Several cancers linked to obesity and a sedentary lifestyle rose every year from 1999 through 2008, even as improved screening and a sharp decline in the number of smokers have helped push down the rate of new cancer diagnoses overall across the U.S., according to a report released Wednesday.
Rates of cancers of the kidney, pancreas, lower esophagus and uterus increased annually through 2008, the latest data available, according to the Annual Report to the Nation on the Status of Cancer. Rates of breast cancer in women at least 50 years old declined 1.3 percent annually from 1999 to 2005 but rose slightly between 2005 and 2008.
The data add to a growing body of evidence that obesity raises the risk of these and some other cancers. As many as one-third of common cancers in industrialized nations are linked to excess weight and lack of physical activity, according to the International Agency for Research on Cancer. Obesity rates leveled off in the U.S. a decade ago, but an estimated 68.8% of adults remain overweight or obese, according to the CDC, and cancers can take years to develop.
Obesity-related cancers include common ones, such as breast and colorectal cancer, as well as less common ones, such as pancreatic cancer. Excess weight can also decrease the chance of survival once a patient is diagnosed. The burden "is pretty substantial," said Marcus Plescia, director of the division of cancer prevention and control at the Centers for Disease Control and Prevention and an author of the study.
The report, published online Wednesday in the journal Cancer, is by researchers from the CDC, the North American Association of Central Cancer Registries, the National Cancer Institute, and the American Cancer Society.
The evidence of a causal link with cancer, while not yet definitive, is far clearer with excess weight and lack of physical activity than with specific foods or nutrients.
"People might think they can do themselves the most good by taking a vitamin or mineral supplement, when actually what they need to do, to do the most good, is to be physically active and control their weight," said June Stevens, head of the department of nutrition at the University of North Carolina's Gillings School of Global Public Health.