World Health Organization Links 8 More Cancer Types to Excess Weight

The International Agency for Research on Cancer (IARC), part of the World Health Organization, has added 8 types of cancer to those it had previously linked to being overweight or obese. The newly linked cancer types are: stomach, liver, gallbladder, pancreatic, ovarian, thyroidmultiple myeloma, and meningioma (a tumor of the lining over the brain and spinal cord).

IARC also confirmed its previous conclusions, that excess weight is a risk factor for cancers of the esophagus, colon and rectum, breast (in postmenopausal women), kidney, and endometrium. IARC also said being overweight or obese may raise the risk of breast cancer in men, diffuse large B-cell lymphoma, and fatal prostate cancer.

A summary of the findings is being published August 25, 2016 in The New England Journal of Medicine.

BMI and cancer risk

To assess the link between cancer risk and weight, 21 international experts looked at more than 1,000 studies. Most of the studies used body mass index (BMI) to define whether people were overweight or obese.

BMI is a number based on your weight and height. In general, the higher the number, the more body fat a person has. You are considered to be overweight if your BMI is 25 or higher. You are considered to be obese if your BMI is 30 or higher. You can figure out your BMI using an online calculator.

In 2013, an estimated 4.5 million deaths worldwide were caused by overweight and obesity, according to IARC. The identification of new weight-related cancer types will increase the number of deaths attributable to excess weight.

Susan Gapstur, PHD, MPH, American Cancer Society Vice President of epidemiology research, served on the IARC panel of experts. She says there are many ways that excess weight increases cancer risk, which may be different for different types of cancer:

“For example, especially in postmenopausal women, fat cells are an important contributor to sex hormones, such as estrogen, that play a role in the development of endometrial and breast cancer, as well as some other cancers. But there are also other mechanisms that are thought to be important for different types of cancer. These include mechanisms related to abnormal glucose metabolism and excess insulin, altered immune responses, and obesity-related inflammation,” said Gapstur.

Get to and stay at a healthy weight

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 oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Citation: Body Fatness and Cancer – Viewpoint of the IARC Working Group. Published August 25, 2016 in The New England Journal of Medicine. First author Béatrice Lauby Secretan, PhD, the International Agency for Research on Cancer, Lyon, France.


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