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Early detection of breast cancer from regular screening substantially reduces breast cancer mortality and morbidity. Multiple different imaging modalities may be used to screen for breast cancer. Screening recommendations differ based on an individual's risk of developing breast cancer. Numerous factors contribute to breast cancer risk, which is frequently divided into three major categories: average, intermediate, and high risk. For patients assigned female at birth with native breast tissue, mammography and digital breast tomosynthesis are the recommended method for breast cancer screening in all risk categories. In addition to the recommendation of mammography and digital breast tomosynthesis in high-risk patients, screening with breast MRI is recommended. 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.
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Humanos , Feminino , Neoplasias da Mama/diagnóstico por imagem , Detecção Precoce de Câncer , MamografiaRESUMO
Early detection of breast cancer from regular screening substantially reduces breast cancer mortality and morbidity. Multiple different imaging modalities may be used to screen for breast cancer. Screening recommendations differ based on an individual's risk of developing breast cancer. Numerous factors contribute to breast cancer risk, which is frequently divided into three major categories: average, intermediate, and high risk. For patients assigned female at birth with native breast tissue, mammography and digital breast tomosynthesis are the recommended method for breast cancer screening in all risk categories. In addition to the recommendation of mammography and digital breast tomosynthesis in high-risk patients, screening with breast MRI is recommended. 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.
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Neoplasias da Mama , Detecção Precoce de Câncer , Medicina Baseada em Evidências , Sociedades Médicas , Humanos , Neoplasias da Mama/diagnóstico por imagem , Feminino , Detecção Precoce de Câncer/métodos , Estados Unidos , Mamografia/normas , Mamografia/métodos , Medição de Risco , Programas de Rastreamento/métodosRESUMO
Purpose To determine whether time-dependent deep learning models can outperform single time point models in predicting preoperative upgrade of ductal carcinoma in situ (DCIS) to invasive malignancy at dynamic contrast-enhanced (DCE) breast MRI without a lesion segmentation prerequisite. Materials and Methods In this exploratory study, 154 cases of biopsy-proven DCIS (25 upgraded at surgery and 129 not upgraded) were selected consecutively from a retrospective cohort of preoperative DCE MRI in women with a mean age of 59 years at time of diagnosis from 2012 to 2022. Binary classification was implemented with convolutional neural network (CNN)-long short-term memory (LSTM) architectures benchmarked against traditional CNNs without manual segmentation of the lesions. Combinatorial performance analysis of ResNet50 versus VGG16-based models was performed with each contrast phase. Binary classification area under the receiver operating characteristic curve (AUC) was reported. Results VGG16-based models consistently provided better holdout test AUCs than did ResNet50 in CNN and CNN-LSTM studies (multiphase test AUC, 0.67 vs 0.59, respectively, for CNN models [P = .04] and 0.73 vs 0.62 for CNN-LSTM models [P = .008]). The time-dependent model (CNN-LSTM) provided a better multiphase test AUC over single time point (CNN) models (0.73 vs 0.67; P = .04). Conclusion Compared with single time point architectures, sequential deep learning algorithms using preoperative DCE MRI improved prediction of DCIS lesions upgraded to invasive malignancy without the need for lesion segmentation. Keywords: MRI, Dynamic Contrast-enhanced, Breast, Convolutional Neural Network (CNN) Supplemental material is available for this article. © RSNA, 2024.
