Many studies have reported on the link between obesity and cancer.  A review by Brown and Ligibel, published in the Journal of the American College of Cardiology, clearly explains some of the most recent evidence concerning the relationship between excess weight and cancer.  The researchers report that “It is estimated that up to 20% of all cancers are caused by obesity.”

In 2014, The American Institute for Cancer Research (AICR) issued a report linking obesity to higher incidence of many cancers:  ovarian, breast (post-menopausal), endometrial, kidney, gallbladder, esophagus, pancreatic, and colorectal.  (This was later updated to include cancers of the prostate, liver, stomach, mouth, pharynx and larynx.)

The researchers estimated that over 120,000 cases of cancer occurring in the United States every year are attributable to excess body fat. The figure has increased steadily, from the 100,000 preventable cases of cancer cited in 2009 to almost 117,000 estimated in 2013. More obesity-related cancers and increases in incidences have led to the increased estimates.

From the report:  “One third of US adults are obese and another one third are overweight, according to the most recent government statistics. And approximately one-third of children and adolescents ages 6 to 19 are overweight or obese.

“There are several ways in which excess body fat may increase cancer risk. Fat tissue produces proteins called cytokines that can cause chronic inflammation, which increases cancer risk. Being overweight and obese also increases blood levels of insulin and related hormones that can spur the growth of cancer cells.

“In total, AICR/WCRF estimates that approximately 375,000 cases of the most common cancers in the United States can be prevented each year by eating a healthy diet, undertaking regular physical activity, being at a healthy weight and limiting alcohol consumption.”

See here for The National Cancer Institute’s summary about the relationship between obesity and cancer.