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

Bracketed Localization in Breast-Conserving Surgery: Indications and Success Rates From a Single, High Volume, Academic Breast Cancer Center

BACKGROUND

Bracketed localization is a technique used to help localize lesions for breast-conserving surgery (BCS). To date, there are no guidelines for when bracketed localization should be used in clinical practice. Based on our experience, we aim to provide criteria that should prompt surgeons to consider bracketing.

METHODS

A single-institution retrospective chart review was performed on patients who underwent bracketed localization for BCS between 2015 and 2021. Lesion characteristics were recorded including lesion span, number of lesions, histology type on core needle biopsy and surgical specimen, margin status, and need for additional surgery.

RESULTS

One hundred and thirteen cases were analyzed. Imaging showed an average lesion span of 5.0-cm. Multifocal lesions represented 45% of cases. Ductal carcinoma in situ (DCIS) was a histological component in 64% of core needle biopsies and 76% of surgical specimens. Negative margins were achieved in 82% of patients on the first excision. Additional surgery was performed in 17% of patients. Invasive lobular carcinoma had the highest additional surgery rate at 23%. Negative margins with BCS were achieved in 96% of cases, including those with successful re-excision.

DISCUSSION

This descriptive study shows that bracketed localization was most often employed for patients with large lesion spans, multifocality, and a DCIS or invasive lobular component. While these characteristics are typically associated with higher rates of positive margins, our cohort's rate of additional surgery was comparable to the national average for all BCS operations. These results argue that surgeon utilization of bracketed localization may be beneficial in these clinical scenarios.

Cost minimization in breast conserving surgery: a comparative study of radiofrequency spectroscopy and full cavity shave margins

BACKGROUND

In an effort to minimize positive margins and subsequent re-excision after breast conserving surgery (BCS), many providers and facilities have implemented either a Full Cavity Shave (FCS) approach or adding the MarginProbe Radiofrequency Spectroscopy System.

OBJECTIVE

We sought to create a functioning Pro-Forma for use by facilities and payers to evaluate and compare the cost savings of implementing FCS or MarginProbe based on personalized variable inputs.

METHODS

A decision tree demonstrating three possible surgical pathways, BCS, BCS + FCS, and BCS + MarginProbe was developed with clinical inputs for re-excision rate, mastectomy as 2nd surgery, rate of reconstruction, and rate of 3rd surgery derived by a literature review. A surgical pathway cost formula was created using the decision tree and financial inputs derived by utilizing the nation's largest database of privately billed health insurance claims and Medicare claims data (fairhealth.org). Using the surgical pathway formula and financial inputs, a customizable Pro-Forma was created for immediate cost savings analysis of BCS + FCS and BCS + Marginprobe using variable inputs. Costs are from the perspective of third-party payers.

RESULTS

Utilizing MarginProbe to reduce re-excisions for positive margins can be associated with better cost-savings than FCS due to the increased pathology processing costs by using an FCS approach. The reduction in re-excision provided by both FCS and MarginProbe offset their increased expense to various degrees with cost savings of each method improving as baseline re-excisions rates increase, until ultimately each may become cost-neutral or cost-prohibitive when compared to BCS alone. Our data suggest that in the privately insured population, MarginProbe provides a cost-savings over BCS alone when baseline re-excision rates are over 20% and that FCS becomes cost-saving when baseline re-excision rates are over 29%. For Medicare patients, MarginProbe provides a cost-savings when baseline re-excision rates exceed 34%, and FCS becomes cost-saving for re-excision rates over 52%. Our Pro-Forma allows an individual provider or institution to evaluate the cost savings of the FCS approach and/or utilization of the MarginProbe device such that the additional cost or cost-savings of utilizing one or both of these methods can be quickly calculated based on their facility's volume and baseline re-excision rate.

CONCLUSIONS

Our data suggest that utilizing either an FCS approach or the MarginProbe radiofrequency spectroscopy system may be a cost-saving solution to reducing the rate of re-excisions depending on a facility or practice's surgical volume and baseline re-excision rate. The degree to which each of these interventions provides an added cost or cost-savings to healthcare payers can be evaluated by utilizing the Pro-Forma outlined herein with customizable variable inputs.

Positive surgical margins after breast-conserving surgery for ductal carcinoma in-situ: does histologic grade or estrogen receptor status matter?

