**11. Evaluation and assessment of the breast after medical therapy**

Radiological and clinical evaluation of residual tumor size after neoadjuvant chemotherapy (NAC) is vital for decision-making in breast surgical planning. Physical examination, mammography, and ultrasound are not accurate in assessing the tumor response to NAC. Chagpar et al. [101] examined the accuracy of clinical methods of tumor size assessment (physical examination, mammography, and ultrasound) in evaluating the tumor response to chemotherapy. The correlation coefficients for residual tumor size were estimated for physical examination of 0.42, ultrasound 0.42, and mammography 0.41. Interestingly, clinical measurement estimated by each of these modalities in only 66–75% of cases was within one centimeter of the pathologic tumor size. Likewise, Peintinger et al. [102] showed higher accuracy (89%) with the combination of mammography and sonography in predicting pathological residual tumor size after neoadjuvant chemotherapy, but a moderate agreement (69% of patients) in predicting pathologic tumor size within 0.5 cm.

Therefore, breast ultrasound for clinical evaluation of tumor size is moderately useful for patients receiving chemotherapy first [7]. However, breast MRI has shown an equal or better correlation for these patients and offers the best performance in assessing patients' response and predicting pathological tumor size non-invasively [103, 104].

## **12. Intraoperative ultrasound (IOUS) in breast surgery**

Intraoperative US (IOUS) is a non-invasive procedure that enables the surgeon to perform intraoperative localization and guided excision of a nonpalpable breast lesion, as well as ultrasound-guided operation of traditional palpation-guided surgery [105–109].

Widespread preoperative malignant lesion localization strategies for surgery are wire-guided localization (WGL) and radio occult lesion localization (ROLL) guided surgery to ensure the whole removal of imaging findings and allow margin clearance [110–112]. Rahusen et al. [110] reported that IOUS (89%) is superior to wire-guided surgery (55%) concerning tumor-free resection margins. A retrospective multicenter study [113] demonstrated that IOUS for nonpalpable invasive breast cancer was more accurate in obtaining adequate margins with the lowest rate of positive margins in the IOUS group (3.7%) than in the wire-localization group (21.3%) and radioguided occult lesion group (25%). Snider et al. showed a reasonable rate of tumor-free resection margins using IOUS (82%) with a smaller excision volume of healthy breast tissue than wire-guided surgery [114].

A meta-analysis [111] of patients with nonpalpable breast cancer treated with IOUS vs. wire-guided localization (WGL) showed that the rate of involved surgical margins for IOUS varies 0–19%. There was a statistically significant difference between IOUS and WGL regarding tumor-free margins favoring IOUS (OR = 0.52; 95%CI: 0.38–0.71). In the meta-analysis of Pan et al. [112], IOUS is an accurate method for localizing nonpalpable and palpable breast cancers by obtaining a high proportion of negative margins and adequate resection volumes in patients undergoing breast-conserving surgery. Thirteen studies were included. Eight were eligible for the impact of IOUS on the margin status of nonpalpable breast cancers; four were suitable for palpable breast cancers, and one was for both nonpalpable and palpable breast cancers. This meta-analysis showed a statistically significant increase in the rate of negative margins using IOUS for both nonpalpable and palpable breast cancers. IOUS-guidance enabled a significantly higher negative margin rate for non-palpable breast cancers than WGL-guidance (RR =1.26, 95% CI =1.09–1.46 from 6 prospective studies; OR = 1.45, 95% CI =0.86–2.43 from 2 retrospective studies). For palpable breast cancers, the relative risk (RR) for IOUS associated negative margins was 2.36 (95% CI =1.26–4.43) in 2 prospective studies, and OR was 2.71 (95% CI = 1.25–5.87) in 2 retrospective studies.

Breast surgeon-performed IOUS-guided excision does not depend on the radiology or nuclear medicine department. This procedure avoids the need for an additional localization procedure preoperatively, is non-stressful for the patients, and allows accurate intraoperative targeting and immediate confirmation of lesion removal with tumor-free margins. The use of this technique allocates hospital resources efficiently in resource-constraint contexts.

IOUS has demonstrated benefits in patients with palpable early-stage primary invasive breast cancer to completely excise the tumor with negative margins and small excision volumes, improving the result. COBALT-trial [107] was a multicenter randomized controlled trial for palpable cancer, comparing IOUS with palpationguided surgery (PGS). Results of this trial showed a difference in tumor-involved margin of 3% of tumor-involved margins for the invasive component in the IOUS-group compared to 17% in the PGS-group, and thus a significant decrease in additional treatment required in the IOUS group (2% re-excision and 9% boost in IOUS vs. 7% mastectomy, 4% re-excision and 16% boost in the PGS group). Furthermore, secondary results of this trial showed IOUS had smaller odds of having worse cosmetic outcomes than PGS (OR = 0.51, P = 0.045).

*Value of Breast Ultrasound in the Clinical Practice of the Surgeon DOI: http://dx.doi.org/10.5772/intechopen.100520*
