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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Mass-conserving implicit–explicit methods for coupled compressible Navier–Stokes equations

Earth system models are composed of coupled components that separately model systems such as the global atmosphere, ocean, and land surface. While these components are well developed, coupling them in a single system can be a significant challenge. Computational efficiency, accuracy, and stability are principal concerns. In this study we focus on these issues. In particular, implicit–explicit (IMEX) tight and loose coupling strategies are explored for handling different time scales. For a simplified model for the air–sea interaction problem, we consider coupled compressible Navier–Stokes equations with an interface condition. Under the rigid-lid assumption, horizontal momentum and heat flux are exchanged through the interface. Several numerical experiments are presented to demonstrate the stability of the coupling schemes. Here, we show both numerically and theoretically that our IMEX coupling methods are mass conservative for a coupled compressible Navier–Stokes system with the rigid-lid condition

42 ENGINEERING↗
DOE OSTI2023

Toward implementation of carbon-conservation networks in nonmodel organisms

Decarboxylation — the release of carbon dioxide (CO 2 ) from a substrate — reduces the carbon yield of bioproduced chemicals. When overlaid onto central carbon metabolism, carbon-conservation networks (CCNs) that reroute flux around CO 2 release can theoretically achieve higher carbon yields for products derived from intermediates that traditionally require CO 2 release, such as acetyl-CoA. Recently, CCNs have started to be implemented in model organisms to produce compounds at higher carbon yields. However, implementation of CCNs in nonmodel hosts may have the greatest impact given their ability to assimilate a larger array of feedstocks, greater environmental tolerance, and unique biosynthetic pathways, ultimately enabling access to a wider range of products. Here, we review recent advances in CCNs with a focus on their application to nonmodel organisms. The differences in central carbon metabolism among different nonmodel hosts reveal opportunities to engineer and apply new CCNs.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Performance analysis and implementation details of the Energy Conserving Semi-Implicit Method code (ECsim)

We present in this work the implementation of the Energy Conserving Semi-Implicit Method in a parallel code called ECsim. This new code is a three-dimensional, fully electromagnetic particle in cell (PIC) code. It is written in C/C++ and uses MPI to allow massive parallelization. ECsim is unconditionally stable in time, eliminates the finite grid instability, and has the same cycle scheme as the explicit code with a computational cost comparable to other semi-implicit PIC codes. All these features make it a very valuable tool to address situations which have not been possible to analyze until now with other PIC codes. In this work, we show the details of the algorithm implementation and we study its performance in different systems. ECsim is compared with another semi-implicit PIC code with different time and spectral resolution, showing its ability to address situations where other codes fail.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

Multidisciplinary benchmarks of a conservative spectral solver for the nonlinear Boltzmann equation

The Boltzmann equation describes the evolution of the phase-space probability distribution of classical particles under binary collisions. Approximations to it underlie the basis for several scholarly fields, including aerodynamics and plasma physics. While these approximations are appropriate in their respective domains, they can be violated in niche but diverse applications which require direct numerical solution of the original nonlinear Boltzmann equation. An expanded implementation of the Galerkin–Petrov conservative spectral algorithm is employed to study a wide variety of physical problems. Enabled by distributed precomputation, solutions of the spatially homogeneous Boltzmann equation can be achieved in seconds on modern personal hardware, while spatially-inhomogeneous problems are solvable in minutes. Here, several benchmarks are presented focusing on accuracy compared to both analytic theoretical predictions and other Boltzmann solvers. These benchmarks span several physical domains including weakly ionized plasma, gaseous fluids, and atomic-plasma interaction.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2024

Conservative discontinuous Galerkin interpolation: Sheared boundary conditions

Local studies of accretion disks and laboratory magnetized plasmas employ analytical coordinate mappings that introduce sheared boundary conditions (BCs). Here, we present a discontinuous Galerkin (DG) algorithm to apply such BCs based on projections and quadrature-free integration. The procedure is high-order accurate, preserves moments exactly and works in multiple dimensions. Tests of increasing complexity are provided, beginning with translations of one and two dimensional fields, followed by 3D and 5D simulations with sheared (twist-shift) BCs. Results show that the algorithm is (p + 1)-order accurate in the DG representation and (p + 2) -order accurate in the cell averages, with p being the order of the polynomial basis. Quantification of the algorithm's hyperdiffusion and discussion of aliasing errors are given. This technique enables conservative local simulations of plasma turbulence with DG, not possible until now.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2017

