High-grade Ductal Carcinoma In Situ Research Articles

Abstract PO4-25-10: Towards personalized medicine for DCIS - the role of hormone receptors, HER2, and Ki67 status in high-grade DCIS

Abstract Objective: This study aimed to investigate the molecular details in breast ductal carcinoma in situ (DCIS). Expression status of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and Ki67 were investigated among luminal A (LumA), luminal B HER2-negative (LumB HER2-), luminal B HER2-positive (LumB HER2+), HER2-enriched, and triple-negative (TPN), subtypes of DCIS. Materials & Methods: The study comprised formalin-fixed paraffin-embedded (FFPE) specimens of 357 DCIS grade 3 cases diagnosed between 1996 – 2018. Routine diagnostic immunohistochemical (IHC) staining were performed. DCIS cases were classified as LumA, LumB HER2-, LumB HER2+, HER2-enriched or TPN, according to the 2013 St. Gallen guidelines, which is used for molecular subtyping of invasive breast carcinoma (IBC). Each subtype was sorted into three subcategories: “pure” meaning those without an invasive component; “w/invasive” meaning those with an invasive component; and “all” meaning the entire group of the given subtype. Furthermore, ER and PR-receptor expression was registered for LumA, LumB HER2- and LumB HER2+ cases as intervals. The distribution of Ki67 was analyzed within each subtype. For some analyses, we combined the LumA and LumB HER2- subtypes into one entire group. The inter-observer variability of Ki67 was calculated by setting a cut-off value of 20% (2013 St. Gallen). A cohort (n = 47) of DCIS cases with a median Ki67 value of 18% was selected. Ki67 was calculated by analyzing 200 DCIS cells in two separate hotspots. Cohen's Kappa coefficient was calculated based on these data. HER2 (IHC) was scored based on ASCO/CAP guidelines established for routine diagnostic work-up for IBC. 16 equivocal cases (2+) were further investigated using dual SISH. Results: 98% of “all” cases of the LumA subtype showed an ER ≥ 50%. PR expression ≥ 50% was found in 91% of cases in this subtype. The incidence of ER-receptor at a cut-off ≥ 50% in the LumA subtype was significantly higher than that in the LumB HER2- and LumB HER2+ subtypes (p < 0.0001, Chi-square). In contrast, there was a statistically significant reduction in ER-receptor expression at a cut-off < 10% in LumA compared to the latter subtypes. The proportion of cases with PR-receptors with a cut-off of < 20% showed significant differences between LumA, LumB HER2- and LumB HER2+ subtypes (1.6%; 47% and 37%, respectively). There was also a significantly higher proportion of PR-receptor ≥ 50% cases among the LumA subtype. We found a significant association between PR < 20% and HER2 (3+) in luminal subtypes (p < 0.0004, Fisher's exact). There was no significant difference in ER/PR expression in “pure” cases of luminal subtypes of DCIS versus those with an invasive component (p = 0.1831, Chi-square). The Ki67 in the entire population (n = 357) varied from < 1% to > 80%. The mean and median were around 20% in those subtypes whose classifications were not depended on Ki67. There was a significant difference in the distribution of Ki67 when cases of LumA “all” and those of LumB HER2- “all” were combined as one entire group and were compared to LumB HER2+ “all” and HER2-enriched “all” (p-adjusted < 0.0001, Kruskal Wallis). The assessment of Ki67 among different observers showed a Cohen's kappa coefficient of 0.29 – 0.31 (fair agreement). We compared the HER2 (IHC) 0, 1+ and 2+ score among LumA and LumB HER2- subtypes and did not find a statically significant difference, when the “pure” and “w/invasive” were compared (p = 0.603, Chi-square). Conclusions: Ki67 was highly variable in DCIS grade 3. Inter-observer agreement was (as expected) suboptimal, and the cut-off at 20% defined by the 2013 St Gallen guidelines for IBC is not reliable for the distinction of LumA and LumB HER2 subtypes of DCIS. The LumB subtype of DCIS is heterogeneous with considerable variability among the four IHC markers used in the present study. A low PR is strongly associated with HER2 (3+), in luminal subtypes (p < 0.0004, Fisher's exact). Citation Format: Hossein Schandiz, Lorant Farkas, Daehoon Park, Solveig Norheim Andersen, Jürgen Geisler, Torill Sauer. Towards personalized medicine for DCIS - the role of hormone receptors, HER2, and Ki67 status in high-grade DCIS [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-25-10.

Abstract PO5-13-11: Quantitative Assessment of HER2 Expression in Intraductal Neoplasms of the Breast

Abstract HER2 (ERBB2) is an established prognostic and predictive marker for patients with invasive breast cancer and used in HER2-targeted therapy. The clinical and biological significance of expression of HER2 protein in patients with intraductal neoplasms of the breast is not well characterized. In this study, we used our HS-HER2 (High Sensitivity-HER2) which is a CAP/CLIA certified laboratory derived test (LDT) using quantitative immunofluorescence (QIF). We evaluated HER2 expression in DCIS (ductal carcinoma in situ), LCIS (lobular carcinoma in situ) and benign lesions to correlate with their clinicopathologic characteristics. Thirty- eight cases of DCIS, and fourteen cases of LCIS and thirty benign cases were selected from the Yale Pathology department archives and 252 ROIs (regions of interest) were annotated by a board-certified pathologist. DCIS is classified according to the three-tier nuclear grading system: low, intermediate, and high-nuclear grade. LCIS is classified as PLCIS (pleomorphic variant) and CLCIS (classic LCIS) according to the WHO classification of breast tumors. Serial sections of FFPE tumor specimens were used to accurately quantify the HER2 expression by the HS-HER2 assay and the acquisition by QuPath v.04 with Qymia extension. According to the LOD (limit of detection,3 amol/mm2), LOQ (limit of quantification, 9 amol/mm2) and LOL (limit of linearity, 23 amol/mm2) of the optimized HS-HER2 assay as performed in our CLIA lab shows a broad range of HER2 expression in both DCIS and LCIS lesions, ranging from 0.7 amol/mm2 to 111.4 amol/mm2 in DCIS and 3.6 amol/mm2 to 49.9 amol/mm2 in LCIS. High grade DCIS lesions express higher average HER2 levels (111.4 + 0.7 amol/mm2) than combined low and intermediate grade DCIS (77.9 +1.9 amol/mm2) with no significant difference between low/intermediate and high-grade DCIS. CLCIS lesions express higher average HER2 level (49.9 + 3.6 amol/mm2) than PLCIS (35.1 + 5.4amol/mm2) but again this is not statistically significant. HER protein expression is relatively low in benign lesions ranging from 0.8 to 8.4 amol/mm2. Using the HS-HER2 assay, our results show quantitative level HER2 levels in DCIS and LCIS breast lesions. These findings may be important as HER2 targeted therapies that work in gene-unamplified cancer (HER2 conjugated ADCs) gain broader usage in the clinic. Citation Format: Nay Nwe Nyein Chan, Haiying Zhan, Revekka Khaimova, Thazin Aung, Charles Robbins, Patricia Gaule, David Rimm. Quantitative Assessment of HER2 Expression in Intraductal Neoplasms of the Breast [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-13-11.

