ABSTRACT
INTRODUCTION: The increment of breast cancer screening coverage should lead to an increase in the proportion of early tumors diagnosed and the decrease of the cancer-related mortality. However, the effectiveness of opportunistic mammography screening is not well documented for public health systems in middle-income countries. PATIENTS AND METHODS: We conducted an ecologic study to evaluate the association of mammography coverage with trends in breast cancer stage distribution. We used data from a total of 42,850 breast cancer patients, diagnosed between 2000 and 2016, combined with estimated mammography coverage from 3 surveys (2003, 2008, and 2013). RESULTS: Biannual mammography coverage increased from 62.4% in 2003 to 73.9% in 2013. From 2000 to 2016, the proportion of in situ tumors increased 6.9%, the proportion of localized tumors increased 3.9%, the proportion of regional tumors decreased 6.9% and the frequency of distant tumors decreased 4% (P < .00001). CONCLUSION: Mammography coverage in the context of opportunistic breast cancer screening was associated with the increase of in situ and localized tumors and decrease of regional and distant tumors.