False-negative rate of combined mammography and ultrasound for women with palpable breast masses

Mammography and ultrasound are often used concurrently for patients with palpable breast masses. While mammography has a false-negative rate of approximately 15 %, the addition of breast ultrasound decreases this rate among patients with palpable breast masses. There are no recent outcome data regarding the use of combined reporting of ultrasound and mammography (CRUM) for palpable breast masses. In this study, female patients presenting with a palpable breast mass were retrospectively reviewed in a prospectively entered database at a single institution from June 2010 to July 2013. All cancer cases and false-negative cases using CRUM were identified. Cancer rates, false-negative rates, and negative predictive values were calculated based on CRUM breast imaging-reporting and data system (BI-RADS) categories. One thousand two hundreds and twelve female patients presenting with a palpable breast mass were identified; 77 % of patients had CRUM and 73 % (682/932) were BI-RADS 1–2. Despite negative or benign BI-RADS, 9.5 % of patients with BI-RADS 1–2 (65/682) underwent biopsy, compared to 96 % of patients with a BI-RADS 4–5 designation. Eighty-one patients were found to have cancers; 2 had BI-RADS 1–2 imaging. The false-negative rate of CRUM was 2.4 % (2/81). Since 69 % (428/617) of BI-RADS 1–2 patients without tissue diagnosis had follow-up imaging and/or clinical exam (median: 27 months, range: 2–62 months) and none developed cancers, the cancer rate and negative predictive value of a palpable breast mass of BI-RADS 1–2 were estimated to be 0.3 % (2/682) and 99.7 %, respectively. In the modern era of combined imaging for breast masses, a patient with a low suspicion exam can be reassured with a negative CRUM report.