Malignancy Rates of Suspicious Breast Lesions in Patients on Annual Screening or Regular Follow-up Ultrasonography

ABSTRACT

PURPOSE: The objective of this study is to investigate the malignancy rates of BIRADS 4 and 5 lesions detected on annual screening or follow-up US and to correlate the malignancy rates with the rationales for biopsy. MATERIALS AND METHODS: Between 2010 and 2011, among 2837 patients who underwent US-guided core-needle biopsy, 423 patients underwent screening or regular follow-up US examinations. Lesions were classified into four groups newly detected suspicious lesions, benign lesions with interval growth, benign lesions with suspicious changes of US features and benign lesions with interval growth and suspicious changes of US features. RESULTS: The malignancy rates were as follows BI-RADS 4A low suspicion of malignancy, 8.1% (31/379); 4B intermediate suspicion of malignancy, 56% (14/25); 4C moderate suspicion of malignancy, 71.4% (10/14); 5 highly suggestive of malignancy, 100% (5/5). The malignancy rates for the four groups were as follows newly detected suspicious lesions, 17.46% (51/292); benign lesions with interval growth, 7.77% (7/90); benign lesions with suspicious changes of US features, 4% (1/25); benign lesions with interval growth and suspicious changes of US features, 6.25% (1/16). Comparison of the malignancy rate of newly detected suspicious lesions with that of benign lesions with interval growth revealed a statistically significant difference (p=0.038). No significant differences were observed between the other groups (p>0.05). CONCLUSION: The malignancy rates of suspicious lesions detected on annual screening or follow-up US were similar to those of the reported BI-RADS data. A higher malignancy rate was observed for newly detected suspicious lesions than for lesions with interval growth.