Abstract PO4-21-01: Recurrent Desmoid Tumor and Ductal Carcinoma In Situ in an African-American Woman: A Case Report and Discussion on Disparities for These Two Cancer Subtypes

Abstract Introduction: Disparities in cancer care in patients from different races and ethnicities unfortunately do exist and are well described in literature. Hormonal-driven cancers, such as some soft-tissue tumors and DCIS, have been demonstrated to impact African-American women (AAW) disproportionately. These patients are at increased risk for not only development of these cancers, but also experience disparities in survival, treatment outcomes, and modalities of treatment. Clinical Case: A 47-year-old premenopausal AAW with past medical history of recurrent desmoid sarcoma of the abdomen and ductal carcinoma in-situ (DCIS) of the left breast presented to oncology clinic with recurrent abdominal mass. The patient was originally diagnosed with DCIS in the left breast in 2018 and subsequently underwent left breast mastectomy with TRAM reconstruction and fat graft later that year. In 2020, the patient noticed a left lower abdominal growth that quickly enlarged and became painful. She underwent imaging without biopsy and was taken to surgery in April 2021 with tumor removal and mesh placement. Pathology showed desmoid fibromatosis infiltrating skeletal muscle and involving the inked resection margin of the specimen. Conservative re-excision and additional therapy was recommended but not done at the time. In 2022, the patient had resection of the area again with pathology of the incisional scar showing skin and deep soft tissue foci suspicious for recurrent desmoid fibromatosis extending to the inked deep margin. No mesh was placed, and the wound closed almost completely. The patient was not aware of positive margins at the time. In January 2023, patient again notice a new bump that was bothersome. Initial CT and MRI without finding of defined mass, but with right rectus thickening and enlarged right external iliac lymph node. Core biopsy in June 2023 confirmed recurrent desmoid fibromatosis. In April 2023, annual screening with mammogram was performed with a finding of 2.9 cm cluster of heterogenous calcification in the right breast. Diagnostic mammogram and ultrasound performed. Core needle biopsy was subsequently performed in May with pathology consistent with high grade DCIS with low ER and PR positivity. Lymph node biopsy was negative, but clinically positive. She is currently undergoing further genetic testing with surgical workup for mastectomy. Discussion and Conclusion: AAW diagnosed with DCIS have higher all-cause and disease specific mortality in comparison to white women (WW) diagnosed with DCIS. AAW are also at increased risk of aggressive secondary breast cancers in both the ipsilateral and contralateral breast in comparison to other races. In regards to tumor biology, WW have been shown to have higher ER and PR positivity in both primary and primary breast cancers than AAW. In many of these large-scale studies higher mortality, recurrence, and metastasis in AAW have been identified regardless of treatment modality. Research into differences in treatment between AAW and WW has shown that AAW, in contrast to our patient case, are more likely to undergo endocrine and radiation therapy rather than mastectomy. Although there does not seem to be an increased risk of desmoid fibromatosis in AAW when compared to WW, other soft-tissue tumors and malignancies do show a predilection for AAW. Incidence of sarcoma in black patients is higher than white patients, and black patients also have poorer survival outcomes. This case provides an example of the intersectionality of two cancer subtypes that impact black patients disproportionately. More evidence is required to unearth the reasons why these two cancer subtypes which are driven by similar processes impact AAW to a greater degree. Citation Format: Vinita Akula, Jessica Jones. Recurrent Desmoid Tumor and Ductal Carcinoma In Situ in an African-American Woman: A Case Report and Discussion on Disparities for These Two Cancer Subtypes [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-21-01.

Abstract PO2-08-11: The MAGIC study: Universal whole genome tumour and germline sequencing of newly diagnosed breast cancer identifies a high proportion of ER+ BRCA-like tumours

