Municipal distribution and trend of the incidence of breast cancer in the health area of León, Spain (1996-2010)

BACKGROUND: Breast cancer is the most common amongst women. The aim of this study was to analyze the incidence and geographical distribution of breast cancer in the health area of León. METHODS: We designed an observational descriptive study that included women enrolled in the Hospital Tumor Registry of the Centro Asistencial Universitario in León with a diagnosis of breast malignant neoplasm (ICD-9: 174, ICD-10: 50) between 01/01/1996 and 31/12/2010 and resident in the health area of León. To study the spatial distribution, we estimated municipal relative risks (RR) smoothed by fitting the Besag, York and Mollié model and the posterior probability (PP) of RR > 1 using Bayesian methods. RESULTS: A total of 2379 cases were included. The number of new cases and the crude incidence rate have both increased in every triennium, from 72,7 (1996-1998) to 101,5 (2008-2010) per 100,000 women. The age adjusted rates per 100,000 women (European standard population) increased from 58,0 during the first triennium to 69,4 during the last one. An average annual increase of 1,3% was observed. Several municipalities from the health area of León showed risks higher than a 10%. The PP were higher than 0.9 only in the municipality of León. CONCLUSION: The observed rates are among the lowest in our country. Nevertheless, the number of cases and the incidence rates have increased progressively.Financiado con recursos propios del grupo de investigación en Interacción Gen-Ambiente-Salud. Universidad de León.S