Breast Magnetic Resonance Imaging for Preoperative Evaluation of Breast Cancer: A Systematic Review and Meta-Analysis.

Purpose: Preoperative breast magnetic resonance imaging (MRI) is known to detect additional cancers that are occult on mammography and ultrasound. There is debate as to whether these additional lesions affect clinical outcomes. The objective of this systematic review was to summarize the evidence on whether additional information on disease extent obtained with preoperative breast MRI in patients with newly diagnosed breast cancer affects surgical management, rates of recurrence, survival, re-excision, and early detection of bilateral cancer. Methods: Embase, MEDLINE, and Cochrane Central Register of Controlled Trials were searched until January 2021 (partial update July 2022) for studies comparing outcomes with versus without pre-operative MRI. Included were both randomized controlled trials and other comparative studies provided MRI and control groups had equivalent disease and patient characteristics or methods such as multivariable analysis or propensity score matching were used to control potential confounders. Results: The search resulted in 26,399 citations, of which 8 randomized control trials, 1 prospective cohort study, and 42 retrospective studies met the inclusion criteria. Use of MRI resulted in decreased rates of reoperations (OR = 0.73, 95% CI = 0.63 to 0.85), re-excisions (OR = 0.63, 95% CI = 0.45 to 0.89), and recurrence (HR = 0.77, 95% CI = 0.65 to 0.90). Increased detection of synchronous contralateral breast cancers led to a reduction in metachronous contralateral breast cancer (HR = 0.71, 95% CI = 0.59 to 0.85). Hazard ratios for recurrence-free and overall survival were 0.77 (95% CI = 0.53 to 1.12) and 0.89 (95% CI = 0.74 to 1.07). Conclusion: This systematic review indicates substantial benefits of pre-operative breast MRI in decreasing reoperations and recurrence.

Diagnostic interval for non-screening patients undergoing mammography during the COVID-19 pandemic.

OBJECTIVE: During the COVID-19 pandemic, there was a temporary cessation of mammography screening. However, in some facilities, diagnostic breast imaging services continued for patients with a high clinical suspicion of breast cancer. The objective of this study was to evaluate changes in the diagnostic interval (DI) of non-screening patients presenting for diagnostic mammography during the first wave of the COVID-19 pandemic. METHODS: Retrospective chart review was performed on patients presenting for non-screening diagnostic mammography from April 1 to June 30, 2020 (pandemic group) and April 1 to June 30, 2019 (pre-pandemic group). Age, reason for referral, number and type of imaging studies/biopsies necessary for a final diagnosis were recorded. Diagnostic interval (DI) was defined as the number of days from the date of the diagnostic mammogram to the date of the final diagnosis. RESULTS: Compared to the pre-pandemic group (n = 64), the pandemic group (n = 77) showed a reduction in DI of the entire cohort (pandemic: 1 day; pre-pandemic: 15 days, p < 0.0001) for patients not requiring tissue sampling (pandemic: 1 day; pre-pandemic: 11 days, .p < 0.0001) and those requiring tissue sampling with benign pathology (pandemic 9 days; pre-pandemic, 33 days, p = 0.0002). A higher percentage of patients in the pandemic group had their assessment completed during the initial visit (pandemic: 50.6%; pre-pandemic: 23.4%, p = 0.0009). CONCLUSION: During the first wave of the COVID-19 pandemic, the DI for patients with non-screening-related diagnostic mammography was significantly shorter, with a higher percentage of patients completing their assessments on the initial visit, compared to one year prior. KEY POINTS: • Despite reductions in manpower and clinical services, during pandemic times, it is possible to maintain a diagnostic breast imaging service for women at high clinical suspicion for breast cancer. • During pandemic times, breast imaging departments should consider restructuring to a Rapid Diagnostic Unit model with a navigation team that follows patients through the assessment process to a final diagnosis. • Departmental restructuring and patient navigation during pandemic times could either maintain or shorten the diagnostic interval for patients presenting for diagnostic mammography.

Practical Guidelines for Managing Patients With Hidradenitis Suppurativa: An Update.

