Predictors of re-excision in wire-guided wide local excision for early breast cancer: a Western Australian multi-centre experience

Localisation accuracy with iodine-125 seed versus wire guidance for breast cancer surgery

INTRODUCTION

Impalpable breast lesions generally require image-guided localisation for breast-conserving surgery. A standard technique is to place a hook wire (HW) within the lesion. Radioguided occult lesion localisation using iodine seeds (ROLLIS) involves inserting a 4.5 mm iodine-125 seed (seed) into the lesion. We hypothesised that a seed could be more precisely positioned in relation to the lesion than a HW and that this may be associated with a lower re-excision rate.

METHODS

Retrospective review of consecutive participant data from three ROLLIS RCT (ACTRN12613000655741) sites. Participants underwent preoperative lesion localisation (PLL) with seed or HW between September 2013 and December 2017. Lesion and procedural characteristics were recorded. Distances between (1) any part of the seed or thickened segment of the HW ('TSHW') and the lesion/clip ('distance to device' DTD) and (2) centre of the TSHW/seed and centre of the lesion/clip (device centre to target centre 'DCTC') were measured on immediate postinsertion mammograms. Pathological margin involvement and re-excision rates were compared.

RESULTS

A total of 390 lesions (190 ROLLIS and 200 HWL) were analysed. Lesion characteristics and guidance modality used were similar between groups. Ultrasound-guided DTD and DCTC for seed were smaller than for HW (77.1% and 60.6%, respectively, P-value < 0.001). Stereotactic-guided DCTC for seeds was 41.6% smaller than for HW (P-value = 0.001). No statistically significant difference in the re-excision rates was found.

CONCLUSION

Iodine-125 seeds can be more precisely positioned for preoperative lesion localisation than HW, however, no statistically significant difference in re-excision rates was detected.

Surgical outcomes after radioactive 125I seed versus hookwire localization of non-palpable breast cancer: a multicentre randomized clinical trial

BACKGROUND

Previous studies have suggested improved efficiency and patient outcomes with 125I seed compared with hookwire localization (HWL) in breast-conserving surgery, but high-level evidence of superior surgical outcomes is lacking. The aim of this multicentre pragmatic RCT was to compare re-excision and positive margin rates after localization using 125I seed or hookwire in women with non-palpable breast cancer.

METHODS

Between September 2013 and March 2018, women with non-palpable breast cancer eligible for breast-conserving surgery were assigned randomly to preoperative localization using 125I seeds or hookwires. Randomization was stratified by lesion type (pure ductal carcinoma in situ (DCIS) or other) and study site. Primary endpoints were rates of re-excision and margin positivity. Secondary endpoints were resection volumes and weights.

RESULTS

A total of 690 women were randomized at eight sites; 659 women remained after withdrawal (125I seed, 327; HWL, 332). Mean age was 60.3 years in the 125I seed group and 60.7 years in the HWL group, with no difference between the groups in preoperative lesion size (mean 13.2 mm). Lesions were pure DCIS in 25.9 per cent. The most common radiological lesion types were masses (46.9 per cent) and calcifications (28.2 per cent). The localization modality was ultrasonography in 65.5 per cent and mammography in 33.7 per cent. The re-excision rate after 125I seed localization was significantly lower than for HWL (13.9 versus 18.9 per cent respectively; P = 0.019). There were no significant differences in positive margin rates, or in specimen weights and volumes.

CONCLUSION

Re-excision rates after breast-conserving surgery were significantly lower after 125I seed localization compared with HWL. Registration number: ACTRN12613000655741 (http://www.ANZCTR.org.au/).

Magnetic Seed Localization (Magseed) for excision of impalpable breast lesions-The North Wales experience

