Handheld cellular telephone use and risk of brain cancer

Context A relative paucity of data exist on the possible health effects of using cellular telephones. Objective To test the hypothesis that using handheld cellular telephones is related to the risk of primary brain cancer. Design and Setting Case-control study conducted in 5 US academic medical centers between 1994 and 1998 using a structured questionnaire. Patients A total of 469 men and women aged 18 to 80 years with primary brain cancer and 422 matched controls without brain cancer. Main Outcome Measure Risk of brain cancer compared by use of handheld cellular telephones, in hours per month and years of use. Results The median monthly hours of use were 2.5 for cases and 2.2 for controls. Compared with patients who never used handheld cellular telephones, the multivariate odds ratio (OR) associated with regular past or current use was 0.85 (95% confidence interval [CI], 0.6-1.2). The OR for infrequent users (<0.72 h/mo) was 1.0 (95% CI, 0.5-2.0) and for frequent users (>10.1 h/mo) was 0.7 (95% CI, 0.3-1.4). The mean duration of use was 2.8 years for cases and 2.7 years for controls; no association with brain cancer was observed according to duration of use (P=.54), In cases, cerebral tumors occurred more frequently on the same side of the head where cellular telephones had been used (26 vs 15 cases; P=.06), but in the cases with temporal lobe cancer a greater proportion of tumors occurred in the contralateral than ipsilateral side (9 vs 5 cases; P=.33). The OR was less than 1.0 for all histologic categories of brain cancer except for uncommon neuroepitheliomatous cancers (OR, 2.1; 95% CI, 0.9-4.7). Conclusions Our data suggest that use of handheld cellular telephones is not associated with risk of brain cancer, but further studies are needed to account for longer induction periods, especially for slow-growing tumors with neuronal features.