Cancer and Obesity

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April is the Canadian Cancer Society’s Daffodil Month, when awareness and funds are raised to support research, fight cancer and help save lives.

Excess body weight contributes to nearly 12% of cancer cases in Canada. “Several cancer sites have strong associations with excess body weight, yet the number of Canadians who are overweight or obese is increasing,” Darren Brenner, PhD, assistant professor at University of Calgary Cumming School of Medicine in Alberta, Canada, told Endocrine Today. “By returning to body weight levels of 1990 over the next 30 years, we could avoid nearly 60,000 Canadians having a diagnosis of cancer.”

The link between obesity and cancer has been made, supported by research, for over a decade now but what is the mechanism by which they are related?

Several possible mechanisms have been suggested to explain the association of obesity with increased risk of certain cancers, here are a few:

  • Fat tissue produces excess amounts of estrogen, high levels of which have been associated with the risk of breast, endometrial, and some other cancers;
  • People with obesity often have increased levels of insulin and insulin-like growth factor in their blood (a condition known as hyperinsulinemia or insulin resistance), which may promote the development of certain tumors;
  • Fat cells produce hormones, called adipokines, which may stimulate or inhibit cell growth. For example, leptin, which is more abundant in obese people, seems to promote cell proliferation, whereas adiponectin, which is less abundant in obese people, may have antiproliferative effects. Thus, the leptin-adiponectin ratio may be important for tumor cell aggressiveness;
  • Fat cells may also have direct and indirect effects on other tumor growth regulators;
  • People with obesity often have chronic low-level inflammation, which has been associated with increased cancer risk;
  • Other possible mechanisms include altered immune responses, and oxidative stress.

“In the past, smoking was by far the major risk factor for cancer, but now healthcare professionals should also be aware that patients who have diabetes or are overweight also have an increased risk,” Jonathan Pearson-Stuttard, a clinical research fellow at Imperial College London’s Faculty of Medicine, said. Bariatric surgery can help contribute to successful long-term management of weight problems for overweight and obese individuals.


If you’d like to learn more about how a bariatric procedure might help you to gain better health overall, get in touch with one of our Program Advisors today at (888) 278-7952 or Connect through our website at