ACR Appropriateness Criteria® Imaging of Invasive Breast Cancer.

As the proportion of women diagnosed with invasive breast cancer increases, the role of imaging for staging and surveillance purposes should be determined based on evidence-based guidelines. It is important to understand the indications for extent of disease evaluation and staging, as unnecessary imaging can delay care and even result in adverse outcomes. In asymptomatic patients that received treatment for curative intent, there is no role for imaging to screen for distant recurrence. Routine surveillance with an annual 2-D mammogram and/or tomosynthesis is recommended to detect an in-breast recurrence or a new primary breast cancer in women with a history of breast cancer, and MRI is increasingly used as an additional screening tool in this population, especially in women with dense breasts. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Outcomes of atypical lobular hyperplasia managed by active surveillance or immediate surgery.

BACKGROUND: Atypical lobular hyperplasia (ALH) is typically diagnosed via needle core biopsy (NCB) and is commonly removed surgically in light of upgrade to malignancy rates of 1%-5%. As studies on radiographic outcomes of ALH managed by active surveillance (AS) are limited, we investigated the upgrade rates of surgically excised ALH as well as radiographic progression during AS. METHODS: In this retrospective study, 125 patients with 127 ALH lesions diagnosed via NCB at Weill Cornell Medicine from 2015 to 2021 were included. The upgrade rate to cancer was determined for patients who had surgical management ≤6 months after biopsy. Among patients with ALH managed by AS, we investigated radiographic progression on 6-month interval imaging. RESULTS: Of 127 ALH lesions, 75% (n = 95) were immediately excised and 25% (n = 32) were observed under AS. The upgrade rate of immediately excised ALH was 2.1% (n = 2; invasive ductal carcinoma [IDC], T1N0 and IDC, and T1Nx). In the AS cohort, no ALH lesions progressed radiographically during the follow-up period of 22.5 months (median), with all remaining stable (50%, n = 16), resolving (47%, n = 15), or decreasing in size (3%, n = 1). CONCLUSIONS: In this study, NCB-diagnosed ALH had a low upgrade to malignancy rate (2.1%), and no ALH lesions managed by AS progressed radiographically during the follow-up period of 22.5 months. These results support AS as the favorable option for patients with pure ALH on biopsy, with surgical excision for lesions that progress on surveillance.

Current Practice and Variation in Same-Day Services in Breast Imaging: A Multi-Institutional National Survey of the Society of Breast Imaging Membership.

OBJECTIVE: The availability of same-day services in breast imaging is an important topic given potential advantages for timely diagnoses and patient experiences, but there are potential barriers that lead facilities to not offer these services. We sought to understand current practice patterns and radiologist perspectives on offering same-day services. METHODS: The Society of Breast Imaging (SBI) Patient Care & Delivery Committee developed a 19-question survey that was emailed to all 3449 active members of the SBI in May 2023. An exemption from the institutional review board was obtained at the lead author's institution. The survey consisted of 19 questions that were designed to understand the scope, perceptions, barriers, and logistics of same-day services. Comparisons were made between responses for offering same-day services (screening interpretation, diagnostic examinations, biopsies) and respondent demographics. RESULTS: A total of 437 American and Canadian members participated, yielding a response rate of 12.7%. Respondents were most commonly in private practice (43.0%, 188/437), working in an outpatient medical center-based clinic (41.9%, 183/437), and without trainees (64.5%, 282/437). Respondents estimated 12.1% of screening examinations were interpreted while patients waited, which was significantly more common in free-standing breast imaging clinics (P = .028) and practices without trainees (P = .036). Respondents estimated 15.0% of diagnostic examinations were performed same day, which was more common in academic and private practices (P = .03) and practices without trainees (P = .01). Respondents estimated 11.5% of biopsies were performed the same day as the recommendation, which had no association with practice type/context, presence of trainees, number of mammography units, number of radiologists, or number of technologists. Long patient travel distance and limited patient mobility were the most cited reasons for offering patients same-day services. CONCLUSION: Offering same-day breast imaging services varies among institutions and may be influenced by factors such as practice context and type and the presence of trainees.

Breast Radiologists' Perceptions on the Detection and Management of Invasive Lobular Carcinoma: Most Agree Imaging Beyond Mammography Is Warranted.