The breast surgical community has faced huge challenges due to close working relationships with radiologists who are in short supply. Breast lesion localization is moving away from the traditional wire technique, which requires an on-site radiologist to support theater scheduling. In North Wales, the introduction of Magseed for impalpable breast lesion localization has facilitated theater scheduling in the absence of same day radiology presence. We audited our first 200 Magseed cases to assess the safety and efficacy of the technique, the ease of use, and patient experience. Data were entered prospectively into an excel data base relating to Magseed cases. Data collected included demographics, pre and postoperative lesion size, histology, margin positivity, and re-excision rates. Data were submitted in real time by the radiologist performing Magseed insertion to ascertain degree of difficulty. A PROMS questionnaire was designed and sent to patients undergoing Magseed vs wire localizations. Two hundred patients underwent Magseed-guided wide local excision between May 2018 and January 2020 across 2 district general hospital sites in North Wales. Histology: 69% IDC, 20% ILC, and 11% others. Mean preoperative size 12.3 mm, postoperative size 19 mm. Re-excision rate 15%. Re-excision for DCIS was significantly more likely than for invasive disease (p < 0.0001). A significant difference was also observed between radiological mean preoperative tumor size estimate and actual histological tumor size in patients undergoing margin re-excision (p = 0.000019). Wire-guided re-excision rate was 21% in the same unit. PROMs found the procedure well tolerated by patients. Surgeons and radiologists reported Magseed to be user-friendly with minimal learning curve. Magseed use for impalpable breast lesion localization is safe, user friendly, and well tolerated by patients. It produces favorable re-excision rates when compared to published figures for wire-guided excision. The presence of DCIS and preoperative radiological size underestimation was associated with margin re-excision.

Optical palpation for tumor margin assessment in breast-conserving surgery

Intraoperative margin assessment is needed to reduce the re-excision rate of breast-conserving surgery. One possibility is optical palpation, a tactile imaging technique that maps stress (force applied across the tissue surface) as an indicator of tissue stiffness. Images (optical palpograms) are generated by compressing a transparent silicone layer on the tissue and measuring the layer deformation using optical coherence tomography (OCT). This paper reports, for the first time, the diagnostic accuracy of optical palpation in identifying tumor within 1 mm of the excised specimen boundary using an automated classifier. Optical palpograms from 154 regions of interest (ROIs) from 71 excised tumor specimens were obtained. An automated classifier was constructed to predict the ROI margin status by first choosing a circle diameter, then searching for a location within the ROI where the circle was ≥ 75% filled with high stress (indicating a positive margin). A range of circle diameters and stress thresholds, as well as the impact of filtering out non-dense tissue regions, were tested. Sensitivity and specificity were calculated by comparing the automated classifier results with the true margin status, determined from co-registered histology. 83.3% sensitivity and 86.2% specificity were achieved, compared to 69.0% sensitivity and 79.0% specificity obtained with OCT alone on the same dataset using human readers. Representative optical palpograms show that positive margins containing a range of cancer types tend to exhibit higher stress compared to negative margins. These results demonstrate the potential of optical palpation for margin assessment.

Predictors of Reexcision following Breast-Conserving Surgery for Ductal Carcinoma In Situ

BACKGROUND

Reexcision following breast-conserving surgery (BCS) in women with ductal carcinoma in situ (DCIS) results in adjuvant treatment delays, higher health care costs, and undesirable cosmetic outcomes. The purpose of this study is to determine patient, imaging, pathological, and surgical predictors of reexcision following BCS for DCIS.

PATIENTS AND METHODS

A retrospective review of women with DCIS who had BCS from 2007 to 2016 was conducted. Patient, imaging, pathological, and surgical features, in addition to surgical outcomes, were collected from medical records. Standard statistical tests were used to compare features between patients who did and did not undergo at least one reexcision. A multivariable logistic regression model was fit to assess features associated with reexcision.

RESULTS

A total of 547 women (mean age 59 years; range 30-88 years) diagnosed with DCIS at core needle biopsy underwent BCS. Of all women, 31.6% (173/547) had at least one reexcision. With multivariable analysis, features associated with reexcision included younger patient age (adjusted odds ratio [aOR] 0.98, 95% confidence interval [CI] 0.97-1.0, p = 0.049), African-American race (aOR 2.66, 95% CI 1.13-6.26, p = 0.03), biopsy modality of ultrasound (aOR 2.35, 95% CI 1.22-4.53, p = 0.01), and earlier year of surgery (aOR 0.92, 95% CI 0.86-0.98, p = 0.01). No pathological features of DCIS were associated with reexcision risk.

CONCLUSIONS

In our cohort of nearly 550 women with DCIS who underwent BCS, 31.6% had at least one reexcision. Features associated with reexcision include younger patient age, African-American race, biopsy modality of ultrasound, and earlier year of surgery.

