Obesity and Inactivity Raise Cancer Risks

By Janice Lloyd, USA TODAY

The decline in deaths from all cancers combined continued in the USA from 2004 to 2008, but a major government report highlights a worrisome rise in cases tied to obesity and inactivity.

Although the overall rate of new cancer cases is declining, the report confirms research showing excess weight and a sedentary lifestyle are risk factors for one-fourth to one-third of common cancers. About a third of adults, nearly 78 million, are obese, roughly 30 or more pounds over a healthy weight.

“Americans don’t understand the association between cancer and obesity,” says physician Marcus Plescia, director of the Division of Cancer Prevention for the Centers for Disease Control and Prevention (CDC). “They know about the links, (from obesity) to diabetes, heart disease and arthritis, but many don’t know about this.”

The report, published Wednesday in the journal Cancer, is co-authored by researchers from the CDC, the North American Association of Central Cancer Registries, the National Cancer Institute (NCI), and the American Cancer Society.

Maintaining a healthy weight and getting sufficient exercise may be among the most important ways to prevent cancer, the authors write. The risk factors are second only to tobacco as preventable causes of disease and death in the USA.

Obesity also diminishes quality of life for cancer survivors and may worsen the prognosis for several cancers, the authors write.

The American Cancer Society estimates that a third of the more than 572,000 cancer deaths in the USA each year can be attributed to diet and physical activity habits, including being overweight, while another third are caused by exposure to tobacco products.

“Because we know how to treat people better now, they live longer with cancer,” says Rachel Ballard-Barbash, associate director of the applied research program at NCI. “You can improve prognosis and quality of life by losing weight, improving nutrition, and exercising. It is similar to what we learned about heart disease.”

The biggest increase in new cases was seen in kidney cancer: 2.9% a year among men from 1999 to 2008, 3.3% among women. Also increasing: pancreatic cancer, adenocarcinoma of the esophagus, and uterine cancer.

Obesity and inactivity can lead to cancer by altering hormone and insulin levels, causing chronic hypertension and contributing to damaging inflammatory agents.

Overall, cancer death rates decreased an average of 1.6% a year between 2004 and 2008, the most recent years for which data are available.

“If we want to see continued decrease in the mortality rates for cancer, we have to promote behaviors such as losing weight, being active, and giving up smoking,” says report co-author Ahmedin Jamal, vice president of surveillance research for the American Cancer Society.

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