Intra-operative assessment of excised breast tumour margins using ClearEdge imaging device

L-ICG as an optical agent to improve intraoperative margin detection in breast-conserving surgery: a prospective study

PURPOSE

Precise tumor excision is important in breast-conserving surgery (BCS). This study explores the safety and accuracy of fluorescence image-guided BCS (FIGS) using a lidocaine mucilage-ICG compound (L-ICG).

METHODS

54 patients who underwent BCS from August 2020 to September 2023 were enrolled. L-ICG was locally injected 0.5 cm from the tumor border. FIGS was performed to guide the tumor excision. Frozen sectioning of surgical field biopsies was used to assess the intraoperative margin status. The primary outcome measures were margin width and positive margin rates. Cosmetic outcome was evaluated by the modified version of Breast-QTM Breast-Conserving Therapy Module (Postoperative) and breast cosmetic outcome assessment criteria.

RESULTS

The median cranial, caudal, medial, and lateral margin widths were 8 mm (interquartile range [IQR], 3-14), 5.5 mm (IQR, 2-15), 6 mm (IQR, 3-15), and 8 mm (IQR, 3-15), respectively. Five out of 54 (9.3%) patients had an intraoperative positive margin. Intraoperatively extended resection was performed for four patients and mastectomy for the remaining one. This further reduced the positive margin rate to 1.9% at final histopathology. 50 patients received cosmetic outcome evaluation, 100% of them were "somewhat satisfied" or "very satisfied" with the appearance of the operated breast when clothed and 98% of them were scaled as "Good" or "Excellent" in their appearance of the operated breast. No serious adverse events were observed. With a median follow-up of 12.8 months, no events for tumor relapse were observed.

CONCLUSION

L-ICG-based FIGS is a promising technique to guide precise tumor excision in BCS.

Toward real-time margin assessment in breast-conserving surgery with hyperspectral imaging

Margin assessment in breast-conserving surgery (BSC) remains a critical challenge, with 20-25% of cases resulting in inadequate tumor resection, increasing the risk of local recurrence and the need for additional treatment. In this study, we evaluate the diagnostic performance of hyperspectral imaging (HSI) as a non-invasive technique for assessing resection margins in ex vivo lumpectomy specimens. A dataset of over 200 lumpectomy specimens was collected using two hyperspectral cameras, and a classification algorithm was developed to distinguish between healthy and tumor tissue within margins of 0 and 2 mm. The proposed approach achieved its highest diagnostic performance at a 0 mm margin, with a sensitivity of 92%, specificity of 78%, accuracy of 83%, Matthews correlation coefficient of 68%, and an area under the curve of 89%. The entire resection surface could be imaged and evaluated within 10 minutes, providing a rapid and non-invasive alternative to conventional margin assessment techniques. These findings represent a significant advancement toward real-time intraoperative margin assessment, highlighting the potential of HSI to enhance surgical precision and reduce re-excision rates in BCS.

Technologies and techniques to improve precision in breast conserving surgery

Imprecision in breast conserving surgery results in high rates of take back to theatre for reexcision of margins. This paper reviews the various approaches to improving the precision of oncological margin control in breast conserving surgery. The review describes the rationale for improved tissue characterization over tumor localization and explores technology-free approaches, as well as progress being made to develop and test innovative technological solutions.

A systematic scoping review exploring variation in practice in specimen mammography for Intraoperative Margin Analysis in Breast Conserving Surgery and the role of artificial intelligence in optimising diagnostic accuracy

PURPOSE

Specimen Mammography (SM) is commonly used in Breast Conserving Surgery (BCS) for intraoperative margin analysis. A systematic scoping review was conducted to identify sources of methodological variation in Specimen Mammography Interpretation (SMI) and assess the role of Artificial Intelligence (AI) techniques to optimise Diagnostic Accuracy (DA).

METHODS

Embase, Pubmed, Cochrane and web of science databases were searched. Studies were included if SM was used for margin analysis for BCS with reported DA compared with pathological margin status and data extracted.

RESULTS

1242 unique studies were identified, of which 40 were included. 39/40 studies did not utilise AI for SMI, with 4 studies comparing 2 relevant techniques, giving 43 non-AI study arms for analysis. There was wide variation in SM techniques, including number of views and location of SM. Specialist performing SMI in usual clinical practice was surgeon (13/39 studies;33 %), radiologist(s) (16/39;41 %), surgeon and radiologist (3/39;8 %) or not stated (7/39;18 %) which differed from the study specialist in 15/39 (38 %) of studies. Diagnostic accuracy in studies ranged from sensitivity 19-91.7 % and specificity 25-100 %.

CONCLUSIONS

There is marked variation in current techniques used for SM for intraoperative margin analysis with correspondingly disparate DA. Only 1 study applied AI to SMI, and we identify how AI could optimise SMI and a template for future work to apply AI techniques to SMI, reduce unwarranted variation and optimise DA.