Handheld volumetric manual compression-based quantitative microelastography

Compression optical coherence elastography (OCE) typically requires a mechanical actuator to impart a controlled uniform strain to the sample. However, for handheld scanning, this adds complexity to the design of the probe and the actuator stroke limits the amount of strain that can be applied. In this work, we present a new volumetric imaging approach that utilizes bidirectional manual compression via the natural motion of the user's hand to induce strain to the sample, realizing compact, actuator-free, handheld compression OCE. In this way, we are able to demonstrate rapid acquisition of three-dimensional quantitative microelastography (QME) datasets of a tissue volume (6 × 6 × 1 mm³ ) in 3.4 seconds. We characterize the elasticity sensitivity of this freehand manual compression approach using a homogeneous silicone phantom and demonstrate comparable performance to a benchtop mounted, actuator-based approach. In addition, we demonstrate handheld volumetric manual compression-based QME on a tissue-mimicking phantom with an embedded stiff inclusion and on freshly excised human breast specimens from both mastectomy and wide local excision (WLE) surgeries. Tissue results are coregistered with postoperative histology, verifying the capability of our approach to measure the elasticity of tissue and to distinguish stiff tumor from surrounding soft benign tissue.

Three-dimensional mapping of the attenuation coefficient in optical coherence tomography to enhance breast tissue microarchitecture contrast

Effective intraoperative tumor margin assessment is needed to reduce re-excision rates in breast-conserving surgery (BCS). Mapping the attenuation coefficient in optical coherence tomography (OCT) throughout a sample to create an image (attenuation imaging) is one promising approach. For the first time, three-dimensional OCT attenuation imaging of human breast tissue microarchitecture using a wide-field (up to ~45 × 45 × 3.5 mm) imaging system is demonstrated. Representative results from three mastectomy and one BCS specimen (from 31 specimens) are presented with co-registered postoperative histology. Attenuation imaging is shown to provide substantially improved contrast over OCT, delineating nuanced features within tumors (including necrosis and variations in tumor cell density and growth patterns) and benign features (such as sclerosing adenosis). Additionally, quantitative micro-elastography (QME) images presented alongside OCT and attenuation images show that these techniques provide complementary contrast, suggesting that multimodal imaging could increase tissue identification accuracy and potentially improve tumor margin assessment.

A comparison of stereotactic and tomosynthesis-guided localisation of impalpable breast lesions

INTRODUCTION

Impalpable breast cancers require precise pre-operative lesion localisation to minimise re-excision rates. Conventional techniques include hookwire insertion using stereotactic guidance. Newer techniques include the use of tomosynthesis guidance and the use of iodine-125 seeds. This study compares the accuracy of lesion localisation with hookwire or seed insertion using prone stereotactic or upright tomosynthesis guidance.

METHODS

This registered quality improvement activity did not require formal ethics approval. The post-localisation images for 116 lesions were reviewed. The distance from the lesion or breast biopsy marker to the hookwire or seed was measured on post-insertion mammograms. The relative placement accuracy of hookwire or seed using prone stereotactic or upright tomosynthesis guidance was compared. A lesion to seed or wire distance > 10 mm was considered technically unsatisfactory.

RESULTS

94.8% of the seeds and wires inserted via prone stereotactic guidance were accurately placed, compared with 89.6% of those inserted via upright tomosynthesis. There were twice as many technically unsatisfactory insertions under upright tomosynthesis guidance. The majority of the unsatisfactory insertions using upright tomosynthesis occurred when the lesion was at or below the level of the nipple and the insertion was performed craniocaudally.

CONCLUSION

The degree of accuracy of pre-operative localisation of impalpable breast lesions is significantly higher with the use of prone stereotactic rather than upright tomosynthesis guidance. This was most evident with the placement of I-125 seeds, and in cases where the target lesion was located below the level of the nipple.

Handheld probe for quantitative micro-elastography

Optical coherence elastography (OCE) has been proposed for a range of clinical applications. However, the majority of these studies have been performed using bulky, lab-based imaging systems. A compact, handheld imaging probe would accelerate clinical translation, however, to date, this had been inhibited by the slow scan rates of compact devices and the motion artifact induced by the user's hand. In this paper, we present a proof-of-concept, handheld quantitative micro-elastography (QME) probe capable of scanning a 6 × 6 × 1 mm volume of tissue in 3.4 seconds. This handheld probe is enabled by a novel QME acquisition protocol that incorporates a custom bidirectional scan pattern driving a microelectromechanical system (MEMS) scanner, synchronized with the sample deformation induced by an annular PZT actuator. The custom scan pattern reduces the total acquisition time and the time difference between B-scans used to generate displacement maps, minimizing the impact of motion artifact. We test the feasibility of the handheld QME probe on a tissue-mimicking silicone phantom, demonstrating comparable image quality to a bench-mounted setup. In addition, we present the first handheld QME scans performed on human breast tissue specimens. For each specimen, quantitative micro-elastograms are co-registered with, and validated by, histology, demonstrating the ability to distinguish stiff cancerous tissue from surrounding soft benign tissue.

