Radioactive seed localization is a safe and effective tool for breast cancer surgery: an evaluation of over 25,000 cases

Radioactive seed localization (RSL) provides a precise and efficient method for removing non-palpable breast lesions. It has proven to be a valuable addition to breast surgery, improving perioperative logistics and patient satisfaction. This retrospective review examines the lessons learned from a high-volume cancer center's RSL program after 10 years of practice and over 25 000 cases. We provide an updated model for assessing the patient's radiation dose from RSL seed implantation and demonstrate the safety of RSL to staff members. Additionally, we emphasize the importance of various aspects of presurgical evaluation, surgical techniques, post-surgical management, and regulatory compliance for a successful RSL program. Notably, the program has reduced radiation exposure for patients and medical staff.

The Presence of Extensive Lymphovascular Invasion (LVI) is Associated with Higher Risk of Recurrence in Curatively Treated Breast Cancer Patients

PURPOSE/OBJECTIVE(S)

Lymphovascular invasion (LVI) is a pathological feature seen in breast cancer that may be an important step in cancer metastasis. Multiple datasets have demonstrated a correlation between LVI and local-regional recurrence (LRR). Whether the extent of LVI is an incremental determinant of LRR risk is unknown. We describe clinical outcomes in women with invasive breast cancer stratified by: 1) absence of LVI (neg), 2) LVI focal or suspicious (FS-LVI), 3) usual (non-extensive) LVI (LVI) and 4) extensive LVI (E-LVI).

MATERIALS/METHODS

Between December 2009 and August 2021, there were 8,837 patients with early-stage breast cancer (T1-2 and N0-2a) were treated with curative intent and were evaluable. Clinical-pathological details were abstracted by retrospective review. The description of LVI was abstracted from pathology reports. Recurrence and survival outcomes were compared based on the extent of LVI.

RESULTS

Of the 8837 patients studied, 5584 were neg, 461 had FS-LVI, 2315 had LVI, and 477 had E-LVI. The E-LVI cohort had baseline characteristics suggestive of higher risk such as younger median age, higher proportion of grade 3, more nodal positivity, more mastectomy (67% vs 48%), and higher use of chemotherapy compared to LVI. The cumulative incidence of LRR and DM was highest in the E-LVI group. Using LVI as the reference, the presence of E-LVI, age, tumor size, ER status, grade, mastectomy, and close/positive margins were independent variables for LRR on Cox multivariable regression (Table 1). To assess the effect with an alternate statistical method, we created propensity matched cohorts (matched for age, size, receptors, grade, surgery type, margins and chemotherapy/RT use); a statistical difference in OS was noted between groups with LVI vs E-LVI (HR 1.44 (CI 1.06-1.96, p = 0.018), but not in LRR (HR 1.31 (CI 0.87-1.97, p = 0.2) or DM (HR 1.16 (CI 0.88-1.53, p = 0.3).

CONCLUSION

Our work suggests that patients with E-LVI are at a higher risk for LRR compared to patients with usual LVI, despite maximal standard of care treatment. This is important because E-LVI can be determined from breast specimens, and may help define indications for RNI/PMRT when nodal information is not available.

Oncotype Recurrence Score (RS) at the Extremes of Tumor Size: Which Drives Clinical Outcomes?

PURPOSE/OBJECTIVE(S)

Tumor size is an established and independent risk factor for local-regional recurrence (LRR) and distant recurrence (DM). More recently, the recurrence score calculated from a 21-gene expression assay (Oncotype DXTM, Exact Sciences) has also been correlated with LRR and DM. We sought to determine the impact of the interaction between tumor size and Oncotype RS, particularly when the variables are in discrepancy with each other. More specifically, we evaluated clinical outcomes in patients with small tumors (≤1 cm) and high RS (≥26) and, separately, in patients with large tumors (>5 cm) with low RS.

MATERIALS/METHODS

Between 2008 and 2020, 310 patients were identified retrospectively as having been treated for early-stage, hormone-receptor positive, Her2-negative breast cancers with tumor size ≤1 cm that were node-negative and had RS ≥ 26 at our institution. In addition, 64 patients were identified with tumor size >5 cm and RS < 26 (irrespective of nodal status). Locoregional recurrence rates (LRR) and invasive recurrence rates (composite of LRR and distant recurrence) were estimated using the Kaplan-Meier method.