Hidradenitis suppurativa (HS) is a chronic, inflammatory skin disease that is characterized by the formation of comedones, papules, nodules, abscesses and sinus tracts in the axillary, inframammary, groin, and gluteal areas. Up to 3.8% of the Canadian population has HS, though due to a lack of awareness of HS, many patients are initially misdiagnosed and do not receive adequate treatment early on in the disease course. Once a diagnosis of HS is made, developing an effective management plan can be a dilemma for many providers. There is significant variability in response to any given therapy within the HS patient population and many HS patients have other medical comorbidities which must be taken into consideration. The aim of this review is to provide a practical approach for all healthcare providers to diagnose and manage HS and its associated comorbidities. A sample electronic medical record template for HS management was developed by the Canadian Hidradenitis Suppurativa Foundation Executive Board and is intended for use in clinical settings. This will help to increase collaboration between primary healthcare providers, dermatologists, and other medical specialists and ultimately improve the quality of care that HS patients receive.

The surgeon's perspective: a retrospective study of wide local excisions taken to healthy subcutaneous fat in the management of advanced hidradenitis suppurativa

Background: Hidradenitis suppurativa (HS) is a chronic debilitating folliculopilosebaceous disease that affects the skin most commonly in the axilla, groin, inframammary, genital and buttock areas. Surgical intervention may be an appropriate option in selected cases, but there is a risk of recurrence. The purpose of this study was to assess the results of wide local excision (WLE) to healthy subcutaneous fat with secondary intention healing in patients with HS who were under concurrent surgical and dermatologic care. Methods: We conducted a retrospective review of 192 consecutive HS consultations to a general surgical service, identifying patients treated with WLE. Cases involving minor procedures (deroofing, incision and drainage) were excluded. Data on patient demographics, surgical site, method of closure, complications and recurrence were extracted from patient charts. We also conducted a literature review of surgical procedures in the management of HS. Results: A total of 66 patients underwent 133 WLE to healthy subcutaneous fat. All patients were under concurrent medical care directed by a dermatologist. No medical therapies, including biological treatments, were interrupted or withheld for surgery. One hundred procedures were closed primarily with rotation or advancement flaps and 33 by secondary intention healing. Local recurrence occurred in 18% of primary closures and 18% of secondary intention closures (p = 0.98, χ2 test, no difference between groups). One patient with secondary intention healing returned to the emergency department for bleeding; 34% of patients with primary closure experienced some dehiscence (23% major, 11% minor separation). Two patients with axillary disease had restrictions in their ability to raise their arm that required physiotherapy. Median follow-up was 14.5 (range 1­55) months. Conclusion: Resection to healthy subcutaneous fat during WLE provides disease control comparable to that with deeper resections, simplifying care.

Contexte: L'hidradénite suppurée (HS) est une maladie invalidante chronique du follicule pilo-sébacé qui affecte la peau principalement au niveau de l'aisselle, de l'aine, du pli sous-mammaire et du siège. Une intervention chirurgicale pourrait être une option appropriée dans certains cas, mais il y a un risque de récurrence. Le but de cette étude était d'évaluer les résultats d'une excision locale large (ELL) jusqu'aux tissus adipeux sous-cutanés sains suivie de cicatrisation secondaire chez des patients atteints d'HS recevant concomitamment des soins chirurgicaux et dermatologiques. Méthodes: Nous avons procédé à une revue rétrospective de 192 consultations consécutives pour HS dans un service de chirurgie générale et nous avons recensé les patients traités par ELL. Les cas impliquant des interventions mineures (par incisiondrainage) ont été exclus. Les données démographiques, le site chirurgical, la méthode de suture, les complications et les récurrences ont été enregistrés à partir des dossiers des patients. Nous avons aussi procédé à une revue de la littérature sur les interventions chirurgicales pour l'HS. Résultats: En tout, 66 patients ont subi 133 interventions d'ELL jusqu'aux tissus adipeux sous-cutanés sains. Tous les patients prenaient concomitamment un traitement médicamenteux sous la supervision d'un dermatologue. Aucun des traitements médicamenteux, y compris les agents biologiques, n'a été suspendu ou interrompu pour la chirurgie. Cent interventions ont été refermées principalement par lambeaux de rotation ou d'avancement et 33 par cicatrisation secondaire. Les récurrences locales ont affecté 18 % des fermetures primaires et 18 % des fermetures par cicatrisation secondaire (p = 0,98, test du χ2, aucune différence entre les groupes). Un patient soumis à la cicatrisation secondaire est retourné aux urgences pour un saignement; 34 % des patients ayant subi une fermeture primaire ont présenté un certain degré de déhiscence (23 % majeure, 11 % mineure). Deux patients ayant une atteinte axillaire ont connu des restrictions dans leur capacité de lever les bras et ont dû faire de la physiothérapie. Le suivi médian a été de 14,5 (éventail de 1 à 55) mois. Conclusion: La résection jusqu'aux tissus adipeux sous-cutanés sains durant l'ELL permet de maîtriser la maladie aussi bien que les résections plus profondes, mais simplifie les soins.