Can environmental impact assessments alone conserve freshwater fish biota? Review of the Chilean experience

Chile was one of many countries that initiated environmental impact assessments in the 1990s, and has relied on their use for species conservation and territorial planning without the use of larger-scale environmental and ecological planning. The capacity of Chile's environmental impact assessment system (SEIA) to evaluate resident freshwater fishes and the potential impacts of water projects and aquaculture activities – two categories of projects that create direct threats to freshwater fishes – are assessed. Of the 3997 such submissions to the SEIA, only 0.6% conducted any freshwater fish assessment, and only 0.1% conducted any quantitative assessment of expected impacts from the associated project. The small number of assessments was characterized by poor study design, inconsistent sampling methodology, and species misidentification. Traditional assessments failed to include freshwater fish ecology in the general assessment framework. The new strategic environmental evaluation system only underscores the need for vastly improved field sampling protocols and assessment methodologies.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Society of Surgical Oncology–American Society for Radiation Oncology Consensus Guideline on Margins for Breast-Conserving Surgery With Whole-Breast Irradiation in Stages I and II Invasive Breast Cancer

Purpose: To convene a multidisciplinary panel of breast experts to examine the relationship between margin width and ipsilateral breast tumor recurrence (IBTR) and develop a guideline for defining adequate margins in the setting of breast conserving surgery and adjuvant radiation therapy. Methods and Materials: A multidisciplinary consensus panel used a meta-analysis of margin width and IBTR from a systematic review of 33 studies including 28,162 patients as the primary evidence base for consensus. Results: Positive margins (ink on invasive carcinoma or ductal carcinoma in situ) are associated with a 2-fold increase in the risk of IBTR compared with negative margins. This increased risk is not mitigated by favorable biology, endocrine therapy, or a radiation boost. More widely clear margins than no ink on tumor do not significantly decrease the rate of IBTR compared with no ink on tumor. There is no evidence that more widely clear margins reduce IBTR for young patients or for those with unfavorable biology, lobular cancers, or cancers with an extensive intraductal component. Conclusions: The use of no ink on tumor as the standard for an adequate margin in invasive cancer in the era of multidisciplinary therapy is associated with low rates of IBTR and has the potential to decrease re-excision rates, improve cosmetic outcomes, and decrease health care costs.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Outcomes of Low-Risk Ductal Carcinoma In Situ in Southeast Asian Women Treated With Breast Conservation Therapy

Purpose: To examine the outcomes of Southeast Asian (SEA) women with low-risk ductal carcinoma in situ (DCIS) treated with breast-conserving surgery (BCS) and adjuvant radiation therapy. Methods and Materials: Retrospective chart reviews of patients treated with BCS for DCIS from 1995 to 2011 were performed. Patients meeting the selection criteria from Eastern Cooperative Oncology Group 5194 were included. Most patients received adjuvant radiation therapy (RT) consisting of whole-breast RT delivered to 50 Gy followed by a 10-Gy boost to the tumor bed. Results: Of 744 patients with pathologic diagnosis of pure DCIS identified, 273 met the selection criteria: low-intermediate grade (LIG), n=219; high grade (HG), n=54. Median follow-up for these patients was 60 months. There were 8 ipsilateral breast tumor recurrences (IBTRs) in total, 7 of which were DCIS. The estimated actuarial IBTR rates at 5 and 10 years for the entire cohort are 1.8% and 4.3%, respectively. Of the 219 patients with LIG DCIS, 210 received RT and 9 did not. There were 7 IBTRs in LIG DCIS, 2 among the 9 patients who did not receive RT. The IBTR rates in LIG DCIS at 5 and 10 years are 2.3% and 4.2%, respectively. All patients with HG DCIS received RT. There was only 1 IBTR occurring beyond 5 years, giving an estimated IBTR rate of 4.5% at 10 years. Conclusions: SEA women with screen-detected DCIS have exceedingly low rates of IBTR after BCS, comparable to that observed in reports of similar patients with low-risk DCIS treated with adjuvant radiation.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Identification of Patients at Very Low Risk of Local Recurrence After Breast-Conserving Surgery

