Mammography Coverage and Tumor Stage in the Opportunistic Screening Context

We assessed the effect of mammography screening in the context of opportunistic screening. There was an increase in screening coverage. The proportion of early stages increased during the same period. 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.