Hypothesis: Ultrasound (US) of the breast will accurately measure breast tumor size when compared with size as determined by pathologic examination.
Design: Retrospective case series.
Setting: University hospital-based breast center.
Patients: Thirty-five women with a diagnosis of breast cancer who had US as a component of their evaluation.
Main outcome measure: Tumor size as measured by US compared with size measured by pathologic examination.
Results: Size measured by US ranged from 0.45 to 3.81 cm. Size measured by pathologic examination ranged from 0.5 to 5 cm. The mean difference of size measured by US vs pathologic size was 0.4 cm (P = .01). When only tumors with invasive ductal histology are evaluated, the mean difference in size is 0.33 cm (P = .008). The range of difference was -1.6 cm to +0.42 cm. Seventeen percent of invasive ductal tumors were underestimated by more than 1 cm; none were underestimated by more than 2 cm.
Conclusions: This study demonstrates that, although US tends to underestimate the pathologic tumor size, 83% of invasive ductal tumors fall within a 1-cm and 100% fall within a 2-cm extension of the US-measured tumor size. Therefore, it is possible to use US to monitor the extent of treatment size when developing very localized therapeutic tools.