Optical Emission Spectroscopy for the Real-Time Identification of Malignant Breast Tissue

Breast conserving resection with free margins is the gold standard treatment for early breast cancer recommended by guidelines worldwide. Therefore, reliable discrimination between normal and malignant tissue at the resection margins is essential. In this study, normal and abnormal tissue samples from breast cancer patients were characterized ex vivo by optical emission spectroscopy (OES) based on ionized atoms and molecules generated during electrosurgical treatment. The aim of the study was to determine spectroscopic features which are typical for healthy and neoplastic breast tissue allowing for future real-time tissue differentiation and margin assessment during breast cancer surgery. A total of 972 spectra generated by electrosurgical sparking on normal and abnormal tissue were used for support vector classifier (SVC) training. Specific spectroscopic features were selected for the classification of tissues in the included breast cancer patients. The average classification accuracy for all patients was 96.9%. Normal and abnormal breast tissue could be differentiated with a mean sensitivity of 94.8%, a specificity of 99.0%, a positive predictive value (PPV) of 99.1% and a negative predictive value (NPV) of 96.1%. For 66.6% patients all classifications reached 100%. Based on this convincing data, a future clinical application of OES-based tissue differentiation in breast cancer surgery seems to be feasible.

Multifractal analysis of cellular ATR-FTIR spectrum as a method for identifying and quantifying cancer cell metastatic levels

Cancer is a leading cause of mortality today. Sooner a cancer is detected, the more effective is the treatment. Histopathological diagnosis continues to be the gold standard worldwide for cancer diagnosis, but the methods used are invasive, time-consuming, insensitive, and still rely to some degree on the subjective judgment of pathologists. Recent research demonstrated that Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy can be used to determine the metastatic potential of cancer cells by evaluating their membrane hydration. In the current study, we demonstrate that the conversion of ATR-FTIR spectra using multifractal transformation generates a unique number for each cell line's metastatic potential. Applying this technique to murine and human cancer cells revealed a correlation between the metastatic capacity of cancer cells within the same lineage and higher multifractal value. The multifractal spectrum value was found to be independent of the cell concentration used in the assay and unique to the tested lineage. Healthy cells exhibited a smaller multifractal spectrum value than cancer cells. Further, the technique demonstrated the ability to detect cancer progression by being sensitive to the proportional change between healthy and cancerous cells in the sample. This enables precise determination of cancer metastasis and disease progression independent of cell concentration by comparing the measured spectroscopy derived multifractal spectrum value. This quick and simple technique devoid of observer bias can transform cancer diagnosis to a great extent improving public health prognosis worldwide.

High wavenumber Raman spectroscopy for intraoperative assessment of breast tumour margins

Optimal oncological results and patient outcomes are achieved in surgery for early breast cancer with breast conserving surgery (BCS) where this is appropriate. A limitation of BCS occurs when cancer is present at, or close, to the resection margin - termed a 'positive' margin - and re-excision is recommended to reduce recurrence rate. This is occurs in 17% of BCS in the UK and there is therefore a critical need for a way to assess margin status intraoperatively to ensure complete excision with adequate margins at the first operation. This study presents the potential of high wavenumber (HWN) Raman spectroscopy to address this. Freshly excised specimens from thirty patients undergoing surgery for breast cancer were measured using a surface Raman probe, and a multivariate classification model to predict normal versus tumour was developed from the data. This model achieved 77.1% sensitivity and 90.8% specificity following leave one patient out cross validation, with the defining features being differences in water content and lipid versus protein content. This demonstrates the feasibility of HWN Raman spectroscopy to facilitate future intraoperative margin assessment at specific locations. Clinical utility of the approach will require further research.

Image Translation of Breast Ultrasound to Pseudo Anatomical Display by CycleGAN

Ultrasound imaging is cost effective, radiation-free, portable, and implemented routinely in clinical procedures. Nonetheless, image quality is characterized by a granulated appearance, a poor SNR, and speckle noise. Specific for breast tumors, the margins are commonly blurred and indistinct. Thus, there is a need for improving ultrasound image quality. We hypothesize that this can be achieved by translation into a more realistic display which mimics a pseudo anatomical cut through the tissue, using a cycle generative adversarial network (CycleGAN). In order to train CycleGAN for this translation, two datasets were used, "Breast Ultrasound Images" (BUSI) and a set of optical images of poultry breast tissues. The generated pseudo anatomical images provide improved visual discrimination of the lesions through clearer border definition and pronounced contrast. In order to evaluate the preservation of the anatomical features, the lesions in both datasets were segmented and compared. This comparison yielded median dice scores of 0.91 and 0.70; median center errors of 0.58% and 3.27%; and median area errors of 0.40% and 4.34% for the benign and malignancies, respectively. In conclusion, generated pseudo anatomical images provide a more intuitive display, enhance tissue anatomy, and preserve tumor geometry; and can potentially improve diagnoses and clinical outcomes.

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.

In situ Raman spectroscopy and machine learning unveil biomolecular alterations in invasive breast cancer

SIGNIFICANCE

As many as 60% of patients with early stage breast cancer undergo breast-conserving surgery. Of those, 20% to 35% need a second surgery because of incomplete resection of the lesions. A technology allowing in situ detection of cancer could reduce re-excision procedure rates and improve patient survival.

AIM

Raman spectroscopy was used to measure the spectral fingerprint of normal breast and cancer tissue ex-vivo. The aim was to build a machine learning model and to identify the biomolecular bands that allow one to detect invasive breast cancer.

APPROACH

The system was used to interrogate specimens from 20 patients undergoing lumpectomy, mastectomy, or breast reduction surgery. This resulted in 238 ex-vivo measurements spatially registered with standard histology classifying tissue as cancer, normal, or fat. A technique based on support vector machines led to the development of predictive models, and their performance was quantified using a receiver-operating-characteristic analysis.

