According to WHO, being overweight or obese is the second most important preventable cause of cancer after tobacco. Â More than 630,000 people in the U.S. are diagnosed with a cancer associated with overweight and obesity. Obesity is a leading cancer risk factor.
The link between obesity and heart disease and diabetes are well considered. Â However, there is the emerging link between obesity and cancer.
According to a study by WHOâ€™s Cancer research agency, obesity is to blame for nearly half a million cases of cancer a year, with overweight women at a far greater risk than men are. A group of researchers at Comell University in New York found that obesity results in stiffer breast tissue that promotes the growth of cancer.
The World Cancer Research Fund also stated that the cumulative evidence of the link between putting too much weight and advanced prostate cancer is strong.
In India, the National Family Health Survey, a government health survey, found that number of overweight men in the country has doubled over the past decade. In case of women, one in five women is overweight. A study done by National Cancer Institute, Maryland(US), revealed that excess of weight during the early 20s puts one at an increased risk of developing cancer as compared to those who maintained a healthy weight throughout life.
How obesity increases the risk of cancer:-
- Obese people have increased blood levels of insulin and insulin â€“like growth factors-1(IGF-1). High levels of insulin and IGF-1 may promote the development of kidney, colon, and prostate cancers.
- Fat tissue produce excess amounts of estrogen, high levels of which have been associated with increased risk of breast, ovarian and some other cancers.
- Fat cells produce Adipokines (hormone) that may stimulate or inhibit call growth.
- Fat cells may also have direct or indirect effects on tumor growth regulators; including Mammalian target of rapamycin (Mtor) and AMP-activated protein kinase.
- People with obesity often have chronic low-level unresolved inflammation, which has been associated with increased cancer risk.
- Other possible mechanism includes altered immune responses, effect on the nuclear factor Kappa B system and Oxidative stress.
Different cancers have been associated with obesity are following:-
- Multiple Myeloma(cancer of blood cells)
- Adenocarcinoma of the esophagus
- Meningioma(Cancer of the tissue covering the brain and spinal cord
Obesity continues to be one of the critical health issues worldwide. Controlling body weight through proper diet and exercise is very important to keep cancer at bay.