Abstract Background: Identification of germline mutations in hereditary breast cancer (HBC) genes can have profound benefits in the treatment of breast cancer (BC) and manging risk for patient and the family. In addition, sequencing of the tumours can reveal clinically relevant somatic features, such as homologous recombination deficiency (HRD) and mutational signatures, that can guide treatment which are not discernible by germline sequencing alone. We hypothesised that current standard of care where women diagnosed with BC are not routinely offered tumour sequencing is suboptimal as fails to exploit all therapeutic vulnerabilities which can be exploited in the treatment of BC. The MAGIC study is the first prospective trial in Australia of unselected invasive BCs in general oncology practice combining both germline and tumour sequencing. Methods: The MAGIC study included a total of 651 consecutive consented patients presenting with non-metastatic BC between June 2020 to March 2023. It included invasive BC, high-grade DCIS and pleomorphic LCIS. The sequencing was conducted in two phases; for phase one, 157 cases underwent whole genome sequencing (WGS) on both germline and matched BC DNA while for phase two, 494 cases underwent only germline whole exome sequencing. Germline variants were interrogated for pathogenic variants in BRCA1, BRCA2, PALB2, ATM, CHEK2, BARD1, BRIP1, RAD51B, RAD51C, RAD51D, MLH1, MSH2, MSH6, PMS2, CDH1, PTEN, STK11, TP53 and NTHL1. Tumour homologous recombination (HR) repair deficiency was calculated using HRDetect (Nat Med 2017;23:517). For BCs showing a high HRDetect score ( >0.75) all HBC gene promoter CpG islands were assessed for hypermethylation using the Twist NGS Methylation system. Mutational signatures were calculated from somatic mutations identified from whole genome sequenced BCs using the DeconstructSig package in R (Genome Biol. 2016;17:31) and referenced against the COSMIC v2 signature catalogue. Results: Actionable germline variants in any HBC gene were identified in 7.7% of cases (7.8% of invasive and 6.1% of in situ BC) with 5.2% having an actionable mutation in an HR pathway gene (BRCA1, BRCA2, PALB2 and RAD51C). Most cases with pathogenic variants showed bi-allelic inactivation in the tumour. All BRCA1, BRCA2 and PALB2 tumours showed high HRDetect and/or HRD scores consistent with loss of HR repair function, indicating them to be the underlying hereditary driver of the BC. One BC with a pathogenic PMS2 variant showed retention of the wild-type allele with no evidence of a mismatch repair mutational signature suggesting PMS2 was not the driver of this BC. Of the 157 BC in phase one that underwent WGS and did not have a germline pathogenic HBC gene variant, 16% (18/117 invasive and 3/13 DCIS) had an HRDetect score of >0.7 indicative of a homologous recombination repair defect and therefore biologically a “BRCA-like” tumour. Of these 21 BRCA-like cases, only 3 invasive BCs had clear somatic bi-allelic inactivation of an HBC gene that could explain the high HRDetect score (2 BRCA1 and 1 BRCA2). One of the 21 BRCA-like cases had a germline variant of unknown significance (VUS) in an HBC gene (a BRCA2 missense variant in an ER+ tumour. The tumour showed loss of the wild-type allele). Of the BRCA-like cases, 71% were ER positive which included 3 invasive lobular cancers. Conclusion: Tumour sequencing identified three times as many cases that might be eligible for HR repair defect targeted therapy than germline testing alone (16% versus 5.2%). Unlike a previous study (Ann Oncol., 2019 30:1071-1079), the majority of the BRCA-like BCs were ER+ with no evidence of a VUS in a known HBC gene suggesting these are driven by novel germline or somatic mutations in genes involved in DNA HR repair. Citation Format: Ian Campbell, Lisa Devereux, Kirsten Hogg, Luxi Lal, Michelle Sinclair, Lesley Stafford, Magnus Zethoven, Anita Skandarajah, Paul James, Geoffrey Lindeman, Bruce Mann, Dilanka De Silva. The MAGIC study: Universal whole genome tumour and germline sequencing of newly diagnosed breast cancer identifies a high proportion of ER+ BRCA-like tumours [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-08-11.

Abstract PO1-09-02: Universal genetic testing for women with newly diagnosed breast cancer identified many mutations, impacted clinical management and caused no psychological distress to patients

Abstract Background: For newly diagnosed breast cancer (BC) patients, identification of pathogenic germline mutations in hereditary breast cancer (HBC) genes can inform clinical management and risk mitigation strategies and identify patients who would benefit from targeted therapy and clinical trials. Offering germline testing based on NCCN or other guidelines fails to identify all patients with germline HBC gene mutations, potentially with adverse consequences for patients and their families. As an integral part of the study, we have explored the acceptance of universal testing among patients and clinicians. Methods: This is the largest Australian multi-centre prospective study exploring the prevalence of hereditary pathogenic variants in the Australian BC population. 650 newly diagnosed consecutive, consented patients with non-metastatic breast cancer or high-grade DCIS were recruited from May 2020 to March 2023 in 2 phases. Phase 1 (n=157) offered a combination of germline and somatic sequencing. Germline testing was performed by whole genome sequencing on DNA from blood or saliva, and the data analyzed for actionable HBC gene mutations, including large genomic rearrangements. Germline variants were interrogated for pathogenic variants in BRCA1, BRCA2, PALB2, ATM, CHEK2, BARD1, BRIP1, RAD51B, RAD51C, RAD51D, MLH1, MSH2, MSH6, PMS2, CDH1, PTEN, STK11, TP53 and NTHL1.Tumour sequencing will be reported separately. Phase 2 (n=493) included germline exome sequencing with no somatic sequencing. The objectives were to assess the additional actionable HBC gene mutations identified by universal testing compared to algorithmic based (MANCHESTER and BOADICEA scores) and NCCN guidelines, the clinical impact of this identification and the prevalence of germline mutations in the general BC population. A 3-generation pedigree was constructed for every patient for accurate estimation of NCCN, MANCHESTER, and BOADICEA scores. Phase 1 patients completed surveys of perceptions of universal testing, psychological distress and cancer-specific worry pre- and post-testing. Results: 50 carriers of actionable germline mutations were identified: (7.7%). BRCA1 (n=10), BRCA2 (n=12), PALB2 (n=7), CHEK2 (n=10), ATM (n=4), PMS2 (n=2), MSH6 (n=1), RAD51C (n=2), and BARD1 (n=3). One carrier had both PALB2 and CHEK2 mutations. Updated NCCN guidelines (2023 version) identified 44/50 pathogenic germline variant carriers (88%). The BOADICEA and MANCHESTER scores only identified 22 carriers (44%). Immediate clinical management changed due to the discovery of HBC gene in 40/50 (80%). Among 105 participants, cancer-specific distress declined from pre- to post-testing. Anxiety, stress and depression did not change. 90/103 participants agreed that genetic testing should be routine, 100/104 reported their decision to undergo testing as correct. All (n=25) BC clinicians reported that genetic test results were helpful for important treatment decisions and none that testing was distressing to patients. Conclusion: HBC gene mutation prevalence was 7.7%. Universal germline HBC gene testing is the best method for detecting carriers. Current testing guidelines would have missed HBC genes which would have impacted clinical management. Updated NCCN guidelines were sensitive in the detection of HBC gene mutation, but more than half of HBC gene mutations were missed by Australian standards. Discovery of HBC gene mutations led to changed management in most cases. Universal testing is highly acceptable to clinicians and patients who reported no adverse impact on psychological distress or cancer-specific worry and no decision regret. Germline mutations identified and their impact on management Citation Format: Dilanka De Silva, Lesley Stafford, Anita Skandarajah, Michelle Sinclair, Lisa Devereux, Kirsten Hogg, Maira Kentwell, Allan Park, luxi Lal, Magnus Zethoven, Madawa Jayawardena, Fiona Chan, Paul James, Geoffrey Lindeman, Ian Campbell, Bruce Mann. Universal genetic testing for women with newly diagnosed breast cancer identified many mutations, impacted clinical management and caused no psychological distress to patients [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-09-02.