RESULTS

Patient characteristics are shown in Table 1. In the group of patients with small tumors and high RS, the 5- and 10-year invasive recurrence rates with 95% CI were 8% (4.2-12) and 17% (8.2-26). The 5- and 10-year locoregional recurrence rates with 95% CI were 5.8% (2.7-8.8) and 15% (6.2-23). In the group of patients with large tumors and low RS, 10-year rates could not be estimated with the available data. The 5- and 8-year invasive recurrence rates with 95% CI were 3.2% (0-7.5) and 3.2% (0-7.5). The 5- and 8-year locoregional recurrence rates with 95% CI were 1.6% (0-4.7) and 1.6% (0-4.7).

CONCLUSION

Our findings suggest that patients with small tumors and high RS are at a higher risk for LRR compared to the average ≤1 cm node-negative breast cancer based on published data on the effect of tumor size on LRR and DM. Similarly, tumors larger than 5 cm with low RS appear to behave indolently and in a manner consistent with more favorable risk (despite their large size). These findings may have important implications for the tailoring of local-regional treatment strategies.

Perception of the Scholarly Work Project by DNP/DNAP Graduates: A Preliminary Survey

The purpose of this descriptive pilot survey was to understand the experiences of students completing scholarly work projects for practice doctorate programs. With this work, we hoped to fill the literature gap and to inform curriculum. A descriptive survey was used to answer the question: How do graduates of entry level and completion degree Doctor of Nursing Practice (DNP) and Doctor of Nurse Anesthesia Practice (DNAP) programs perceive the scholarly work requirements? The Chi-square test of independence was used to compare whether there was a statistically significant association between the responses to the survey question and the demographic variable. Only 46 DNP/DNAP graduates (4%) completed the survey. The survey results indicated that students in completion programs believed that their scholarly work empowered them to conduct future scholarly work as compared with the entry-topractice cohorts. Variables addressing each aspect of scholarly work project were described by the participants. This preliminary work provides a glimpse into the experience of scholarly work projects for the practice doctorate. To provide greater depth and understanding of this important aspect of doctoral education, a larger sampling of graduates is needed. A collaborative study might be beneficial.

Opioid-Free Anesthesia and Certified Registered Nurse Anesthetists: Barriers to Implementation

While knowledge surrounding opioid-free anesthesia (OFA) has increased in current literature, there is an absence of research specific to nurse anesthesia practice. This study aimed to identify the number of surveyed Certified Registered Nurse Anesthetists (CRNAs) who incorporated OFA into practice and uncovered barriers to its implementation. This quantitative survey solicited data from 2,883 CRNAs across the United States. Of the participants, 81% administered OFA, and 88% felt that OFA techniques are beneficial in anesthesia practice. The results of the survey revealed that gender may be a barrier to the implementation of OFA. Female respondents were less likely to administer OFA often due to the facility culture. The level of education also influenced how CRNAs perceived their facility's culture as a barrier. Perceived access to a variety of multimodal anesthetics was also problematic. While most of those surveyed had administered OFA and acknowledged its benefit, barriers to wider implementation still exist.

Discovery of over 200 new and expanded genetic conditions using GeneMatcher

GeneMatcher is a platform through which various stakeholders can connect with others interested in candidate gene findings. GeneDx, a diagnostic laboratory, has utilized GeneMatcher over the last seven years to successfully facilitate connections between clinicians and researchers, generating fruitful research collaborations. Our ultimate goal in reporting candidate gene findings is to amass sufficient evidence to establish novel disease–gene relationships (DGRs), thus providing diagnostic answers to families and clinicians. Our database of over 300,000 clinical exomes has been a major driver of DGR discovery. Our laboratory accounts for over 20% of total GeneMatcher submissions. Largely fueled by GeneMatcher matches, we have published over 200 articles involving new DGRs or expanded phenotypes for known disease‐causing genes in the past three years. These endeavors require commitments to sharing data and dedicating resources to investigate potential matches. Ultimately, GeneMatcher enables collaboration on a broad scale: we are grateful to the clinicians, researchers, patients, and caregivers who have partnered with us to accelerate the pace of DGR discovery. GeneMatcher opens the door to new partnerships, new discoveries, and families finding answers that otherwise may not have been possible.

