US-guided 14-gauge core-needle breast biopsy: Results of a validation study in 1352 cases

Purpose: To retrospectively determine the false-negative rate and the underestimation rate of ultrasonography (US)-guided 14-gauge core-needle breast biopsy (CNB) in nonpalpable lesions, with validation at surgical excision histologic examination and with stability during clinical and imaging follow-up. Materials and Methods: Informed consent was waived by the institutional review board for this retrospective review of 1352 cases. In 1061 cases, patients underwent surgical excision of lesions visible at US subsequent to US-guided 14-gauge CNB. Followup of another 291 benign lesions at US-guided 14-gauge CNB histologic examination showed stability during clinical and imaging follow-up for at least 2 years. US and histologic findings were reviewed and compared for agreement. A false-negative finding was defined as pathologically proved cancer for which biopsy results were benign. The false-negative rate was defined as the proportion of all breast cancers with a diagnosis of benign disease at US-guided 14-gauge CNB. The underestimation rate was defined as an upgrade of a high-risk lesion at US-guided 14-gauge CNB to malignancy at surgery. Results: US 14-gauge CNB yielded 671 (63.2%) malignant, 86 (8.1%) high-risk, and 304 (28.7%) benign lesions. Each of the 291 benign lesions without surgery remained stable during follow-up. The agreement of US-guided 14-gauge CNB results, surgical excision findings, and follow-up results was 95.8% (kappa = 0.93). False-negative findings were encountered in 11 (0.8%) of 1352 cases, and the false-negative rate was 1.6% (11 of 671 malignancies). All false-negative findings were prospectively identified owing to discordance between imaging results and US-guided 14-gauge CNB histologic findings. The underestimation rate was 31.4%. Conclusion: US-guided 14-gauge CNB is an alternative to surgical excision for assessing nonpalpable breast lesions. (C) RSNA, 2008.