Previous imaging findings of breast cancers that occurred in combined screening negatives

Purpose: To retrospectively evaluate previous imaging findings of breast cancers that occurred in women whose combined screening using both mammography and ultrasonography was negative. Materials and methods: A search of the institutional database identified 65 patients with breast cancers who had comparable previous negative screening mammography and ultrasonography (BI-RADS category 1 or 2) within 2 years. We classified each case as true or false negative. The previous imaging findings and the final outcome were analyzed. Results: Among 65 cases, 42 (65%) were true negatives, 23 (35%) were false negatives. The abnormalities of false negatives were underestimated in 16 (70%) and unrecognized in 7 (30%). The findings were calcifications (n = 8) or a mass (n = 6) on mammography, a mass (n = 5) or a non-mass (n = 3) on ultrasonography and a density on mammography correlated with non-mass on ultrasonography (n = 1). Ductal carcinoma in situ among false and true negatives accounted for 5 (22%) and 7 (17%), respectively. Symptomatic cancers among false and true negatives were 6 (26%) and 13 (31%), respectively. Conclusion: Breast cancers that rarely occurred in combined screening negatives are often retrospectively seen as minimal abnormalities on previous imaging studies.