Last week’s article on metabolic syndrome outlined how lifestyle factors, including obesity, can lead to chronic disease. Included in these chronic diseases are many different forms of cancer. Cancer can be tricky to link to any one cause because there are so many different types. There is clear evidence, however, that many different forms of cancer have a direct link to obesity.
Globally, roughly 30 percent of the population is overweight or obese. In the U.S. however, these numbers are even more staggering, with approximately two-thirds of our population falling into the overweight or obese criteria. Recent reports by the Centers for Disease Control and Prevention show the grim statistics that these rates are having on cancer prevalence. An estimated 40% of all cancer diagnoses in America are now linked with obesity, accounting for about 630,000 cases in 2014.
While no two types of cancer are the same, the International Agency for Research on Cancer has made a distinct connection between overweight and obesity and 13 types of cancer. These include meningioma, multiple myeloma, adenocarcinoma of the esophagus, cancers of the thyroid, post-menopausal breast, gallbladder, stomach, liver, pancreas, kidney, ovarian, uterus, and colorectal. The American Association for Cancer Research now ranks excess weight as second, only to tobacco use, in relative contribution to cancer incidence.
Women have about two times greater risk than men for developing obesity-related cancer. The CDC estimates that of all cancers, 55% in women and 24% in men are related to overweight and obesity. As far as ethnicity goes, African-Americans and Caucasians had the highest rates. Overall, data shows that between 2005 and 2014, obesity-related cancers increased by roughly 7%, with colon cancer being the only exception due to new screening processes and technologies.
So what is the connection between obesity and cancer? The evidence and research is still unclear on a definitive answer, but there are several plausible explanations. Excess belly fat is known to produce the hormone estrogen, which some cancers, particularly breast and endometrial, are sensitive to. This is a potential contributing factor to the higher rates in women compared to men. This is also a serious concern for the obesity rates in children and adolescents because carrying excess weight and therefore producing excess estrogen for many years significantly heightens the risk of cancer in adulthood. Furthermore, we must look at the cause of the obesity in the first place, which is more often than not overconsumption of processed foods. These processed foods are likely high in carbohydrates, which are broken down into glucose by the body. This glucose is used as an energy source for our cells, but it is also the preferred fuel for cancer cells.
Maintaining a healthy body weight is by no means an assurance to remain cancer-free. What it will do, however, is greatly reduce the risk of developing certain types of cancer. That’s a good enough reason for me.
Yours in Health, Dr. Alex
Project Wellness Company - Madison, WI