Finger-mounted quantitative micro-elastography

We present a finger-mounted quantitative micro-elastography (QME) probe, capable of measuring the elasticity of biological tissue in a format that avails of the dexterity of the human finger. Finger-mounted QME represents the first demonstration of a wearable elastography probe. The approach realizes optical coherence tomography-based elastography by focusing the optical beam into the sample via a single-mode fiber that is fused to a length of graded-index fiber. The fiber is rigidly affixed to a 3D-printed thimble that is mounted on the finger. Analogous to manual palpation, the probe compresses the tissue through the force exerted by the finger. The resulting deformation is measured using optical coherence tomography. Elasticity is estimated as the ratio of local stress at the sample surface, measured using a compliant layer, to the local strain in the sample. We describe the probe fabrication method and the signal processing developed to achieve accurate elasticity measurements in the presence of motion artifact. We demonstrate the probe's performance in motion-mode scans performed on homogeneous, bi-layer and inclusion phantoms and its ability to measure a thermally-induced increase in elasticity in ex vivo muscle tissue. In addition, we demonstrate the ability to acquire 2D images with the finger-mounted probe where lateral scanning is achieved by swiping the probe across the sample surface.

Optical palpation for the visualization of tumor in human breast tissue

Accurate and effective removal of tumor in one operation is an important goal of breast-conserving surgery. However, it is not always achieved. Surgeons often utilize manual palpation to assess the surgical margin and/or the breast cavity. Manual palpation, however, is subjective and has relatively low resolution. Here, we investigate a tactile imaging technique, optical palpation, for the visualization of tumor. Optical palpation generates maps of the stress at the surface of tissue under static preload compression. Stress is evaluated by measuring the deformation of a contacting thin compliant layer with known mechanical properties using optical coherence tomography. In this study, optical palpation is performed on 34 freshly excised human breast specimens. Wide field-of-view (up to ~46 × 46 mm) stress images, optical palpograms, are presented from four representative specimens, demonstrating the capability of optical palpation to visualize tumor. Median stress reported for adipose tissue, 4 kPa, and benign dense tissue, 8 kPa, is significantly lower than for invasive tumor, 60 kPa. In addition, we demonstrate that optical palpation provides contrast consistent with a related optical technique, quantitative micro-elastography. This study demonstrates that optical palpation holds promise for visualization of tumor in breast-conserving surgery.

Clinical feasibility of optical coherence micro-elastography for imaging tumor margins in breast-conserving surgery

It has been demonstrated that optical coherence micro-elastography (OCME) provides additional contrast of tumor compared to optical coherence tomography (OCT) alone. Previous studies, however, have predominantly been performed on mastectomy specimens. Such specimens typically differ substantially in composition and geometry from the more clinically relevant wide-local excision (WLE) specimens excised during breast-conserving surgery. As a result, it remains unclear if the mechanical contrast observed is maintained in WLE specimens. In this manuscript, we begin to address this issue by performing a feasibility study of OCME on 17 freshly excised, intact WLE specimens. In addition, we present two developments required to sustain the progression of OCME towards intraoperative deployment. First, to enable the rapid visualization of en face images required for intraoperative assessment, we describe an automated segmentation algorithm to fuse en face micro-elastograms with OCT images to provide dual contrast images. Secondly, to validate contrast in micro-elastograms, we present a method that enables co-registration of en face images with histology of WLE specimens, sectioned in the orthogonal plane, without any modification to the standard clinical workflow. We present a summary of the observations across the 17 specimens imaged in addition to representative micro-elastograms and OCT images demonstrating contrast in a number of tumor margins, including those involved by invasive ductal carcinoma, mucinous carcinoma, and solid-papillary carcinoma. The results presented here demonstrate the potential of OCME for imaging tumor margins.

