Anat Kornecki

Background: Neoadjuvant partial breast irradiation using stereotactic body radiotherapy (SBRT) has emerged as a strategy to induce tumor and immune responses in early-stage, low-risk breast cancer. While prior studies have demonstrated encouraging response rates and evidence of immune modulation, the optimal radiotherapy regimen for immune priming remains unclear. SIGNAL 2.0 is a randomized phase II trial designed to compare the biological and immunological impact of a single-fraction versus three-fraction neoadjuvant SBRT. Materials and Methods: Sixty-one postmenopausal patients ≥ 50 years with unifocal, hormone positive, node-negative invasive ductal carcinoma < 3 cm were randomized 1:1 to receive either 21 Gy in one fraction or 30 Gy in three fractions, delivered to the tumor in the prone position. Core biopsies were collected pre-SBRT and 14–20 days post-SBRT at the time of surgery. Immune markers were assessed using tumor-infiltrating lymphocyte (TIL) scoring, NanoString nCounter PanCancer Immune Profiling, and NanoString GeoMx Digital Spatial Profiling (DSP). Results: Available tumor samples from 47 patients underwent paired tissue analysis. Three-fraction SBRT induced 200 differentially expressed genes, including enrichment of pathways related to adaptive immune activation, with significant increases in expression levels of macrophages, dendritic cells, neutrophils and CD8 T-cells. Proteomic profiling also identified a significant increase in the expression levels of neutrophils, Treg cells, macrophages, and NK cells in the tumor microenvironment of the samples from patients receiving the three-fraction regimen. Conclusions: Neoadjuvant SBRT induces measurable immune activation, with three-fraction regimens generating more extensive transcriptional, proteomic, and cellular immune changes than a single fraction. Three-fraction neoadjuvant SBRT may provide superior immune priming, providing a foundation for future trials integrating neoadjuvant radiotherapy with immunomodulatory therapies.

This guideline presents Part IV of the Canadian Association of Radiologists (CAR) Practice Guidelines on Breast Imaging and Intervention and addresses breast magnetic resonance imaging (MRI). As the most sensitive imaging modality for breast cancer detection, MRI plays an established and expanding role in screening, staging, problem-solving, and treatment monitoring. This guideline provides updated recommendations on indications, technical requirements, contrast administration, reporting standards, quality assurance, patient safety, and facility readiness for MRI-guided intervention. Emphasis is placed on bilateral imaging protocols, multimodality correlation, and integration within multidisciplinary breast care. This guideline is intended to be used alongside the other components of the CAR Breast Practice Guidelines series, which collectively replace the 2016 consolidated guidelines and reflecting current evidence and clinical practice in Canada. While defining best practices and minimum expectations, this guideline supports flexibility in application based on patient factors, available resources, and evolving knowledge, with clinical judgment remaining the responsibility of the supervising radiologist.

This guideline presents Part II of the Canadian Association of Radiologists (CAR) Practice Guidelines on Breast Imaging and Intervention and addresses the clinical application of contrast-enhanced mammography (CEM). Reflecting the expanding evidence base and increasing clinical adoption of CEM since 2016, this guideline provides updated recommendations on indications, examination technique, contrast administration, image interpretation, reporting standards, quality control, and patient safety. Particular emphasis is placed on the role of CEM in diagnostic problem-solving, preoperative staging, and selected screening scenarios when breast MRI is unavailable or contraindicated. This guideline is intended to be used in conjunction with the other 4 components of the CAR Breast Practice Guidelines series, which together replace the previous consolidated guidelines and align with national and international best practices. While establishing minimum standards and best practices, this guideline recognizes the influence of evolving technology, regional resources, and patient-specific considerations, and affirms that clinical judgment remains the responsibility of the supervising radiologist.

This guideline presents Part III of the Canadian Association of Radiologists (CAR) Practice Guidelines on Breast Imaging and Intervention and focuses on breast ultrasound. Recommendations address the diagnostic, supplemental screening, and interventional roles of ultrasound in contemporary breast imaging practice. Topics include clinical indications, equipment and technical performance, axillary assessment, documentation, structured reporting using BI-RADS ^® , quality assurance, and personnel qualifications, with attention to both handheld and automated whole-breast ultrasound techniques. This guideline emphasizes the importance of multimodality correlation, timely diagnostic assessment, and appropriate integration of ultrasound into the overall breast imaging pathway. It is intended to be used in conjunction with the other components of the CAR Breast Practice Guidelines series and complements the CAR Breast Disease Imaging Referral Guidelines. While outlining consensus-based best practices and minimum standards, this guideline acknowledges that local expertise, patient characteristics, and resource availability may influence implementation, with final responsibility for interpretation and management decisions resting with the radiologist.