OBJECTIVE: To determine breast radiologists' confidence in detecting invasive lobular carcinoma (ILC) on mammography and the perceived need for additional imaging in screening and preoperative settings. METHODS: A 16-item anonymized survey was developed, and IRB exemption obtained, by the Society of Breast Imaging (SBI) Patient Care and Delivery Committee and the Lobular Breast Cancer Alliance. The survey was emailed to 2946 radiologist SBI members on February 15, 2023. The survey recorded demographics, perceived modality-specific sensitivity for ILC to the nearest decile, and opinions on diagnosing ILC in screening and staging imaging. Five-point Likert scales were used (1 = strongly disagree, 2 = disagree, 3 = neutral, 4 = agree, 5 = strongly agree). RESULTS: Response rate was 12.4% (366/2946). Perceived median (interquartile range) modality-specific sensitivities for ILC were MRI 90% (80-90), contrast-enhanced mammography 80% (70-90), molecular breast imaging 80% (60-90), digital breast tomosynthesis 70% (60-80), US 60% (50-80), and 2D mammography 50% (30-60). Only 25% (85/340) respondents were confident in detecting ILC on screening mammography in dense breasts, while 67% (229/343) were confident if breasts were nondense. Most agreed that supplemental screening is needed to detect ILC in women with dense breasts (272/344, 79%) or a personal history of ILC (248/341, 73%), with 34% (118/334) indicating that supplemental screening would also benefit women with nondense breasts. Most agreed that additional imaging is needed to evaluate extent of disease in women with newly diagnosed ILC, regardless of breast density (dense 320/329, 97%; nondense 263/329, 80%). CONCLUSION: Most breast radiologists felt that additional imaging beyond mammography is needed to more confidently screen for and stage ILC.

Screening in Women With BRCA Mutations Revisited.

Patients with BRCA1 or BRCA2 gene mutations are at high risk for the development of breast cancer. This article reviews the current evidence for breast cancer screening of patients with BRCA1 or BRCA2 pathogenic gene mutations if they have not undergone prophylactic mastectomy. It will review the current evidence-based imaging recommendations for different modalities and ages of screening initiation in screening this patient population at high risk. Special considerations in transgender BRCA1 and BRCA2 mutation carriers are also discussed.

Active Surveillance of Atypical Ductal Hyperplasia of the Breast.

BACKGROUND: When needle core biopsy (NCB) of the breast yields atypical ductal hyperplasia (ADH), excision is typically recommended. The natural history of ADH undergoing active surveillance (AS) is not well described. We investigate the rates of upgrade to malignancy of excised ADH and the rates of radiographic progression under AS. MATERIALS AND METHODS: We retrospectively reviewed records of 220 cases of ADH on NCB. Of patients who had surgery within 6 months of NCB, we examined the malignancy upgrade rate. In the AS cohort, we examined rates of radiographic progression on interval imaging. RESULTS: The malignancy upgrade rate among patients who underwent immediate excision (n = 185) was 15.7%: 14.1% (n = 26) ductal carcinoma in situ (DCIS) and 1.6% (n = 3) invasive ductal carcinoma (IDC). Upgrade to malignancy was less common in lesions <4 mm in size (0%) or with focal ADH (5%), and more common among lesions presenting with a radiographic mass (26%). Among the 35 patients who underwent AS, median follow-up was 20 months. Two lesions progressed on imaging (incidence 3.8% at 2 years). One patient without radiographic progression was found to have IDC at delayed surgery. The remaining lesions remained stable (46%), decreased in size (11%), or resolved (37%). CONCLUSIONS: Our findings suggest that AS is a safe approach to managing ADH on NCB for most patients. This could spare many patients with ADH from unnecessary surgery. Given that AS is being investigated for low-risk DCIS in multiple international prospective trials, these results suggest that AS should also be investigated for ADH.

Bleeding Events After Image-Guided Breast Biopsies: Comparison of Patients Temporarily Discontinuing Versus Maintaining Antithrombotic Therapy During Biopsy.