Phyllodes tumour of the breast and margins: How much is enough

Summary: Phyllodes breast tumours are fairly uncommon, and they can be benign, borderline or malignant. General surgeons usually encounter them following the surgical excision of a breast lump that had the appearance of a fibroepithelial lesion. The surgeon is then faced with the question of what to do to establish an acceptable treatment margin. In this discussion, we recommend a plan for the management of Phyllodes tumours based on a review of the recent literature, confirmed by a retrospective review of the results from our centre. A negative margin is acceptable treatment following a lumpectomy for Phyllodes tumours. Only patients with a positive margin should undergo a revision.

Proceeding report of the Symposium on Hidradenitis Suppurativa Advances (SHSA).

Hidradenitis Suppurativa (HS) is a chronic debilitating skin condition that impairs the productivity and the quality of patients` lives. HS has recently drawn lots of attention among scholars to further expand their knowledge but it still loads with uncertainties and gaps to be explored. This publication addresses these uncertainties, and provides a road-map for researchers, scholars and clinicians from different disciplines for their future studies about HS. This is a proceeding report of the first Symposium on Hidradenitis Suppurativa Advances (SHSA), and it reviews the scientific sessions about the epidemiology, pathophysiology, presentations, and management of HS. This symposium was a great opportunity for experts in the HS field to exchange their knowledge, and improve their mutual understanding of this disease.

Approach to the Management of Patients With Hidradenitis Suppurativa: A Consensus Document.

BACKGROUND: Hidradenitis suppurativa (HS) is a painful, debilitating, and poorly understood condition, which is suboptimally diagnosed, managed, and treated. Evidence supporting various treatment modalities is sparse. OBJECTIVES: To incorporate scientific evidence and expert opinions to develop useful guidance for the evaluation and management of patients with HS. METHODS: An expert panel of Canadian dermatologists and surgeons developed statements and recommendations based on available evidence and clinical experience. The statements and recommendations were subjected to analysis and refinement by the panel, and voting was conducted using a modified Delphi technique with a prespecified cutoff agreement of 75%. RESULTS: Ten specific statements and recommendations were accepted by the expert panel. These were grouped into 4 domains: diagnosis and assessment, treatment and management, comorbidities and a multidisciplinary approach, and education. CONCLUSIONS: These statements and recommendations will serve to increase awareness of HS and provide a framework for decisions involving diagnosis and management. Evidence suggests that antibacterial and anti-tumour necrosis factor therapies are effective in the treatment of HS. This is supported by the clinical experience of the authors. Further clinical research and the establishment of multidisciplinary management teams will continue to advance management of HS in Canada.

CJS debate: Is mammography useful in average-risk screening for breast cancer?

SUMMARY: Given recent the debate over breast cancer screening that was reignited by the 25-year follow-up data from the Canadian National Breast Screening Study, the Canadian Journal of Surgery commissioned a group of Canadian experts to debate the value of screening mammography. We discuss the Canadian study and summarize the arguments in favour of and against screening mammography for average-risk patients. We also provide summary recommendations for the use of mammography.

Standardized Protocols for Clinical and Histopathological Characterization of Hidradenitis Suppurativa Tissue Specimens.

Methods for describing and reporting the clinical and histological characteristics of cutaneous tissue samples from patients with hidradenitis suppurativa (HS) are not currently standardized, limiting clinicians' and scientists' ability to uniformly record, report, and communicate about the characteristics of tissue used in translational experiments. A recently published consensus statement outlined morphological definitions of typical HS lesions, but no consensus has been reached regarding clinical characterization and examination of HS tissue samples. Here we aimed to establish a protocol for reporting histopathologic and clinical characteristics of HS tissue specimens. This study was conducted from May 2023 to August 2023. Experts in clinical care, dermatopathology, and translational research were recruited, and a modified Delphi technique was used to develop a protocol for histologic reporting and clinical characterization of submitted tissue specimens from HS patients. A total of 27 experts participated (14 dermatologists, 3 fellowship-trained dermatopathologists, 3 plastic surgeons, 3 general surgeons, and 4 research scientists) in creating and reviewing protocols for the clinical and histopathological examination of HS tissue specimens. The protocols were formatted as a synoptic report and will help consistently classify specimens in biobanks based on histological features and more accurately report and select samples used in translational research projects.