Use of bilateral prophylactic nipple-sparing mastectomy in patients with high risk of breast cancer

BACKGROUND

Nipple-sparing mastectomy (NSM) is being performed increasingly for risk reduction in high-risk groups. There are limited data regarding complications and oncological outcomes in women undergoing bilateral prophylactic NSM. This study reviewed institutional experience with prophylactic NSM, and examined the indications, rates of postoperative complications, incidence of occult malignant disease and subsequent breast cancer diagnosis.

METHODS

Women who had bilateral prophylactic NSM between 2000 and 2016 were identified from a prospectively maintained database. Rates of postoperative complications, incidental breast cancer, recurrence and overall survival were evaluated.

RESULTS

A total of 192 women underwent 384 prophylactic NSMs. Indications included BRCA1 or BRCA2 mutations in 117 patients (60·9 per cent), family history of breast cancer in 35 (18·2 per cent), lobular carcinoma in situ in 29 (15·1 per cent) and other reasons in 11 (5·7 per cent). Immediate breast reconstruction was performed in 191 patients. Of 384 NSMs, 116 breasts (30·2 per cent) had some evidence of skin necrosis at follow-up, which resolved spontaneously in most; only 24 breasts (6·3 per cent) required debridement. Overall, there was at least one complication in 129 breasts (33·6 per cent); 3·6 and 1·6 per cent had incidental findings of ductal carcinoma in situ and invasive breast cancer respectively. The nipple-areola complex was preserved entirely in 378 mastectomies. After a median follow-up of 36·8 months, there had been no deaths and no new breast cancer diagnoses.

CONCLUSION

These findings support the use of prophylactic NSM in high-risk patients. The nipples could be preserved in the majority of patients, postoperative complication rates were low, and, with limited follow-up, there were no new breast cancers.

Breast cancer in young black women

BACKGROUND

Young age at breast cancer diagnosis is associated with negative prognostic outcomes, and breast cancer in black women often manifests at a young age. This study evaluated the effect of age on breast cancer management and outcomes in black women.

METHODS

This was a retrospective cohort study of all black women treated for invasive breast cancer between 2005 and 2010 at a specialized tertiary-care cancer centre. Clinical and treatment characteristics were compared by age. Kaplan-Meier methodology was used to estimate overall survival (OS) and disease-free survival (DFS).

RESULTS

A total of 666 black women were identified. Median BMI was 30 (range 17-56) kg/m² and median tumour size was 16 (1-155) mm. Most tumours were oestrogen receptor-positive (66·4 per cent). Women were stratified by age: less than 40 years (74, 11·1 per cent) versus 40 years or more (592, 88·9 per cent). Younger women were significantly more likely to have a mastectomy, axillary lymph node dissection and to receive chemotherapy, and were more likely to have lymphovascular invasion and positive lymph nodes, than older women. The 5-year OS rate was 88·0 (95 per cent c.i. 86·0 to 91·0) per cent and the 5-year DFS rate was 82·0 (79·0 to 85·0) per cent. There was no statistically significant difference in OS by age (P = 0·236). Although DFS was inferior in younger women on univariable analysis (71 versus 88 per cent; P < 0·001), no association was found with age on multivariable analysis.

CONCLUSION

Young black women with breast cancer had more adverse pathological factors, received more aggressive treatment, and had worse DFS on univariable analysis. Young age at diagnosis was, however, not an independent predictor of outcome.

Applying the Care Group model to tuberculosis control: findings from a community-based project in Mozambique

BACKGROUND

We describe the effectiveness of an innovative community-based social mobilization approach called Care Groups to improve the effectiveness of the national tuberculosis (TB) program by increasing TB testing and improving treatment outcomes in six districts of rural Mozambique.

METHODS

The Care Group approach, which was implemented in a population of 218 191, enabled a facilitator to meet every 6 months with 10-12 community health volunteers (forming a Care Group) to share key TB messages and then for them to convey these messages over the subsequent 6 months to 10-12 households. Three household surveys were performed over 5 years to measure population-level changes in knowledge and behaviors. Data from village TB, laboratory, and district registers were also used to monitor activities and outcomes.

RESULTS

There were substantial improvements in TB-related knowledge and behaviors in the number of patients initiating treatment, in the percentage of patients receiving directly observed treatment, in treatment success, and in TB-related mortality.