Re-excision rate after sector resection for breast cancer: A 5-year retrospective cohort study

BACKGROUND

Positive margins after Breast conserving surgery (BCS) for breast cancer can result in local recurrence (LR) requiring further surgery. This can lead to unnecessary patient anxiety, poor prognosis and impose additional economic burden to our health system. The aim of this study is to assess the rate of re-excision for positive margins after BCS using the sector resection technique.

METHODS

This single centre retrospective cohort study included all women who underwent BCS using sector resection between the years of 2012 and 2016. A total of 456 patients underwent sector resection. We evaluated the margin status, re-excision rates and their predictive risk factors.

RESULTS

415 (91%) patients had clear margins. 41 (9%) patients underwent further re-excision for positive or close margin. 75.6% of those patients had DCIS and 51% had invasive carcinoma involving the margins. Patient and tumour characteristics associated with an increased risk of positive margin were women under the age of 50 (p = 0.19), tumours >50 mm (p = 0.001), grade-2 (p = 0.48) and grade-3 (p = 0.63), HER-2 positivity (p = 0.02), sentinel lymph node positivity (p = 0.03), and patients undergoing axillary lymph node dissection (p = 0.01).

CONCLUSION

BCS using the sector resection technique has a low re-excision rate for positive margins. Younger patients and aggressive tumour biology are important predictive risk factors for positive margins.

Wide-field quantitative micro-elastography of human breast tissue

Currently, 20-30% of patients undergoing breast-conserving surgery require a second surgery due to insufficient surgical margins in the initial procedure. We have developed a wide-field quantitative micro-elastography system for the assessment of tumor margins. In this technique, we map tissue elasticity over a field-of-view of ~46 × 46 mm. We performed wide-field quantitative micro-elastography on thirteen specimens of freshly excised tissue acquired from patients undergoing a mastectomy. We present wide-field optical coherence tomography (OCT) images, qualitative (strain) micro-elastograms and quantitative (elasticity) micro-elastograms, acquired in 10 minutes. We demonstrate that wide-field quantitative micro-elastography can extend the range of tumors visible using OCT-based elastography by providing contrast not present in either OCT or qualitative micro-elastography and, in addition, can reduce imaging artifacts caused by a lack of contact between tissue and the imaging window. Also, we describe how the combined evaluation of OCT, qualitative micro-elastograms and quantitative micro-elastograms can improve the visualization of tumor.

Simplifying the assessment of human breast cancer by mapping a micro-scale heterogeneity index in optical coherence elastography

Surgical treatment of breast cancer aims to identify and remove all malignant tissue. Intraoperative assessment of tumor margins is, however, not exact; thus, re-excision is frequently needed, or excess normal tissue is removed. Imaging methods applicable intraoperatively could help to reduce re-excision rates whilst minimizing removal of excess healthy tissue. Optical coherence elastography (OCE) has been proposed for use in breast-conserving surgery; however, intraoperative interpretation of complex OCE images may prove challenging. Observations of breast cancer on multiple length scales, by OCE, ultrasound elastography, and atomic force microscopy, have shown an increase in the mechanical heterogeneity of malignant breast tumors compared to normal breast tissue. In this study, a micro-scale mechanical heterogeneity index is introduced and used to form heterogeneity maps from OCE scans of 10 ex vivo human breast tissue samples. Through comparison of OCE, optical coherence tomography images, and corresponding histology, malignant tissue is shown to possess a higher heterogeneity index than benign tissue. The heterogeneity map simplifies the contrast between tumor and normal stroma in breast tissue, facilitating the rapid identification of possible areas of malignancy, which is an important step towards intraoperative margin assessment using OCE.

Wide-field optical coherence micro-elastography for intraoperative assessment of human breast cancer margins

Incomplete excision of malignant tissue is a major issue in breast-conserving surgery, with typically 20 - 30% of cases requiring a second surgical procedure arising from postoperative detection of an involved margin. We report advances in the development of a new intraoperative tool, optical coherence micro-elastography, for the assessment of tumor margins on the micro-scale. We demonstrate an important step by conducting whole specimen imaging in intraoperative time frames with a wide-field scanning system acquiring mosaicked elastograms with overall dimensions of ~50 × 50 mm, large enough to image an entire face of most lumpectomy specimens. This capability is enabled by a wide-aperture annular actuator with an internal diameter of 65 mm. We demonstrate feasibility by presenting elastograms recorded from freshly excised human breast tissue, including from a mastectomy, lumpectomies and a cavity shaving.