RESULTS

Raman spectroscopy combined with machine learning detected normal breast from ductal or lobular invasive cancer with a sensitivity of 93% and a specificity of 95%. This was achieved using a model based on only two spectral bands, including the peaks associated with C-C stretching of proteins around 940    cm - 1 and the symmetric ring breathing at 1004    cm - 1 associated with phenylalanine.

CONCLUSIONS

Detection of cancer on the margins of surgically resected breast specimen is feasible with Raman spectroscopy.

New Technology for the Breast Surgeon

New innovations aid the breast surgeon with better ability to localize tumors using wireless techniques, reduce re-excision rates by intraoperative margin evaluation and perform aesthetically; pleasing, and safe surgeries. In addition to improving oncological outcomes, we can continue to improve the quality of life for our patients through evolving surgeries including nerve-sparing mastectomies, robotic mastectomies, and lymphovascular surgeries (LYMPHA). Our article reviews current and evolving techniques and technology that all breast surgeons should add to his or her armamentarium to provide optimal surgical care.

Routine four-quadrant cavity shaving at the time of wide local excision for breast cancer reduces re-excision rate

INTRODUCTION

Breast conservation therapy (BCT) has been shown to have comparable long-term survival outcomes when compared with mastectomy. Clearance of excision margin is one of the mainstays of the surgical treatment, which if not achieved at the first operation of BCT results in the need for subsequent surgery.

METHODS

This study evaluated the impact of routinely taken cavity shavings on re-excision rates. This retrospective two-centre study describes the use of routine four-quadrant cavity shaving in 449 patients with consecutively treated with wide local excision for invasive cancer or ductal carcinoma in situ.

RESULTS

The overall incomplete excision rate was 10.6%. Routine cavity shaving prevented the need for re-excision in 84 patients (18.7%) and identified the need for further re-excision in 33 patients (7.3%). Median time from surgery to radiotherapy was 50 days (range 13-209) for non-re-excised patients versus 78 days (range 47-260) for re-excised patients (p<0.001). Median time to chemotherapy (n=75) was 44 days (range 14-106) for non-re-excised patients versus 56 days (range 35-116) for re-excised patients (p=0.017).

CONCLUSIONS

This study demonstrates that routine cavity shaving decreases re-excision rate in patients treated with wide local excision and prevents delays to adjuvant treatment due to incomplete excision.

Investigating the feasibility of a hand-held photoacoustic imaging probe for margin assessment during breast conserving surgery

Approximately 19 % of breast cancer patients undergoing breast conserving surgery (BCS) must return for a secondary surgery due to incomplete tumour removal. Our previous work demonstrated that the lower lipid content, characteristic of tumour tissue, was observed as regions of hypo-intense photoacoustic (PA) contrast. The goal of this work was to evaluate feasibility of a low-frequency, hand-held PA imaging probe for surgical margin assessment based on lipid content differences. Here, we describe (i) the design of a prototype hand-held PA imaging probe, (ii) the effect of limited-bandwidth on image contrast, (iii) accuracy towards hypo-intense contrast detection, (iv) the limited-view characteristics of the single sensor design, and (iv) early imaging results of an ex-vivo breast cancer specimen. The probe incorporates a single polyvinylidene fluoride acoustic sensor, a 1-to-4 optical fibre bundle and a polycarbonate axicon lens for light delivery. Imaging results on phantoms designed to mimic positive margins demonstrated the ability to detect gaps in optical absorption as small as 1 mm in width. Compared to images from a near full-view PAI system, the hand-held PAI probe had higher signal to noise ratio but suffered from negativity image artifacts. Lumpectomy specimen imaging showed that strong signals can be obtained from the fatty tissue. Taken together, the results show this imaging approach with a hand-held probe has potential for detection of residual breast cancer tissue during BCS; however, more work is needed to reduce the size of the probe to fit within the surgical cavity.

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.

Magnetic resonance imaging system for intraoperative margin assessment for DCIS and invasive breast cancer using the ClearSight™ system in breast-conserving surgery-Results from a postmarketing study

BACKGROUND AND OBJECTIVES

Breast-conserving surgery (BCS) is followed by reoperations in approximately 25%. Reoperations lead to an increased risk of infection and wound healing problems as well as a worse cosmetic outcome. Several technical approaches for an intraoperative margin assessment to decrease the reoperation rate are under evaluation, some of them are still experimental.

METHODS

A prospective single-arm post-marketing study with 60 patients undergoing BCS for ductal carcinoma in situ (DCIS) and invasive breast cancer was conducted. The specimen was intraoperatively examined by the ClearSight™ system, a mobile magnetic resonance imaging system that is based on a diffusion-weighted imaging protocol. However, the results were blinded to the surgeon.

RESULTS

The ClearSight™ system was performed for both ductal and lobular breast cancer and DCIS, with a sensitivity of 0.80 (95% confidence interval [CI]: 0.44-0.96) and a specificity of 0.84 (95% CI 0.72-0.92), with an overall diagnostic accuracy of 80%.

CONCLUSION

Had the ClearSight™ been known to the surgeon intraoperatively, the reoperation rate would have been reduced by 83% for invasive carcinoma, from 10% to 2%, and 50% for DCIS, from 30% to 15% reoperations. A trial designed to examine the impact on reoperation rates is currently ongoing.

