Mobile Phone Use and Risk of Brain Neoplasms and Other Cancers

Prospective Study

Victoria S Benson; Kirstin Pirie; Joachim Schüz; Gillian K Reeves; Valerie Beral; Jane Green

Disclosures

Int J Epidemiol. 2013;42(3):792-802. 

In This Article

Results

Baseline data were collected between 1999 and 2005, and during that period reported mobile phone use increased rapidly. The proportion of study respondents who reported at baseline that they had used a mobile phone rose from 34% of those completing the questionnaire in 1999 to 79% of those completing the questionnaire in 2005, and the proportion reporting use for a duration of 5 or more years rose from 3% in 1999 to 32% in 2005 (Figure 1).

Figure 1.

Reported use of mobile phones by calendar year

In total, 791 710 women with a mean age at baseline of 59.5 years (standard deviation 4.9) were included in analyses of tumour incidence. During an average of 7 years' follow-up, 51 680 incident invasive cancers and 562 incident non-invasive intracranial CNS tumours occurred; neoplasms were diagnosed on average 4.2 years after baseline report of mobile phone use. Table 1 shows the characteristics of the study population, woman-years of follow-up, average years of follow-up per woman and the number of women with intracranial CNS tumours and incident cancer according to never and ever use of a mobile phone as reported at baseline for these analyses. Table 1 also includes details of diagnoses for the 16 665 women who were admitted to hospital with stroke or ischaemic heart disease during follow-up. Mobile phone users were slightly younger, lived in more affluent areas and were more likely to do strenuous exercise, to be a current user of menopausal hormone therapy and to have taken oral contraceptives than never users of a mobile phone; they also drank more alcohol on average but were less likely to be current smokers than never users.

Intracranial CNS Tumours

During follow-up, 1261 intracranial CNS tumours were reported, including 571 gliomas, 251 meningiomas, 110 pituitary tumours and 96 acoustic neuromas (the remaining 233 tumours were predominantly of unspecified type). Table 2 shows relative risks for incident intracranial CNS tumours and other cancers by ever use, daily use and duration of use of a mobile phone. The relative risk for ever use of a mobile phone for incidence of all intracranial CNS tumours taken together was 1.01, 95% CI 0.90–1.14, P = 0.82. For specific CNS tumour types, relative risks were 0.91, 0.76–1.08, P = 0.29; 1.05, 0.81–1.38, P = 0.70; 1.52, 0.99–2.33, P = 0.06; and 1.44, 0.91–2.28, P = 0.12 for glioma, meningioma, pituitary tumours and acoustic neuroma, respectively.

Further details of the relationship between use of mobile phones and incidence of intracranial CNS tumours are shown in Table 3. Relative risks did not vary much between less than daily and daily users, for all CNS tumours taken together or for each CNS tumour type separately. Duration of use of a mobile phone for 5 or more years was associated with an increased risk of acoustic neuroma (RR for 5+ years of use vs. never use, 1.88, 95% CI 1.14–3.11, P = 0.01; test for trend across categories <5, 5–9 and 10+ years of use, P = 0.03). For pituitary tumours, the RR was increased in short-term mobile phone users with duration less than 5 years (RR = 2.31, 95% CI 1.31–4.06, P = 0.004) but there was no evidence for a trend in risk with increasing duration of use (P = 0.23). Excluding the first 3 years of follow-up, or excluding women who answered questions about their use of mobile phones in 1999/2000, did not materially change the findings (Table 3).

National incidence data showed no overall increase in the incidence of acoustic neuroma (ICD-10 D33.3) in either men or women at ages 20–79 years in England from 1998 to 2008 (Figure 2). Trends were similar in men and women, but confidence intervals were wide, as in each year there were only about 160 acoustic neuromas registered in men and 170 in women.

Figure 2.

Annual incidence rates for acoustic neuroma (ICD-10 D33.3), for men and women aged 20–79 years, England, 1998 to 200812

Other Cancers

Risk of all invasive cancers combined was slightly reduced in mobile phone users compared with never users: ever vs never use, RR = 0.97, 95% CI 0.95–0.99, P < 0.001). No significant associations were seen between mobile phone use and risk of cancers of the eye and thyroid, or of other head and neck cancers (Table 2). Nor was ever use of a mobile phone significantly associated with increased risk of invasive cancer at the 15 other sites examined. A significantly reduced risk was found for lung cancer in ever vs never users (RR 0.89, 95% CI 0.84–0.95, P = 0.001).

Vascular Disease

During follow-up, 4073 women had a first hospital admission for stroke and 12 592 had a first admission for ischaemic heart disease. As shown in Table 2, ever use of a mobile phone was associated with a reduced risk of stroke (RR for ever vs never use, 0.88, 95% CI 0.82–0.94, P < 0.001), but not with risk of admission for ischaemic heart disease (RR 1.04, 95% CI 1.00–1.08, P = 0.06).

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