We’ve known for a long time a high—fat diet，obesity and lack of exercise can increase the risk of developing heart disease and type 2 diabetes，two conditions affecting millions of Americans．What we are finding out now is those same lifestyle. factors also play an important role in cancer． That’s the bad news．The good news is you can do something about your lifestyle. If we grew thin ner，exercised regularly，avoided diets rich in red meat and ate diets rich in fruits and vegetables．and stopped using tobacco，we would prevent 70 percent of aU cancers． The strongest evidence of the importance of lifestyle. in cancer is most common cancers arise at dramatically different rates in different parts of the globe Several cancers that are extremelv common in the United States——colon，prostate and breast cancer---are relatively rare in other parts of theworld，occurring only 1／10th or 1／20th as often．Equally striking，when people migrate from other parts of the world to the United States，with in a generation their cancer rates approach those of US whose families have lived in this country for a long time Even if people in other parts of the world stay put，but adopt a U．S．1ifestyle，their risk of cancer rise；as Japanese have embraced Western habits，their rates of colon，breast and prostate cancer have skyrocketed What is it about our lifestyle. that raises the risk of many types of cancer?The main culpritsseem to be the Western diet，obesity and physical inactivity．While we’ve known about the importance of tobacco and cancer for more than 50 years，we are just beginning to understand how diet，ahealthy body weight and regular exercise can protect US against cancer． A striking example of the profound influence of diet was reported last summer in The Journal of the American Medical Association．Doctors determined the eating habits of patients with colon cancer in the years following surgical removal of the cancer．Over the next five years，those who ate a traditional Western diet had a threefold greater likelihood of developing a recurrence of the disease than did those who ate a“prudent”diet rich in fruits and vegetables and including only small amounts of red meat．How had diet affected these patients?The surgery clearly had not removed all their colon cancer cells：prior to the surgery，some cells had already spread from the primary tumor．The West erR diet had somehow stimulated the growth of these small deposits of residual cancer cells． Obesity is the second most important factor in causing cancer in Western populations after to bacco．There is evidence that maintaining a healthy weight is protective against the disease A studyby the American Cancer Society in 2003 found the heaviest people，in comparison with the leanest，had a significantly increased risk of death from 1 0 different kinds of cancer in men，and 12 different kinds in women．The most extreme examples were liver cancer in men and uterine cancer in women． According to paragraph 2，which of the following statements is true?__________