Application of Intraoperative Mass Spectrometry and Data Analytics for Oncological Margin Detection, A Review

OBJECTIVE

A common phase of early-stage oncological treatment is the surgical resection of cancerous tissue. The presence of cancer cells on the resection margin, referred to as positive margin, is correlated with the recurrence of cancer and may require re-operation, negatively impacting many facets of patient outcomes. There exists a significant gap in the surgeons ability to intraoperatively delineate between tissues. Mass spectrometry methods have shown considerable promise as intraoperative tissue profiling tools that can assist with the complete resection of cancer. To do so, the vastness of the information collected through these modalities must be digested, relying on robust and efficient extraction of insights through data analysis pipelines.

METHODS

We review clinical mass spectrometry literature and prioritize intraoperatively applied modalities. We also survey the data analysis methods employed in these studies.

RESULTS

Our review outlines the advantages and shortcomings of mass spectrometry imaging and point-based tissue probing methods. For each modality, we identify statistical, linear transformation and machine learning techniques that demonstrate high performance in classifying cancerous tissues across several organ systems. A limited number of studies presented results captured intraoperatively.

CONCLUSION

Through continued research of data centric techniques, like mass spectrometry, and the development of robust analysis approaches, intraoperative margin assessment is becoming feasible.

SIGNIFICANCE

By establishing the relatively short history of mass spectrometry techniques applied to surgical studies, we hope to inform future applications and aid in the selection of suitable data analysis frameworks for the development of intraoperative margin detection technologies.

Development of intraoperative assessment of margins in breast conserving surgery: a narrative review

OBJECTIVE

We intend to provide an informative and up-to-date summary on the topic of intraoperative assessment of margins in breast conserving surgery (BCS). Conventional methods as well as cutting-edge technologies are analyzed for their advantages and limitations in the hope that clinicians can turn to this for reference. This review can also offer guidance for technicians in the future design of intraoperative margin assessment tools.

BACKGROUND

Achieving negative margins during BCS is one of the vital factors for preventing local recurrence. Conducting intraoperative margin assessment can ensure negative margins to a large extent and possibly relieve patients of the anguish of re-interventions. In recent years, innovative methods for margin assessment during BCS are advancing rapidly. And there is a lack of summary regarding the development of intraoperative margin assessment in BCS.

METHODS

A PubMed search with keywords "intraoperative margin assessment" and "breast conserving surgery" was conducted. Relevant publications were screened manually for its title, abstract and even full text to determine its true relevance. Publications on neo-adjuvant therapy and intraoperative radiotherapy were excluded. References from the searched articles and other supplementary articles were also looked into.

CONCLUSIONS

Conventional methods for margin assessment yields stable outcome but its use is limited because of the demand on pathology staff and the trade-off between time and precision. Conventional imaging techniques pass the workload to radiologists at the cost of a significantly low duration of time. Involving artificial intelligence for image-based assessment is a further improvement. However, conventional imaging is inherently flawed in that occult lesions can't show on the image and the showing ones are ambiguous and open to interpretation. Unconventional techniques which base their judgment on cellular composition are more reassuring. Nonetheless, unconventional techniques should be subjected to clinical trials before putting into practice. And studies regarding comparison between conventional methods and unconventional methods are also needed to evaluate their relative efficacy.

Cavity shaving for invasive breast cancer conservative surgery: Reduced specimen volume and margin positive rates

INTRODUCTION

The cavity shaving (CS) technique was described in breast conserving surgery to reduce the rate of reoperation avoiding the need for intraoperative margin analysis. This study assesses differences in the rates of involvement of the surgical margin (requiring further surgery) and volume of surgical specimens, depending on the use or not of this technique.

MATERIAL AND METHODS

A retrospective cohort study was conducted in patients with breast carcinoma who underwent breast conserving surgery between 2013 and 2019. They were divided into two groups depending on whether the cavity shaving technique was used or not. Primary outcomes of the study included presence of final margin involvement, requiring need for further surgery, and the volume of excised tissue comparing the study groups.

RESULTS

A total of 202 cases were included: 92 in the control group and 110 in the cavity shaving group. Significant differences were found regarding involvement of the final margin (19.57% control group vs. 4.55% cavity shaving group; p = 0.010). The volume of additional surgical specimens were significantly greater in the traditional technique group than in the shaving technique (46.43 vs 13.32 cm³; p = 0.01) as was total specimen volume (143.40 vs 100.63 cm³; p = 0.022).

CONCLUSIONS

CS can reduce the positive margin and re-excision rates without larger-volume resections and should therefore be considered a routine technique in BCS for early-stage breast cancer.

Innovations for the future of breast surgery

BACKGROUND

Future innovations in science and technology with an impact on multimodal breast cancer management from a surgical perspective are discussed in this narrative review. The work was undertaken in response to the Commission on the Future of Surgery project initiated by the Royal College of Surgeons of England.

METHODS

Expert opinion was sought around themes of surgical de-escalation, reduction in treatment morbidities, and improving the accuracy of breast-conserving surgery in terms of margin status. There was emphasis on how the primacy of surgical excision in an era of oncoplastic and reconstructive surgery is increasingly being challenged, with more effective systemic therapies that target residual disease burden, and permit response-adapted approaches to both breast and axillary surgery.

