Ultrasound-guided core needle biopsy of breast masses: How many cores are necessary to diagnose cancer?

PURPOSE: To investigate the number of cores required to diagnose breast cancer using ultrasound (US)-guided core needle biopsy. METHODS: US-guided core biopsy of 150 masses was performed in 144 patients. For each mass, 6 cores were obtained and analyzed separately. The histopathologic diagnosis was classified as benign, malignant, or normal breast tissue. Each core was analyzed separately. For diagnostic purposes, the cases were grouped as follows: group G1 comprised the first core; group G2 comprised the first and second core; group G3 comprised the first 3 cores; up to group G6, which included all 6 cores. The results were also analyzed by tumor size (2 cm). RESULTS: The sensitivity in the diagnosis of breast cancer was 90.1% in group G1 and 94.1% in the remaining groups (G2-G6). In tumors 2 cm the sensitivity was 91.4% for group G1 and 96.6% when 2 or more cores were obtained. CONCLUSION: It appears that 2 cores are sufficient to diagnose breast cancer in this study population assuming no technical error occurred in US guidance of the needle through the mass.