Incremental cancer detection using breast ultrasonography versus breast magnetic resonance imaging in the evaluation of newly diagnosed breast cancer patients

Objective: To compare the incremental cancer detection rate (ICDR) using bilateral whole-breast ultrasonography (BWBUS) vs dynamic contrast-enhanced MRI in patients with primary breast cancer. Methods: A retrospective database search in a single institution identified 259 patients with breast cancer diagnosed from January 2011 to August 2014 who underwent mammography, BWBUS and MRI before surgery. Patient characteristics, tumour characteristics and lesions seen on each imaging modality were recorded. The sensitivity, specificity and accuracy for each modality were calculated. ICDRs according to index tumour histology and receptor status were also evaluated. The effect of additional cancer detection on surgical planning was obtained from the medical records. Results: A total of 266 additional lesions beyond 273 index malignancies were seen on at least 1 modality, of which 121 (45%) lesions were malignant and 145 (55%) lesions were benign. MRI was significantly more sensitive than BWBUS (p=0.01), while BWBUS was significantly more accurate and specific than MRI (p<0.0001). Compared with mammography, the ICDRs using BWBUS and MRI were significantly higher for oestrogen receptorpositive and triple-negative cancers, but not for human epidermal growth factor receptor 2-positive cancers. 22 additional malignant lesions in 18 patients were seen on MRI only. Surgical planning remained unchanged in 8 (44%) of those 18 patients. Conclusion: MRI was more sensitive than BWBUS, while BWBUS was more accurate and specific than MRI. MRIdetected additional malignant lesions did not change surgical planning in almost half of these patients. Advances in knowledge: BWBUS may be a cost-effective and practical tool in breast cancer staging.