What Is Known About the Link Between Obesity and Cancer?

Several recent studies have established a link between being overweight and developing cancer. Many people mistakenly believe that cancer is predominantly an inherited condition. This is not the case. Every individual has an innate or acquired susceptibility to specific types of cancer. However, in the majority of cases, this susceptibility leads to the actual development of cancer only after being driven by one or more external risk factors. One such risk factor is obesity.

Steadily on the rise in America, obesity recently overtook tobacco use as the number one preventable cause of cancer deaths in the United States. The operative word here is “preventable.” Some cancer risk factors, such as advancing age, cannot be avoided. But it is possible to avoid obesity by achieving a healthy body weight through positive lifestyle choices, such as eating a healthy diet, staying physically active, getting enough sleep, and managing stress.

Excess body weight is believed to influence cancer risk through a number of mechanisms. For instance, it can affect the body’s:

• Metabolic and immune system function
• Inflammatory response
• Levels of hormones and growth factors, such as insulin, estrogen, and leptin
• Insulin resistance
• Proteins that influence how the body uses certain hormones, such as sex hormone-binding globulin
• Cellular growth patterns
• Production of gallstones
• Blood pressure

In many ways, the current trend toward body acceptance is positive. However, it can potentially be dangerous if being overweight is viewed as “normal” and the associated risk factors are ignored. Confirmed research shows that obese individuals experience a higher risk of developing cancer, worse outcomes after diagnosis, faster metastasis, and a diminished response to chemotherapy and other treatments, among other things.

“According to the American Institute of Cancer Research, for every 5-point increase in BMI, there is a 50% relative increase in the risk of developing endometrial cancer and a 6% relative increase in the risk of developing ovarian cancer," said Dr. Monica Avila, a gynecologic oncologist in the Gynecologic Oncology Program. "We now know that the excess estrogen stored in fat is driving the formation of tumors. Talk to your doctor today about ways to decrease your cancer risk." 

While the exact connection between excess body fat and cancer is very complex and not completely understood, there is sufficient evidence of a causal relationship to support a general recommendation that all individuals – both adults and children – achieve and maintain a healthy body weight. This can not only decrease the risk of developing cancer, but also provide a multitude of other health and wellness benefits.