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Neoplasias da Mama , Carcinoma Ductal de Mama , Carcinoma Intraductal não Infiltrante , Meios de Contraste , Aprendizado Profundo , Imageamento por Ressonância Magnética , Humanos , Feminino , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/patologia , Neoplasias da Mama/cirurgia , Pessoa de Meia-Idade , Imageamento por Ressonância Magnética/métodos , Estudos Retrospectivos , Carcinoma Intraductal não Infiltrante/diagnóstico por imagem , Carcinoma Intraductal não Infiltrante/patologia , Carcinoma Intraductal não Infiltrante/cirurgia , Carcinoma Ductal de Mama/diagnóstico por imagem , Carcinoma Ductal de Mama/patologia , Carcinoma Ductal de Mama/cirurgia , Idoso , Adulto , Valor Preditivo dos Testes , Interpretação de Imagem Assistida por Computador/métodos , Mama/diagnóstico por imagem , Mama/patologia , Mama/cirurgiaRESUMO
The goal of screening is to detect breast cancers when still curable to decrease breast cancer-specific mortality. Breast cancer screening in the United States is routinely performed with digital mammography and digital breast tomosynthesis. This article reviews breast cancer doubling time by tumor subtype and examines the impact of doubling time on breast cancer screening intervals. By the article's end, the reader will be better equipped to have informed discussions with patients and medical professionals regarding the benefits and disadvantages of the currently recommended screening mammography intervals.
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Neoplasias da Mama , Detecção Precoce de Câncer , Mamografia , Humanos , Neoplasias da Mama/diagnóstico por imagem , Mamografia/métodos , Feminino , Detecção Precoce de Câncer/métodos , Fatores de Tempo , Programas de Rastreamento/métodos , Mama/diagnóstico por imagemRESUMO
This document discusses the appropriate initial imaging in both asymptomatic and symptomatic patients with breast implants. For asymptomatic patients with saline implants, no imaging is recommended. If concern for rupture exists, ultrasound is usually appropriate though saline rupture is often clinically evident. The FDA recently recommended patients have an initial ultrasound or MRI examination 5 to 6 years after initial silicone implant surgery and then every 2 to 3 years thereafter. In a patient with unexplained axillary adenopathy with current or prior silicone breast implants, ultrasound and/or mammography are usually appropriate, depending on age. In a patient with concern for silicone implant rupture, ultrasound or MRI without contrast is usually appropriate. In the setting of a patient with breast implants and possible implant-associated anaplastic large cell lymphoma, ultrasound is usually appropriate as the initial imaging. 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.
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Implantes de Mama , Humanos , Implantes de Mama/efeitos adversos , Medicina Baseada em Evidências , Mamografia , Silicones , Sociedades Médicas , Estados UnidosRESUMO
The NCCN Guidelines for Breast Cancer Screening and Diagnosis provide health care providers with a practical, consistent framework for screening and evaluating a spectrum of clinical presentations and breast lesions. The NCCN Breast Cancer Screening and Diagnosis Panel is composed of a multidisciplinary team of experts in the field, including representation from medical oncology, gynecologic oncology, surgical oncology, internal medicine, family practice, preventive medicine, pathology, diagnostic and interventional radiology, as well as patient advocacy. The NCCN Breast Cancer Screening and Diagnosis Panel meets at least annually to review emerging data and comments from reviewers within their institutions to guide updates to existing recommendations. These NCCN Guidelines Insights summarize the panel's decision-making and discussion surrounding the most recent updates to the guideline's screening recommendations.
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Neoplasias da Mama , Detecção Precoce de Câncer , Humanos , Feminino , Neoplasias da Mama/diagnóstico , Medicina de Família e Comunidade , Pessoal de Saúde , OncologiaRESUMO
BACKGROUND: Annual screening breast MRI is recommended for women at high (≥ 20% lifetime) breast cancer risk, but is underutilized. Guided by the Health Services Utilization Model (HSUM), we assessed factors associated with screening breast MRI among high-risk women. METHODS: From August 2020-January 2021, we recruited an online convenience sample of high-risk women ages 25-85 (N = 232). High-risk was defined as: pathogenic genetic mutation in self or first-degree relative; history of lobular carcinoma in situ; history of thoracic radiation; or estimated lifetime risk ≥ 20%. Participants self-reported predisposing factors (breast cancer knowledge, health locus of control), enabling factors (health insurance type, social support), need factors (perceived risk, screening-supportive social norms, provider recommendation), and prior receipt of screening breast MRI. Multivariable logistic regression analysis with backward selection identified HSUM factors associated with receipt of screening breast MRI. RESULTS: About half (51%) of participants had received a provider recommendation for screening breast MRI; only 32% had ever received a breast MRI. Breast cancer knowledge (OR = 1.15, 95% CI = 1.04-1.27) and screening-supportive social norms (OR = 2.21, 95% CI = 1.64-2.97) were positively related to breast MRI receipt. No other HSUM variables were associated with breast MRI receipt (all p's > 0.1). CONCLUSIONS: High-risk women reported low uptake of screening breast MRI, indicating a gap in guideline-concordant care. Breast cancer knowledge and screening-supportive social norms are two key areas to target in future interventions. Data were collected during the COVID-19 pandemic and generalizability of results is unclear. Future studies with larger, more heterogeneous samples are needed to replicate these findings.
