A high level of education is associated with a higher risk of developing brain tumours, scientists have said. This was particularly the case for gliomas - malignant tumours of the glial tissue of the nervous system - which were more frequently observed in people with a university degree.
Previous studies had already suggested that indicators of socioeconomic position like higher education, income and occupational groupings were linked to an increased risk of brain tumour. However, most findings were conflicted and biased due to poor study design.
This latest research, published in the Journal of Epidemiology & Community Health, aimed to better prevent brain tumours by investigating the connections between different indices of socioeconomic position and the incidence of three tumours - glioma, meningioma and acoustic neuroma (see box).
Education and occupation
The study is a nationwide population-based cohort, involving 4.3 million Swedes born between 1911 and 1961 and living in Sweden in 1991.
Data about their educational attainment, disposable income, marital status, and professional occupation were collected, and they were followed over nearly two decades, from 1993 to 2010, to see if they developed a primary brain tumour.
In total, 5735 brain tumours among men and 7101 among women were identified during the study period. Looking at their socioeconomic status, the researchers found out that men who had been at university for three years were 19% more likely to develop a glioma than those whose educational attainment did not extend beyond the period of compulsory schooling.
Among women, similar associations were found. The magnitude of risk was 23% higher for glioma, and 16% higher for meningioma in women with a university degree.
The evidence was less robust when it came to disposable income and marital status, but the scientists did find differences between individuals based on their professional occupations.
Compared to men and women in manual roles, working in managerial roles was associated with a 50% increased risk of acoustic neuroma among men and a 20% heightened risk of glioma among men - 26% among women.
Though the study's findings may appear quite strong because of the large number of people surveyed, the scientists recognise that they only reveal a correlation.
To explain why people of higher socioeconomic status and education seem more susceptible to brain tumours, the researchers suggest that they may have a better access to medical care and are potentially more aware of the symptoms, so they get diagnosed more frequently.
"We found that higher socioeconomic characteristics were associated with an increased risk of glioma in Swedish men and women, and to a lesser extent with acoustic neuroma in men and meningioma in women. Completeness of cancer registration and detection bias are potential explanations for the differences", the researchers concluded.
Three different types of brain tumours
In the study the scientists looked at the incidence of three different brain tumours: glioma, meningioma and acoustic neuroma.
Gliomas are malignant tumours of the glial tissue of the nervous system. The tumour arises from the glial cells that surround and support neurons in the brain.
Meningiomas are a type of mostly non-cancerous brain tumour arising in the meninges that surround the brain and spinal cord.
Acoustic neuromas are benign brain tumours of one of the nerves connecting the inner ear to the brain. Acoustic neuromas usually grow slowly and don't spread to other parts of the brain.