This guideline presents Part V of the Canadian Association of Radiologists (CAR) Practice Guidelines on Breast Imaging and Intervention and addresses image-guided breast intervention and biopsy procedures. This guideline provides comprehensive recommendations for stereotactic-, tomosynthesis-, ultrasound-, and MRI-guided biopsy, as well as preoperative localization and post-procedural management. Key areas include indications and contraindications, biopsy device and needle selection, tissue marker placement, documentation, radiologic–pathologic correlation, quality assurance, and personnel qualifications. Emphasis is placed on minimally invasive, image-guided procedures as the standard of care for diagnosing palpable and nonpalpable breast lesions. This guideline is intended to be used in conjunction with the other components of the CAR Breast Practice Guidelines series, which together replace the 2016 CAR Breast guidelines and reflect the current evidence base and clinical landscape in Canadian breast imaging. While outlining best practices and minimum standards, this guideline acknowledges variability in patient needs, lesion characteristics, and institutional resources, with ultimate responsibility for procedural decision-making residing with the supervising radiologist.

This guideline presents Part I of the Canadian Association of Radiologists (CAR) Practice Guidelines on Breast Imaging and Intervention and focuses on mammography and digital breast tomosynthesis (DBT). Developed by the CAR Breast Imaging Working Group, this guideline provides updated, evidence-based recommendations for screening and diagnostic mammography, reflecting advances in digital imaging, tomosynthesis, artificial intelligence, and quality assurance since the previous consolidated guidelines published in 2016. Key areas addressed include clinical indications, equipment and technical standards, radiation dose considerations, reporting using BI-RADS ^® , personnel qualifications, and performance benchmarks. This guideline emphasizes the central role of mammography and DBT in breast cancer detection while supporting the integration of emerging technologies to improve diagnostic accuracy and efficiency. It is intended to be used in conjunction with the other 4 components of the CAR Breast Practice Guidelines on Breast Imaging and Intervention and alongside the CAR Breast Disease Imaging Referral Guidelines. While outlining best practices and minimum expectations, this guideline acknowledges that practice variation may be appropriate based on patient factors and available resources, with ultimate responsibility for clinical decision-making resting with the supervising radiologist.

High-risk benign breast lesions are histological abnormalities that present in breast tissue, typically identified by screening or diagnostic imaging. The presence of invasive or in situ breast cancer can be confirmed or ruled out within these lesions, and the risk of developing breast cancer can be reduced by their appropriate management. These potential high-risk lesions reviewed include atypical ductal hyperplasia, mucocele-like lesions, papillary lesions with or without atypia, radial scar/complex sclerosing lesion with or without atypia, atypical lobular hyperplasia, classical lobular carcinoma in situ, pleomorphic/florid lobular carcinoma in situ, flat epithelial atypia, columnar cell change, fibroepithelial lesions with stromal cellularity, spindle cell lesions/mesenchymal lesions, and microglandular adenosis. The lack of a clear consensus on the management of many of these lesions led the Ontario Health (Cancer Care Ontario) (OH-CCO) Breast Cancer Pathway Map Working Group and Breast Cancer Advisory Committee to identify the need for a recommendation document. A multidisciplinary working group was formed, with members representing surgical oncology, radiology, pathology, medical oncology, and genetic counselling. The working group developed a list of high-risk benign lesions to be included in this recommendation report. An updated literature review was completed, and these publications were reviewed by the working group, and recommendations were drafted. When evidence was lacking, the expert opinion was included. These draft recommendations were subjected to an extensive review by experts both within Cancer Care Ontario and across Canada. The recommendations included in this report are relevant to clinicians, primary care physicians, oncologists, radiologists, and pathologists who treat breast cancer and manage breast conditions.

Objective: This retrospective study aims to assess the role of pre-contrast sequences of an MRI-guided breast biopsy (MRIB) exam in confident and accurate lesion site localization based on tissue landmarks. Methods: The charts of all consecutives MRIB that were performed between January 2018 and December 2020 were reviewed. The images of the eligible exams were analyzed by 3 breast radiologists. Each radiologist independently attempted to identify lesion site on pre-contrast MRIB sequences, while blinded to the post-contrast MRIB images. Confidence levels (I-confident, II-not confident, and III-unknown) were assigned by each reviewer. A fourth radiologist assessed the accuracy (≤5 mm-accurate, >5 mm-inaccurate) in lesion site localization using the actual biopsied lesion site and the post-contrast MRIB images as reference. Descriptive statistics were used to calculate the percentage of confidence and accuracy categories for each reviewer, with Chi-square tests applied to analyze relationships between categorical variables. Results: There were 174 female patients with 181 lesions eligible for the trial. When the lesion site is confidently identified on the pre-contrast MRIB images (level 1 confidence), mean grade 1 accuracy was 93.8% ( P < .001). Accuracy decreased with Level II and III confidence (55.3% and 34.2% respectively). Up to 61.4% improved accuracy was demonstrated when combining the performance of 2 reviewers. No correlation was found between breast density, lesion morphology, or biopsy positioning with confidence level or accuracy grade. Conclusion: Careful review of the pre-contrast MRIB images and familiarization with the surrounding tissue landmarks are important steps in confidently and accurately detecting lesion site.