Obesity is an important health issue in the world.
It is estimated that 640 million adults in 2014 and 110 million children and teenagers in 2013 are obese. In men, about 10.8% have obesity; and in women, about 15% are obese.
Overweight and obesity are often caused by lifestyle factors, such as too much energy intake from food and drink, and too little physical activity.
A recent study shows that excess body weight is related to 8 more cancers, and that losing body fatness can lower the cancer risks. The finding is published in The New England Journal of Medicine.
The 8 cancers include cancers of meningioma (a type of brain tumor), gastric cardia (part of the stomach), liver, gallbladder, pancreas, ovary, thyroid, and multiple myeloma (a blood cancer).
In 2002, the International Agency for Research on Cancer (IARC, Lyon, France) reported that losing body fatness could lower the risk of 5 cancers: colon, esophagus (the pathway between pharynx and the stomach), kidney, breast, and corpus uteri cancers.
To examine the relations between excess body weight and cancer risk, researchers from IARC conducted a review about 1000 observational studies.
Most studies provided risk estimates for adult BMI, while some other studies estimated BMI or body shape, change of BMI and weight over time, and waist circumference.
Researchers found that positive relations were shown between BMI and cancer risk, between waist circumference and cancer risk, and between body weight and cancer risk. In addition, the associations were consistent across places in the world.
Moreover, data on weight loss showed that intentional body weight loss could reduce the risk of most cancer.
Researchers suggest that excess body fat can lead to an overproduction of estrogen, testosterone and insulin, which can cause cancer growth.
Therefore, reducing calorie intake to limit weight gain can help prevent tumor development or progression. Weight loss programs should be included in cancer prevention.