Abstract PO3-28-10: MRI Radiomic phenotypes derived from the ECOG-ACRIN E4112 Trial to assess high-risk ductal carcinoma in situ

Abstract INTRODUCTION Ductal carcinoma in situ (DCIS) is a non-lethal pre-invasive breast cancer that can co-exist with invasive disease. Dynamic contrast-enhanced (DCE) MRI is sensitive for the detection of high-grade DCIS and invasive cancer while Oncotype DCIS Score is a 12-gene assay that can assess recurrence risk. In practice, it is difficult to distinguish low- from high-risk DCIS, which leads to overtreatment for up to half of women diagnosed with DCIS. We hypothesize that radiomic phenotypes of DCIS derived from DCE-MRI data may serve as prognostic markers to improve risk stratification by capturing disease heterogeneity. Here we evaluate the ability of these phenotypes to predict DCIS Score and upstaging of DCIS to invasive disease on wide local excision in a multicenter trial. METHODS Data: DCE-MRI data from the ECOG-ACRIN E4112 trial were retrospectively analyzed. Primary analysis focused on participants with data on disease upstaging (N=295), with secondary analysis in a subset (N=174) of participants with DCIS Scores (dichotomized as >55 and 55) and pure DCIS. Clinical information included patient demographics, lesion morphology on MRI, background parenchymal enhancement, DCIS grade, central necrosis, and hormone receptor status. Data analysis: Radiologist-drawn lesion segmentations and publicly available software, CaPTk, were used to compute 64 radiomic features from first post-contrast images for each participant. Radiomic phenotypes were identified using hierarchical clustering on the extracted features. A Chi-square test was used to evaluate the association between radiomic phenotypes and each outcome. The likelihood ratio test was used to compare two logistic regression models: 1)clinical model using only clinical information as predictors and 2) clinical+phenotypes model using clinical information and phenotype assignment as predictors. Each model was used for the prediction of upstaging to invasive disease and DCIS score. Model performance was evaluated as the 10-fold cross-validated area under the receiver operator characteristic curve (AUC). A p< 0.05 was considered significant. RESULTS A total of 45 (15%) cases upstaged to invasive disease. Two radiomic phenotypes were identified: Phenotype 1 indicated greater lesion signal heterogeneity, while Phenotype 2 indicated lower heterogeneity. Radiomic phenotype was strongly associated with disease upstaging (p=0.0034) – with a higher rate of upstaging for Phenotype 1 – but not with DCIS score (p=0.1174, Table 1). For predicting disease upstaging, the clinical+phenotypes model yielded a higher AUC=0.72 and a significantly better fit to the data (p=0.0022) compared to the clinical model parameterized by clinical information alone (AUC=0.69). For predicting DCIS Score, the clinical+phenotypes model (AUC=0.77) showed similar performance compared to the clinical model (AUC=0.76) and no significant improvement in fit to the data (p=0.2920). CONCLUSION Radiomic phenotypes capturing disease heterogeneity show promise as prognostic predictors for predicting disease upstaging in DCIS compared to clinical information alone and may enable more efficient disease management. We observed that phenotypes did not have independent predictive outcome for DCIS score, suggesting that MRI and DCIS Score offer independent information and could be combined in future models to better predict disease recurrence or progression. Clinical applications of radiomic phenotypes may improve risk stratification and potentially result in decreased overtreatment of women diagnosed with DCIS. Table 1: Association between radiomic phenotypes and DCIS outcomes using a Chi square test. Citation Format: Kalina Slavkova, Ruya Kang, Vivian Belenky, Anum Kazerouni, Debosmita Biswas, Hannah Horng, Rhea Chitalia, Michael Hirano, Jennifer Xiao, Ralph Corsetti, Sarah Javid, Derrick Spell, Antonio Wolff, Joseph Sparano, Seema Khan, Christopher Comstock, Justin Romanoff, Jon Steingrimsson, Constantine Gatsonis, Constance Lehman, Savannah Partridge, Despina Kontos, Habib Rahbar. MRI Radiomic phenotypes derived from the ECOG-ACRIN E4112 Trial to assess high-risk ductal carcinoma in situ [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-28-10.

Application of deep learning on mammographies to discriminate between low and high-risk DCIS for patient participation in active surveillance trials

BackgroundDuctal Carcinoma In Situ (DCIS) can progress to invasive breast cancer, but most DCIS lesions never will. Therefore, four clinical trials (COMET, LORIS, LORETTA, AND LORD) test whether active surveillance for women with low-risk Ductal carcinoma In Situ is safe (E. S. Hwang et al., BMJ Open, 9: e026797, 2019, A. Francis et al., Eur J Cancer. 51: 2296–2303, 2015, Chizuko Kanbayashi et al. The international collaboration of active surveillance trials for low-risk DCIS (LORIS, LORD, COMET, LORETTA),  L. E. Elshof et al., Eur J Cancer, 51, 1497–510, 2015). Low-risk is defined as grade I or II DCIS. Because DCIS grade is a major eligibility criteria in these trials, it would be very helpful to assess DCIS grade on mammography, informed by grade assessed on DCIS histopathology in pre-surgery biopsies, since surgery will not be performed on a significant number of patients participating in these trials.ObjectiveTo assess the performance and clinical utility of a convolutional neural network (CNN) in discriminating high-risk (grade III) DCIS and/or Invasive Breast Cancer (IBC) from low-risk (grade I/II) DCIS based on mammographic features. We explored whether the CNN could be used as a decision support tool, from excluding high-risk patients for active surveillance.MethodsIn this single centre retrospective study, 464 patients diagnosed with DCIS based on pre-surgery biopsy between 2000 and 2014 were included. The collection of mammography images was partitioned on a patient-level into two subsets, one for training containing 80% of cases (371 cases, 681 images) and 20% (93 cases, 173 images) for testing. A deep learning model based on the U-Net CNN was trained and validated on 681 two-dimensional mammograms. Classification performance was assessed with the Area Under the Curve (AUC) receiver operating characteristic and predictive values on the test set for predicting high risk DCIS-and high-risk DCIS and/ or IBC from low-risk DCIS.ResultsWhen classifying DCIS as high-risk, the deep learning network achieved a Positive Predictive Value (PPV) of 0.40, Negative Predictive Value (NPV) of 0.91 and an AUC of 0.72 on the test dataset. For distinguishing high-risk and/or upstaged DCIS (occult invasive breast cancer) from low-risk DCIS a PPV of 0.80, a NPV of 0.84 and an AUC of 0.76 were achieved.ConclusionFor both scenarios (DCIS grade I/II vs. III, DCIS grade I/II vs. III and/or IBC) AUCs were high, 0.72 and 0.76, respectively, concluding that our convolutional neural network can discriminate low-grade from high-grade DCIS.