PURPOSE

DCIS has been shown to have a higher rate of positive margins following breast-conserving surgery (BCS) than invasive breast cancer. We aim to analyze certain factors of DCIS, specifically histologic grade and estrogen receptor (ER) status, in patients with positive surgical margins following BCS to determine if there is an association.

METHODS

A retrospective review of our institutional patient registry was performed to identify women with DCIS and microinvasive DCIS who underwent BCS by a single surgeon from 1999 to 2021. Demographics and clinicopathologic characteristics between patients with and without positive surgical margins were compared using chi-square or Student's t-test. We assessed factors associated with positive margins using univariate and multivariable logistic regression.

RESULTS

Of the 615 patients evaluated, there was no significant difference in demographics between the patients with and without positive surgical margins. Increasing tumor size was an independent risk factor for margin positivity (P =  < 0.001). On univariate analysis both high histologic grade (P = 0.009) and negative ER status (P =  < 0.001) were significantly associated with positive surgical margins. However, when adjusted in multivariable analysis, only negative ER status remained significantly associated with margin positivity (OR = 0.39 [95% CI 0.20-0.77]; P = 0.006).

CONCLUSION

The study confirms increased tumor size as a risk factor for positive surgical margins. We also demonstrated that ER negative DCIS was independently associated with a higher rate of positive margins after BCS. Given this information, we can modify our surgical approach to reduce rate of positive margins in patients with large-sized ER negative DCIS.

Extensive Intraductal Component in Breast Cancer: What Role in Disease-Free Survival?

INTRODUCTION

Extensive intraductal component (EIC) associated to early breast cancer could increase the risk locoregional recurrence, but its impact on distant metastases is still unclear. The aim of the present study was to assess the role of EIC on 5-year survival outcomes in patients affected by early breast cancer treated with breast-conserving surgery.

METHODS

A total of 414 consecutive patients with a minimum follow-up of 60 mo were collected from January 2007 to December 2015. Disease-free survival (DFS), distant metastasis-free survival (DMFS), and locoregional recurrence-free survival at 5 y were assessed considering the presence or absence of EIC and other clinical and pathological features.

RESULTS

Absence of EIC was independently associated with worse 5-year DFS (hazard ratio [HR] 1.68, P = 0.008) and 5-year DMFS (HR 1.93, P = 0.007), whereas 5-year locoregional recurrence-free survival was not affected (HR 1.50, P = 0.16). Five-year DFS was increased by EIC in T1 patients (P = 0.03) but not in T2 stage. Moreover, EIC was associated to better DFS in G2 (P = 0.03) and G3 patients (P = 0.01) but not in G1 cases.

CONCLUSIONS

Our results suggest that EIC is independently correlated with increased 5-year DFS and in particular with 5-year DMFS.

Retrospective Cohort Study of Practical Applications of Paramagnetic Seed Localisation in Breast Carcinoma and Other Malignancies

(1) Background: Paramagnetic seeds are a safe alternative for the wire-guided localisation of non-palpable breast lesions, but can also be applied for non-breast lesions. This study presents the experience with a paramagnetic seed, MagSeed® (Endomagnetics Ltd., Cambridge, UK, CE-registered and FDA-cleared), in an academic and non-academic breast centre. (2) Methods: Multicentre, retrospective analysis of 374 consecutive patients who underwent surgery after paramagnetic seed localisation (MSL) between 2018 and 2020. Indications for localisation included non-palpable breast lesions (n = 356), lymph nodes (n = 15) or soft tissue lesions (n = 3). The primary outcome was feasibility and the rate of positive section margins. The secondary outcome was predictive factors for positive section margins. (3) Results: The accurate excision of high-risk breast lesions, lymph nodes and soft tissue lesions was seen in 91.07% (n = 56). Positive section margins were observed in 7.86% (n = 25) after breast conserving surgery for invasive or ductal carcinoma in situ (DCIS) (n = 318). Invasive breast cancer associated with DCIS (p = 0.043) and the size of DCIS (p < 0.001) were significantly correlated with the positive section margins. (4) Conclusion: This study confirms the feasibility of MSL, as well as the higher risk for positive margins in cases of breast carcinoma with associated DCIS. Soft tissue lesions and lymph nodes associated with other malignancies, e.g., melanoma, can also be localised with paramagnetic seeds. This offers perspectives for future applications, such as the de-escalation of axillary treatment in breast cancer.

