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.
|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|
|Participation rate||89 %||-|
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.