RESULTS

Technologies for intraoperative margin assessment can potentially half re-excision rates after breast-conserving surgery, and sentinel lymph node biopsy will become a therapeutic procedure for many patients with node-positive disease treated either with surgery or chemotherapy as the primary modality. Genomic profiling of tumours can aid in the selection of patients for neoadjuvant and adjuvant therapies as well as prevention strategies. Molecular subtypes are predictive of response to induction therapies and reductive approaches to surgery in the breast or axilla.

CONCLUSION

Treatments are increasingly being tailored and based on improved understanding of tumour biology and relevant biomarkers to determine absolute benefit and permit delivery of cost-effective healthcare. Patient involvement is crucial for breast cancer studies to ensure relevance and outcome measures that are objective, meaningful, and patient-centred.

Review of Laser Raman Spectroscopy for Surgical Breast Cancer Detection: Stochastic Backpropagation Neural Networks

Laser Raman spectroscopy (LRS) is a highly specific biomolecular technique which has been shown to have the ability to distinguish malignant and normal breast tissue. This paper discusses significant advancements in the use of LRS in surgical breast cancer diagnosis, with an emphasis on statistical and machine learning strategies employed for precise, transparent and real-time analysis of Raman spectra. When combined with a variety of "machine learning" techniques LRS has been increasingly employed in oncogenic diagnostics. This paper proposes that the majority of these algorithms fail to provide the two most critical pieces of information required by the practicing surgeon: a probability that the classification of a tissue is correct, and, more importantly, the expected error in that probability. Stochastic backpropagation artificial neural networks inherently provide both pieces of information for each and every tissue site examined by LRS. If the networks are trained using both human experts and an unsupervised classification algorithm as gold standards, rapid progress can be made understanding what additional contextual data is needed to improve network classification performance. Our patients expect us to not simply have an opinion about their tumor, but to know how certain we are that we are correct. Stochastic networks can provide that information.

Rapid assessment of breast tumor margins using deep ultraviolet fluorescence scanning microscopy

SIGNIFICANCE

Re-excision rates for women with invasive breast cancer undergoing breast conserving surgery (or lumpectomy) have decreased in the past decade but remain substantial. This is mainly due to the inability to assess the entire surface of an excised lumpectomy specimen efficiently and accurately during surgery.

AIM

The goal of this study was to develop a deep-ultraviolet scanning fluorescence microscope (DUV-FSM) that can be used to accurately and rapidly detect cancer cells on the surface of excised breast tissue.

APPROACH

A DUV-FSM was used to image the surfaces of 47 (31 malignant and 16 normal/benign) fresh breast tissue samples stained in propidium iodide and eosin Y solutions. A set of fluorescence images were obtained from each sample using low magnification (4  ×  ) and fully automated scanning. The images were stitched to form a color image. Three nonmedical evaluators were trained to interpret and assess the fluorescence images. Nuclear-cytoplasm ratio (N/C) was calculated and used for tissue classification.

RESULTS

DUV-FSM images a breast sample with subcellular resolution at a speed of 1.0  min  /  cm2. Fluorescence images show excellent visual contrast in color, tissue texture, cell density, and shape between invasive carcinomas and their normal counterparts. Visual interpretation of fluorescence images by nonmedical evaluators was able to distinguish invasive carcinoma from normal samples with high sensitivity (97.62%) and specificity (92.86%). Using N/C alone was able to differentiate patch-level invasive carcinoma from normal breast tissues with reasonable sensitivity (81.5%) and specificity (78.5%).

CONCLUSIONS

DUV-FSM achieved a good balance between imaging speed and spatial resolution with excellent contrast, which allows either visual or quantitative detection of invasive cancer cells on the surfaces of a breast surgical specimen.

Emerging Technologies for Real-Time Intraoperative Margin Assessment in Future Breast-Conserving Surgery

Clean surgical margins in breast-conserving surgery (BCS) are essential for preventing recurrence. Intraoperative pathologic diagnostic methods, such as frozen section analysis and imprint cytology, have been recognized as crucial tools in BCS. However, the complexity and time-consuming nature of these pathologic procedures still inhibit their broader applicability worldwide. To address this situation, two issues should be considered: 1) the development of nonpathologic intraoperative diagnosis methods that have better sensitivity, specificity, speed, and cost; and 2) the promotion of new imaging algorithms to standardize data for analyzing positive margins, as represented by artificial intelligence (AI), without the need for judgment by well-trained pathologists. Researchers have attempted to develop new methods or techniques; several have recently emerged for real-time intraoperative management of breast margins in live tissues. These methods include conventional imaging, spectroscopy, tomography, magnetic resonance imaging, microscopy, fluorescent probes, and multimodal imaging techniques. This work summarizes the traditional pathologic and newly developed techniques and discusses the advantages and disadvantages of each method. Taking into consideration the recent advances in analyzing pathologic data from breast cancer tissue with AI, the combined use of new technologies with AI algorithms is proposed, and future directions for real-time intraoperative margin assessment in BCS are discussed.

Technology for Intraoperative Margin Assessment in Breast Cancer

BACKGROUND

As breast-conserving surgery (BCS) has become standard for treatment of breast cancer, the need for new technology to improve intraoperative margin assessment (IMA) has become clear. Close or positive margins during BCS lead to additional surgeries, treatment delay, additional stress for patients, and healthcare cost. Academia and industry have developed a diverse field of new technologies to allow surgeons to assess margins in the operating room. These technologies aim to reduce current rates of positive margins on final pathology.