Diagnostic performance of tomosynthesis, digital mammography and a dedicated digital specimen radiography system versus pathological assessment of excised breast lesions

BACKGROUND

The aim of the study was to compare the performance of full-field digital mammography (FFDM), digital breast tomosynthesis and a dedicated digital specimen radiography system (SRS) in consecutive patients, and to compare the margin status of resected lesions versus pathological assessment.

PATIENTS AND METHODS

Resected tissue specimens from consecutive patients who underwent intraoperative breast specimen assessment following wide local excision or oncoplastic breast conservative surgery were examined by FFDM, tomosynthesis and SRS. Two independent observers retrospectively evaluated the visibility of lesions, size, margins, spiculations, calcifications and diagnostic certainty, and chose the best performing method in a blinded manner.

RESULTS

We evaluated 216 specimens from 204 patients. All target malignant lesions were removed with no tumouron-ink. One papilloma had positive microscopic margins and one patient underwent reoperation owing to extensive in situ components. There were no significant differences in measured lesion size among the three methods. However, tomosynthesis was the most accurate modality when compared with the final pathological report. Both observers reported that tomosynthesis had significantly better lesion visibility than SRS and FFDM, which translated into a significantly greater diagnostic certainty. Tomosynthesis was superior to the other two methods in identifying spiculations and calcifications. Both observers reported that tomosynthesis was the best performing method in 76.9% of cases. The interobserver reproducibilities of lesion visibility and diagnostic certainty were high for all three methods.

CONCLUSIONS

Tomosynthesis was superior to SRS and FFDM for detecting and evaluating the target lesions, spiculations and calcifications, and was therefore more reliable for assessing complete excision of breast lesions.

Economic Impact of Reducing Reexcision Rates after Breast-Conserving Surgery in a Large, Integrated Health System

BACKGROUND

Reexcision after breast-conserving surgery (BCS) is costly for patients, but few studies have captured the economic burden to a healthcare system. We quantified operating room (OR) charges as well as OR time and then modeled expected savings of a reexcision reduction initiative.

METHODS

We performed a retrospective cohort review of all breast cancer patients with BCS between January 1, 2016 and December 31, 2020. Operating room charges of disposable supplies and implants as well as operative time were calculated.

RESULTS

During the 5-year period, the 8804 patients who underwent BCS, 1628 (18.5%) required reexcision. The reexcision cohort was younger (61 vs. 64 years, p < 0.001), more likely to have ductal carcinoma in situ (DCIS) (23.7% vs. 15.2%, p < 0.001), and had larger tumors (T1+T2 73.2% vs. 83.1%, p < 0.001). Reexcision costs represented 39% of total costs, the cost per patient for surgery was fourfold higher for reexcision patients. Reexcision operations comprised 14% of total operating room (OR) time (1848 of 13,030 hours). The reexcision rate for 54 surgeons varied from 7.2-39.0% with 46% (n = 25) having a reexcision rate >20%. A model simulating reducing reexcision rates to 20% or below for all surgeons reduced the reexcision rate to 16.2% overall. Using per procedure data, the model predicted a decrease in reexcision operations by 18% (327 operations), OR costs by 14% ($287,534), and OR time by 11% (204 hours).

CONCLUSIONS

Reexcision after BCS represents 39% of direct OR costs and 14% of OR time in our healthcare system. Modest improvements in surgeon reexcision rates may lead to significant economic and OR time savings.

Assessment of photoacoustic tomography contrast for breast tissue imaging using 3D correlative virtual histology

