The bigger your brain, the greater your risk for a deadly brain cancer, new research from Norway suggests.
It's a matter of math: A large brain means more brain cells, and more cells means more cell divisions that can go wrong and cause mutations that trigger cancer, the study authors explained.
"Aggressive brain cancer is a rare type of cancer, but once you have it, the chance of survival is relatively low," said researcher Even Hovig Fyllingen, a Ph.D. student at the Norwegian University of Science and Technology, in Trondheim.
According to the researchers, lifestyle makes a difference for some cancers. For example, people who smoke have a greater risk of lung cancer than nonsmokers. But when it comes to brain cancer, lifestyle matters far less.
Studies have shown that the size of some organs may be important in whether cancer develops. For example, women with large breasts are at a greater risk for breast cancer.
"We wanted to check if this was also the case for brain tumors," Fyllingen said in a university news release.
For the study, Fyllingen and his colleagues used data from the Nord-Trondelag Health Study, which includes health information and blood samples collected from thousands of Norwegians in the Nord-Trondelag area.
Fyllingen used the third version of the survey and compared it with St. Olav's Hospital's neurosurgery database.
The investigators looked at everyone who had surgery for high-grade brain tumors between 2007 and 2015, and compared that data with healthy people from the Nord-Trondelag Health Study.
The researchers used MRI scans to measure the size of the brain and made 3D models so they could measure the intracranial brain volume.
The findings showed that more men than women developed brain tumors.
"Men have a larger brain than women because men's bodies are generally larger," Fyllingen said. "It doesn't mean that men are smarter, but you need to have more brain cells to control a large body."
But it turns out that women with big brains have a greater risk of developing brain tumors, compared with men with big brains, the researchers found.
"Seventy percent more men than women develop brain tumors, but when we correct for head size, it's no longer beneficial to be female," Fyllingen said. "Women with large brains are particularly susceptible. Why that is I have no idea."
The researchers also didn't prove that brain size correlates with cancer risk, just that there was an associaton.
The findings were published recently in the journal Neuro-Oncology.
For more on brain tumors, visit the National Brain Tumor Society.
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