BACKGROUND. Antithrombic (AT) therapy is commonly temporarily discontinued before breast core needle biopsy (CNB), introducing risks of thrombotic events and diagnostic delay. OBJECTIVE. The purpose of this article was to compare the frequency of postbiopsy bleeding events among patients without AT use, patients temporarily discontinuing AT therapy, and patients maintaining AT therapy during breast CNB. METHODS. This retrospective study included 5302 patients (median age, 52 years) who underwent image-guided breast or axillary CNB between January 1, 2014, and December 31, 2019. From January 1, 2014, to December 31, 2016, patients temporarily discontinued all AT therapy for 5 days before CNB; from January 1, 2017, to December 31, 2019, patients maintained AT therapy during CNB. Immediate postbiopsy mammograms were reviewed for imaging-apparent hematoma. Patients were called 24-48 hours after biopsy and asked regarding palpable hematoma and breast bruise. The EMR was reviewed for clinically significant postbiopsy hematoma (i.e., hematoma requiring drainage, primary care or emergency department visit for persistent symptoms, or hospital admission). Bleeding events were compared among groups, including Firth bias-reduced multivariable logistic regression analysis. RESULTS. During CNB, 4665 patients were not receiving AT therapy, 423 temporarily discontinued AT therapy, and 214 maintained AT therapy. Imaging-apparent hematoma occurred in 3% of patients without AT use, 6% of patients discontinuing AT therapy, and 7% of patients maintaining AT therapy (p = .60 [discontinuing vs maintaining]). Palpable hematoma occurred in 2% of patients without AT use, 4% of patients maintaining AT therapy, and 4% of patients discontinuing AT therapy (p = .92 [discontinuing vs maintaining]). Breast bruise occurred in 2% of patients without AT use, 1% of patients discontinuing AT therapy, and 6% of patients maintaining AT therapy (p < .001 [discontinuing vs maintaining]). In multivariable analysis adjusting for age, biopsy imaging modality, needle gauge, number of biopsy samples, and pathologic result, discontinued AT therapy (using maintained AT therapy as reference) was not a significant independent predictor of imaging-apparent hematoma (p = .23) or palpable hematoma (p = .91) but independently predicted decreased risk of bruise (OR = 0.11, p < .001). No patient developed clinically significant postbiopsy hematoma. CONCLUSION. Frequencies of imaging-apparent and palpable hematoma were not significantly different between patients temporarily discontinuing versus maintaining AT therapy. CLINICAL IMPACT. The findings support the safety of continuing AT therapy during CNB. Patients who maintain AT therapy should be counseled regarding risk of bruise.

Axillary Lymphadenopathy After a COVID-19 Vaccine Booster Dose: Time to Resolution on Ultrasound Follow-Up and Associated Factors.

BACKGROUND. Because administration of booster doses of COVID-19 vaccines is ongoing, radiologists are continuing to encounter COVID-19 vaccine-related axillary lymphadenopathy on imaging. OBJECTIVE. The purposes of this study were to assess time to resolution of COVID-19 vaccine-related axillary lymphadenopathy identified on breast ultrasound after administration of a booster dose and to assess factors potentially associated with time to resolution. METHODS. This retrospective single-institution study included 54 patients (mean age, 57 years) with unilateral axillary lymphadenopathy ipsilateral to the site of injection of a booster dose of messenger RNA COVID-19 vaccine visualized on ultrasound (whether an initial breast imaging examination or follow-up to prior screening or diagnostic breast imaging) performed between September 1, 2021, and December 31, 2022, and who underwent follow-up ultrasound examinations until resolution of lymphadenopathy. Patient information was extracted from the EMR. Univariable and multivariable linear regression analyses were used to identify predictors of time to resolution. Time to resolution was compared with that in a previously described sample of 64 patients from the study institution that was used to evaluate time to resolution of axillary lymphadenopathy after the initial vaccination series. RESULTS. Six of the 54 patients had a history of breast cancer, and two had symptoms related to axillary lymphadenopathy (axillary pain in both patients). Among the 54 initial ultrasound examinations showing lymphadenopathy, 33 were screening examinations and 21 were diagnostic examinations. Lymphadenopathy had resolved a mean of 102 ± 56 (SD) days after administration of the booster dose and 84 ± 49 days after the initial ultrasound showing lymphadenopathy. Age, vaccine booster type (Moderna vs Pfizer-BioNTech), and history of breast cancer were not significantly associated with time to resolution in univariable or multivariable analyses (all p > .05). Time to resolution after administration of a booster dose was significantly shorter than time to resolution after administration of the first dose in the initial series (mean, 129 ± 37 days) (p = .01). CONCLUSION. Axillary lymphadenopathy after administration of a COVID-19 vaccine booster dose has a mean time to resolution of 102 days, shorter than the time to resolution after the initial vaccination series. CLINICAL IMPACT. The time to resolution after administration of a booster dose supports the current recommendation for a follow-up interval of at least 12 weeks when vaccine-related lymphadenopathy is suspected.

