Incidence of breast cancer in Piedmont: 1979-1981.

A population-based survey of histologically diagnosed breast cancer was carried out among residents in Piedmont. A total of 5267 incident cases occurring in 1979-1981 was collected, corresponding to an age-standardized (on the world population) incidence rate of 49.5/100,000 per year. Rates (standardized on the population of Piedmont in 1981) were highest in the city of Torino (112.4/100,000 per year) and lowest in the province of Cuneo (67.5), whereas in the other provinces they ranged between 85.3 and 90.0. Estimation of rates in the 54 Local Health Authorities of Piedmont detected up to 2-fold differences between adjacent areas. A correlation was found between rates and size of the population of town of residence. Comparison with age-specific incidence rates from the Cancer Registry of the nearby province of Varese suggested a loss of nonhistologically confirmed cases selectively in older age groups. The distribution of cases diagnosed in 1979 by histologic type is presented. The proportion of diagnoses reported in terms which were consistent with the 1978 WHO Histological Typing of Breast Tumours was 61.3%. It was highest among cases identified in Pathology Services located in University Hospitals and/or diagnosing more than 50 breast cancers per year.