Evaluation of brain cancer risk from cellular phone use

The wide use of cellular phones has raised public concern for its possible relationship with cancer risk because the radio frequency exposure from cellular phones has been suspected as a possible carcinogen. However, the data for evaluating the issue is limited especially for the long term effects because only within the past decade has cellular phone use become nearly ubiquitous. Current results from case-control studies are inconsistent. Recently, a study from the nationwide Danish cohort showed no large association between cellular phone use and cancer risk. To evaluate the possible association between cellular phone use and cancer risk, the cohort data has been re-analyzed and the statistical power was estimated. The results suggested that the cohort data had enough statistical power to detect the weak association (>2% increase) with the overall cancer risk. However, the statistical power for brain tumors was inconsistent. The cohort data had 94% and 99% power to detect 15% and 20% increase in cancer risk respectively, but the power was sharply reduced to 22% and 66% for 5% and 10% increase in brain tumor risk respectively. The cohort data did not have enough statistical power to detect a lower increase in brain tumor risk. Suspected association of the wide use of cellular phones could be small and mainly related to brain tumors. Overall, there is no evidence to rule out cellular phone's carcinogenic effect for brain tumors yet; the possible increase in brain tumor risk could be lower. Further studies should be conducted.