Non-mass-type ductal carcinoma in situ of the breast on ultrasound: Features and pathological analysis.

The aims of this study were to investigate the ultrasound features of non-mass-type ductal carcinoma in situ (DCIS) of the breast and conduct a pathological analysis. Ultrasound images of 32 cases of non-mass-type DCIS of the breast, collected between September 2014 and June 2016, were analyzed. The characteristics of the lesions, including border, internal echogenicity, local glandular hyperplasia, micro-calcification, and intra-tumoral blood flow resistance index (RI), were analyzed, and a concurrent pathological analysis was conducted. Obvious local glandular hyperplasia was commonly observed in the 32 cases of non-mass-type DCIS of the breast. The internal echogenicity varied in intensity, exhibiting a "leopard pattern" or "zebra pattern." Color Doppler imaging revealed abundant blood flow signals within the lesion with an RI of >0.7. Isolated duct dilatation and micro-calcifications were occasionally observed within the lesions. High-grade DCIS was the predominant pathological type of non-mass-type DCIS. Non-mass-type DCIS of the breast often presents with obvious local glandular hyperplasia and varying internal echogenicity. High-grade DCIS is the frequent pathological type. Color Doppler imaging and RI measurement can assist in diagnosing non-mass-type DCIS of the breast.

Surgical outcomes of total duct excision in the diagnosis and management of nipple discharge.

Total duct excision (TDE) is performed for the diagnosis and management of nipple discharge. The Association of Breast Surgery's recent guidelines recommend considering diagnostic surgery for single-duct, blood-stained or clear nipple discharge, and for symptomatic management. We retrospectively reviewed the diagnostic and surgical outcomes of all cases of TDE between January 2013 and November 2019. In total, 259 TDEs were carried out: 219 for nipple discharge, 29 for recurrent mastitis, 3 for screening abnormalities and 8 for breast lumps. Of the nipple discharge group, 121 had blood-stained discharge. Mean patient age was 52 years (range 19-81). Median follow-up time was 45 months (interquartile range 24-63). The following cases were identified on histopathology: 236 benign breast changes, 10 atypical ductal hyperplasia, 4 lobular carcinoma in situ, 2 low-grade ductal carcinoma in situ (DCIS), 3 intermediate-grade DCIS, 2 high-grade DCIS and 2 invasive ductal carcinomas. In total, 3.5% of patients who underwent TDE had a diagnosis of DCIS or invasive carcinoma. Blood-stained discharge was associated with a significant increase in risk of DCIS or carcinoma compared with other nipple discharge colours (p = 0.043). The most common complications of TDE were infection, poor wound healing and haematoma. Nipple discharge recurred in 14.2% of cases. TDE can be considered for the diagnostics and management of nipple discharge. Blood-stained nipple discharge increases the risk of DCIS or malignancy, but the majority of the time TDE reveals benign breast pathology.

Lumpectomy without radiation for ductal carcinoma in situ of the breast: 20-year results from the ECOG-ACRIN E5194 study

We report the 20-year rate of ipsilateral breast event (IBE) for patients with ductal carcinoma in situ (DCIS) treated with lumpectomy without radiation on a non-randomized prospective clinical trial. Patients were enrolled in cohort 1: low- or intermediate-grade DCIS, size ≤ 2.5 cm (n = 561); or cohort 2: high-grade DCIS, size ≤ 1 cm (n = 104). The Kaplan–Meier method was used to estimate time-to-event distributions. Cox proportional hazard methods were used to estimate hazard ratios (HRs) and tests for significance for event times. 561 patients were enrolled in cohort 1 and 104 in cohort 2. After central pathology review, 26% in cohort 1 were recategorized as high-grade and 26% in cohort 2 as low- or intermediate-grade. Mean DCIS size was similar at 7.5 mm in cohort 1 and 7.8 mm in cohort 2. Surgical margin was ≥3 mm in 96% of patients, and about 30% received tamoxifen. Median follow-up was 19.2 years. There were 104 IBEs, of which 54 (52%) were invasive. The IBE and invasive IBE rates increased in both cohorts up to 15 years, then plateaued. The 20-year IBE rates were 17.8% for cohort 1 and 28.7% for cohort 2 (p = 0.005), respectively. Invasive IBE occurred in 9.8% and 15.1% (p = 0.09), respectively. On multivariable analysis, IBE risk increased with size and was higher in cohort 2, but grade and margin width were not significantly associated with IBE. For patients with DCIS treated with excision without radiation, the rate of IBE increased with size and assigned cohort mostly in the first 15 years.

Abstract PR07: Intratumoral injection of mRNA-2752 and anti-PD-1 results in rapid regression of HER2 positive and or Hormone Receptor Negative DCIS: Phase 1 study results