Current breast tumor margin detection methods are destructive, time-consuming, and result in significant reoperative rates. Dual-modality photoacoustic tomography (PAT) and ultrasound has the potential to enhance breast margin characterization by providing clinically relevant compositional information with high sensitivity and tissue penetration. However, quantitative methods that rigorously compare volumetric PAT and ultrasound images with gold-standard histology are lacking, thus limiting clinical validation and translation. Here, we present a quantitative multimodality workflow that uses inverted Selective Plane Illumination Microscopy (iSPIM) to facilitate image co-registration between volumetric PAT-ultrasound datasets with histology in human invasive ductal carcinoma breast tissue samples. Our ultrasound-PAT system consisted of a tunable Nd:YAG laser coupled with a 40 MHz central frequency ultrasound transducer. A linear stepper motor was used to acquire volumetric PAT and ultrasound breast biopsy datasets using 1100 nm light to identify hemoglobin-rich regions and 1210 nm light to identify lipid-rich regions. Our iSPIM system used 488 nm and 647 nm laser excitation combined with Eosin and DRAQ5, a cell-permeant nucleic acid binding dye, to produce high-resolution volumetric datasets comparable to histology. Image thresholding was applied to PAT and iSPIM images to extract, quantify, and topologically visualize breast biopsy lipid, stroma, hemoglobin, and nuclei distribution. Our lipid-weighted PAT and iSPIM images suggest that low lipid regions strongly correlate with malignant breast tissue. Hemoglobin-weighted PAT images, however, correlated poorly with cancerous regions determined by histology and interpreted by a board-certified pathologist. Nuclei-weighted iSPIM images revealed similar cellular content in cancerous and non-cancerous tissues, suggesting malignant cell migration from the breast ducts to the surrounding tissues. We demonstrate the utility of our nondestructive, volumetric, region-based quantitative method for comprehensive validation of 3D tomographic imaging methods suitable for bedside tumor margin detection.

Minimizing re-excision after breast conserving surgery - a review of radiofrequency spectroscopy for real-time, intraoperative margin assessment

INTRODUCTION

For early-stage breast cancer, breast-conserving surgery (BCS) plus radiation is standard-of-care. Nationwide, >20% of BCS patients require re-excision for positive margins, resulting in delayed adjuvant therapy, increased complications, emotional and financial stress for patients, and additional cost to the healthcare system. Although several methods may be employed to mitigate positive margins, no technique can fully address the need. MarginProbe® is an adjunctive tool for real-time intraoperative margin assessment and is shown to reduce positive margins by >50%.

AREAS COVERED

Discussion of the impact of re-excision following BCS, a review of currently available methods for intraoperative margin management, followed by a technology and literature review of the MarginProbe® Radiofrequency Spectroscopy System.

EXPERT OPINION

Re-excision significantly impacts patients, providers and payers. Limitations in the ability to assess margins at time of surgery warrant more advanced methods of residual disease detection. MarginProbe facilitates the most efficient pathway for breast cancer patients through the surgical phase of treatment. The device is well-suited for adoption as the healthcare focus shifts from volume to value and supports the three pillars of the US Department of Health and Human Services' 'Triple-Aim' strategy: improve population health, improve patient experience of care, and reduce per-capita costs.

High-Resolution Full-3D Specimen Imaging for Lumpectomy Margin Assessment in Breast Cancer

BACKGROUND

Two-dimensional (2D) specimen radiography (SR) and tomosynthesis (DBT) for breast cancer yield data that lack high-depth resolution. A volumetric specimen imager (VSI) was developed to provide full-3D and thin-slice cross-sectional visualization at a 360° view angle. The purpose of this prospective trial was to compare VSI, 2D SR, and DBT interpretation of lumpectomy margin status with the final pathologic margin status of breast lumpectomy specimens.

METHODS

The study enrolled 200 cases from two institutions. After standard imaging and interpretation was performed, the main lumpectomy specimen was imaged with the VSI device. Image interpretation was performed by three radiologists after surgery based on VSI, 2D SR, and DBT. A receiver operating characteristic (ROC) curve was created for each method. The area under the curve (AUC) was computed to characterize the performance of the imaging method interpreted by each user.

RESULTS

From 200 lesions, 1200 margins were interpreted. The AUC values of VSI for the three radiologists were respectively 0.91, 0.90, and 0.94, showing relative improvement over the AUCs of 2D SR by 54%, 13%, and 40% and DBT by 32% and 11%, respectively. The VSI has sensitivity ranging from 91 to 94%, specificity ranging from 81 to 85%, a positive predictive value ranging from 25 to 30%, and a negative predicative value of 99%.

CONCLUSIONS

The ROC curves of the VSI were higher than those of the other specimen imaging methods. Full-3D specimen imaging can improve the correlation between the main lumpectomy specimen margin status and surgical pathology. The findings from this study suggest that using the VSI device for intraoperative margin assessment could further reduce the re-excision rates for women with malignant disease.