CONCLUSION

Care Groups are uniquely suited to address some of the challenges of TB control. This project sheds light on a new strategy for engaging communities to address not only TB, but other health priorities as well.

Abstract P6-13-07: Chemotherapy with and without trastuzumab or no treatment in elderly patients with HER2 amplified breast cancer at a single center

Introduction

Trastuzumab with systemic chemotherapy has shown an improvement in outcomes for patients (pts) with HER2 amplified/overexpressed (HER2+) breast cancer. Pts enrolled onto trials were young with a minority of pts at ≥65 years (yrs) of age. Herein, we report the administration of systemic treatment (ST) (chemotherapy and/or trastuzumab) verus no treatment in elderly pts at a single center.

Methods

Patients ≥65 yrs with stage I-III HER2+ (defined as IHC 3+ or FISH &gt;2.0) breast cancer, treated at Memorial Sloan Kettering Cancer Center between 2000-2012, were retrospectively identified from our database.

Clinicopathologic features were retrieved and co-morbidity indexes (CI) were calculated. Pts were divided by hormone receptor (HR) (defined as ER &gt;10% and/or PR &gt;10%) status into HER2+HR- and HER2+HR+. Each group was further divided by use of ST into: chemotherapy and trastuzumab (CT+T), chemotherapy alone (CT) or no systemic treatment (No Rx). Patients receiving neoadjuvant ST or trastuzumab only as ST were excluded from the KM analysis. Primary objective was to identify patterns of treatment recommendation in the elderly population. We explored disease-free survival (DFS) as estimated using the Kaplan-Meier (KM) method.

Results

We identified 300 pts ≥65 yrs with HER2+ tumors. 128 (42.7%) were HER2+HR- and 172 (57.3%) were HER2+HR+. The median follow-up for all patients was 6.1 years (range, 0.07-16.7).

In the HER2+HR- group, 63 (49.2%) patients received CT+T, 25 (19.5%) CT alone, and 40 (31.3%) had no Rx. Anthracycline based chemotherapy was administered to 57/88 (65%) of patients on CT. Women receiving chemotherapy with or without trastuzumab were younger (65-70 vs &gt;70 years of age) (p=.002) and had more advanced tumor stages (p=.003). Their respective 5-yr DFS KM estimates were 0.84, 0.80, and 0.61 (logrank p=0.06).

In the HER2+HR+ group, 77 (44.8%) patients received CT+T, 22 (12.8%) CT alone, and 73 (42.2%) had no Rx. Anthracycline based chemotherapy was administered to 51/99 (51%) of patients on CT. Endocrine therapy was given to 153/172 (89%) of the total cohort. Women receiving chemotherapy with or without trastuzumab were younger (p&lt;.001), and had higher nuclear grade (NG) (p=.04), more lymphovascular invasion (&lt;.001) and more advanced tumor stages (p=.002). Their respective 5-yr DFS KM estimates were 0.84, 1.00, and 0.83 (log rank p=0.02).

Conclusions

At a single center, in the elderly populations at ≥65 years of age with HER2+ HR- and HER2+HR+ breast cancer, pts who received systemic treatment were younger and had higher stage of disease than those who received no treatment. In an exploratory analysis, there appeared to be a benefit of systemic treatment in pts in the HER+HR- group.

Citation Format: Muhsen S, Dang C, Plitas G, Seier K, Stempel M, Patil S, Morrow M, El-Tamer M. Chemotherapy with and without trastuzumab or no treatment in elderly patients with HER2 amplified breast cancer at a single center [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-13-07.

Abstract P6-13-05: Frequency of delivery of systemic chemotherapy in elderly versus younger patients with triple negative breast cancer

Introduction

Chemotherapy (CT) is the standard of care for most triple negative breast cancer (TNBC). Chemotherapy is less commonly recommended in older than younger patients. We aim to explore the frequency of CT delivered in elderly patients when compared to young patients.

