Study type: Epidemiological study (observational study)

A case-case study of mobile phone use and acoustic neuroma risk in Japan. epidem.

Published in: Bioelectromagnetics 2011; 32 (2): 85-93

Aim of study (acc. to author)

A case-case study was conducted in Japan to investigate the association between mobile phone use and the risk of acoustic neuroma.

Further details

Only persons with an acoustic neuroma are included in this case-case study, the affected ear is regarded as the case side, while the opposite ear is regarded as the control side.
Mobile phone use before the two reference dates (1 and 5 years before diagnosis) was analyzed. Regular mobile phone use was defined as using a mobile phone at least once a week for 6 months or longer.

Endpoint/type of risk estimation

Type of risk estimation: (relative risk (RR))

Exposure

Assessment

Exposure groups

Group Description
Group 1 mobile phone use 1 year before diagnosis; years since start of mobile phone use: ≤ 5
Group 2 mobile phone use 1 year before diagnosis; years since start of mobile phone use: 5-10
Group 3 mobile phone use 1 year before diagnosis; years since start of mobile phone use: >10
Group 4 mobile phone use 1 year before diagnosis; weighted average number of calls/day: ≤ 1
Group 5 mobile phone use 1 year before diagnosis; weighted average number of calls/day: 1-3
Group 6 mobile phone use 1 year before diagnosis; weighted average number of calls/day: 3-5
Group 7 mobile phone use 1 year before diagnosis; weighted average number of calls/day: > 5
Group 8 mobile phone use 1 year before diagnosis; weighted average duration of one call: ≤ 1 min
Group 9 mobile phone use 1 year before diagnosis; weighted average duration of one call: 1-3 min
Group 10 mobile phone use 1 year before diagnosis; weighted average duration of one call: 3-5 min
Group 11 mobile phone use 1 year before diagnosis; weighted average duration of one call: > 5 min
Group 12 mobile phone use 1 year before diagnosis; weighted average daily call duration: ≤ 3 min
Group 13 mobile phone use 1 year before diagnosis; weighted average daily call duration: 3-10 min
Group 14 mobile phone use 1 year before diagnosis; weighted average daily call duration: 10-20 min
Group 15 mobile phone use 1 year before diagnosis; weighted average daily call duration: > 20 min
Group 16 mobile phone use 5 year before diagnosis; years since start of mobile phone use: ≤ 5
Group 17 mobile phone use 5 year before diagnosis; years since start of mobile phone use: 5-10
Group 18 mobile phone use 5 year before diagnosis; years since start of mobile phone use: >10
Group 19 mobile phone use 5 year before diagnosis; weighted average number of calls/day: ≤ 1
Group 20 mobile phone use 5 year before diagnosis; weighted average number of calls/day: 1-3
Group 21 mobile phone use 5 year before diagnosis; weighted average number of calls/day: 3-5
Group 22 mobile phone use 5 year before diagnosis; weighted average number of calls/day: > 5
Group 23 mobile phone use 5 year before diagnosis; weighted average duration of one call: ≤ 1 min
Group 24 mobile phone use 5 year before diagnosis; weighted average duration of one call: 1-3 min
Group 25 mobile phone use 5 year before diagnosis; weighted average duration of one call: 3-5 min
Group 26 mobile phone use 5 year before diagnosis; weighted average duration of one call: > 5 min
Group 27 mobile phone use 5 year before diagnosis; weighted average daily call duration: > 5 min
Group 28 mobile phone use 5 year before diagnosis; weighted average daily call duration: ≤ 3 min
Group 29 mobile phone use 5 year before diagnosis; weighted average daily call duration: 3-10 min
Group 30 mobile phone use 5 year before diagnosis; weighted average daily call duration: 10-20 min

Population

Study size

Type Value
Eligible 1,589
Participants 804
Evaluable 787

Conclusion (acc. to author)

Overall, no statistically significant increased risk of acoustic neuroma was identified for regular mobile phone use compared to non-use, with risks of 1.08 (CI 0.93-1.28) for use until 1 year before diagnosis and 1.14 (CI 0.96-1.40) for use until 5 years before diagnosis. A significantly increased risk was observed in cases who reported having used mobile phones on the affected ear for >20 min/day on average (RR 2.74 at 1 year before diagnosis (CI 1.18-7.85) and RR 3.08 at 5 years before diagnosis (CI 1.47-7.41)). Cases with ipsilateral combination of tumor location and more frequently used ear were found to have tumors with smaller diameters, suggesting an effect of detection bias. Furthermore, analysis of the distribution of left and right tumors suggested an effect of tumor-side-related recall bias for recall of mobile phone use at 5 years before diagnosis.
The increased risk identified for mobile phone users with average call duration >20 min/day should be interpreted with caution, taking into account the possibilities of detection bias and recall bias. However, the authors could not conclude that the increased risk was entirely explicable by these biases, leaving open the possibility that mobile phone use increased the risk of acoustic neuroma.

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