Factors associated with imaging and procedural events used to detect breast cancer after screening mammography.

OBJECTIVE: The purpose of this study was to characterize the type and frequency of diagnostic evaluations after screening mammography and to summarize their association with the likelihood of biopsy and subsequent breast cancer diagnosis.
MATERIALS AND METHODS: The data source was 584,470 women with no previous breast cancer from six states in the Breast Cancer Surveillance Consortium. In this observational study, we linked data from 1,207,631 routine screening mammograms performed between January 1, 1996, and December 31, 2002, to data on additional imaging, interventional procedures, and biopsy outcome (benign or malignant). Additional examinations were categorized into diagnostic mammography, sonography, or both. Events were further subdivided by whether they were performed on the same day as the screening examination and whether patients reported breast symptoms. Logistic regression analysis was used to examine the association between additional evaluation performed and the likelihood of biopsy and the likelihood of subsequent breast cancer diagnosis after adjustment for patient and screening mammographic characteristics.
RESULTS: Most (92%) of the screening examinations did not include additional imaging. The probability of biopsy ranged from 0.4% for examinations with no follow-up to 20.1% for those with diagnostic mammography and sonography on the same day as screening among women without symptoms and from 2.1% for those with no follow-up to 18.9% for those with diagnostic mammography and sonography on a day different from screening among women with symptoms. Thirty percent of women without symptoms who underwent biopsy had cancer, whereas 27.1% of women with symptoms who underwent biopsy had cancer. Women who underwent biopsy after screening mammography with diagnostic mammography and sonography on the same day had the highest probability of breast cancer (37.6% among women without symptoms, 36.4% among women with symptoms), whereas those who underwent only sonography performed at a later date had the lowest probability of breast cancer (11.9% among women without symptoms, 17.1% among women with symptoms).
CONCLUSION: Women who undergo screening mammography followed by diagnostic mammography and sonography have a high probability of undergoing biopsy and having the biopsy result of breast cancer when follow-up imaging is performed on the same day as screening mammography whether or not breast symptoms are present. Biopsy performed after sonography in the absence of diagnostic mammography had a low yield of breast cancer.