Intraoperative ultrasound-guided lumpectomy versus wire-guided excision for nonpalpable breast cancer

Ultrasound-guided breast-conserving surgery compared to conventional breast-conserving surgery

PURPOSE

The goal of breast-conserving surgery is to achieve negative tumor margins, since insufficient marginal distance is associated with more local and distant recurrences. This study investigates whether IOUS (intraoperative ultrasound) can reduce the re-resection rate compared to standard breast surgery, regardless of tumor biology and focality.

MATERIALS AND METHODS

The present study is a monocentric, prospective, randomized, and non-blinded parallel group study conducted between 7/2015 and 2/2018. Patients with sonographically visible breast cancer were randomized into two study arms: 1) breast-conserving surgery with IOUS; 2) conventional arm.

RESULTS

364 patients were included in the study and underwent surgery. Tumor biology, size, and focality were equally distributed in both groups (p = 0.497). The study arms did not differ significantly in the proportion of preoperative wire markings (p= 0.084), specimen weight (p = 0.225), surgery duration (p = 0.849), and the proportion of shavings taken intraoperatively (p = 0.903). Positive margins were present in 16.6% of the cases in the IOUS arm and in 20.8% in the conventional arm (p = 0.347). Re-operation was necessary after intraoperative shavings in 14.4% of cases in the US arm and in 21.3% in the conventional arm (p = 0.100).

CONCLUSION

Although the present study showed a clear difference in the rate of positive tumor margins with IOUS compared to conventional breast surgery without IOUS, this was not statistically significant in contrast to the current literature. This could be due to the high expertise of the breast surgeons, the precise wire marking, or the fact that the IOUS technique was not standardized.

Toward Intraoperative Margin Assessment Using a Deep Learning-Based Approach for Automatic Tumor Segmentation in Breast Lumpectomy Ultrasound Images

There is an unmet clinical need for an accurate, rapid and reliable tool for margin assessment during breast-conserving surgeries. Ultrasound offers the potential for a rapid, reproducible, and non-invasive method to assess margins. However, it is challenged by certain drawbacks, including a low signal-to-noise ratio, artifacts, and the need for experience with the acquirement and interpretation of images. A possible solution might be computer-aided ultrasound evaluation. In this study, we have developed new ensemble approaches for automated breast tumor segmentation. The ensemble approaches to predict positive and close margins (distance from tumor to margin ≤ 2.0 mm) in the ultrasound images were based on 8 pre-trained deep neural networks. The best optimum ensemble approach for segmentation attained a median Dice score of 0.88 on our data set. Furthermore, utilizing the segmentation results we were able to achieve a sensitivity of 96% and a specificity of 76% for predicting a close margin when compared to histology results. The promising results demonstrate the capability of AI-based ultrasound imaging as an intraoperative surgical margin assessment tool during breast-conserving surgery.

Intraoperative Ultrasound-Guided Excision of Non-Palpable and Palpable Breast Cancer: Systematic Review and Meta-Analysis

Wire-guided localization (WGL) is the most frequently used localization technique in non-palpable breast cancer (BC). However, low negative margin rates, patient discomfort, and the possibility of wire dislocation have been discussed as potential disadvantages, and re-operation due to positive margins may increase relapse risk. Intraoperative ultrasound (IOUS)-guided excision allows direct visualization of the lesion and the resection volume and reduces positive margins in palpable and non-palpable tumors. We performed a systematic review on IOUS in breast cancer and 2 meta-analyses of randomized clinical trials (RCTs). In non-palpable BC, 3 RCTs have shown higher negative margin rates in the IOUS arm compared to WGL. Meta-analysis confirmed a significant difference between IOUS and WGL in terms of positive margins favoring IOUS (risk ratio 4.34, p < 0.0001, I2 = 0%). 41 cohort studies including 3291 patients were identified, of which most reported higher negative margin and lower re-operation rates if IOUS was used. In palpable BC, IOUS was compared to palpation-guided excision in 3 RCTs. Meta-analysis showed significantly higher rates of positive margins in the palpation arm (risk ratio 2.84, p = 0.0047, I2 = 0%). In 13 cohort studies including 942 patients with palpable BC, negative margin rates were higher if IOUS was used, and tissue volumes were higher in palpation-guided cohorts in most studies. IOUS is a safe noninvasive technique for the localization of sonographically visible tumors that significantly improves margin rates in palpable and non-palpable BC. Surgeons should be encouraged to acquire ultrasound skills and participate in breast ultrasound training.

Intraoperative Margin Trials in Breast Cancer

Purpose of Review

Obtaining negative margins in breast conservation surgery continues to be a challenge. Re-excisions are difficult for patients and expensive for the health systems. This paper reviews the literature on current strategies and intraoperative clinical trials to reduce positive margin rates.

Recent Findings

The best available data demonstrate that intraoperative imaging with ultrasound, intraoperative pathologic assessment such as frozen section, and cavity margins have been the most successful intraoperative strategies to reduce positive margins. Emerging technologies such as optical coherence tomography and fluorescent imaging need further study but may be important adjuncts.

Summary

There are several proven strategies to reduce positive margin rates to < 10%. Surgeons should utilize best available resources within their institutions to produce the best outcomes for their patients.

Optimal localization strategies for non-palpable breast cancers –A network meta-analysis of randomized controlled trials

Purpose

Mammographic screening programmes have increased detection rates of non-palpable breast cancers. In these cases, wire-guided localization (WGL) is the most common approach used to guide breast conserving surgery (BCS). Several RCTs have compared WGL to a range of novel localization techniques. We aimed to perform a network meta-analysis (NMA) of randomized controlled trials (RCTs) comparing methods of non-palpable breast cancer localization.

Methods

A NMA was performed according to PRISMA-NMA guidelines. Analysis was performed using R packages and Shiny.

Results

24 RCTs assessing 9 tumour localization methods in 4236 breasts were included. Margin positivity and reoperation rates were 16.9% (714/4236) and 14.3% (409/2870) respectively. Cryo-assisted localization had the highest margin positivity (28.2%, 58/206) and reoperation (18.9%, 39/206) rates. Compared to WGL (n = 2045 from 24 RCTs) only ultrasound guided localization (USGL) (n = 316 from 3 RCTs) significantly lowered margin positivity (odds ratio (OR): 0.192, 95% confidence interval (CI): 0.079–0.450) and reoperation rates (OR: 0.182, 95%CI: 0.069–0.434). Anchor-guided localization (n = 52, 1 RCT) significantly lowered margin positivity (OR: 0.229, 95%CI: 0.050–0.938) and magnetic-marker localization improved patient satisfaction (OR: 0.021, 95%CI: 0.001–0.548). There was no difference in operation duration, overall complications, haematoma, seroma, surgical site infection rates, or specimen size/vol/wt between methods.

Conclusion

USGL and AGL are non-inferior to WGL for the localization of non-palpable breast cancers. The reported data suggests that these techniques confer reduced margin positivity rates and requirement for re-operation. However, caution when interpreting results relating to RCTs with small sample sizes and further validation is required in larger prospective, randomized studies.

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Ultrasound-guided (USGL) and anchor-guided (AGL) localization had optimal outcomes.

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These methods significantly lowered margin positivity (odds ratio: 0.192 & 0.229).

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However, small sample sizes in trials evaluating USGL and AGL limit these results.

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Operation duration, complications, or specimen data were comparable for all methods.