Surgical Procedural Definitions for Hidradenitis Suppurativa Developed by Expert Delphi Consensus.

Importance: Various surgical approaches for hidradenitis suppurativa (HS) have been described in the literature, but the nomenclature is inconsistent. Excisions have been described as wide, local, radical, and regional with variable descriptions of margins. Deroofing procedures have been described with various approaches though descriptions of the approach are generally more uniform. No international consensus has been formed to globally standardize terminology for HS surgical procedures. Lack of such agreement may contribute to misunderstanding or misclassification in HS procedural research studies and impair clear communication among clinicians or between clinicians and patients. Objective: To create a set of standard definitions for HS surgical procedures. Design, Setting, and Participants: This consensus agreement study was conducted from January to May 2021 using the modified Delphi consensus method to reach agreement among a group of international HS experts regarding standardized definitions for an initial set of HS surgical terms, including "incision and drainage," "deroofing/unroofing," "excision," "lesional excision," and "regional excision," ultimately expanded to 10 terms. Provisional definitions were drafted based on existing literature and discussion among an expert 8-member steering committee. Online surveys were disseminated to members of the HS Foundation, direct contacts of the expert panel, and the HSPlace listserv to reach physicians with considerable experience with HS surgery. Consensus was defined as greater than 70% agreement to accept a definition. Results: In the first and second modified Delphi round, 50 and 33 experts participated, respectively. Ten surgical procedural terms and definitions reached consensus with greater than 80% agreement. Overall, the term "local" excision was abandoned and replaced with the descriptors "lesional" or "regional" excision. Of note, "regional" replaced the terms "wide" and "radical" excision. Furthermore, modifiers such as "partial" vs "complete" should also be included when describing surgical procedures. A combination of these terms helped formulate the final glossary of HS surgical procedural definitions. Conclusion and Relevance: An international group of HS experts agreed on a set of definitions describing surgical procedures frequently used by clinicians and in the literature. The standardization and application of such definitions are vital to allow for accurate communication, reporting consistency, and uniform data collection and study design in the future.

Preoperative Breast Magnetic Resonance Imaging: An Ontario Health (Cancer Care Ontario) Clinical Practice Guideline.

BACKGROUND: The use of preoperative breast magnetic resonance imaging (MRI) after the diagnosis of breast cancer by mammography and/or ultrasound is inconsistent. METHODS: After conducting a systematic review and meta-analysis comparing preoperative breast MRI versus no MRI, we reconvened to prepare a clinical practice guideline on this topic. RESULTS: Based on the evidence that MRI improved recurrence, decreased the rates of reoperations (re-excisions or conversion mastectomy), and increased detection of synchronous contralateral breast cancer, we recommend that preoperative breast MRI should be considered on a case-by-case basis in patients diagnosed with breast cancer for whom additional information about disease extent could influence treatment. Based on stronger evidence, preoperative breast MRI is recommended in patients diagnosed with invasive lobular carcinoma for whom additional information about disease extent could influence treatment. For both recommendations, the decision to proceed with MRI would be conditional on shared decision-making between care providers and the patient, taking into account the benefits and risks of MRI as well as patient preferences. Based on the opinion of the Working Group, preoperative breast MRI is also recommended in the following more specific situations: (a) to aid in surgical planning of breast conserving surgery in patients with suspected or known multicentric or multifocal disease; (b) to identify additional lesions in patients with dense breasts; (c) to determine the presence of pectoralis major muscle/chest wall invasion in patients with posteriorly located tumours or when invasion of the pectoralis major muscle or chest wall is suspected; (d) to aid in surgical planning for skin/nipple-sparing mastectomies, autologous reconstruction, oncoplastic surgery, and breast conserving surgery with suspected nipple/areolar involvement; and (e) in patients with familial/hereditary breast cancer but who have not had recent breast MRI as part of screening or diagnosis.

Impact of 18F-Labeled Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography Versus Conventional Staging in Patients With Locally Advanced Breast Cancer.

