Neurosurgeon and stem cell scientist viviane tabar and colleagues at memorial sloan-kettering cancer center in new york city first took glioma samples from the operating room and looked for chromosomal abnormalities in the endothelial cells lining the tumor 's blood vessels .
The raw data , in fact , showed that " long-term heavy use " - that is , talking on a cell phone for 30 minutes a day for 10 years - increased the odds of developing glioma by 40 percent .
However , a breakdown of the latest findings , seen bythe daily telegraph , shows that six of eight interphone studies found some rise in the risk of glioma ( the most common brain tumour ) , with one finding a 39 per cent increase .