Obesity Linked to Cancer Risk, Study Says

Obesity plays a much larger role in developing cancer than previously thought, accounting for 14% of cancers in men and 20% in women, according to a study published April 24 in the New England Journal of Medicine, the Los Angeles Times reports. The findings make excess weight second only to smoking as a preventable cause of cancer. The study was conducted by researchers at the American Cancer Society on 404,576 men and 495,477 women with an average age of 57 over a 16-year period. Researchers grouped the participants by weight according to their body-mass index. The study found that compared with people of normal weight, men in the highest weight group were 52% more likely to die from cancer and women in the highest weight group were 62% more likely to die from cancer. Increased likelihood of cancer among the heaviest women and men are as follows:

• Among the heaviest women, researchers found that deaths from uterine cancer were six times more likely, deaths from kidney cancer were almost five times more likely, deaths from cervical cancer were three times more likely and deaths from breast, gallbladder, pancreas and esophageal cancers were more than twice as likely.
  
• Among the heaviest men, deaths from liver cancer were more than six times more likely, deaths from pancreatic cancer were more than twice as likely and deaths from gallbladder, stomach and colorectal cancers were 75% more likely (Maugh, Los Angeles Times, 4/24).
  

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While researchers "have only a limited understanding" of why obesity causes cancers, they believe that fat tissue may lead to an overproduction of steroid hormones that play a "crucial role" in endocrine-related cancer and that obesity leads to excess insulin production and an increase in insulin-like growth-factor receptors that have previously been linked to cancer. In addition, researchers suspect that obesity may make cancer more difficult to detect as the disease is obscured by excess fat tissue, and treatment may be problematic as fat absorbs chemotherapy drugs (Los Angeles Times, 4/24). According to Dr. William Dietz, director of the division of nutrition and physical activity at the CDC, "This study provides very important additional information that emphasizes the reason why obesity needs to be targeted as a major health problem in the United States" (Uhlman, Philadelphia Inquirer, 4/24). Eugenia Calle, director of analytic epidemiology at the American Cancer Society and lead author of the study, said that the nation's obesity problem needs to be addressed as aggressively as the fight against tobacco. Calle added that just as public education campaigns and regulatory changes tackled smoking, similar changes need to be made to ensure that people make healthier choices about food and exercise (Hellmich, USA Today, 4/24). NBC's "Nightly News" reported on the study. The segment includes comments from Calle (Hager, "Nightly News," NBC, 4/23). The full segment is available in Windows Media online.