The detection of pCR after PST by contrast-enhanced ultrasonography for breast cancer

Background Primary systemic therapy (PST; such as chemotherapy) has been approved as the standard therapy. Breast-conserving surgery is involved in 60–70% of breast cancer operations, and cancer can spread in the period between the initial treatment and preoperative chemotherapy. To reduce the residual tumor in persistent disease of breast tissue, determining the margin including normal tissue when removing the tumor is very difficult. With the development of the color Doppler method, contrast-enhanced ultrasonography (CEUS) allows visualization of the tumor bloodstream. The availability and efficacy of CEUS for setting the resection margin in breast-conserving surgery were examined and compared with MRI imaging as tools for making decisions for breast-conserving surgery. Methods One hundred seventy patients underwent breast cancer operations: 59 were PST(+) and 111 PST(−). Imaging studies, ultrasonography and MRI, to measure the size of the tumor were performed twice, before and after chemotherapy, for PST patients. This was carried out not only to measure the residual tumor size after PST, but also to detect whether pathologically complete response (pCR) had been achieved or not. Fifty-nine patients received CEUS after PST, and we determined the precision of CEUS and conventional US. Results The sensitivity of CEUS for pCR was 80.0% (95% CI 0.571–0.88), specificity 98.0% (95% CI 0.933–0.996), positive predictive value 88.9% (95% CI 0.635–0.978) and negative predictive value 96.0% (95% CI 0.914–0.976). The difference between the pathological examination and ultrasonography, conventional ultrasonography and CEUS was −4.455 ± 2.02 and 2.582 ± 2.298 cm (95% CI −13.11 to −0.96, p = 0.0235); CEUS was near the diameter of the actual pathological examination. Conclusion Contrast-enhanced ultrasonography is suitable for the preoperative examination, especially after PST, to determine the resection margin before breast-conserving surgery and detects pCR, which can help to avoid surgical procedures in the future.