Malignant disease observed in a cohort of women. A validation of Swedish Cancer Registry data.

A longitudinal study of altogether 1462 women aged 38 to 60 years started in Gothenburg, Sweden in 1968-69. Based on information from the population study and from the Swedish Cancer Registry 35 women had a history of malignant disease when initially examined in 1968-69. During a 12-year follow-up period a total of 79 malignant tumours developed in 73 women. A comparison was made between the 1988 Cancer Registry listing and the observations made in the population study. All but one out of 103 cases (99%) were registered in the Cancer Registry and all but one (99%) in the population study. It may be concluded that the accuracy of the population study registration as well as that of the Cancer Registry at that time were very high. This enables us to draw relatively safe conclusions from our own material when testing for risk factors.