The Inter-Regional Epidemiological Study of Childhood Cancer (IRESCO). Study design, control selection and data collection.

The Inter-Regional Epidemiological Study of Childhood Cancer (IRESCC) was established to investigate the role of possible aetiological factors in childhood cancer, with particular emphasis on environmental exposures to the foetus and family history of certain diseases including cancer. Incident cases occurring in three Health Service regions (the West Midlands, Yorkshire and North Western) were matched for age and sex with two sets of control children. A total of 555 cases and 1110 controls were entered into the study. The parents of each index child were interviewed with respect to events during the relevant pregnancy, occupation, smoking habits, and past medical history of themselves, the child's siblings and other relatives. Ninety-three per cent of case parents approached agreed to be interviewed, and approximately 90% of controls were ranked first or second on the control selection lists. After the interview information was verified by reference to antenatal and other medical records. Obstetric and general practitioner records were abstracted for approximately 90% of cases and controls. Information derived from the interview and that from medical records was coded separately. The data collected by each region have been pooled and case-control comparisons of potential aetiological factors will be carried out, using matched triplet analyses.