Is brain cancer an occupational disease of cardiologists?

OBJECTIVE: To assess the plausibility of radiation as a cause of the statistically unusual event of two cardiologists in Toronto, Ontario who were diagnosed with brain tumours in 1997.
DESIGN: Computation of the expected occurrence of brain cancer in Ontario cardiologists and review of the epidemiological literature pertaining to radiation and brain cancer. DATA SYNTHESIS: The occurrence of these two cases is a statistically unusual event--a 'cluster'. There are several plausible explanations for this cluster. First, this may be a chance occurrence, and the tumours may have no causative factors in common. Second, the cause may be radiation exposure. A connection to occupational radiation exposure is biologically plausible, but risk assessment suggests that it is unlikely that this effect would have been observable in the small population of Ontario cardiologists.
CONCLUSIONS: Initiation of brain tumours during cardiac fluoroscopic procedures is plausible. Physicians are reminded to practise radiation safety methods during fluoroscopic procedures. The diagnosis of two additional brain tumours in Canadian interventional cardiologists during the past 10 years would confirm the occupational causation theory. The author invites physicians to report knowledge of the diagnosis of brain tumours in Canadian cardiologists to the author or to the editors.