Clinical outcomes of mammography in the National Breast and Cervical Cancer Early Detection Program, 2009-2012

Abstract

Purpose: The National Breast and Cervical Cancer Early Detection Program (NBCCEDP) enrolls asymptomatic women for cancer screening and symptomatic women for diagnostic services. This study describes the results of mammograms provided by the NBCCEDP, by examination indication (screening or diagnostic), and by age group.

Methods: For the first NBCCEDP-funded mammogram received during 2009-2012, we calculated age-specific percentages of abnormal findings, rates of follow-up testing, and invasive and in situ breast cancer diagnoses per 1,000 mammograms. Logistic regression was used to estimate the odds for each of these outcomes by examination indication.

Results: The NBCCEDP provided 941,649 screening, 175,310 diagnostic, and 30,434 unknown indication mammograms to 1,147,393 women. The percentage with abnormal mammograms was higher for diagnostic mammograms (40.1 %) than for screening mammograms (15.5 %). Compared with women aged 40-49 years, fewer women aged 50-64 years had abnormal results for screening (13.7 vs. 19.7 %) and diagnostic mammograms (37.7 vs. 42.7 %). Follow-up rates per 1,000 mammograms were lower among women aged 50-64 compared to those aged 40-49 (screening: 143.9 vs. 207.5; diagnostic: 645.3 vs. 760.9); biopsy rates exhibited a similar pattern (screening: 24.1 vs. 32.9; diagnostic: 167.7 vs. 169.7). For screening mammograms, older women had more cancers detected than younger women (invasive: 3.6 vs. 2.2; in situ: 2.3 vs. 2.0). Similarly, for diagnostic mammograms, cancer detection was higher for older women (invasive: 67.8 vs. 36.6; in situ: 17.4 vs. 11.1).

Conclusions: Abnormal mammograms and diagnostic follow-up procedures were less frequent in women aged 50-64 years compared to women aged 40-49 years, while breast cancer detection was higher, regardless of indication for the mammogram. Some of these differences between age groups were greater for screening mammograms than for diagnostic mammograms. Cancer detection rates were higher for diagnostic mammograms compared with screening mammograms. These findings support the NBCCEDP's priority of serving women aged 50-64 years and providing both screening and diagnostic mammograms.