Lack of definitive presurgical pathological diagnosis is associated with inadequate surgical margins in breast-conserving surgery

PURPOSE

To determine the impact of definitive presurgical diagnosis on surgical margins in breast-conserving surgery (BCS) for primary carcinomas; clinicopathological features were also analyzed.

METHODS

This retrospective study included women who underwent BCS for primary carcinomas in 2016 and 2017. Definitive presurgical diagnosis was defined as having a presurgical core needle biopsy (CNB) and not being upstaged between biopsy and surgery. Biopsy data and imaging findings including breast density were retrieved. Inadequate surgical margins (IM) were defined per latest ASCO and ASTRO guidelines. Univariable and multivariable analyses were performed.

RESULTS

360 women (median age, 66) met inclusion criteria with 1 having 2 cancers. 82.5% (298/361) were invasive cancers while 17.5% (63/361) were ductal carcinoma in situ (DCIS). Most biopsies were US-guided (284/346, 82.0%), followed by mammographic (60/346, 17.3%), and MRI-guided (2/346, 0.6%). US and mammographic CNB yielded median samples of 2 and 4, respectively, with a 14G needle. 15 patients (4.2%) lacked presurgical CNB. The IM rate was 30.0%. In multivariable analysis, large invasive cancers (>20 mm), dense breasts, and DCIS were associated with IM (p = 0.029, p = 0.010, and p = 0.013, respectively). Most importantly, lack of definitive presurgical diagnosis was a risk factor for IM (OR, 2.35; 95% CI: 1.23-4.51, p = 0.010). In contrast, neither patient age (<50) nor aggressive features (e.g., LVI) were associated with IM.

CONCLUSION

Lack of a definitive presurgical diagnosis was associated with a two-fold increase of IM in BCS; other risk factors were dense breasts, large invasive cancers, and DCIS.

Diagnostic Accuracy of Quantitative Micro-Elastography for Margin Assessment in Breast-Conserving Surgery

Inadequate margins in breast-conserving surgery (BCS) are associated with an increased likelihood of local recurrence of breast cancer. Currently, approximately 20% of BCS patients require repeat surgery due to inadequate margins at the initial operation. Implementation of an accurate, intraoperative margin assessment tool may reduce this re-excision rate. This study determined, for the first time, the diagnostic accuracy of quantitative micro-elastography (QME), an optical coherence tomography (OCT)-based elastography technique that produces images of tissue microscale elasticity, for detecting tumor within 1 mm of the margins of BCS specimens. Simultaneous OCT and QME were performed on the margins of intact, freshly excised specimens from 83 patients undergoing BCS and on dissected specimens from 7 patients undergoing mastectomy. The resulting three-dimensional images (45 × 45 × 1 mm) were coregistered with postoperative histology to determine tissue types present in each scan. Data from 12 BCS patients and the 7 mastectomy patients served to build a set of images for reader training. One hundred and fifty-four subimages (10 × 10 × 1 mm) from the remaining 71 BCS patients were included in a blinded reader study, which resulted in 69.0% sensitivity and 79.0% specificity using OCT images, versus 92.9% sensitivity and 96.4% specificity using elasticity images. The quantitative nature of QME also facilitated development of an automated reader, which resulted in 100.0% sensitivity and 97.7% specificity. These results demonstrate high accuracy of QME for detecting tumor within 1 mm of the margin and the potential for this technique to improve outcomes in BCS. SIGNIFICANCE: An optical imaging technology probes breast tissue elasticity to provide accurate assessment of tumor margin involvement in breast-conserving surgery.

Reoperation rate after breast conserving surgery as quality indicator in breast cancer treatment: A reappraisal

Aim

To analyse the role of repeated breast surgery (RBS) after breast conserving surgery (BCS) as a quality indicator in a consecutive series of breast cancer patients.

Methods

Data from 1233 breast cancer patients submitted to BCS from 2015 to 2019 were reviewed. The influence of several variables on RBS rate (182/1232; 14.8%) was examined. Univariate and multivariate analyses were conducted to look for significant associations with the risk of RBS.

