(CNN) -- More than 100,000 cases of cancer each year are caused by excess body fat, according to a report released Thursday in Washington.
Researchers with the American Institute for Cancer Research looked at seven cancers with known links to obesity and calculated actual case counts that were likely to have been caused by obesity.
Specifically, the report says that 49 percent of endometrial cancers are caused by excess body fat. That number is followed by 35 percent of esophageal cancer cases; 28 percent of pancreatic cancer cases; 24 percent of kidney cancer cases; 21 percent of gallbladder cancer cases; 17 percent of breast cancer cases; and 9 percent of colorectal cancer cases.
"This is the first time that we've put real, quantifiable case numbers on obesity-related cancers," said Glen Weldon, the American Institute for Cancer Research educational director. In addition, he said, it's not just causing cancer that's an issue.
"Obesity not only raises the risk for getting cancer," Weldon said. "It also has a negative effect on survival and can make treatment more difficult."
Although there is no concrete science on why obesity increases a person's risk for cancer, scientists hypothesize that excess estrogen released by body fat could be the culprit in cancers such as estrogen-receptor positive breast cancers.
Studies have also shown that increased body fat can lead to increased levels of oxidative stress and inflammatory compounds in the blood, which are linked to DNA mutation and diseased cell growth, as is seen in many cancers.
The American Cancer Society applauded the new research, but said the report is only the first step.
"This helps to communicate the magnitude of the problem," said Dr. Michael Thun, vice president emeritus at the American Cancer Society.
"While the study addresses the magnitude of the problem, it does not propose potential solutions. The bottom line for people concerned about this issue is to try to balance the calories you take in with those your body expends every day."
In addition to cancer, obesity is a known cause of heart disease, diabetes, high blood pressure and strokes.