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Neoplasias da Mama , COVID-19 , Feminino , Humanos , Detecção Precoce de Câncer , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/epidemiologia , Autorrelato , Pandemias , Imageamento por Ressonância MagnéticaRESUMO
Objective: Given variability in how practices manage patients on antithrombotic medications, we undertook this study to understand the current practice of antithrombotic management for patients undergoing percutaneous breast and axillary procedures. Methods: A 20-item survey with multiple-choice and write-in options was emailed to 2094 active North American members of the Society of Breast Imaging (SBI) in March 2021. Data were collected anonymously and analyzed quantitatively, with free-text responses categorized by themes. Results: Three-hundred twenty-six of 2094 members (15.6%) completed the survey. Eighty-seven percent (274/313) reported having a policy for managing antithrombotic medications. Fifty-nine percent (185/312) reported routinely withholding medications before biopsy, more commonly in the Northeast and South (Pâ =â 0.08). Withholding of medications did not vary by lesion location (182/308, 59%, breast vs 181/308, 58.7%, axillary; Pâ =â 0.81). Respondents were statistically more likely to withhold medications if using a vacuum-assisted device for all classes of antithrombotic medications (Pâ <â 0.001). Up to 50.2% (100/199) on warfarin and 33.6% (66/196) on direct oral anticoagulants had medications withheld more stringently than guidelines suggest. Conclusion: Based on a survey of SBI members, breast imaging practices vary widely in antithrombotic management for image-guided breast and axillary procedures. Of the 60% who withhold antithrombotic medications, a minority comply with recommended withhold guidelines, placing at least some patients at potential risk for thrombotic events. Breast imaging radiologists should weigh the risks and benefits of withholding these medications, and if they elect to withhold should closely follow evidence-based guidelines to minimize the risks of this practice.
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Palpable masses in women are the most common symptom associated with breast cancer. This document reviews and evaluates the current evidence for imaging recommendations of palpable masses in women less than 30 to over 40 years of age. There is also a review of several different scenarios and recommendations after initial imaging. Ultrasound is usually the appropriate initial imaging for women under 30 years of age. If ultrasound findings are suspicious or highly suggestive of malignancy (BIRADS 4 or 5), it is usually appropriate to continue with diagnostic tomosynthesis or mammography with image-guided biopsy. No further imaging is recommended if the ultrasound is benign or negative. The patient under 30 years of age with a probably benign ultrasound may undergo further imaging; however, the clinical scenario plays a role in the decision to biopsy. For women between 30 to 39 years of age, ultrasound, diagnostic mammography, tomosynthesis, and ultrasound are usually appropriate. Diagnostic mammography and tomosynthesis are the appropriate initial imaging for women 40 years of age or older, as ultrasound may be appropriate if the patient had a negative mammogram within 6 months of presentation or immediately after mammography findings are suspicious or highly suggestive of malignancy. If the diagnostic mammogram, tomosynthesis, and ultrasound findings are probably benign, no further imaging is necessary unless the clinical scenario indicates a biopsy. 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.