METHODS

We selected recently developed IMA technologies, some of which have undergone large clinical trials and others that are still in early stage development. Technologies were categorized based on underlying methodology to differentiate malignant and normal tissue: spectroscopy, electrical properties, optical imaging and molecular imaging. Additionally, this review details clinical investigations, relevant statistical analysis as well as strengths and weaknesses of the various technologies.

CONCLUSION

Numerous technical innovations are being implemented to diminish rates of positive margins at breast tumor resection. Close collaboration among cross-disciplinary teams to further develop many of these technologies as well as completion of larger scale clinical studies are required to define an optimal approach. Development with an eye toward prioritizing sensitivity/specificity as well as healthcare cost containment has the potential to make a significant impact on this ongoing clinical need in breast cancer surgery.

Raman spectroscopy for rapid intra-operative margin analysis of surgically excised tumour specimens

Raman spectroscopy, a form of vibrational spectroscopy, has the ability to provide sensitive and specific biochemical analysis of tissue. This review article provides an in-depth analysis of the suitability of different Raman spectroscopy techniques in providing intra-operative margin analysis in a range of solid tumour pathologies. Surgical excision remains the primary treatment of a number of solid organ cancers. Incomplete excision of a tumour and positive margins on histopathological analysis is associated with a worse prognosis, the need for adjuvant therapies with significant side effects and a resulting financial burden. The provision of intra-operative margin analysis of surgically excised tumour specimens would be beneficial for a number of pathologies, as there are no widely adopted and accurate methods of margin analysis, beyond histopathology. The limitations of Raman spectroscopic studies to date are discussed and future work necessary to enable translation to clinical use is identified. We conclude that, although there remain a number of challenges in translating current techniques into a clinically effective tool, studies so far demonstrate that Raman Spectroscopy has the attributes to successfully perform highly accurate intra-operative margin analysis in a clinically relevant environment.

Re-Excision Rates in Breast-Conserving Surgery for Invasive Breast Cancer after Neoadjuvant Chemotherapy with and without the Use of a Radiopaque Tissue Transfer and X-ray System

Background

Significant re-excision rates in breast-conserving surgery (BCS) after neoadjuvant systemic chemotherapy may result from difficulties in defining the surgical target particularly in cases with excellent treatment response. Devices allowing an exact topographic localisation of the lesion in the resected tissue could reduce re-excision rates by optimising the intraoperative detection of involved margins.

Methods

80 patients with invasive breast cancer receiving BCS after neoadjuvant chemotherapy were included in this non-randomized case-control study. 40 patients with specimen radiography performed in a standard approach (control group) were compared to 40 patients with use of a radiopaque tissue transfer system (study group).

Results

19/80 (23.75%) patients required re-excision because of involved margins; among those, 14/40 (35%) were in the control group and 5/40 (12.5%) in the study group. The association between the use of the radiopaque tissue transfer system and the lower re-excision rate was statistically significant (p = 0.023).

Conclusion

Our analysis provides a rationale for the routine use of a radiopaque tissue transfer system for specimen radiography in BCS after neoadjuvant chemotherapy for invasive breast cancer in order to reduce re-excision rates.

Towards mm-wave spectroscopy for dielectric characterization of breast surgical margins

PURPOSE

The evaluation of the surgical margin in breast conservative surgery is a matter of general interest as such treatments are subject to the critical issue of margin status as positive surgical margins can undermine the effectiveness of the procedure. The relatively unexplored ability of millimeter-wave (mm-wave) spectroscopy to provide insight into the dielectric properties of breast tissues was investigated as a precursor to their possible use in assessment of surgical margins.

METHODS

We assessed the ability of a mm-wave system with a roughly hemispherical sensitive volume of ∼3 mm radius to distinguish malignant breast lesions in prospectively and consecutively collected tumoral and non-tumoral ex-vivo breast tissue samples from 91 patients. We characterized the dielectric properties of 346 sites in these samples, encompassing malignant, fibrocystic disease and normal breast tissues. An expert pathologist subsequently evaluated all measurement sites.

RESULTS

At multivariate analysis, mm-wave dielectric properties were significantly correlated to histologic diagnosis and fat content. Further, using 5-fold cross-validation in a Bayesian logistic mixed model that considered the patient as a random effect, the mm-wave dielectric properties of neoplastic tissues were significantly different from normal breast tissues, but not from fibrocystic tissue.

CONCLUSION

Reliable discrimination of malignant from normal, fat-rich breast tissue to a depth compatible with surgical margin assessment requirements was achieved with mm-wave spectroscopy.

Complete excision with narrow margins provides equivalent local control to wider excision in breast conservation for invasive cancer

Background

Society of Surgical Oncology and American Society for Radiation Oncology guidelines define clear margins in breast-conserving therapy (BCT) as 'no ink on tumour', in contrast to the attainment of margins of at least 1 mm widely practised in the UK. The primary aim of this study was to explore clinical, surgical and tumour-related factors associated with local recurrence after BCT, with a secondary aim of assessing the impact of margin re-excision on the risk of local recurrence.

Methods

Patient demographics, surgical details, tumour characteristics and local recurrence were recorded for consecutive women with BCT undergoing surgery between January 1997 and January 2007. Margins were defined as clear (greater than 1 mm), close (less than 1 mm but no ink on tumour), reaches (ink on tumour) and clear after re-excision.