Methods

Patients ≤50yrs and ≥70 yrs with stage I-III TNBC defined as ER &lt;10% PR &lt; 10% HER2 IHC &lt; 3+ or FISH &lt; 2.0 and treated at our institution from 2000-2011 were identified from our institutional breast cancer database. Clinicopathologic features were retrieved and co-morbidity indexes (CI) were calculated. Patients were grouped by age and CT use, and features were compared between groups using chi-square tests. Cause of death was reported as dead of disease (DOD) or dead of other causes (DOC) when available; otherwise, it was recorded as dead of unknown causes (DUC). OS survival was estimated using the Kaplan-Meier (KM) methods. Cumulative incidence functions for competing risks were calculated and compared between groups using Gray's test. Competing risks regression was performed for multivariate analysis.

Results

We identified 901 pts with TNBC; 664 (73.7%) were ≤50yrs and 237 (26.3%) were ≥70 yrs. Median followup is 7 yrs (range, 0-16.8yrs).

Younger women diagnosed with TNBC were more likely to have stronger family history of breast cancer (p&lt;.001), to present with palpable masses (p&lt;.001), higher nuclear grade (NG) (p&lt;.001), larger tumors (p=.04), more involved nodes (p=.01), advanced tumor stage (p=.02) and to receive systemic chemotherapy (&lt;.001). Anthracycline-based chemotherapy was administered to 486 (80.3%) in women ≤50yrs and only to 42 (36.5%) in the ≥70 yrs cohort (p&lt;0.001). Chemotherapy data was missing on 2 pts in ≤50 yrs and 4 pts ≥70 for a total cohort of 662 patients ≤50 yrs and 233 pts ≥70 yrs.

The 5 year rates of DOD were similar between both groups at 10.6% (range, 8.3-13.2) for pts ≤50yrs and 10.8% (range, 7.0-15.4) (p=0.52) for the older group; meanwhile, the 5 year OS rates were significantly different between both groups at 87.5% (range, 84.7-90.0) for pts ≤50yrs and 74.3% (range, 68.2-80.0) (p&lt;.001) for the older group since older women die at higher rates from causes other than disease.

CT was given to 115 (49%) patients of the ≥70 yrs cohort with a selection biased by larger tumors (p&lt;.001) and more advanced stages (p&lt;.001). There was no significant difference however, between tumor size (p=0.47) and stage (p=0.98) when comparing the 609 (92%) pts ≤50 yrs and the 115 (49%) of ≥70 yrs patients who received CT.

When categorized based on age and receipt of CT, in the 662 pts ≤ 50 yrs, 609 (92%) and 53 (8%) received CT vs no CT respectively; in the 233 pts ≥70 yrs, 115 (49%) and 118 (50%) received CT vs no CT; the cumulative incidence curves for DOD were not statistically different for the four groups (p=0.85) at 5 years.

Conclusions

In our series, CT was given to 92% of patients ≤ 50 yrs of age. In the elderly pts ≥ 70 yrs of age, CT was limited to 50% of patients, namely those with worse clinicopathologic features.

Citation Format: Muhsen S, Dang C, Plitas G, Knezevic A, Stempel M, Patil S, Morrow M, El-Tamer M. Frequency of delivery of systemic chemotherapy in elderly versus younger patients with triple negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-13-05.

Abstract ES7-1: Challenges in the management of locoregional recurrence

The increasing trend toward tailoring treatment of the primary breast cancer with limited surgery of both the breast and axilla has increased the challenge of managing locoregional recurrence (LRR). In the era when patients uniformly had axillary dissection, the appropriateness of repeat sentinel node biopsy was not a question. Similarly, the dogma that all ipsilateral breast tumor recurrences must be treated with mastectomy if the breast has been previously irradiated is also being challenged. LRR events are infrequent with modern multi-modality therapy, and there are no randomized trials to address these questions.

Re-operative sentinel node (SN) biopsy after breast conserving surgery therapy (BCT) has been shown to be feasible, with the likelihood of identifying additional SNs related to the number of nodes excised at the time of initial SN biopsy. The accuracy of SN biopsy after mastectomy is less clear. However, the impact of identification of nodal disease on management of LRR is controversial. In a study of 12 patients with isolated chest wall recurrence post mastectomy, 10/12 had successful mapping and 7/10 had an axillary SN. The absence of nodal metastases was an indication to avoid supraclavicular RT (Johnson J. Ann Surg Oncol 2016;23:715). In a study of 83 patients with in breast (n=79) or chest wall recurrence who were clinically node negative, 47 had axillary surgery and 36 did not. At a median of 4.2 years after LR, rates of axillary and non-axillary local recurrence, distant metastases, and death did not differ significantly between groups (Ugras S. Ann Surg Oncol 2016). With the findings of the CALOR trial that systemic chemotherapy is beneficial in the management of LRR, the finding of axillary metastases is less likely to influence systemic therapy than in the past and repeat axillary staging could potentially be avoided.