Purpose: To identify clinical and pathological factors that identify groups of women with stage I breast cancer with a 5-year risk of local recurrence (LR) ≤1.5% after breast-conserving therapy (BCS) plus whole-breast radiation therapy (RT). Methods and Materials: Study subjects were 5974 patients ≥50 years of age whose cancer was diagnosed between 1989 and 2006, and were referred with pT1 pN0 invasive breast cancer treated with BCS and RT. Cases of 5- and 10-year LR were examined using Kaplan-Meier methods. Recursive partitioning analysis was performed in patients treated with and without endocrine therapy to identify combinations of factors associated with a 5-year LR risk ≤1.5%. Results: The median follow-up was 8.61 years. Median age was 63 years of age (range, 50 to 91). Overall 5-year LR was 1.5% (95% confidence interval [CI], 1.2%-1.9%) and 10-year LR was 3.4% (95% CI, 2.8%-4.0%). Of 2830 patients treated with endocrine therapy, patient subsets identified with 5-year LR ≤1.5% included patients with grade 1 histology (n=1038; LR, 0.2%; 95% CI, 0%-0.5%) or grade 2 histology plus ≥60 years of age (n=843; LR, 0.5%; 95% CI, 0%-1.0%). Ten-year LR for these groups were 0.8% (95% CI, 0.1%-1.6%) and 0.9% (95% CI, 0.2%-1.6%), respectively. Of 3144 patients treated without endocrine therapy, patients with grade 1 histology plus clear margins had 5-year LR ≤1.5% (n=821; LR, 0.6%; 95% CI, 0.1%-1.2%). Ten-year LR for this group was 2.2% (95% CI, 1.0%-3.4%). Conclusions: Histologic grade, age, margin status, and use of endocrine therapy identified 45% of a population-based cohort of female patients over age 50 with stage I breast cancer with a 5-year LR risk ≤1.5% after BCS plus RT. Prospective study is needed to evaluate the safety of omitting RT in patients with such a low risk of LR.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Pattern of Ipsilateral Breast Tumor Recurrence After Breast-Conserving Therapy

Purpose: To analyze the incidence and prognostic factors of ipsilateral breast tumor recurrence (IBTR) after breast-conserving therapy (BCT) in a large, population-based, single-center study with long-term follow-up. Methods and Materials: We analyzed 3595 cases in which BCT was performed in 3824 women with stage I or II breast cancer. The incidence of IBTR was analyzed over time and was based on IBTR as first event. Results: The 15-year local relapse-free survival was 90.9%. The hazard estimates for IBTR showed a time course with 2 peaks, the first at approximately 5 years and the second, twice as high, at 12 years. Stratifying subjects by age and margin status showed that, for women ≤40 years old with negative margins, adjuvant systemic therapy led to a 5-fold reduced risk of recurrence compared to none, and the presence of lymph vascular space invasion (LVSI) had a 3-fold increased risk compared to its absence. For women >40 years old, the presence of LVSI (hazard ratio [HR] 2.5) and the presence of lobular carcinoma in situ in the lumpectomy specimen (HR 2.3) were the only 2 risk factors. Conclusions: We demonstrated a pattern in risk of IBTR over time, with 2 peaks, first at approximately 5 years and a second, much higher peak at approximately 12 years, especially for women ≤40 years old. For women ≤40 years old with tumor-free resection margins, we noted that the absence of adjuvant systemic therapy and the presence of LVSI were independent prognostic factors of IBTR. For women >40 years old, the presence of LVSI and the presence of lobular carcinoma in situ were independent risk factors.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Dosimetric Inhomogeneity Predicts for Long-Term Breast Pain After Breast-Conserving Therapy