Results

A total of 1045 women of median age 54 (range 18-86) years were studied. Median follow-up was 89 (range 4-196) months. Local recurrence occurred in 52 patients (5·0 per cent). Ink on tumour was associated with local recurrence (hazard ratio (HR) 4·86, 95 per cent c.i. 1·49 to 15·79; P = 0·009). Risk of local recurrence was the same for close and clear margins (HR 1·03, 0·40 to 2·62; P = 0·954). In women with involved margins, re-excision was still associated with an increased local recurrence risk (HR 2·50, 1·32 to 4·72; P = 0·005). Oestrogen receptor negativity increased risk (HR 2·28, 1·28 to 4·06; P = 0·005).

Conclusion

Adequately excised margins, even when under 1 mm, provide equivalent outcomes to wider margins in BCT. Achieving complete excision at primary surgery achieves the lowest rates of local recurrence.

Update of the American Society of Breast Surgeons Toolbox to address the lumpectomy reoperation epidemic

In 2015, the American Society of Breast Surgeons (ASBrS) convened a multidisciplinary consensus conference, the Collaborative Attempt to Lower Lumpectomy Reoperation Rates (CALLER). The CALLER conference endorsed a "toolbox" of multiple processes of care for which there was evidence that they were associated with fewer reoperations. We present an update of the toolbox taking into consideration the latest advances in decreasing re excision rates. In this review, we performed a comprehensive review of the literature from 2015-2018 using search terms for each tool. The original ten tools were updated with the latest evidence from the literature and our strength of recommendation. We added an additional section looking at new tools and techniques that may provide more accurate intraoperative assessment of margins. The updates on the CALLER Toolbox for lumpectomy will help guide surgeons to various resources to aid in the removal of breast cancer, while being aware of cosmesis and decreasing re excision rates.

Review of methods for intraoperative margin detection for breast conserving surgery

Breast conserving surgery (BCS) is an effective treatment for early-stage cancers as long as the margins of the resected tissue are free of disease according to consensus guidelines for patient management. However, 15% to 35% of patients undergo a second surgery since malignant cells are found close to or at the margins of the original resection specimen. This review highlights imaging approaches being investigated to reduce the rate of positive margins, and they are reviewed with the assumption that a new system would need high sensitivity near 95% and specificity near 85%. The problem appears to be twofold. The first is for complete, fast surface scanning for cellular, structural, and/or molecular features of cancer, in a lumpectomy volume, which is variable in size, but can be large, irregular, and amorphous. A second is for full, volumetric imaging of the specimen at high spatial resolution, to better guide internal radiologic decision-making about the spiculations and duct tracks, which may inform that surfaces are involved. These two demands are not easily solved by a single tool. Optical methods that scan large surfaces quickly are needed with cellular/molecular sensitivity to solve the first problem, but volumetric imaging with high spatial resolution for soft tissues is largely outside of the optical realm and requires x-ray, micro-CT, or magnetic resonance imaging if they can be achieved efficiently. In summary, it appears that a combination of systems into hybrid platforms may be the optimal solution for these two very different problems. This concept must be cost-effective, image specimens within minutes and be coupled to decision-making tools that help a surgeon without adding to the procedure. The potential for optical systems to be involved in this problem is emerging and clinical trials are underway in several of these technologies to see if they could reduce positive margin rates in BCS.

Intra-operative spectroscopic assessment of surgical margins during breast conserving surgery

Background

In over 20% of breast conserving operations, postoperative pathological assessment of the excised tissue reveals positive margins, requiring additional surgery. Current techniques for intra-operative assessment of tumor margins are insufficient in accuracy or resolution to reliably detect small tumors. There is a distinct need for a fast technique to accurately identify tumors smaller than 1 mm² in large tissue surfaces within 30 min.

Methods

Multi-modal spectral histopathology (MSH), a multimodal imaging technique combining tissue auto-fluorescence and Raman spectroscopy was used to detect microscopic residual tumor at the surface of the excised breast tissue. New algorithms were developed to optimally utilize auto-fluorescence images to guide Raman measurements and achieve the required detection accuracy over large tissue surfaces (up to 4 × 6.5 cm²). Algorithms were trained on 91 breast tissue samples from 65 patients.

Results

Independent tests on 121 samples from 107 patients - including 51 fresh, whole excision specimens - detected breast carcinoma on the tissue surface with 95% sensitivity and 82% specificity. One surface of each uncut excision specimen was measured in 12–24 min. The combination of high spatial-resolution auto-fluorescence with specific diagnosis by Raman spectroscopy allows reliable detection even for invasive carcinoma or ductal carcinoma in situ smaller than 1 mm².

Conclusions

This study provides evidence that this multimodal approach could provide an objective tool for intra-operative assessment of breast conserving surgery margins, reducing the risk for unnecessary second operations.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1002-2) contains supplementary material, which is available to authorized users.

Novel techniques for intraoperative assessment of margin involvement

Breast conserving surgery (BCS) is now the standard of care for the majority of women with early stage breast cancer. There is a finite rate of ipsilateral breast tumour recurrence (IBTR) for breast conserving therapy (BCT) with annual rates of less than 1% for specialist breast practices. There has been recent consensus on the definition of an adequate resection margin for both invasive and noninvasive breast cancer treated with BCS, although some variation in margin policy persists with definitions of 'no tumour at ink', 1 and 2 mm margin mandates. Despite the development of methods for intraoperative assessment of margins, up to 20% of patients require further surgery (cavity re-excision or completion mastectomy) to achieve clear surgical margins. In the past decade, several novel technologies for intraoperative margin assessment have been explored with the aim of reducing rates of re-operation and its attendant patient anxiety, inconvenience and additional cost. Ongoing studies are addressing the safety, feasibility and cost-effectiveness of these novel technologies relative to methods in routine clinical usage.