In the untreated breast, drainage to the contralateral axilla is very rare and contralateral axillary metastases classify a patient as Stage IV. After initial axillary dissection, between 4% and 33% of patients with local recurrence will have contralateral axillary drainage. In a systemic review of 48 cases of contralateral nodal recurrence without other distant metastatic disease, at a mean follow-up of 50.3 months disease free survival was 65% and overall survival 83% after treatment that included both local and systemic therapy (Moossdorff M. Eur J Surg Oncol 2015;41:1128). These findings raise the possibility that in the setting of LR, contralateral axillary metastases should be treated aggressively for cure after excluding distant metastases.

Citation Format: Morrow M. Challenges in the management of locoregional recurrence [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr ES7-1.

Abstract P2-12-03: Impact of the SSO-ASTRO consensus guidelines on invasive margins on the re-excision rate among patients undergoing breast conserving surgery (BCS)

Background: BCS has been historically associated with a high re-excision rate, driven in part by lack of consensus on what constitutes an adequate negative margin. The SSO-ASTRO consensus guideline on invasive margins defined a negative margin as no ink on tumor based on evidence suggesting that more widely clear margins do not further decrease the risk of recurrence, potentially reducing the need for re-excision. In a large nationwide cohort of breast cancer patients undergoing BCS for invasive breast cancer we evaluate the rates of re-excision following BCS before and after the SSO-ASTRO consensus guidelines were disseminated.

Methods: Breast cancer patients undergoing BCS for invasive breast cancer between January 2012 and December 2015 were identified among female beneficiaries in the MarketScan database. Patients receiving chemotherapy before surgery were excluded. Based upon presentation of the guideline recommendations in October 2013, the pre-guideline period was defined from January 2012 to September 2013. On-line publication of the guideline in February 2014 led to definition of the post-guideline period from March 2014 onwards. The peri-guideline period was defined as the time between the pre and post-guideline intervals. Any re-excision or mastectomy within 3 months of initial BCS was identified using ICD-9 or CPT codes. Overall re-excision rates and 95% CI were calculated; groups were compared using X2test. We used a regression model to evaluate the association between pre-peri-post guideline period and re-excision while adjusting for important covariates. Results are expressed as risk ratios (RRs) and 95%CI.

Results: A total of 38,573 patients were included (20,159 in the pre-guideline, 4,607 peri-guideline and 13,807 post-guideline). The overall re-excision rate was 23.9% (95%CI 23.4-24.3). The pre-guideline re-excision rate was 25.3% (95%CI 24.7-29.9) compared to 21.6% (95%CI 20.9-22.3] in the post-guideline period. (p&lt;0.001). The rate of mastectomy as the final surgical procedure was 20.2% in the pre-guideline period and 19.1% in the post-guideline (p=0.15). We observed significant geographic variability by state in the decrease of the re-excision rates. No change in re-excision rates was seen in Mississippi, Vermont, Georgia, Oregon, West Virginia, Arkansas, Oklahoma and Tennessee. An absolute decrease greater than 10% in the re-excision rate was observed in Indiana, Nebraska, Alabama, Maine and Nevada. In the multivariable analysis, patients undergoing BCS in the post-guideline period had a statistically significant decrease in the risk of re-excision compared to patients undergoing surgery in the pre-guideline period (RR=0.87; 95%CI 0.84-0.91; p&lt;0.001).

Conclusions: There has been a statistically significant decrease in the re-excision rate after BCS associated with the time of the dissemination of the SSO-ASTRO consensus guideline on invasive margins. The wide geographical variation observed suggests differences in the adoption rates. Our study confirms the impact that guidelines have modifying patterns of practice, reducing the frequency of unnecessary surgical interventions.

Citation Format: Chavez-MacGregor M, Lei X, Morrow M, Giordano SH. Impact of the SSO-ASTRO consensus guidelines on invasive margins on the re-excision rate among patients undergoing breast conserving surgery (BCS) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-12-03.