrian believes that just as growing numbers of Americans have quit their smoking habits, they can beat the obesity trap, and avoid the cancers and other diseases that result.

"We've had huge success in this country with smoking," added Mozaffarian.  "We've gone from about 55 percent smokers to 25 percent smokers in about 40 years."

For close to 50 years, the U.S. government has adopted policies to discourage people from taking up smoking and to encourage smokers to quit.  The policies include education campaigns, high taxes on tobacco product sales and laws against selling tobacco to anyone under the age of 18. The new Cancer Society report says the resulting drop in lung cancer deaths accounts for almost 40 percent of the decline in overall cancer deaths.

Dr. Mozaffarian says public health officials should use the anti-smoking campaign as a model to get people at risk of obesity to improve their diets. 

"It's not going to happen in a year, but in a decade or two, if we really have a sustained understanding of the impact of diet on health in this country and the economic burdens that it causes, we really could have a sea change, and relatively quickly," said Mozaffarian.

And the result, he predicts, will be a decline in the number of obesity-related deaths.