Abstract Background: High-grade DCIS with immune infiltrates may be contained by the immune system, but are at risk for progression to invasive disease. Spatial proximity of CD8+/PD-1+ T cells and PD-L1+ cells predict response to chemotherapy and PD-1 inhibitors in hormone negative (HR-) invasive tumors. DCIS with high-risk features (such as HR- and or Her2+) often have T cell infiltrates. We hypothesized that intratumoral (ITu) administration of pembrolizumab (ITu-P) could potentiate the immune response and avoid systemic toxicities. We also explored whether the addition of mRNA-2752 (Moderna), an mRNA based therapeutic encoding T cell co-stimulator OX40L and proinflammatory cytokines IL-23 and IL-36g, would synergize adaptive anti-cancer immune responses of immune checkpoint injection alone. Since mortality for DCIS is extremely low, we proposed ITu treatment to avoid systemic adverse effects. In a phase 1 dose escalation study of single agent ITu-P we found 2 doses of 8 mg, administered 2-3 wks apart, was tolerable, induced immunological changes within the DCIS lesions, but had little clinical benefit. Herein, we expanded the number of injections to 4 and also tested a combination with ITu mRNA-2752 (ITu-M), to determine if we could find a dose that was both tolerable and elicited anti-tumor responses. Methods: This study evaluated ITu-P monotherapy (8mg, q2-3 wks x 4 doses; n=5) and combination ITu-P (8, 4, or 2mg) + ITu-M (4, 2, or 1mg) (n=10). DCIS with >2 high-risk features were eligible: age<45; high grade, extensive comedo necrosis; palpable mass; HR-; HER2+; size >5 cm, or microinvasion (<10% of lesion with invasive cancer). Dose was reduced based on AEs. Patients (pts) had MRI before and after 2 injections. Core biopsy/surgery was conducted after the last MRI. Baseline and biopsy/surgery breast tissue specimens were analyzed for immune infiltrates by multiplex immunofluorescence (mIF) staining. Results: In the ITu-P monotherapy expanded cohort, T cell density increased except when there was a paucity of T cells pre-treatment. Only 1 pt demonstrated a reduction in lesion size (clinically and on MRI); no side effects were seen. Of 10 pts enrolled in the combination (ITu-P + ITu-M) cohort, 80% responded: 2 non responders had <5% T cells and the 8 responders had > 6% T cell infiltrates at baseline. In 4 pts, all DCIS (3-8 cm) resolved completely (pCR) and 4 pts had a PR. Two CRs had post-therapy core biopsies only and remain NED with >1 yr follow-up (MRI). Pts experienced Gr1/2 fever, myalgias, and fatigue, enlargement of regional nodes, and erythema and induration of the breast lasting 4-20 days. No AEs > grade 2 were noted. The tolerable dose was 1mg ITu-M + 4mg ITu-P. Conclusion: The combination of ITu-P + ITu-M demonstrated modulation of the tumor immune microenvironment and robust antitumor activity in high-risk DCIS (typically HR- or HER2+) with pre-existing T cell infiltrates. mIF analyses suggest that the degree of immune infiltrate at baseline is associated with complete response. A study evaluating monotherapy ITu-M is in progress. Citation Format: Laura J. Esserman, Kirithiga Ramalingam, Rachel Woody, Alexa Glencer, Christopher Schwartz, Hidetoshi Mori, Jasmine Wong, Gillian Hirst, Jennifer Rosenbluth, Nola Hylton, Natsuko Onishi, Alexander D. Borowsky, Michael J. Campbell. Intratumoral injection of mRNA-2752 and anti-PD-1 results in rapid regression of HER2 positive and or Hormone Receptor Negative DCIS: Phase 1 study results [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr PR07.

Deep-learning model to improve histological grading and predict upstaging of atypical ductal hyperplasia / ductal carcinoma in situ on breast biopsy.

Risk stratification of atypical ductal hyperplasia (ADH) and ductal carcinoma in situ (DCIS), diagnosed using breast biopsy, has great clinical significance. Clinical trials are currently exploring the possibility of active surveillance for low-risk lesions, whereas axillary lymph node staging may be considered during surgical planning for high-risk lesions. We aimed to develop a machine-learning algorithm based on whole-slide images of breast biopsy specimens and clinical information to predict the risk of upstaging to invasive breast cancer after wide excision. Patients diagnosed with ADH/DCIS on breast biopsy were included in this study, comprising 592 (740 slides) and 141 (198 slides) patients in the development and independent testing cohorts, respectively. Histological grading of the lesions was independently evaluated by two pathologists. Clinical information, including biopsy method, lesion size, and Breast Imaging Reporting and Data System (BI-RADS) classification of ultrasound and mammograms, were collected. Deep DCIS consisted of three deep neural networks to evaluate nuclear grade, necrosis, and stromal reactivity. Deep DCIS output comprised five parameters: total patches, lesion extent, Deep Grade, Deep Necrosis, and Deep Stroma. Deep DCIS highly correlated with the pathologists' evaluations of both slide- and patient-level labels. All five parameters of Deep DCIS were significantly associated with upstaging to invasive carcinoma in subsequent wide excisional specimens. Using multivariate logistic regression, Deep DCIS predicted upstaging to invasive carcinoma with an area under the curve (AUC) of 0.81, outperforming pathologists' evaluation (AUC, 0.71 and 0.69). After including clinical and hormone receptor status information, performance further improved (AUC, 0.87). This combined model retained its predictive power in two subgroup analyses: the first subgroup included unequivocal DCIS (excluding cases of ADH and DCIS suspicious for microinvasion) (AUC, 0.83), while the second excluded cases of high-grade DCIS (AUC, 0.81). The model was validated in an independent testing cohort (AUC, 0.81). This study demonstrated that deep-learning models can refine histological evaluation of ADH and DCIS on breast biopsies, which may help guide future treatment planning.

Sonography-based multimodal information platform for identifying the surgical pathology of ductal carcinoma in situ

BackgroundThe risk of ductal carcinoma in situ (DCIS) identified by biopsy often increases during surgery. Therefore, confirming the DCIS grade preoperatively is necessary for clinical decision-making. PurposeTo train a three-classification deep learning (DL) model based on ultrasound (US), combining clinical data, mammography (MG), US, and core needle biopsy (CNB) pathology to predict low-grade DCIS, intermediate-to-high-grade DCIS, and upstaged DCIS. Materials and MethodsData of 733 patients with 754 DCIS cases confirmed by biopsy were retrospectively collected from May 2013 to June 2022 (N1), and other data (N2) were confirmed by biopsy as low-grade DCIS. The lesions were randomly divided into training (n=471), validation (n=142), and test (n = 141) sets to establish the DCIS-Net. Information on the DCIS-Net, clinical (age and sign), US (size, calcifications, type, breast imaging reporting and data system [BI-RADS]), MG (microcalcifications, BI-RADS), and CNB pathology (nuclear grade, architectural features, and immunohistochemistry) were collected. Logistic regression and random forest analyses were conducted to develop Multimodal DCIS-Net to calculate the specificity, sensitivity, accuracy, receiver operating characteristic curve, and area under the curve (AUC). ResultsIn the test set of N1, the accuracy and AUC of the multimodal DCIS-Net were 0.752–0.766 and 0.859–0.907 in the three-classification task, respectively. The accuracy and AUC for discriminating DCIS from upstaged DCIS were 0.751–0.780 and 0.829–0.861, respectively. In the test set of N2, the accuracy and AUC of discriminating low-grade DCIS from upstaged low-grade DCIS were 0.769–0.987 and 0.818–0.939, respectively. DL was ranked from one to five in the importance of features in the multimodal-DCIS-Net. ConclusionBy developing the DCIS-Net and integrating it with multimodal information, diagnosing low-grade DCIS, intermediate-to high-grade DCIS, and upstaged DCIS is possible. It can also be used to distinguish DCIS from upstaged DCIS and low-grade DCIS from upstaged low-grade DCIS, which could pave the way for the DCIS clinical workflow.