Purpose: The objective of this cross-sectional study was to characterize long-term breast pain in patients undergoing breast-conserving surgery and radiation (BCT) and to identify predictors of this pain. Methods and Materials: We identified 355 eligible patients with Tis-T2N0M0 breast cancer who underwent BCT in 2007 to 2011, without recurrent disease. A questionnaire derived from the Late Effects Normal Tissue Task Force (LENT) Subjective, Objective, Management, Analytic (SOMA) scale was mailed with 7 items detailing the severity, frequency, duration, and impact of ipsilateral breast pain over the previous 2 weeks. A logistic regression model identified predictors of long-term breast pain based on questionnaire responses and patient, disease, and treatment characteristics. Results: The questionnaire response rate was 80% (n=285). One hundred thirty-five patients (47%) reported pain in the treated breast, with 19 (14%) having pain constantly or at least daily; 15 (11%) had intense pain. The pain interfered with daily activities in 11 patients (8%). Six patients (4%) took analgesics for breast pain. Fourteen (10%) thought that the pain affected their quality of life. On univariable analysis, volume of breast tissue treated to ≥105% of the prescribed dose (odds ratio [OR] 1.001 per cc, 95% confidence interval [CI] 1.000-1.002; P=.045), volume treated to ≥110% (OR 1.009 per cc, 95% CI 1.002-1.016; P=.012), hormone therapy use (OR 1.95, 95% CI 1.12-3.39; P=.02), and other sites of pain (OR 1.79, 95% CI 1.05-3.07; P=.03) predicted for long-term breast pain. On multivariable analysis, volume ≥110% (OR 1.01 per cc, 95% CI 1.003-1.017; P=.007), shorter time since treatment (OR 0.98 per month, 95% CI 0.96-0.998; P=.03), and hormone therapy (OR 1.84, 95% CI 1.05-3.25; P=.03) were independent predictors of pain. Conclusion: Long-term breast pain was common after BCT. Although nearly half of patients had pain, most considered it tolerable. Dosimetric inhomogeneity independently predicted for pain and should be minimized to the greatest extent possible.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Long-term Outcomes of Hypofractionation Versus Conventional Radiation Therapy After Breast-Conserving Surgery for Ductal Carcinoma In Situ of the Breast

Purpose: Whole-breast radiation therapy (XRT) after breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS) may decrease the risk of local recurrence, but the optimal dose regimen remains unclear. Past studies administered 50 Gy in 25 fractions (conventional); however, treatment pattern studies report that hypofractionated (HF) regimens (42.4 Gy in 16 fractions) are frequently used. We report the impact of HF (vs conventional) on the risk of local recurrence after BCS for DCIS. Methods and Materials: All women with DCIS treated with BCS and XRT in Ontario, Canada from 1994 to 2003 were identified. Treatment and outcomes were assessed through administrative databases and validated by chart review. Survival analyses were performed. To account for systematic differences between women treated with alternate regimens, we used a propensity score adjustment approach. Results: We identified 1609 women, of whom 971 (60%) received conventional regimens and 638 (40%) received HF. A total of 489 patients (30%) received a boost dose, of whom 143 (15%) received conventional radiation therapy and 346 (54%) received HF. The median follow-up time was 9.2 years. The median age at diagnosis was 56 years (interquartile range [IQR], 49-65 years). On univariate analyses, the 10-year actuarial local recurrence–free survival was 86% for conventional radiation therapy and 89% for HF (P=.03). On multivariable analyses, age <45 years (hazard ratio [HR] = 2.4; 95% CI: 1.6-3.4; P<.0001), high (HR=2.9; 95% CI: 1.2-7.3; P=.02) or intermediate nuclear grade (HR=2.7; 95% CI: 1.1-6.6; P=.04), and positive resection margins (HR=1.4; 95% CI: 1.0-2.1; P=.05) were associated with an increased risk of local recurrence. HF was not significantly associated with an increased risk of local recurrence compared with conventional radiation therapy on multivariate analysis (HR=0.8; 95% CI: 0.5-1.2; P=.34). Conclusions: The risk of local recurrence among individuals treated with HF regimens after BCS for DCIS was similar to that among individuals treated with conventional radiation therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

