Obesity may increase brain tumor risk

A new study has found that obesity may lead to development of some types of brain tumor. The report published in the journal Neurology, suggested that people who are overweight or obese are at an increasing risk of developing a type of brain tumor known as meningioma. According to the study, the risk was said to increase by 54% for obese people and 21% for those who are overweight.

According to the Centers for Disease Control and Prevention (CDC), 69% of adults aged 20 and over in the U.S. are either overweight or obese. Obesity is the step after overweight. A study conducted in 2003 showed that obese or overweight adults aged 50 or over, accounted for 14% (in men) and 20% (in women) of all cancer deaths in the U.S. This risk could be avoided by losing only 12 pounds.
Out of approximately 688,000 people living with a primary brain tumor or central nervous system tumor in the United States, 138,000 have benign tumors and 550,000 have malignant tumors.

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Meningioma – accounting for about 30 percent of brain tumors, arises from meninges – the membranes surrounding the brain and spinal cord. The odds of developing meningioma are about five to eight cases per 100,000 each year. Although most meningiomas are benign (noncancerous), rarely, some are found to be malignant (cancerous). Some meningiomas are in between benign and malignant and are classified as atypical.

Meningiomas are most common in older women. But, males at any age are also at risk. This type of tumour grows slowly, but can be fatal when they grow bigger and interfere with brain functions.
The other type of brain tumor which the study - carried out by Gundula Behrens, PhD. of the University of Regensburg, Germany, focused on is known as Glioma.

About 33 percent of brain tumors are glioma. It got its name from glial cells in the brain where it grows. Glial cells are the tissue that surrounds and supports the brain neurons. These types of tumors are called intrinsic brain tumors because they reside within brain matters and frequently blend with normal brain tissue. [Read more Avoid obesity: Have home-cooked meals, turn off the TV while eating]

Malignant tumors in the brain are very difficult to fight. American Academy of Neurology (AAN) blames prior exposure to brain radiation as the most solid risk factor for developing brain tumor. But for the more than 120 types of brain tumor, the cause is still a mystery.
The study team was led by Gundula Behrens from the University of Regensburg in Germany. She and her team attempted to find out what role did weight and physical activity play on the risk of developing meningioma and glioma.

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The team studied the meta-analyses of 18 previous researches that involved Body Mass Index (BMI) and physical activity of 2,982 patients with meningioma and 3,057 patients with glioma.

Study showed that people who were overweight with 25 to 29.9 BMI were 21% more likely to develop meningioma, and people who were obese with a BMI of 30 or over were 54% more likely to develop glioma, compared with people with a healthy body weight and BMI of below 24.9.
The study also showed that people who were very active in physical activities were 27% less likely to develop meningioma than the people with least amount of physical activity.

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“Given the high prevalence of obesity and the unfavorable prognosis for this type of tumor, these findings may be relevant for strategies aimed at reducing the risk of meningioma,” said Behrens.
The researchers didn’t find any relationship between overweight and glioma, which has a similar rate of occurrence as meningioma.
 
Behrens believes that excess weight and increased risk of meningioma might be linked with several biological processes.

Estrogen is known to facilitate the development of meningioma and excess weight entails a higher rate of estrogen production. Excess weight is also linked with high insulin levels which might facilitate the growth of meningioma.

The lead author also pointed out that while the study links excess weight and inadequate exercise with meningioma, it does not prove that this is actually the cause. She thinks that people with meningioma may have lessened their physical activity from the time they were diagnosed with the tumor.

This analysis supports an earlier conclusion drawn in 2008 by a study that said that "the incidence of glioma or meningioma tumors increases with increasing height and increasing BMI."
The 2008 analysis was published in British Journal of Cancer.