Mobile phone use and risk of glioma in adults: Results are difficult to interpret because of limitations

EDITOR—The UK part of the Interphone study concluded that mobile phone use is not associated with an increased risk of glioma.1 However, ≥ 10 years ipsilateral use yielded an odds ratio of 1.60 (95% confidence interval 0.92 to 2.76) and contralateral use an odds ratio of 0.78 (0.85 to 1.3).

Only 51% of the cases and 45% of the controls participated. Controls were more affluent than non-participating controls and participating cases. Mobile phone use is associated with social class. In our study use of cellular telephones was reported by 48% of the most affluent cases and 36% of the least affluent.2 3

Credit: MARTIN LEE/REX

Use of cordless telephones was not assessed and in the analysis of laterality the “unexposed” group contained subjects with exposure to microwaves on the opposite side of the head.

In table 3, 13 of the 14 odds ratios are < 1.0 and one is > 1.0, indicating non-random variation. Patients with brain tumours (cases) may not be best interviewed face to face shortly after their operation because of cognitive behavioural defects such as memory loss and aphasia. The interviewers knew that it was a case under interview.

Our publication on malignant brain tumours on this topic is not cited, though available on 14 July 2005.4 We found an increased risk for high grade astrocytoma with > 10 years' latency. The current publication does not give results for high and low grade glioma separately.1

The article cites critics of our studies published even before our results appeared in the scientific literature. Two of the cited reports have never been published in a peer reviewed journal and are not possible to rebut. The third cited report was published in 2000, when our first large case-control study was ongoing and no data had been reported.