How does obesity influence cancer risk?

An estimated 4% of cancers in men and 7% of cancers in women are associated with obesity, according to the NCI.

People who are obese are at increased risk for various cancer types, including breast, colon, endometrial, gallbladder, esophageal, pancreatic and thyroid cancers.

The percentage of cancer cases attributable to obesity during 2007 was 40% for certain cancer types, such as endometrial cancer and esophageal adenocarcinoma, according to data from the NCI.

There are various reasons for the association between obesity and cancer risk.

Fat tissue increases levels of estrogen, which is then associated with the risk for breast, endometrial and other cancer types. Tumors may develop when there are increased levels of insulin-like growth factor-1 in the blood. Obese individuals often have increased IGF-1 levels. Further, obesity is often associated with subacute inflammation, which is also associated with an increase in the risk for cancer.

Increasing data indicate losing weight may decrease the risk for cancer among obese people.

Additional information may be found at these websites:

http://www.cancer.gov/cancertopics/factsheet/Risk/obesity

http://www.cancer.org/cancer/cancercauses/dietandphysicalactivity/bodyweightandcancerrisk/body-weight-and-cancer-risk-effects

http://www.cdc.gov/obesity/data/adult.html