A case-case study of mobile phone use and XXXX risk in Japan.

@entity5 @entity5513
Results of case-control studies of mobile phone use and @entity5513 have been inconsistent. We conducted a case-case study of mobile phone use and @entity5513 using a self-administered postal questionnaire. A total of 1589 cases identified in 22 hospitals throughout Japan were invited to participate, and 787 cases (51%) actually participated. Associations between laterality of mobile phone use prior to the reference dates (1 and 5 years before diagnosis) and @entity5 location were analyzed. The overall risk ratio was 1.08 (95% confidence interval (CI), 0.93-1.28) for regular mobile phone use until 1 year before diagnosis and 1.14 (95% CI, 0.96-1.40) for regular mobile phone use until 5 years before diagnosis. A significantly increased risk was identified for mobile phone use for >20   min/day on average, with risk ratios of 2.74 at 1 year before diagnosis, and 3.08 at 5 years before diagnosis. Cases with ipsilateral combination of @entity5 location and more frequently used ear were found to have @entity5 with smaller diameters, suggesting an effect of detection bias. Furthermore, analysis of the distribution of left and right @entity5 suggested an effect of @entity5 -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 and recall biases. However, we 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 @entity5513 .
