Epidemiological study (observational study)

Association between vestibular schwannomas and mobile phone use epidem.

By: Moon IS, Kim BG, Kim J, Lee JD, Lee WS

Published in: Tumour Biol 2014; 35 (1): 581-587

Aim of study (acc. to author)

The association between vestibular schwannoma and mobile phone use was investigated in a case-control study and a case-case analysis in South Korea.

Further details

Regular mobile phone use was defined as having made or received a call on average at least once per week during at least 6 months.
In the case-case analysis the location and tumor volume were analyzed using imaging and a three-dimensional volume calculation.

Endpoint/type of risk estimation

brain tumor: vestibular schwannoma

Type of risk estimation:

incidence

(odds ratio (OR))

Exposure

- mobile communications
- mobile phone
- personal

Assessment

questionnaire: start of mobile phone use, average daily number of outgoing and incoming calls, average call duration, dominant hand, proportion of calls using the left and right ears, hands-free device use
calculation: average daily amount of mobile phone use was calculated by multiplying the average number of calls per day by the average talk time of one call; cumulative hours of mobile phone use were calculated by multiplying the average daily amount of mobile phone use by the duration of mobile phone use.

Exposure groups

Group	Description
Group 1	mobile phone use ≤ 10 years: short-term use
Group 2	mobile phone use > 10 years: long-term use
Group 3	daily amount of mobile phone use ≤ 20 min: light daily use
Group 4	daily amount of mobile phone use> 20 min: heavy daily use
Group 5	cumulative mobile phone use ≤ 2,000 hours: cumulative light use
Group 6	cumulative mobile phone use > 2,000 hours: cumulative heavy use
Group 7	preferred ear during call > 75% on the same side as the tumor: ipsilateral
Group 8	preferred ear during call > 75% opposite to tumor location: contralateral

Population

Group:
- men
- women
Age: ≥ 18 years
Observation period: January 1991 - December 2010
Study location: South Korea (Seoul)

Case group

Characteristics: vestibular schwannoma, pathologically confirmed
Data source: Department of Otorhinolaryngology at Severance Hospital, Seoul

Control group

patients who received comprehensive routine medical checkups (including brain MRI) in the same hospital
Matching:
- sex
- age
- general health conditions
- case:control = 1:2

Study size

	Cases	Controls
Eligible	207	-
Contacted	134	-
Participants	119	238
Participation rate	89 %	-

Statistical analysis method:

logistic regression
Chi-square test
Fisher's exact test

Results (acc. to author)

The results of the case-control study showed no association between mobile phone use and vestibular schwannoma (OR 0.956, CI 0.906-1.009).
In the case-case analysis, the average tumor volume of regular mobile phone users was significantly larger than that of non-regular users (OR 1.125, CI 1.041-1.216). Restricting the analysis to regular users, there was no significant difference (OR 1.045, CI 0.987-1.107) in tumor size between long-term users (group 2) and short-term users (group 1), but a significant difference was observed between heavy users (group 4) and light users (group 3) based on daily amount of use (OR 1.073, CI 1.008-1.141) and between cumulative heavy users (group 6) and light users (group 5) based on estimated cumulative hours (OR 1.088, CI 1.023-1.157). When the analysis was further limited to regular users who had serviceable hearing, a difference (OR 4.5, CI 0.585-34.6) was observed between ipsilateral users (n=12) and contralateral users (n=6).
The authors conclude that tumors may coincide with the more frequently used ear of mobile phones and tumor volume that showed strong correlation with amount of mobile phone use, thus there is a possibility that mobile phone use may affect tumor growth.

Study funded by

National Research Foundation (NRF) of Korea

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