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Neoplasias da Mama , Sociedades Médicas , Humanos , Feminino , Estados Unidos , Adulto , Pessoa de Meia-Idade , Lactente , Medicina Baseada em Evidências , Mamografia , Neoplasias da Mama/diagnóstico por imagemRESUMO
Talimogene laherparepvec (T-VEC) is an oncolytic virus hypothesized to enhance triple-negative breast cancer (TNBC) responses to neoadjuvant chemotherapy (NAC). This article describes the phase 2 trial of T-VEC plus NAC (ClinicalTrials.gov ID: NCT02779855 ). Patients with stage 2-3 TNBC received five intratumoral T-VEC injections with paclitaxel followed by doxorubicin and cyclophosphamide and surgery to assess residual cancer burden index (RCB). The primary end point was RCB0 rate. Secondary end points were RCB0-1 rate, recurrence rate, toxicity and immune correlates. Thirty-seven patients were evaluated. Common T-VEC toxicities were fevers, chills, headache, fatigue and injection site pain. NAC toxicities were as expected. Four thromboembolic events occurred. The primary end point was met with an estimated RCB0 rate = 45.9% and RCB0-1 descriptive rate = 65%. The 2-year disease-free rate is equal to 89% with no recurrences in RCB0-1 patients. Immune activation during treatment correlated with response. T-VEC plus NAC in TNBC may increase RCB0-1 rates. These results support continued investigation of T-VEC plus NAC for TNBC.
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Melanoma , Terapia Viral Oncolítica , Neoplasias de Mama Triplo Negativas , Humanos , Terapia Viral Oncolítica/métodos , Melanoma/patologia , Terapia Neoadjuvante , Neoplasias de Mama Triplo Negativas/patologiaAssuntos
Neoplasias da Mama , Humanos , Feminino , Mama , Imageamento por Ressonância Magnética , RadiografiaRESUMO
Breast cancer is the second leading cause of cancer mortality in adult women in the United States. Screening mammography reduces breast cancer mortality between 22% and 48%; however, screening mammography remains underutilized. Screening mammography utilization data are available from insurance claims, electronic medical records, and patient self-report via surveys, and each data source has unique benefits and challenges. Numerous barriers exist that adversely affect the use of screening mammography in the United States. This article will review screening mammography utilization in the United States, explore factors that impact utilization, and briefly discuss strategies to improve utilization.
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Neoplasias da Mama , Mamografia , Adulto , Estados Unidos/epidemiologia , Feminino , Humanos , Neoplasias da Mama/diagnóstico , Detecção Precoce de CâncerRESUMO
Given that 20% to 40% of women who have percutaneous breast biopsy subsequently undergo breast surgery, knowledge of imaging women with a history of benign (including high-risk) disease or breast cancer is important. For women who had surgery for nonmalignant pathology, the surveillance recommendations are determined by their overall risk. Higher-than-average risk women with a history of benign surgery may require screening mammography starting at an earlier age before 40 and may benefit from screening MRI. For women with breast cancer who have undergone initial excision and have positive margins, imaging with diagnostic mammography or MRI can sometimes guide additional surgical planning. Women who have completed breast conservation therapy for cancer should get annual mammography and may benefit from the addition of MRI or ultrasound to their surveillance regimen. The ACR 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 in which peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.
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Neoplasias da Mama , Mamografia , Feminino , Humanos , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/cirurgia , Neoplasias da Mama/patologia , Detecção Precoce de Câncer , Sociedades Médicas , Medicina Baseada em EvidênciasRESUMO
For women with genetic risk of breast cancer, the addition of screening breast MRI to mammography has become a standard. The order and interval of annual imaging can be variable among providers. To evaluate the clinical implications related to the timing, we conducted a chart review on a cohort of women (N = 276) with high-risk (BRCA1, BRCA2, CDH1, PTEN and TP53) and moderate high-risk (ATM and CHEK2) predisposition to breast cancer in a 48-month follow up. The estimated MRI detection rate in the entire group is 1.75% (18 per 1000 MRI tests). For the high-risk group, the estimated rate is 2.98% (30 per 1000 MRI tests). Many women discovered their genetic risk at an age much older (average age of the high-risk group was 48 years) than the age recommended to initiate enhanced screening (age 20 to 25 years). In total, 4 of the 11 primary breast cancers detected were identified by screening MRI within the first month after initial visit, which were not detected by previous mammography, suggesting the benefit of initiating MRI immediately after the discovery of genetic risk. Breast screening findings for women with Lynch syndrome and neurofibromatosis type 1 were also included in this report.
