Contrary Trend: Some Weight-Related Cancers on Rise in US

Nick Mulcahy

October 03, 2017

Overall cancer rates have been declining in the United States since the 1990s. But contrary to this trend, some weight-related cancers were on the rise annually from 2005 to 2014, new data from Centers for Disease Control and Prevention (CDC) indicate.

Excessive body weight is associated with at least 13 different types of cancer among American adults, and the newly released data, which were published online today in the Morbidity and Mortality Weekly Report, reveal trends for those 13 cancers.

During the 10-year study period, incidence rates increased significantly each year for six of the cancers: thyroid cancer (4.0% per year), liver cancer (2.9%), gastric cardia cancer (1.2%), endometrial cancer (1.1%), pancreatic cancer (0.8%), and kidney cancer (0.7%).

On the other hand, incidence rates decreased significantly each year for three cancers: meningioma (-3.8%), colorectal cancer (-2.9%), and ovarian cancer (-2.0%).

The incidence rates were stable for the remaining four cancers: adenocarcinoma of the esophagus, gallbladder cancer, multiple myeloma, and postmenopausal breast cancer.

"Today's report shows in some types of cancers, we are going in the wrong direction," said Anne Schuchat, MD, deputy director of the CDC, during a telephone call with reporters.

Overall, the rate of weight-related cancers decreased by 2% between 2005 and 2014, according to the authors, led by C. Brooke Steele, DO, of the CDC's Division of Cancer Prevention and Control.

Only when colorectal cancer was dropped from these calculations was there an increase of 7% of overweight- or obesity-related cancers during this period.

The CDC authors explained why they both included and dropped colorectal cancer in their analysis of trends for the period 2005-2014.

"Because screening for colorectal cancer can reduce colorectal cancer incidence through detection of precancerous polyps before they become cancerous, trends with and without colorectal cancer were analyzed," they write.

Overall, the rates of non-obesity-related cancers declined during 2005-2014, the report authors also observed.

The CDC team also looked at incidence rates in 2014 alone. They report that cancers associated with overweight and obesity accounted for 40% of cancers diagnosed in the United States in that year. About 2 in 3 of these cancers were in adults aged 50 to 74 years.

"A majority of American adults weigh more than recommended ― and being overweight or obese puts people at higher risk for a number of cancers ― so these findings are a cause for concern," said Brenda Fitzgerald, MD, director of the CDC, in a press statement that accompanied the new report. "By getting to and keeping a healthy weight, we all can play a role in cancer prevention."

Weight-related cancer incidence rates in 2014 were also higher among females than males and were higher among black and white adults compared with adults in other ethnic/racial groups.

In the new study, overweight was defined as having a body mass index (BMI) of 25 to 29.9 kg/m2; obesity was defined as having a BMI of 30 kg/m2 or higher. BMI is a person's weight in kilograms divided by the square of the person's height in meters.

MMWR Morb Mortal Wkly Rep. Published online October 3, 2017. Full text

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