Case-control study on the use of mobile and cordless phones and the risk for malignant melanoma in the head and neck region

The incidence of cutaneous malignant melanoma has increased during the last decades in Sweden as in many other countries. Besides of ultraviolet radiation and constitutional factors such as light-sensitive skin and poor ability to tan few risk factors are established. Some studies indicate that electromagnetic fields might be of concern. In this case-control study we assessed use of mobile and cordless phones in 347 cases with melanoma in the head and neck region and 1184 controls. These subjects constituted 82% and 80%, respectively, that answered the questionnaire. Overall no increased risk was found. However, in the most exposed area; temporal, cheek and ear, cumulative use >365h of mobile phone yielded in the >1-5-year latency group odds ratio (OR)=2.1, 95% confidence interval (CI)=0.7-6.1 and cordless phone use gave OR=2.1, 95% CI=1.1-3.8. Highest OR was calculated for first use of mobile or cordless phone before the age of 20 years regardless of anatomical localisation in the head and neck region. No interaction was found with established risk factors such as red, medium blond or fair hair colour, blue eyes, skin type I or II (never or sometimes tanned), severe sunburns as teenager or heredity. The results must be interpreted with caution due to low numbers and potential methodological shortcomings in a case-control study. However, the findings might be consistent with a late carcinogenic effect from microwaves, i.e. tumour promotion, but need to be confirmed.