Correlating sonography, mammography, and pathology in the assessment of breast cancer size

Background: With the increasing use of neoadjuvant and minimally invasive therapy, the accuracy of preoperative determination of breast tumor size becomes important. Therefore, we undertook this study to compare mammography and ultrasonography (US). Methods: A total of 180 invasive breast cancer patients were prospectively examined by mammography and US; 146 eligible patients had tumors visualized by both modalities. Results: In 69% of cases, US was better than or equivalent to mammography in determining tumor size. Both underestimated tumor size; mean (median) underestimation was 3.8 ± 0.7 mm (1.7 mm) by US and 3.5 ± 0.9 mm (2 mm) by mammogram. Maximal tumor dimension was accurate within 5 mm in 65% of cases by mammography and 75% of cases by US. For mammographically determined size (versus pathologic size) correlation, r, was 0.4 and for US it was 0.63 and improved for only T1 and T2 tumors. Conclusions: These data suggest that US is more accurate than mammography in assessing breast cancer size.