Transient ipsilateral breast edema following COVID-19 vaccination.

While ipsilateral lymphadenopathy following COVID-19 vaccination is a relatively common finding on mammography and breast ultrasound transient ipsilateral breast edema is rare with only a few published case reports. Radiologists should be aware of this potential imaging appearance of the breast and axilla following COVID-19 vaccination given the imaging features of edema such as trabecular thickening, skin thickening, and increased echogenicity can overlap with benign and malignant breast conditions such as mastitis and inflammatory breast cancer. We describe a case of transient ipsilateral breast edema after COVID-19 vaccination followed by a discussion summarizing the current understanding and management of transient ipsilateral breast edema following COVID-19 vaccination.

Time for Resolution of COVID-19 Vaccine-Related Axillary Lymphadenopathy and Associated Factors.

BACKGROUND. The variable clinical course of subclinical lymphadenopathy detected on breast imaging after COVID-19 vaccination creates management challenges and has led to evolving practice recommendations. OBJECTIVE. The purpose of this study was to assess the duration of axillary lymphadenopathy ipsilateral to COVID-19 vaccination detected by breast imaging and to assess factors associated with the time until resolution. METHODS. This retrospective single-center study included 111 patients (mean age, 52 ± 12 years) with unilateral axillary lymphadenopathy ipsilateral to mRNA COVID-19 vaccine administration performed within the prior 8 weeks that was detected on breast ultrasound performed between January 1, 2021, and October 1, 2021, and who underwent follow-up ultrasound examinations at 4- to 12-week intervals until resolution of the lymphadenopathy. Patient information was extracted from medical records. Cortical thickness of the largest axillary lymph node on ultrasound was retrospectively measured and was considered enlarged when greater than 3 mm. Multivariable linear regression analysis was used to identify independent predictors of time until resolution. RESULTS. The mean cortical thickness at the initial ultrasound examination was 4.7 ± 1.2 mm. The lymphadenopathy resolved a mean of 97 ± 44 days after the initial ultrasound examination, 127 ± 43 days after the first vaccine dose, and 2.4 ± 0.6 follow-up ultrasound examinations. A significant independent predictor of shorter time to resolution was Pfizer-BioNTech (rather than Moderna) vaccination (ß = -18.0 [95% CI, -34.3 to -1.7]; p = .03]. Significant independent predictors of longer time to resolution were receipt of the second dose after the initial ultrasound examination (ß = 19.2 [95% CI, 3.1-35.2]; p = .02) and greater cortical thickness at the initial ultrasound examination (ß = 8.0 [95% CI, 1.5-14.5]; p = .02). Patient age, history of breast cancer, and axillary symptoms were not significantly associated with time to resolution (all p > .05). CONCLUSION. Axillary lymphadenopathy detected with breast ultrasound after COVID-19 mRNA vaccination lasts longer than reported in initial vaccine clinical trials. CLINICAL IMPACT. The prolonged time to resolution supports not delaying screening mammography because of recent COVID-19 vaccination. It also supports the professional society recommendation of a follow-up interval of at least 12 weeks when vaccine-related lymphadenopathy is suspected.

Breast Imaging for Transgender Individuals: Assessment of Current Practice and Needs.

PURPOSE: The aim of this study was to investigate breast radiologists' practices related to recording sex and gender in the electronic medical record, knowledge and attitudes about breast cancer screening recommendations for transgender individuals, and experience and willingness to enter screening mammography data from transgender patients into databases that document service provision and outcomes of cancer detection protocols. METHODS: A 19-question anonymous survey was distributed by e-mail to all active physician members of the Society of Breast Imaging. Response characteristics were assessed as frequencies and percentages and compared between groups using the Fisher exact test or χ2 test. The degree of agreement between questions was assessed using the McNemar test. RESULTS: Four hundred one radiologists across the United States and Canada responded (response rate 18%). Recording birth-assigned sex distinct from gender identity was reported by 44 of 352 respondents (13%). Depending on geographic region, 38% to 62% of breast radiologists followed screening guidelines for transgender women, and 226 of 349 (65%) did not provide screening recommendations for transgender men. Of 400, 324 (81%) believed that the evidence base for screening transgender individuals is incomplete, and 247 of 352 (70%) were either unsure of or had no Lesbian, Gay, Bisexual, Transgender, Queer competency training. A majority (247 of 401 [62%]) of respondents reported that they would enroll transgender patients in existing or novel national databases. CONCLUSIONS: In the practice of breast imaging, there is a substantial need to record transgender and other gender-nonconforming information. Breast radiologists differ in their practice and knowledge regarding screening of transgender women and men but expressed interest in contributing data to facilitate longitudinal databases needed to inform cancer screening guidelines.