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Neoplasias da Mama , Adulto , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/genética , Detecção Precoce de Câncer/métodos , Feminino , Predisposição Genética para Doença , Humanos , Imageamento por Ressonância Magnética/métodos , Mamografia/métodos , Pessoa de Meia-Idade , Adulto JovemRESUMO
Objective: To quantitatively evaluate intratumoral habitats on dynamic contrast-enhanced (DCE) breast MRI to predict pathologic breast cancer response to stereotactic ablative body radiotherapy (SABR). Methods: Participants underwent SABR treatment (28.5 Gy x3), baseline and post-SABR MRI, and breast-conserving surgery for ER/PR+ HER2- breast cancer. MRI analysis was performed on DCE T1-weighted images. MRI voxels were assigned eight habitats based on high (H) or low (L) maximum enhancement and the sequentially numbered dynamic sequence of maximum enhancement (H1-4, L1-4). MRI response was analyzed by percent tumor volume remaining (%VR = volume post-SABR/volume pre-SABR), and percent habitat makeup (%HM of habitat X = habitat X voxels/total voxels in the segmented volume). These were correlated with percent tumor bed cellularity (%TC) for pathologic response. Results: Sixteen patients completed the trial. The %TC ranged 20%-80%. MRI %VR demonstrated strong correlations with %TC (Pearson R = 0.7-0.89). Pre-SABR tumor %HMs differed significantly from whole breasts (P = 0.005 to <0.00001). Post-SABR %HM of tumor habitat H4 demonstrated the largest change, increasing 13% (P = 0.039). Conversely, combined %HM for H1-3 decreased 17% (P = 0.006). This change correlated with %TC (P < 0.00001) and distinguished pathologic partial responders (≤70 %TC) from nonresponders with 94% accuracy, 93% sensitivity, 100% specificity, 100% positive predictive value, and 67% negative predictive value. Conclusion: In patients undergoing preoperative SABR treatment for ER/PR+ HER2- breast cancer, quantitative MRI habitat analysis of %VR and %HM change correlates with pathologic response.
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OBJECTIVE: This study evaluates breast MRI response of ER/PR+ HER2- breast tumors to pre-operative SABR with pathologic response correlation. METHODS: Women enrolled in a phase 2 single institution trial of SABR for ER/PR+ HER2- breast cancer were retrospectively evaluated for radiologic-pathologic correlation of tumor response. These patients underwent baseline breast MRI, SABR (28.5 Gy in 3 fractions), follow-up MRI 5 to 6 weeks post-SABR, and lumpectomy. Tumor size and BI-RADS descriptors on pre and post-SABR breast MRIs were compared to determine correlation with surgical specimen % tumor cellularity (%TC). Reported MRI tumor dimensions were used to calculate percent cubic volume remaining (%VR). Partial MRI response was defined as a BI-RADs descriptor change or %VR ≤ 70%, while partial pathologic response (pPR) was defined as %TC ≤ 70%. RESULTS: Nineteen patients completed the trial, and %TC ranged 10% to 80%. For BI-RADS descriptor analysis, 12 of 19 (63%) showed change in lesion or kinetic enhancement descriptors post-SABR. This was associated with lower %TC (29% vs. 47%, P = .042). BI-RADS descriptor change analysis also demonstrated high PPV (100%) and specificity (100%) for predicting pPR to treatment (sensitivity 71%, accuracy 74%), but low NPV (29%). MRI %VR demonstrated strong linear correlation with %TC (R = 0.70, P < .001, Pearson's Correlation) and high accuracy (89%) for predicting pPR (sensitivity 88%, specificity 100%, PPV 100%, and NPV 50%). CONCLUSION: Evaluating breast cancer response on MRI using %VR after pre-operative SABR treatment can help identify patients benefiting the most from neoadjuvant radiation treatment of their ER/PR+ HER2- tumors, a group in which pCR to neoadjuvant therapy is rare.