In the Modern Treatment Era, Is Breast Conservation Equivalent to Mastectomy in Women Younger Than 40 Years of Age? A Multi-Institution Study

Purpose: Mastectomy is often recommended for women ≤40 years of age with breast cancer, as young women were under-represented in the landmark trials comparing breast conservation therapy (BCT) to mastectomy. We hypothesized that, in the modern treatment era, BCT and mastectomy result in equivalent local control rates in young women. Methods and Materials: Breast cancer cases arising between 1975 and 2013 in women ≤40 years old were collected from the tumor registries of 2 large healthcare systems in Utah. Kaplan-Meier estimates and Cox proportional hazards models were used to analyze freedom from locoregional recurrence (FFLR), overall survival (OS), and relapse-free survival (RFS). Results: This analysis identified 853 BCT candidates. A comparison of BCT to mastectomy after 2000 showed FFLR, RFS, and OS were all similar. Rate for FFLR at 10 years was 94.9% versus 92.1% for BCT and mastectomy, respectively (P=.57). For women whose cancer was diagnosed after 2000, who received BCT, FFLR and RFS rates were improved compared to those whose cancer was diagnosed prior to 2000 (P<.05), whereas OS (P=.46) rates were similar. Among those who underwent mastectomy, FFLR, OS, and RFS were significantly improved (P<.05) with diagnosis after 2000. Conclusions: FFLR rates for young women, ≤40 years of age, have significantly improved for BCT and mastectomy over time. If patients were treated after 2000, BCT appears to be safe and equivalent to mastectomy at 10 years in terms of FFLR, OS, and RFS.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Survival After Conservative Management Versus External Beam Radiation Therapy in Elderly Patients With Localized Prostate Cancer

Purpose: To compare survival in elderly men with clinically localized prostate cancer (PCa) according to treatment type, defined as radiation therapy (RT) with or without androgen deprivation therapy (ADT) versus conservative management (observation). Methods and Materials: In the Surveillance, Epidemiology, and End Results (SEER)–Medicare linked database, we identified 23,790 patients aged 80 years or more with clinically localized PCa treated with either RT or observation between 1991 and 2009. Competing risks analyses focused on cancer-specific mortality and other-cause mortality, after accounting for confounders. All analyses were repeated after stratification according to grade (well-differentiated vs moderately differentiated vs poorly differentiated disease), race, and United States region, in patients with no comorbidities and in patients with at least 1 comorbidity. Analyses were repeated within most contemporary patients, namely those treated between 2001 and 2009. Results: Radiation therapy was associated with more favorable cancer-specific mortality rates than observation in patients with moderately differentiated disease (hazard ratio [HR] 0.79; 95% confidence interval [CI] 0.66-0.94; P=.009) and in patients with poorly differentiated disease (HR 0.58; 95% CI 0.49-0.69; P<.001). Conversely, the benefit of RT was not observed in well-differentiated disease. The benefit of RT was confirmed in black men (HR 0.54; 95% CI 0.35-0.83; P=.004), across all United States regions (all P≤.004), in the subgroups of the healthiest patients (HR 0.67; 95% CI 0.57-0.78; P<.001), in patients with at least 1 comorbidity (HR 0.69; 95% CI 0.56-0.83; P<.001), and in most contemporary patients (HR 0.55; 95% CI 0.46-0.66; P<.001). Conclusions: Radiation therapy seems to be associated with a reduction in the risk of death from PCa relative to observation in elderly patients with clinically localized PCa, except for those with well-differentiated disease.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Geographic Disparity in the Use of Hypofractionated Radiation Therapy Among Elderly Women Undergoing Breast Conservation for Invasive Breast Cancer

