Weight, Obesity and Cancer

"Obesity is a major risk factor for cardiovascular disease, certain types of cancer, and type 2 diabetes."
-Centers for Disease Control

Does obesity cause cancer?

After tobacco, obesity is the second highest cancer risk factor. Studies have not shown that weight and obesity cause all cancers. However, research suggests that in some people with cancer, excessive extra weight may contribute to and cause cancer development and cancer growth. Obesity and cancer are strongly linked. Living with a healthy weight is an essential part of an integrative cancer care plan for both cancer treatment and cancer prevention.

What causes obesity?

Experts suggest that the chief causes of obesity are a sedentary lifestyle with physical inactivity and a poor diet. Exercise and Cancer and Movement provides physical activity to help control weight. Supporting your health and healing with your proper weight is not only about the numbers you see on the scale. The food you put in your mouth is critical. Learn more in Diet and Cancer.

What are some potential ways in which obesity increases cancer risk and cancer growth?

Researchers continue to evaluate this important question. Some possible ways in which obesity increases cancer risk and cancer growth include the following.

• Increases the body's production of hormones, including insulin and insulin-like growth factor 1 (IGF-1), which stimulate tumor development and cancer growth while inhibiting cancer cell death
• Increases inflammation in the body associated with cancer
• Contributes to cancer growth by causing cells to divide more rapidly
• Often involves a sedentary lifestyle with physical inactivity known to contribute to many health risk factors such as cancer
• Often involves a poor diet known to contribute to many health risk factors such as cancer

What are some statistics about the relationship between obesity and cancer?

The World Cancer Research Fund and the American Institute for Cancer Research analyzed the relationship between obesity and cancer in a 2009 policy report.

• The report concluded that excess body weight has the largest effect on endometrial cancer, causing an estimated 49 percent of cases or 20,700 people with endometrial cancer per year.

Being overweight or obese also caused the following.

• 35 percent of esophageal cancers (5,800 people per year)
• 28 percent of pancreatic cancers (11,900 people per year)
• 24 percent of kidney cancers (13,900 people per year)
• 21 percent of gallbladder cancers (2,000 people per year)
• 17 percent of breast cancers (33,000 people per year)
• 9 percent of colon cancers (13,200 people per year)

How many people in the United States are overweight or obese today?

Rates of obesity have steadily increased over the past few decades in the United States, according to data from the Centers for Disease Control and Prevention's National Health and Nutrition Examination Survey.

Obesity has more than doubled from 15 percent of adults in the early 1970s to 34 percent of obese adults and 67 percent of overweight or obese adults in 2005-2006.

The Centers for Disease Control (CDC) provides Obesity Trends from 1985 to 2008. As of 2008, with the exception of Colorado, all states have a prevalence of obesity over 20 percent with most states at over 25 percent. Six states had a prevalence of equal to or greater than 30 percent.

The following statistics about obesity come from the American Cancer Society (ACS), Surveillance Research.

• Approximately two-thirds of Americans are overweight or obese¹.

• In the past 20 years, overweight prevalence among adolescents aged 12 to 19 more than tripled, from 5% to 17.1%. Increases have occurred across race, ethnicity, and gender; Non-Hispanic African American girls have the highest rates of overweight².

• The percent of obese adults aged 20 to 74 years varied little from 1960-1962 to 1976-1980. In contrast, obesity rates more than doubled between 1976-1980 and 2003-2004, from 15.1% to 33.0%. In 2005-2006, obesity prevalence in men (34.0%) and women (36.4%) did not significantly change from that in 2003-2004³.

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References

1. Ogden CL, Carroll MD, Curtin LR, McDowell MA, Tabak CJ, Flegal KM. Prevalence of overweight and obesity in the United States, 1999-2004. JAMA. 2006;295(13):1549-1555.
2. National Health and Nutrition Examination Survey, Hispanic Health and Nutrition Examination Survey (1982—84). Centers for Disease Control and Prevention, National Center for Health Statistics, Health, United States, 2004, with Chartbook on Trends in the Health of Americans. Hyattsville, Maryland: 2004. Ogden CL, et al. Prevalence of Overweight and Obesity in the United States, 1999-2004. JAMA2006;295(13):1549-55.
3. Behavioral Risk Factor Surveillance System Public Use Data Tape 2005, 2006, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, 2006, 2007.