PURPOSE: Patients with locally advanced breast cancer (LABC) typically undergo staging tests at presentation. If staging does not detect metastases, treatment consists of curative intent combined modality therapy (neoadjuvant chemotherapy, surgery, and regional radiation). Positron emission tomography-computed tomography (PET-CT) may detect more asymptomatic distant metastases, but the evidence is based on uncontrolled studies. METHODS: For inclusion, patients had histological evidence of invasive ductal carcinoma of the breast and TNM stage III or IIb (T3N0, but not T2N1). Consenting patients from six regional cancer centers in Ontario were randomly assigned to 18F-labeled fluorodeoxyglucose PET-CT or conventional staging (bone scan, CT of the chest/abdomen and pelvis). The primary end point was upstaging to stage IV. A key secondary outcome was receiving curative intent combined modality therapy (ClinicalTrials.gov identifier: NCT02751710). RESULTS: Between December 2016 and April 2022, 184 patients were randomly assigned to whole-body PET-CT and 185 patients to conventional staging. Forty-three (23%) PET-CT patients were upstaged to stage IV compared with 21 (11%) conventional staged patients (absolute difference, 12.3% [95% CI, 3.9 to 19.9]; P = .002). Consequently, treatment was changed in 35 (81.3%) of 43 upstaged PET-CT patients and 20 (95.2%) of the 21 upstaged conventional patients. Subsequently, 149 (81%) patients in the PET-CT group received combined modality treatment versus 165 (89.2%) patients in the conventional staging group (absolute difference, 8.2% [95% CI, 0.1 to 15.4]; P = .03). CONCLUSION: In patients with LABC, PET-CT detected more distant metastases than conventional staging, and fewer PET-CT patients received combined modality therapy. Our randomized trial demonstrates the utility of the PET-CT staging strategy.

Outcome Measures for the Evaluation of Treatment Response in Hidradenitis Suppurativa for Clinical Practice: A HiSTORIC Consensus Statement.

Importance: Although several clinician- and patient-reported outcome measures have been developed for trials in hidradenitis suppurativa (HS), there is currently no consensus on which measures are best suited for use in clinical practice. Identifying validated and feasible measures applicable to the practice setting has the potential to optimize treatment strategies and generate generalizable evidence that may inform treatment guidelines. Objective: To establish consensus on a core set of clinician- and patient-reported outcome measures recommended for use in clinical practice and to establish the appropriate interval within which these measures should be applied. Evidence Review: Clinician- and patient-reported HS measures and studies describing their psychometric properties were identified through literature reviews. Identified measures comprised an item reduction survey and subsequent electronic Delphi (e-Delphi) consensus rounds. In each consensus round, a summary of outcome measure components and scoring methods was provided to participants. Experts were provided with feasibility characteristics of clinician measures to aid selection. Consensus was achieved if at least 67% of respondents agreed with use of a measure in clinical practice. Findings: Among HS experts, response rates for item reduction, e-Delphi round 1, and e-Delphi round 2 surveys were 76.4% (42 of 55), 90.5% (38 of 42), and 92.9% (39 of 42), respectively; among patient research partners (PRPs), response rates were 70.8% (17 of 24), 100% (17 of 17), and 82.4% (14 of 17), respectively. The majority of experts across rounds were practicing dermatologists with 18 to 19 years of clinical experience. In the final e-Delphi round, most PRPs were female (12 [85.7%] vs 2 males [11.8%]) and aged 30 to 49 years. In the final e-Delphi round, HS experts and PRPs agreed with the use of the HS Investigator Global Assessment (28 [71.8%]) and HS Quality of Life score (13 [92.9%]), respectively. The most expert-preferred assessment interval in which to apply these measures was 3 months (27 [69.2%]). Conclusions and Relevance: An international group of HS experts and PRPs achieved consensus on a core set of HS measures suitable for use in clinical practice. Consistent use of these measures may lead to more accurate assessments of HS disease activity and life outcomes, facilitating shared treatment decision-making in the practice setting.

Is knowledge translation adequate? A quality assurance study of staging investigations in early stage breast cancer patients.

After primary surgery, patients diagnosed with early stage breast cancer undergo radiological investigations based on pathologic stage of disease to rule out distant metastases. Published guidelines can aid clinicians in determining which tests are appropriate based on stage of disease. We wished to assess the consistency of radiological staging in an academic community oncology setting with standard guidelines and to determine the overall impact of non-adherence to these guidelines. A retrospective cohort study was conducted for new breast cancer patients seen at a single institution between January 2009 and April 2010. Patients were included if initial diagnosis and primary surgery was at this institution. Pathologic stage and radiological tests completed were recorded. A literature review was performed and the results were compared with those from this study to determine overall adherence rates. Subsequently, a cost analysis was performed to determine the financial impact at this centre. 231 patients met eligibility criteria for inclusion in this study. A large proportion of patients were over-staged with 129 patients (55%) undergoing unnecessary investigations according to guidelines. Specifically, 59% of stage I patients and 58% of stage II patients were over-investigated. Distant metastases at the time of diagnosis were found in three patients, all of whom had stage III disease (1.3%). The literature reviewed revealed similar non-adherence rates in other centres. The estimated cost of such non-adherence is in the range of $78 (CDN) per new early stage breast cancer patient seen at this centre. This oncology centre has a low adherence to practice guidelines for staging investigations in breast cancer patients, with 55% of patients undergoing unnecessary tests. Very few patients had metastases at diagnosis, and all had pathological stage III disease. Efforts may need to focus on improving knowledge translation across clinical oncology settings to increase guideline adherence.