Tailored radiation dose according to margin width for patients with ductal carcinoma in situ after breast-conserving surgery

A 2 mm resection margin is considered adequate for ductal carcinoma in situ (DCIS). We assessed the effectiveness of a tailored radiation dose for margins < 2 mm and the appropriate margin width for high-risk DCIS. We retrospectively evaluated 137 patients who received adjuvant radiotherapy after breast-conserving surgery for DCIS between 2013 and 2019. The patients were divided into three– positive, close (< 2 mm), and negative (≥ 2 mm) margin groups. Radiation dose to the tumor bed in equivalent dose in 2 Gy fractions were a median of 66.25 Gy, 61.81 Gy, and 59.75 Gy for positive, close, and negative margin groups, respectively. During a median follow-up of 58 months, the crude rates of local recurrence were 15.0%, 6.7%, and 4.6% in the positive, close, and negative margin groups, respectively. The positive margin group had a significantly lower 5-year local recurrence-free survival (LRFS) rate compared to the close and negative margin groups in propensity-weighted log-rank analysis (84.82%, 93.27%, and 93.20%, respectively; p = 0.008). The difference in 5-year LRFS between patients with the high- and non-high-grade tumors decreased as the margin width increased (80.4% vs. 100.0% for margin ≥ 2 mm, p < 0.001; 92.3% vs. 100.0% for margin ≥ 6 mm, p = 0.123). With the radiation dose tailored for margin widths, positive margins were associated with poorer local control than negative margins, whereas close margins were not. Widely clear margins (≥ 2 mm) were related to favorable local control for high-grade DCIS.

The natural history of ductal carcinoma in situ (DCIS) in simulation models: A systematic review.

Assumptions on the natural history of ductal carcinoma in situ (DCIS) are necessary to accurately model it and estimate overdiagnosis. To improve current estimates of overdiagnosis (0-91%), the purpose of this review was to identify and analyse assumptions made in modelling studies on the natural history of DCIS in women. A systematic review of English full-text articles using PubMed, Embase, and Web of Science was conducted up to February 6, 2023. Eligibility and all assessments were done independently by two reviewers. Risk of bias and quality assessments were performed. Discrepancies were resolved by consensus. Reader agreement was quantified with Cohen's kappa. Data extraction was performed with three forms on study characteristics, model assessment, and tumour progression. Thirty models were distinguished. The most important assumptions regarding the natural history of DCIS were addition of non-progressive DCIS of 20-100%, classification of DCIS into three grades, where high grade DCIS had an increased chance of progression to invasive breast cancer (IBC), and regression possibilities of 1-4%, depending on age and grade. Other identified risk factors of progression of DCIS to IBC were younger age, birth cohort, larger tumour size, and individual risk. To accurately model the natural history of DCIS, aspects to consider are DCIS grades, non-progressive DCIS (9-80%), regression from DCIS to no cancer (below 10%), and use of well-established risk factors for progression probabilities (age). Improved knowledge on key factors to consider when studying DCIS can improve estimates of overdiagnosis and optimization of screening.

Subtypes of high-grade breast ductal carcinoma in situ (DCIS): incidence and potential clinical impact

ObjectiveThe purpose of this study was to investigate and classify the molecular subtypes of high-grade ductal carcinoma in situ (DCIS) and identify possible high-risk subtypes. The heterogenicity of DCIS with variable clinical and histopathological presentations has been recognized. Nevertheless, only histopathological grading and diameter are currently implemented in clinical decision-making following the diagnosis of DCIS. The molecular subtypes of DCIS and their IHC surrogate markers have not been defined in conventional treatment guidelines and recommendations. We applied the definitions of molecular subtypes according to the IHC surrogate markers defined for IBC and subclassified high-grade DCIS, accordingly.MethodsHistopathological specimens were collected, revised, and regraded from 494 patients diagnosed with DCIS between 1996 and 2018. Other in situ and papillary lesions observed in breast biopsies were excluded from this study. 357 high-grade DCIS cases were submitted to IHC analysis. The markers investigated were ER, PR, HER2, and Ki67.Results45 cases were classified as grade 1, 19 as grade 2, and 430 as grade 3. Sixty patients with high-grade DCIS had an additional invasive component in the surgical specimen. Thirty-three patients were diagnosed with recurrent DCIS or invasive cancer (minimum one year after their primary DCIS diagnosis). The proportions of luminal A and luminal B HER2-negative subtypes varied depending on whether 2011 or 2013 St. Gallen Consensus Conference guidelines were adopted. Luminal A was the most prevalent subtype, according to both classifications. The luminal B HER2-positive subtype was found in 22.1% of cases, HER2-enriched subtype in 21.8%, and TPN subtype in 5.6%. There were strong indications that HER2-enriched subtype was significantly more frequent among DCIS with invasive component (p = 0.0169).ConclusionsHigh-grade DCIS exhibits all the molecular subtypes previously identified in IBC, but with a somewhat different distribution in our cohort. HER2-enriched subtype is substantially related to the presence of an invasive component in DCIS; consequently, it is regarded as a high-risk entity.

Preoperative diagnosis of ductal carcinoma in situ of the breast over a 24-year period.

The method of diagnosis of ductal carcinoma in situ (DCIS) has changed since the 1980s. The aim of this audit was to assess changes in the preoperative diagnosis of DCIS since the introduction of needle core biopsy, particularly the proportion with a preoperative biopsy diagnosis of DCIS. The preoperative diagnoses of patients with a final diagnosis of DCIS in the surgical specimen were reviewed (i) in 809 patients who presented through breast screening from 1997 to 2021, and (ii) in all patients in 5 individual years at 5-year intervals from 2000 to 2020 (254 in total). For screening-detected DCIS the proportion with a preoperative diagnosis of DCIS increased from 75% to 98% over the study period. In a detailed analysis of all cases of DCIS in 5 separate years the proportion with a preoperative diagnosis of DCIS increased from 68% in 2000 to 96% in 2020. For high-grade DCIS the proportion increased from 87% to 97%, and for low- or intermediate-grade DCIS from 48% to 93%. The proportion of women who had vacuum-assisted biopsy increased from 7% in 2000 to 58% in 2015. There was a small increase in the number of biopsies that had basal cytokeratin and oestrogen receptor immunohistochemistry to aid diagnosis. There has been an increase in the preoperative diagnosis of DCIS, particularly of low- or intermediate-grade, over the last two decades. The increasing use of vacuum-assisted biopsy is likely to be a major contributory factor to this increase.

