A large brain means more brain cells, and the more cells you have, the more cell divisions that can go wrong and create mutations that lead to cancer, said Even Hovig Fyllingen, a PhD candidate at the Norwegian University of Science and Technology (NTNU).
"Aggressive brain cancer is a rare type of cancer, but once you have it, the chance of survival is relatively low," Fyllingen said.
"Several studies have shown that the size of different organs is an important factor in cancer development. For example, women with larger breasts have a greater risk of breast cancer. We wanted to check if this was also the case for brain tumours," he said.
The research used data from the Nord-Trondelag Health Study which comprises health data and blood samples collected in multiple waves of data gathering from thousands of Norwegians in the Nord-Trondelag county region.
Fyllingen compared the data to St Olavs Hospital's neurosurgery database.
He extracted data on everyone who had been operated on for high-grade gliomas (brain tumours) between 2007 and 2015 and compared their data with healthy controls from the study.
The researchers used MRI scans to measure the size of the brain. Then 3D models were made from them so that the intracranial brain volume could be measured in millilitres.
The study also shows that more men than women develop brain tumours.
"Men have a larger brain than women because men's bodies are generally larger. It doesn't mean that men are smarter, but you need to have more brain cells to control a large body," said Fyllingen.
"This is also the case with animals. In bigger bodies, organs like the heart, lungs and brain are also bigger," he said.
Yet it turns out that women with big brains have a greater risk of developing brain tumours compared to men with big brains, researchers said.
"Seventy per cent more men than women develop brain tumours, but when we correct for head size, it's no longer beneficial to be female. Women with large brains are particularly susceptible," said Fyllingen.