Exploring Access to Surgical Interventions for Hidradenitis Suppurativa: Retrospective Population-Based Analysis.

BACKGROUND: Hidradenitis suppurativa (HS) is a painful inflammatory disorder that confers significant distress to patients, with surgery as an integral treatment modality. OBJECTIVE: To inform improvements in care, patterns in HS surgery were assessed. METHODS: A retrospective population-based analysis was performed on Ontario billing claims for HS surgery across a period of 10 years from January 1, 2008 to December 31, 2017. HS surgery was defined as the excision of inguinal, perineal, or axillary skin and sweat glands for hidradenitis. The top 5 billing specialties, including general and plastic surgery, were analyzed. The total number of procedures performed as well as the number performed per physician were investigated. Patient and physician locations were compared. RESULTS: A total of 7195 claims for the excision of inguinal, perineal, or axillary skin and sweat glands for HS were submitted across the study period. Annual HS surgery claims showed an increasing trend across 10 years, ranging between 4.9 and 5.8 per 100,000 population. However, overall, for every additional year, the number of claims per 100,000 population only increased slightly, by 0.03 claims. The number of providers steadily decreased, ranging between 1.7 and 1.9 per 100,000, with approximately twice as many general than plastic surgeons. However, again overall, for every additional year, the number of providers per 100,000 population decreased slightly, by 0.002 physicians. The mean annual number of procedures per physician rose from 2.8 to 3.1. In rural areas, analyzed per claim, general surgeons performed the majority of surgeries (1318/2003, 65.8%), while in urban areas, surgeries were more equally performed by general (2616/5192, 50.4%) and plastic (2495/5192, 48.1%) surgeons. Of HS surgery claims, 25.7%-35.9% were provided by a physician residing in a different area than the patient receiving care. CONCLUSIONS: No significant improvements in access to HS surgery were seen across the study period, with access potentially worsening with annual HS claims rising overall and number of providers decreasing, with patients travelling further to access surgery. System barriers across the continuum of HS diagnosis and management must be evaluated to improve access to surgical care.

Management of the Axilla in Early-Stage Breast Cancer: Ontario Health (Cancer Care Ontario) and ASCO Guideline.

PURPOSE: To provide recommendations on the best strategies for the management and on the best timing and treatment (surgical and radiotherapeutic) of the axilla for patients with early-stage breast cancer. METHODS: Ontario Health (Cancer Care Ontario) and ASCO convened a Working Group and Expert Panel to develop evidence-based recommendations informed by a systematic review of the literature. RESULTS: This guideline endorsed two recommendations of the ASCO 2017 guideline for the use of sentinel lymph node biopsy in patients with early-stage breast cancer and expanded on that guideline with recommendations for radiotherapy interventions, timing of staging after neoadjuvant chemotherapy (NAC), and mapping modalities. Overall, the ASCO 2017 guideline, seven high-quality systematic reviews, 54 unique studies, and 65 corollary trials formed the evidentiary basis of this guideline. RECOMMENDATIONS: Recommendations are issued for each of the objectives of this guideline: (1) To determine which patients with early-stage breast cancer require axillary staging, (2) to determine whether any further axillary treatment is indicated for women with early-stage breast cancer who did not receive NAC and are sentinel lymph node-negative at diagnosis, (3) to determine which axillary strategy is indicated for women with early-stage breast cancer who did not receive NAC and are pathologically sentinel lymph node-positive at diagnosis (after a clinically node-negative presentation), (4) to determine what axillary treatment is indicated and what the best timing of axillary treatment for women with early-stage breast cancer is when NAC is used, and (5) to determine which are the best methods for identifying sentinel nodes.Additional information is available at www.asco.org/breast-cancer-guidelines.