New research suggests that weight and physical activity levels may affect the risk of certain brain cancer.
Excess weight was associated with a higher risk of a type of brain cancer known as meningioma. The study found that obesity increased the risk of meningioma by 54% and being overweight increased the risk by 21%.
Conversely, people who were physically active reduced the risk of meningioma by 27%.
The study additionally found that being heavier was not linked to the risk of a second deadlier form of brain cancer called glioma. Although there was an association between more physical activity and a lower risk of glioma, the association was too weak and therefore was not statistically significant.
The study was able to show an association between weight and physical activity and the risk of meningioma, unfortunately it was not designed to prove a cause-and-effect relationship.
Meningioma and glioma are the most common types of brain tumors in adults, however these tumors remain relatively rare.
Five years after a diagnosis, 63% of people with meningioma will still be alive. On the other hand, glioma is far more deadly, there is only a 4% survival rate at five years.
About 5 to 8 people of every 100,000 will be diagnosed with meningioma every year. About five to seven of every 100,000 people will receive a glioma diagnosis in a given year.
The current research was a review of 18 previous studies involving more than 6,000 people. Some of the studies compared patients with healthy counterparts. Some studies looked at body mass index and cancer risk while other looked at physical activity and cancer risk.
Researchers assert that the relationship between meningioma risk and exercise may be more complicated. It is possible that brain tumor symptoms led some patients to reduce their normal physical activity even before their diagnosis.