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Neoplasias da Mama/metabolismo , Neoplasias da Mama/radioterapia , Patologia Cirúrgica/métodos , Radioterapia de Intensidade Modulada/métodos , Receptor ErbB-2/metabolismo , Receptores de Estrogênio/metabolismo , Adulto , Idoso , Neoplasias da Mama/patologia , Feminino , Seguimentos , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Estudos RetrospectivosRESUMO
Breast cancer screening recommendations for transgender and gender nonconforming individuals are based on the sex assigned at birth, risk factors, and use of exogenous hormones. Insufficient evidence exists to determine whether transgender people undergoing hormone therapy have an overall lower, average, or higher risk of developing breast cancer compared to birth-sex controls. Furthermore, there are no longitudinal studies evaluating the efficacy of breast cancer screening in the transgender population. In the absence of definitive data, current evidence is based on data extrapolated from cisgender studies and a limited number of cohort studies and case reports published on the transgender community. 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 include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.
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Neoplasias da Mama , Pessoas Transgênero , Neoplasias da Mama/diagnóstico por imagem , Diagnóstico por Imagem , Detecção Precoce de Câncer , Feminino , Humanos , Recém-Nascido , Sociedades Médicas , Estados UnidosRESUMO
Background Suppression of background parenchymal enhancement (BPE) is commonly observed after neoadjuvant chemotherapy (NAC) at contrast-enhanced breast MRI. It was hypothesized that nonsuppressed BPE may be associated with inferior response to NAC. Purpose To investigate the relationship between lack of BPE suppression and pathologic response. Materials and Methods A retrospective review was performed for women with menopausal status data who were treated for breast cancer by one of 10 drug arms (standard NAC with or without experimental agents) between May 2010 and November 2016 in the Investigation of Serial Studies to Predict Your Therapeutic Response with Imaging and Molecular Analysis 2, or I-SPY 2 TRIAL (NCT01042379). Patients underwent MRI at four points: before treatment (T0), early treatment (T1), interregimen (T2), and before surgery (T3). BPE was quantitatively measured by using automated fibroglandular tissue segmentation. To test the hypothesis effectively, a subset of examinations with BPE with high-quality segmentation was selected. BPE change from T0 was defined as suppressed or nonsuppressed for each point. The Fisher exact test and the Z tests of proportions with Yates continuity correction were used to examine the relationship between BPE suppression and pathologic complete response (pCR) in hormone receptor (HR)-positive and HR-negative cohorts. Results A total of 3528 MRI scans from 882 patients (mean age, 48 years ± 10 [standard deviation]) were reviewed and the subset of patients with high-quality BPE segmentation was determined (T1, 433 patients; T2, 396 patients; T3, 380 patients). In the HR-positive cohort, an association between lack of BPE suppression and lower pCR rate was detected at T2 (nonsuppressed vs suppressed, 11.8% [six of 51] vs 28.9% [50 of 173]; difference, 17.1% [95% CI: 4.7, 29.5]; P = .02) and T3 (nonsuppressed vs suppressed, 5.3% [two of 38] vs 27.4% [48 of 175]; difference, 22.2% [95% CI: 10.9, 33.5]; P = .003). In the HR-negative cohort, patients with nonsuppressed BPE had lower estimated pCR rate at all points, but the P values for the association were all greater than .05. Conclusions In hormone receptor-positive breast cancer, lack of background parenchymal enhancement suppression may indicate inferior treatment response. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Philpotts in this issue.