Current margin practice and effect on re-excision rates following the publication of the SSO-ASTRO consensus and ABS consensus guidelines: a national prospective study of 2858 women undergoing breast-conserving therapy in the UK and Ireland

INTRODUCTION

There is variation in margin policy for breast conserving therapy (BCT) in the UK and Ireland. In response to the Society of Surgical Oncology and American Society for Radiation Oncology (SSO-ASTRO) margin consensus ('no ink on tumour' for invasive and 2 mm for ductal carcinoma in situ [DCIS]) and the Association of Breast Surgery (ABS) consensus (1 mm for invasive and DCIS), we report on current margin practice and unit infrastructure in the UK and Ireland and describe how these factors impact on re-excision rates.

METHODS

A trainee collaborative-led multicentre prospective study was conducted in the UK and Ireland between 1st February and 31st May 2016. Data were collected on consecutive BCT patients and on local infrastructure and policies.

RESULTS

A total of 79 sites participated in the data collection (75% screening units; average 372 cancers annually, range 70-900). For DCIS, 53.2% of units accept 1 mm and 38% accept 2-mm margins. For invasive disease 77.2% accept 1 mm and 13.9% accept 'no ink on tumour'. A total of 2858 patients underwent BCT with a mean re-excision rate of 17.2% across units (range 0-41%). The re-excision rate would be reduced to 15% if all units applied SSO-ASTRO guidelines and to 14.8% if all units followed ABS guidelines. Of those who required re-operation, 65% had disease present at margin.

CONCLUSION

There continues to be large variation in margin policy and re-excision rates across units. Altering margin policies to follow either SSO-ASTRO or ABS guidelines would result in a modest reduction in the national re-excision rate. Most re-excisions are for involved margins rather than close margins.

Use of a handheld terahertz pulsed imaging device to differentiate benign and malignant breast tissue

Since nearly 20% of breast-conserving surgeries (BCS) require re-operation, there is a clear need for developing new techniques to more accurately assess tumor resection margins intraoperatively. This study evaluates the diagnostic accuracy of a handheld terahertz pulsed imaging (TPI) system to discriminate benign from malignant breast tissue ex vivo. Forty six freshly excised breast cancer samples were scanned with a TPI handheld probe system, and histology was obtained for comparison. The image pixels on TPI were classified using (1) parameters in combination with support vector machine (SVM) and (2) Gaussian wavelet deconvolution in combination with Bayesian classification. The results were an accuracy, sensitivity, specificity of 75%, 86%, 66% for method 1, and 69%, 87%, 54% for method 2 respectively. This demonstrates the probe can discriminate invasive breast cancer from benign breast tissue with an encouraging degree of accuracy, warranting further study.

Rapid evaporative ionisation mass spectrometry of electrosurgical vapours for the identification of breast pathology: towards an intelligent knife for breast cancer surgery

BACKGROUND

Re-operation for positive resection margins following breast-conserving surgery occurs frequently (average = 20-25%), is cost-inefficient, and leads to physical and psychological morbidity. Current margin assessment techniques are slow and labour intensive. Rapid evaporative ionisation mass spectrometry (REIMS) rapidly identifies dissected tissues by determination of tissue structural lipid profiles through on-line chemical analysis of electrosurgical aerosol toward real-time margin assessment.

METHODS

Electrosurgical aerosol produced from ex-vivo and in-vivo breast samples was aspirated into a mass spectrometer (MS) using a monopolar hand-piece. Tissue identification results obtained by multivariate statistical analysis of MS data were validated by histopathology. Ex-vivo classification models were constructed from a mass spectral database of normal and tumour breast samples. Univariate and tandem MS analysis of significant peaks was conducted to identify biochemical differences between normal and cancerous tissues. An ex-vivo classification model was used in combination with bespoke recognition software, as an intelligent knife (iKnife), to predict the diagnosis for an ex-vivo validation set. Intraoperative REIMS data were acquired during breast surgery and time-synchronized to operative videos.

RESULTS

A classification model using histologically validated spectral data acquired from 932 sampling points in normal tissue and 226 in tumour tissue provided 93.4% sensitivity and 94.9% specificity. Tandem MS identified 63 phospholipids and 6 triglyceride species responsible for 24 spectral differences between tissue types. iKnife recognition accuracy with 260 newly acquired fresh and frozen breast tissue specimens (normal n = 161, tumour n = 99) provided sensitivity of 90.9% and specificity of 98.8%. The ex-vivo and intra-operative method produced visually comparable high intensity spectra. iKnife interpretation of intra-operative electrosurgical vapours, including data acquisition and analysis was possible within a mean of 1.80 seconds (SD ±0.40).

CONCLUSIONS

The REIMS method has been optimised for real-time iKnife analysis of heterogeneous breast tissues based on subtle changes in lipid metabolism, and the results suggest spectral analysis is both accurate and rapid. Proof-of-concept data demonstrate the iKnife method is capable of online intraoperative data collection and analysis. Further validation studies are required to determine the accuracy of intra-operative REIMS for oncological margin assessment.