Purpose: To evaluate geographic heterogeneity in the delivery of hypofractionated radiation therapy (RT) for breast cancer among Medicare beneficiaries across the United States. Methods and Materials: We identified 190,193 patients from the Centers for Medicare and Medicaid Services Chronic Conditions Warehouse. The study included patients aged >65 years diagnosed with invasive breast cancer treated with breast conservation surgery followed by radiation diagnosed between 2000 and 2012. We analyzed data by hospital referral region based on patient residency ZIP code. The proportion of women who received hypofractionated RT within each region was analyzed over the study period. Multivariable logistic regression models identified predictors of hypofractionated RT. Results: Over the entire study period we found substantial geographic heterogeneity in the use of hypofractionated RT. The proportion of women receiving hypofractionated breast RT in individual hospital referral regions varied from 0% to 61%. We found no correlation between the use of hypofractionated RT and urban/rural setting or general geographic region. The proportion of hypofractionated RT increased in regions with higher density of radiation oncologists, as well as lower total Medicare reimbursements. Conclusions: This study demonstrates substantial geographic heterogeneity in the use of hypofractionated RT among elderly women with invasive breast cancer treated with lumpectomy in the United States. This heterogeneity persists despite clinical data from multiple randomized trials proving efficacy and safety compared with standard fractionation, and highlights possible inefficiency in health care delivery.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Timing of Radiation Therapy and Chemotherapy After Breast-Conserving Surgery for Node-Positive Breast Cancer: Long-Term Results From International Breast Cancer Study Group Trials VI and VII

Purpose: To update the previous report from 2 randomized clinical trials, now with a median follow-up of 16 years, to analyze the effect of radiation therapy timing on local failure and disease-free survival. Patients and Methods: From July 1986 to April 1993, International Breast Cancer Study Group trial VI randomly assigned 1475 pre-/perimenopausal women with node-positive breast cancer to receive 3 or 6 cycles of initial chemotherapy (CT). International Breast Cancer Study Group trial VII randomly assigned 1212 postmenopausal women with node-positive breast cancer to receive tamoxifen for 5 years, or tamoxifen for 5 years with 3 early cycles of initial CT. For patients who received breast-conserving surgery (BCS), radiation therapy (RT) was delayed until initial CT was completed; 4 or 7 months after BCS for trial VI and 2 or 4 months for trial VII. We compared RT timing groups among 433 patients on trial VI and 285 patients on trial VII who received BCS plus RT. Endpoints were local failure, regional/distant failure, and disease-free survival (DFS). Results: Among pre-/perimenopausal patients there were no significant differences in disease-related outcomes. The 15-year DFS was 48.2% in the group allocated 3 months initial CT and 44.9% in the group allocated 6 months initial CT (hazard ratio [HR] 1.12; 95% confidence interval [CI] 0.87-1.45). Among postmenopausal patients, the 15-year DFS was 46.1% in the no-initial-CT group and 43.3% in the group allocated 3 months initial CT (HR 1.11; 95% CI 0.82-1.51). Corresponding HRs for local failures were 0.94 (95% CI 0.61-1.46) in trial VI and 1.51 (95% CI 0.77-2.97) in trial VII. For regional/distant failures, the respective HRs were 1.15 (95% CI 0.80-1.63) and 1.08 (95% CI 0.69-1.68). Conclusions: This study confirms that, after more than 15 years of follow-up, it is reasonable to delay radiation therapy until after the completion of standard CT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Close Margins Less Than 2 mm Are Not Associated With Higher Risks of 10-Year Local Recurrence and Breast Cancer Mortality Compared With Negative Margins in Women Treated With Breast-Conserving Therapy

The 2014 Society of Surgical Oncology–American Society for Radiation Oncology consensus suggested “no ink on tumor” is a sufficient surgical margin for invasive breast cancer treated with breast-conserving surgery (BCS). Whether close margins <2 mm are associated with inferior outcomes remains controversial. This study evaluated 10-year outcomes by margin status in a population-based cohort treated with BCS and adjuvant radiation therapy (RT).

62 RADIOLOGY AND NUCLEAR MEDICINE↗