Results

Surgical workload, BCS rate and clinicopathological variables were consistent over the study period, while RBS rate decreased after the introduction of shaving of cavity margins (from 17.9% to 9.5%). Tumor persistence at RBS was higher for mastectomy vs. re-excision (87.3% vs. 37.8%; p = 0.05), inconclusive vs. positive diagnostic biopsy (48.2% vs. 69.4%; p = 0.003), ductal carcinoma in situ vs. invasive carcinoma (69.0% vs. 51.3%; p = 0.046) and lower after neoadjuvant therapy (14.3% vs. 57.8%; p = 0.044). Several clinicopathological variables were associated with the risk of RBS, but only multifocality [Odds Ratio (OR): 1.8; p = 0.009], microcalcifications (OR: 2.0, p = 0.000), neoadjuvant therapy (OR: 0.4; p = 0.014), pathological intraoperative assessment (OR: 0.6; p = 0.010) and shaving of cavity margins (OR: 0.3; p = 0.000) retained independent value at multivariate analysis.

Conclusions

RBS rate can be reduced by shaving of cavity margins. Current standards for RBS should not be made more stringent due to the existence of non-actionable risk factors. The value of RBS as a quality indicator should be scrutinzed.

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Some breast cancer patients need a reoperation for incomplete tumor excision after breast conserving surgery.

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Reoperation rates show wide variations (10%–50%) among different Countries.

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Shaving of cavity margins may reduce the reoperation rate, but non-invasive and multicentric lesiona are non-actionable risk factors

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The value of reoperation rate as a quality indicator of breast cancer surgery is questionable.

The Value of Repeated Breast Surgery as a Quality Indicator in Breast Cancer Care

Breast-conserving surgery, a major achievement in surgical oncology, has allowed an increasing number of breast cancer patients to avoid the mutilation of mastectomy. However, mastectomy still is performed in certain circumstances although breast-conserving surgery would be equally safe. Many reasons, including patients' and surgeons' personal motivations, influence the decision-making process before the final choice between breast preservation and mastectomy. The importance of quality measurement and reporting in medicine is increasingly recognized, and breast surgery is no exception. The substantial variability of re-excision rates for positive surgical margins after a first attempt at breast-conserving surgery suggests that improvement is possible. Therefore, the re-excision rate has been proposed as a quality metric for assessing and comparing the performance of different institutions. Indeed, re-excision rates can be reduced by actionable factors such as accurate preoperative local staging, localization of occult lesions, and intraoperative assessment of the oriented specimen. However, equally important non-actionable risk factors pertaining the biology, detectability, and resectability of the tumor also should be taken into account. Therefore, if the re-excision rate has to be used as a performance indicator of breast surgical care, critical interpretation of results with accurate case-mix adjustment are mandatory, and reasonable targets must be appropriately set so that surgeons treating patients at higher risk of positive margins are not unduly penalized.

Factors Associated with Reoperation in Breast-Conserving Surgery for Cancer: A Prospective Study of American Society of Breast Surgeon Members

Background

More than 20% of patients undergoing initial breast-conserving surgery (BCS) for cancer require reoperation. To address this concern, the American Society of Breast Surgeons (ASBrS) endorsed 10 processes of care (tools) in 2015 to be considered by surgeons to de-escalate reoperations. In a planned follow-up, we sought to determine which tools were associated with fewer reoperations.

Methods

A cohort of ASBrS member surgeons prospectively entered data into the ASBrS Mastery^® registry on consecutive patients undergoing BCS in 2017. The association between tools and reoperations was estimated via multivariate and hierarchical ranking analyses.

Results

Seventy-one surgeons reported reoperations in 486 (12.3%) of 3954 cases (mean 12.7% [standard deviation (SD) 7.7%], median 11.5% [range 0–32%]). There was an eightfold difference between surgeons in the 10th and 90th percentile performance groups. Actionable factors associated with fewer reoperations included routine planned cavity side-wall shaves, surgeon use of ultrasound (US), neoadjuvant chemotherapy, intra-operative pathologic margin assessment, and use of a pre-operative diagnostic imaging modality beyond conventional 2D mammography. For patients with invasive cancer, ≥ 24% of those who underwent reexcision did so for reported margins of < 1 or 2 mm, representing noncompliance with the SSO-ASTRO margin guideline.

Conclusions

Although ASBrS member surgeons had some of the lowest rates of reoperation reported in any registry, significant intersurgeon variability persisted. Further efforts to lower rates are therefore warranted. Opportunities to do so were identified by adopting those processes of care, including improved compliance with the SSO-ASTRO margin guideline, which were associated with fewer reoperations.