The study, by researchers from Austria, Norway, and Sweden who were funded by World Cancer Research Fund (WCRF), suggests people with high blood pressure are more likely to be diagnosed with brain tumours and that for some types the risk may be double.
The researchers took the blood pressure measurements of 580,000 people and then looked to see if they later went on to develop a benign or malignant brain tumour.
A total of 1,312 of participants in the study, which has been published in the Journal of Hypertension, were diagnosed with a brain tumour during the follow-up (an average of 10 years after their blood pressure was measured).
The results suggested the 20 per cent of participants with the highest blood pressure readings were twice as likely to later be diagnosed with meningioma or malignant glioma (types of brain tumour that accounted for 784 of the 1,312 cases in the study) as the 20 per cent with the lowest readings.
Scientists have urged caution because while the findings are interesting –particularly as little is known about the cause of brain tumours – more research would be needed before it is possible to be confident that high blood pressure really does increase risk of brain tumour, of which about 9,000 cases are diagnosed in the UK every year.
Dr Rachel Thompson, Deputy Head of Science for WCRF, said: “Because this is a single study, the jury is still out on whether the high blood pressure is what caused the increased brain tumour risk among the people in this study or whether there is another unexplained reason for it. We would want to see this finding repeated by other studies before we could be confident that blood pressure really is a risk factor for brain tumours.
“But regardless of whether the findings of this study are confirmed or disproved by further research, there are very good reasons why having high blood pressure is a bad thing.
“While the possible link between blood pressure and cancer needs more research, it is already well-established that having high blood pressure increases risk of strokes and heart disease. And there is strong evidence that having too much salt in your diet and being overweight, which both increase risk of high blood pressure, also increase risk of cancer.”
Michael Edlinger, epidemiologist at the Medical Statistics Department in Innsbruck in Austria, the lead researcher of the study, said: “These results are interesting because the large number of people in this study and the fact that more than 1,000 of them developed brain tumours mean it is unlikely that the findings are down to chance.
“But this does not mean we can be confident that it is the high blood pressure that has caused the increase in brain tumour risk, as there are some limitations to our study.
“For example, we did not have data on whether the participants were using any medication, such as treatment for high blood pressure, which could have affected the results. And just like with the more speculative claims of mobile phone risks, we do not exactly know how such risks could work to cause the occurrence of these tumours.
“This is why more research is needed into whether high blood pressure increases risk of brain tumour.”
World Cancer Research Fund (WCRF) raises awareness that cancer is largely preventable and helps people make choices to reduce their chances of developing the disease.
This includes research into how cancer risk is related to diet, physical activity, and weight management, and education programmes that highlight the fact that about a third of cancers could be prevented through changes to lifestyle. For more information on the charity’s work, visit www.wcrf-uk.org
The WCRF report, called Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective, was launched in November 2007 and is the most comprehensive report ever published on the link between cancer and lifestyle. For more information, visit www.dietandcancerreport.org