1. Department of Research; Cancer Registry of Norway; PB 5313 Majorstuen Oslo 0304 Norway
2. Oslo Centre for Biostatistics and Epidemiology; Oslo University Hospital; PB 4950 Nydalen Oslo 0424 Norway
3. Oslo Ischemia Study; Oslo University Hospital; Oslo Norway
4. Department of Public Health and General Practice; Norwegian University of Science and Technology; PB 8905 Trondheim 7491 Norway