Weight Linked to Nearly 500,000 Cancers Worldwide

An international team of researchers estimates that 481,000 new cancer cases each year (3.6%) are likely caused by overweight or obesity, defined as having a body mass index (BMI) of 25 or higher. Almost ⅔ of the cancer cases related to weight are in North America and Europe.

The study analyzed data from countries and regions worldwide to calculate the percentage of cancer cases that could be attributed to high BMI in 2012. The study was published November 25, 2014 in The Lancet Oncology.

Differences around the world

Excess weight is associated with more cancers in developed countries than in developing countries. The study found that in 2012, the highest number of weight-related cancers was in North America, with 111,000, almost ¼ (25%) of the worldwide total. The lowest number was in sub-Saharan Africa, with 7,300 cases, about 1.5% of the worldwide total.

The researchers estimate 118,000 cases of cancer, or about ¼ of all weight-related cancers, could have been avoided if the worldwide average BMI in 2012 had stayed the same as it was in 1982.

Lead researcher Melina Arnold, PhD, said in a statement, "Our findings add support for a global effort to address the rising trends in obesity. The global prevalence of obesity in adults has doubled since 1980. If this trend continues, it will certainly boost the future burden of cancer, particularly in South America and North Africa, where the largest increases in the rate of obesity have been seen over the last 30 years."

Differences among men and women

Weight-related cancer is a bigger problem for women than for men. In part this is because weight is a risk factor for some cancers seen only in women, such as post-menopausal breast cancer and endometrial cancer. But weight is also a risk factor for cancer types that both men and women get, including colon, esophagus, kidney, and pancreatic cancer.

In women, weight was responsible for 345,000 cancer cases in 2012, or 5.4%. In men, weight was responsible for 136,000 new cancer cases, or 1.9%. Among women, post-menopausal breast cancer, endometrial cancer, and colon cancer made up almost ¾ of the weight-related cancer cases. Among men, colon and kidney cancers made up more than ⅔ of the weight-related cancer cases.

Get to and stay at a healthy weight

Being overweight or obese can increase cancer risk in many ways. One of the main ways is that excess weight causes the body to produce and circulate more estrogen and insulin, hormones that can stimulate cancer growth.

Eating right and getting enough physical activity can help you get to and stay at a healthy weight. The American Cancer Society recommends adults get at least 150 minutes of moderate-intensity activity (the level of a brisk walk) or 75 minutes of vigorous activity (the level of a run) every week, preferably spread throughout the week.

You should eat at least 2 ½ cups of vegetables and fruits each day. Eat less red meat (beef, pork, or lamb), bacon, sausage, luncheon meats, hot dogs, and other processed meats. Instead, focus more on fish, poultry, and beans. Choose whole-grain breads, pasta, and cereals. Limit sugary drinks, desserts and other high-sugar foods.

For those who are overweight or obese, losing even a small amount of weight has health benefits and is a good place to start.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Global Burden of Cancer Attributable to High Body-Mass Index in 2012: A Population-Based Study. Published November 25, 2014 in The Lancet Oncology. First author Melina Arnold, PhD, International Agency for Research on Cancer, Lyon, France.

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