Accelerated partial breast irradiation (APBI) for ductal carcinoma in situ.

e12516 Background: Landmark studies of accelerated partial breast irradiation (APBI) included patients with DCIS, but with limited guidance regarding subgroups of in situ disease. Suitability criteria defined by national guidelines for APBI are narrowly constrained among those with DCIS, and controversy persists regarding optimal patient selection. Here, we report disease outcomes for a heterogeneous cohort of patients with DCIS who received APBI. Methods: Using a prospectively maintained institutional database, we identified patients with DCIS who underwent lumpectomy and adjuvant APBI from 2000 to 2022. Clinicopathologic characteristics were collected, and patients were classified as suitable, cautionary, or unsuitable for APBI by the latest American Society for Radiation Oncology (ASTRO) criteria. Outcomes of interest included local recurrence (LR), overall survival (OS), and follow up time. Cumulative incidence functions were calculated to estimate the incidence of LR over time. All statistical analyses were performed in R version 4.2.2. Results: The cohort comprised 176 patients, median age 60 years (IQR 52, 66). Median DCIS size was 9 mm (IQR 4, 15 mm), and approximately 20% had multifocal disease. Most patients had negative final surgical margins (160, 91%), with 10 patients having ≤2 mm margins and 6 having ≤1 mm margins for DCIS. 18 (10%) patients had nuclear grade I disease, 111 (63%) had grade II disease, and 33 (19%) had grade III disease, with a small subset classified as grade I-II or II-III. Most patients (161, 91%) had ER+ DCIS, and 72 (41%) received endocrine therapy. By ASTRO criteria, 118 (67%) patients were suitable for APBI, 57 (32%) cautionary, and 1 (0.6%) was unsuitable. At a median 24 months of follow up (range 2 to 127 months) we observed only one LR, yielding a 2-year LR rate of 0.6%. The LR occurred in the cautionary group, yielding a 2-year LR rate of 1.8% for the cautionary subset. The patient with LR was 56 years old, with 24 mm of high grade DCIS, ER+, with lumpectomy to negative margins, and did not receive endocrine therapy. No breast cancer mortality events were observed. Conclusions: Our early-term results exhibit excellent local control for patients with DCIS who received lumpectomy and APBI, even among those classified as “cautionary” by national guidelines. Although our findings are limited by short follow up, these results suggest that broadening the application of APBI for patients with DCIS may warrant further investigation.

High-Grade Ductal Carcinoma In Situ of the Breast With Regressive Changes: Radiological and Clinicopathological Findings.

Tumour regression is defined as continuity of changes leading to the elimination of a neoplastic population and is reflected as periductal fibrosis and intraductal tumour attenuation. The aim of this study was to describe the radiological and clinicopathological characteristics of high-grade breast ductal carcinoma in situ (DCIS) with regressive changes (RC). Thirty-two cases of high-grade DCIS with RC on biopsy specimens followed by excision were included. The mammographic, ultrasonographic (US), and magnetic resonance imaging (MRI) findings of cases were retrospectively reviewed according to the breast imaging reporting and data system (BI-RADS) lexicon. Clinical and histopathological findings [comedonecrosis, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) status and Ki-67 proliferation index] were recorded. The rate of upgrade to invasive cancer after surgical excision and lymph node involvement were evaluated. The most common mammographic finding was microcalcifications alone (68.8%). The most frequently seen findings on US were microcalcifications only (21.9%), followed by microcalcifications and hypoechoic area (18.7%). On MRI, most lesions presented as clumped non-mass enhancement with segmental distribution. ER/PR negativity (53.1%, 65.6%), HER2 positivity (56.3%) and high Ki-67 (62.5%), which are known to be associated with more aggressive behavior, were found to be proportionally higher. The rate of upgrade to invasive cancer was 21.8%. DCIS with RC lesions present most often as microcalcifications alone on both mammography and US. MRI features are not distinguishable from those of other DCIS lesions. DCIS with RC lesions show biomarker status reflecting more aggressive behavior and high upgrade rate to invasive cancer.

The effectiveness of an ultrafast breast MRI protocol in the differentiation of benign and malignant breast lesions

To evaluate the effectiveness of an ultrafast breast magnetic resonance imaging (MRI) protocol in differentiating benign and malignant breast lesions. Fifty-four patients with Breast Imaging Reporting and Data System (BI-RADS) 4 or 5 lesions were recruited between July 2020 to May 2021. A standard breast MRI was performed with the inclusion of the ultrafast protocol between the unenhanced sequence and the first contrast-enhanced sequence. Three radiologists performed image interpretation in consensus. Ultrafast kinetic parameters analysed included the maximum slope (MS), time to enhancement (TTE), and arteriovenous index (AVI). These parameters were compared using receiver operating characteristics with p-values of <0.05 considered to indicate statistical significance. Eighty-three histopathological proven lesions from 54 patients (mean age 53.87 years, SD 12.34, range 26-78 years) were analysed. Forty-one per cent (n=34) were benign and 59% (n=49) were malignant. All malignant and 38.2% (n=13) benign lesions were visualised on the ultrafast protocol. Of the malignant lesions, 77.6% (n=53) were invasive ductal carcinoma (IDC) and 18.4% (n=9) were ductal carcinoma in situ (DCIS). The MS for malignant lesions (13.27%/s) were significantly larger than for benign (5.45%/s; p<0.0001). No significant differences were seen for TTE and AVI. The area under the ROC curve (AUC) for the MS, TTE, and AVI were 0.836, 0.647, and 0.684, respectively. Different types of invasive carcinoma had similar MS and TTE. The MS of high-grade DCIS was also similar to that of IDC. Lower MS values were observed for low-grade (5.3%/s) compared to high-grade DCIS (14.8%/s) but the results were not significant statistically. The ultrafast protocol showed potential to discriminate between malignant and benign breast lesions with high accuracy using MS.