Variations and Challenges to Performing Outside Study Interpretations in Breast Imaging: A National Survey of the Society of Breast Imaging Membership.

OBJECTIVE: Second-opinion interpretations of outside facility breast imaging provide value-added care but are operationally challenging for breast radiologists. Our objective was to survey members of the Society of Breast Imaging (SBI) to assess practice patterns and perceived barriers to performing outside study interpretations (OSIs). METHODS: An anonymous survey was developed by the Patient Care and Delivery Committee of the SBI and distributed via e-mail to SBI radiologist members. Survey questions included practice demographics and OSI volumes, billing practices, clinical scenarios, and imaging modalities, logistics, and barriers. Responses were aggregated and comparisons were made by univariate analysis using likelihood ratio tests, t-tests, and Spearman's rank correlation tests as appropriate. Ordinal or nominal logistic modeling and linear regression modeling was also performed. RESULTS: There were 371 responses (response rate of 13%). Most respondents practice at an affiliated specialty breast care center (306/371, 83%) and said their practice performed OSIs (256/371, 69%). Academic practices reported the highest OSI volumes (median 75 per month) and were most likely to indicate increases in OSI volumes over time (100/144, 69%). The most common indication for OSI was second opinion for a biopsy recommendation (245/256, 96%). Most practices provide a final BI-RADS assessment (183/261, 70%). The most cited barrier to performing OSIs was physician time constraints (252/369, 68%). CONCLUSION: Breast imaging OSI practice patterns are variable among SBI members with notable differences by practice setting and multiple barriers identified. More unified guidelines and recommendations may be needed for radiologists to better perform this valuable task.

Bleeding Complications After Breast Core-needle Biopsy-An Approach to Managing Patients on Antithrombotic Therapy.

Image-guided core-needle breast and axillary biopsy (CNB) is the standard-of-care procedure for the diagnosis of breast cancer. Although the risks of CNB are low, the most common complications include bleeding and hematoma formation. Post-procedural bleeding is of particular concern in patients taking antithrombotic therapy, but there is currently no widely established standard protocol in the United States to guide antithrombotic therapy management. In the face of an increasing number of patients taking antithrombotic therapy and with the advent of novel classes of anticoagulants, the American College of Radiology guidelines recommend that radiologists consider cessation of antithrombotic therapy prior to CNB on a case-by-case basis. Lack of consensus results in disparate approaches to patients on antithrombotic therapy undergoing CNB. There is further heterogeneity in recommendations for cessation of antithrombotic therapy based on the modality used for image-guided biopsy, target location, number of simultaneous biopsies, and type of antithrombotic agent. A review of the available data demonstrates the safety of continuing antithrombotic therapy during CNB while highlighting additional procedural and target lesion factors that may increase the risk of bleeding. Risk stratification of patients undergoing breast interventional procedures is proposed to guide both pre-procedural decision-making and post-procedural management. Radiologists should be aware of antithrombotic agent pharmacokinetics and strategies to minimize post-procedural bleeding to safely manage patients.

Mode of detection matters: Differences in screen-detected versus symptomatic breast cancers.

OBJECTIVE: Although extensive analyses evaluating screening mammography for breast cancer have been published, some utilized databases do not distinguish between modes of detection, which confounds the conclusions made about the impact of screening mammography. METHODS: A retrospective cohort study of women at our institution with pathologically-proven breast cancer from January 2015 to April 2018 was conducted. Subjects were categorized by their mode of diagnosis: screening or non-screening. Patient demographics, tumor characteristics, and treatments were compared between detection methods using Wilcoxon rank-sum test for continuous variables and chi-squared or Fisher's exact test. RESULTS: 1026 breast cancers were analyzed. 80.8% of screen-detected breast cancers were invasive. Compared to symptomatically detected cancers, screen-detected were smaller (median size 8 mm vs. 15 mm, p < 0.001), less invasive (80.8% vs. 94.3), had a lower pathologic grade (29% grade 3 vs. 45.7%, p < 0.001), a lower clinical stage, and less aggressive histology (51.9% low Ki67 vs. 30.5%, and 88.2% HER2 negative vs. 76.6%, p < 0.001). Screen-detected cancers were less likely to have extramammary disease (13.2% positive lymph nodes vs. 34.0% and 0.4% distant metastases vs. 6.9%, p < 0.001). Women with screen-detected cancers were more likely to undergo conservative treatment (74.8% underwent lumpectomy vs. 59.9%, and 80.0% received no chemotherapy vs. 51.3%, p < 0.001). CONCLUSION: In this study, while the vast majority of screen-detected cancers were invasive, they were more likely to be smaller, less aggressive, and a lower pathologic grade and clinical stage. Furthermore, women with screen-detected cancers were less likely to have extramammary disease and more likely to undergo conservative treatment.

