Background: Case-control studies have reported an increased risk of brain tumors after 10 or more years of cell phone use. Objective: To model brain cancer trends by extracting characteristic risk functions from reported data and to use these for projecting future trends accounting for possible influences from mobile phone use. Methods: Normally occurring DNA brain cell damage during one year was assumed to be associated with a cancer risk function that is increasing over time but balanced by a DNA repair function reducing the amount of potential carcinogen damages over time. By model parameter adjustments of risk functions, calculated age-adjusted rates were made to best fit the reported data. The model also accounted for increasing levels of initial DNA brain damage or decreasing repair efficiency, caused by cell phone use. Results: DNA brain cell damage has an average latency time of over 30 years before increased brain cancer rates would be expected. Mobile phone use may lead to a reduced DNA repair function resulting in about a 2-fold increase in brain cancer incidence, or with an increasing rate of initial DNA brain damage from mobile phone use a 25-fold increase in brain cancer incidence may result.