Population-based effects of mammography screening in bavaria on the distribution of TNM-T categories with respect to different histological subgroups

Abstract

Background: Organized mammography screening was implemented in Bavaria in 2003, with a target population of about 1.5 million women (aged 50-69 years). We evaluated the population-based effects of mammography screening on the distribution of tumor-node-metastasis (TNM)-T categories with regard to different histological subgroups of breast cancer. Patients and Methods: Women diagnosed with breast cancer between 2002 and 2008 were included. The annual agespecific incidence rates separated by T category were calculated for different histological subgroups and plotted against time. Time trends were analyzed not only in the screening population but also based on women aged 15-49 and ≥70 years, respectively. Furthermore, correlation coefficients were calculated in order to evaluate the possible association between participation rate and incidence of certain TNM-T categories. Results: With ductal carcinomas, the incidence of early-stage tumors shows a strong increase in the screening population and a significant correlation with the participation rate, whereas with lobular carcinomas there is a stagnation of incidence in women aged 50-69 years irrespective of TNM-T category. Conclusions: Short-term effects of mammography screening can already be demonstrated. However, depending on breast cancer type, not all women appear to benefit from screening. The expected long-term reduction of breast cancer mortality remains to be seen. Copyright © 2012 S. Karger AG, Basel.