Unilateral axillary adenopathy in the setting of COVID-19 vaccine: Follow-up.

With the Pfizer-BioNTech, Moderna, and now Johnson and Johnson COVID-19 vaccines readily available to the general population, the appearance of vaccine-induced axillary adenopathy on imaging has become more prevalent. We are presenting follow up to the first reported four cases of vaccine induced unilateral axillary adenopathy on imaging to our knowledge, which demonstrate expected self-resolving adenopathy. Our hope is that by providing this follow-up and reviewing current management guidelines, clinicians as well as patients will appreciate that this is an expected, benign, and self-resolving finding. In addition, we hope to quell any vaccine hesitancy brought about by recent mainstream media attention to this topic and ultimately empower patients to receive both the COVID-19 vaccine and undergo routine screening mammography, as both are vital to their health.

Merkel cell carcinoma of the breast: A case report.

Merkel cell carcinoma (MCC) of the breast is a very rare and aggressive type of neuroendocrine carcinoma of the breast (NECB) that typically occurs in older and immunocompromised individuals often presenting as a large palpable mass (Albright et al., 20181). Imaging features of MCC are similar to other NECBs, typically appearing as an oval circumscribed mass on mammography and as an irregular mass with increased vascularity on sonography (Jeon et al., 20142). While both MCC and primary NECB demonstrate positive immunostaining for synaptophysin, obtaining immunohistochemical stains for specific markers, such as CK7 and CK20 is imperative to confirm the diagnosis of MCC (Albright et al., 20181). We present a case of a 57-year-old female patient with no personal or family history of breast cancer, who presented for evaluation of a palpable abnormality in her left breast. Initial diagnostic mammogram demonstrated a circumscribed mass in the upper outer quadrant of the left breast corresponding to the palpable area of concern, which correlated to an irregular mass with increased vascularity on targeted ultrasound, similar to other NECBs. Pathologic results after tissue sampling yielded poorly differentiated primary NECB. Following neoadjuvant chemotherapy, the patient underwent a lumpectomy and further immunohistochemical stains of the lumpectomy specimen demonstrated diffusely positive synaptophysin, negative CK7, and positive CK20, consistent with MCC of the breast.

Breast cancer in women under age 40: A decade of trend analysis at a single institution.

BACKGROUND: Women should be evaluated for breast cancer risk by age 30 to assess for screening need. Recent trends in breast cancer in this population may further inform recommendations. OBJECTIVE: The aim of this study was to analyze trends over time in the rate of breast cancer, tumor characteristics and treatment in women under age 40. METHODS: Retrospective cohort study of women under age 40 at our institution diagnosed with breast cancer from January 2007 to April 2018 was conducted. Patient demographics, tumor characteristics and treatment outcomes were collected. Descriptive statistics and the Mann-Kendell Trend test were calculated. Two-proportion z-tests were used to compare proportions of stage, pathology and treatment between 2007-2013 and 2014-2018. RESULTS: 197 women under age 40 were treated for a new diagnosis of breast cancer at our institution. A higher proportion of women were diagnosed with invasive carcinoma in 2013-2018 (91%) compared to 2007-2012 (78%), p = 0.008. A higher proportion of women were diagnosed with advanced stage disease (stage III-IV) in 2013-2018 (24%) compared to 2007-2012 (2%), p = 0.001. No statistically significant evidence for an increasing trend of overall rate of breast cancer over the last 11 years (p = 0.419) was observed. CONCLUSIONS: While no statistically significant increase in overall rate of breast cancer was noted, an increase in invasive and later staged breast cancers was observed. CLINICAL IMPACT: Rise in more aggressive cancers in a population that is largely not screened may have implications both on the individual young woman's morbidity as well as on a public health level.