The Interphone study on use of mobile phones and brain tumour risk included 13 countries during the study period 2000 – 2004. The major results were published after a delay of 6 years in 2010. In the last decile of cumulative exposure > 1,640 h a statistically significant increased risk for glioma was found, OR = 1.40, 95 % CI =1.03-1.89. In the other categories of cumulative use a decreased risk was found. Bias and confounding were discussed as potential reasons for that. Analysing only subjects with regular use of a mobile phone yielded OR = 1.82, 95 % CI = 1.15-2.89 in the group with highest cumulative use.
There was an age difference between cases and controls in the Interphone study and furthermore cases and the matched controls were interviewed at different time periods, controls usually later than cases. This is problematic for mobile phone use with rapid penetration of the use in the population. In a recently published alternative analysis, cases and controls nearest in age and time for interview were included. The association between mobile phone use and glioma was strengthened thereby. Thus, among regular users in the 10th decile (> 1,640 h) cumulative use gave OR = 2.82, 95 % CI = 1.09-7.32. The authors concluded that there was ‘stronger positive association among long-term users and those in the highest categories of cumulative call time and number of calls.’.
Since the IARC evaluation in 2011 on exposure to radiofrequency radiation form mobile phones, and other devices that emit such radiation, and brain tumour risk additional research has strengthened the association. It is by now time to re-evaluate the scientific evidence on the cancer risk from radiofrequency radiation.