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Dive into the research topics where Shayna L. Showalter is active.

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Featured researches published by Shayna L. Showalter.


Breast Journal | 2017

Survival after Breast‐Conserving Surgery with Whole Breast or Partial Breast Irradiation in Women with Early Stage Breast Cancer: A SEER Data‐base Analysis

Surbhi Grover; Sommer Nurkic; Marie Diener-West; Shayna L. Showalter

Randomized clinical trials have demonstrated equivalency in survival outcomes for early stage breast cancer patients treated with either mastectomy or breast‐conserving surgery (BCS) with radiation. Recent, state‐level data confirm comparable survival outcomes. Using Surveillance Epidemiology and End Research (SEER) data, we sought to evaluate survival outcomes among patients with early stage breast cancer treated with mastectomy, BCS with whole breast irradiation (BCS + WBI), or BCS with accelerated partial breast irradiation (BCS + APBI). Data on women 50 years or older diagnosed with a node negative invasive breast cancer (≤3 cm in size) between 1995 and 2009 were extracted from the SEER data base. Women treated with mastectomy alone or BCS with radiation were eligible for analysis. Kaplan–Meier estimates and Cox proportional hazard models were used to compare overall survival (OS) and cancer‐specific survival (CSS) among the treatment groups. 150,171 women fulfilled inclusion criteria. OS was significantly improved among women treated with BCS and WBI or BCS and APBI compared to mastectomy alone. Adjusted hazard ratios for death in BCS with WBI or APBI (versus mastectomy alone) were 0.73 (95% CI: 0.71, 0.76) and 0.68 (95% CI: 0.58, 0.79), respectively. Adjusted CSS was also significantly improved in patients treated with BCS and WBI (HR 0.80, 95% CI: 0.76, 0.85) as compared to mastectomy. BCS with radiation (WBI or APBI) was associated with significantly improved OS and CSS, versus mastectomy alone. These results support the use of BCS with WBI or APBI (in well selected patients) for the treatment of breast cancer.


Brachytherapy | 2015

Intraoperative breast radiation therapy with image guidance: Findings from CT images obtained in a prospective trial of intraoperative high-dose-rate brachytherapy with CT on rails

Daniel M. Trifiletti; Timothy N. Showalter; Bruce Libby; David R. Brenin; Anneke T. Schroen; Kelli A. Reardon; Shayna L. Showalter

PURPOSE Intraoperative radiation therapy (IORT) is an increasingly popular approach to breast conserving therapy in the treatment of early-stage breast cancer. A drawback to IORT compared with postoperative adjuvant radiation therapy is that it is not performed using image guidance. Our aim was to report on how our institutions unique IORT workflow integrates CT image guidance and how these CT images were used intraoperatively to change applicator positioning. METHODS AND MATERIALS We retrospectively reviewed the first 29 patients who participated in a prospective clinical trial of breast IORT at our institution. All patients underwent lumpectomy, multicatheter balloon placement, intraoperative CT scan, and high-dose-rate brachytherapy treatment delivery to 12.5 Gy to 1 cm from the balloon surface. This report focuses on the intraoperative CT findings that led to clinical changes, followed by repeat CT for IORT treatment planning. RESULTS After initial intraoperative CT, 7 patients underwent an additional intraoperative CT scan (24.1%). In 6 patients, the initial intraoperative CT scan identified large air cavities and/or poor tissue conformity. This defect could be improved in all patients with adjustment of the balloon applicator before planning and delivering IORT. Intraoperative CT scan was used in one patient to localize a biopsy clip and aided in excision to negative margin. CONCLUSIONS In our study, intraoperative CT identifies actionable findings in breast IORT, including residual tumor or errors in applicator positioning, in almost 25% of patients. Clinical results of the described trial will serve to further validate this image-guided approach to IORT.


Journal of Medical Imaging and Radiation Oncology | 2018

Utility of CT imaging in a novel form of high-dose-rate intraoperative breast radiation therapy

Taryn E. Hassinger; Timothy N. Showalter; Anneke T. Schroen; David R. Brenin; Adam C. Berger; Bruce Libby; Shayna L. Showalter

Intraoperative radiation therapy (IORT) is an alternative to whole breast radiation following breast conserving surgery. Conventional breast IORT is limited by lack of cross‐sectional imaging. In response, our institution developed Precision Breast IORT (PB‐IORT) which utilizes intraoperative computed tomography (CT) images for confirmation of brachytherapy applicator placement and for treatment planning. The purpose of this study was to determine the utility of CT imaging in PB‐IORT in the first 103 patients treated in two prospective clinical trials.


Breast Journal | 2018

Impact of patient health literacy on surgical treatment of breast cancer

Jessica Keim-Malpass; Aubrey Doede; Fabian Camacho; Christine Kennedy; Shayna L. Showalter

Little is known about the role of low health literacy (LHL) among breast surgical oncology patients. We initiated a prospective health literacy assessment to determine the relationship between health literacy and surgical treatment. Among 512 patients, univariate analysis revealed no statistical significance in the relationship of health literacy to breast surgery type, contralateral prophylactic mastectomy, or reconstruction following mastectomy. In a multivariate analysis, women with LHL were less likely to undergo reconstruction (aOR 0.81, 95% CI 0.69‐0.94, P value = .006). Tailored interventions are needed to combat disparities in cancer treatment associated with LHL, with focus on reconstruction following mastectomy.


Brachytherapy | 2018

Comparison of heart dose in early-stage left-sided breast cancers treated with intraoperative radiation therapy or whole-breast irradiation with deep inspiratory breath hold

Clayton E. Alonso; Einsley Janowski; Bruce Libby; Shayna L. Showalter

PURPOSE To compare heart dose between patients treated with lumpectomy and either intraoperative radiation therapy (IORT) with CT-guided high-dose-rate brachytherapy (precision breast IORT [PB-IORT]) or whole-breast irradiation with deep inspiratory breath hold (WBI-DIBH) for early-stage left-sided breast cancers. METHODS AND MATERIALS We retrospectively identified the 17 patients with left-sided breast cancers treated with PB-IORT on a phase I clinical trial and 17 patients with left-sided tumors who had undergone lumpectomy and adjuvant WBI-DIBH. Dosimetric data were obtained. T-testing was performed and biologically effective doses (BEDs) were calculated using an α/β ratio of 2 Gy. RESULTS Mean heart dose was significantly lower with WBI-DIBH compared with PB-IORT (0.61 vs. 0.87 Gy, p = 0.006). Mean heart BED was lower with WBI-DIBH (0.62 vs. 1.3 Gy2, p = 0.0001). Nominal maximum heart dose was higher with WBI-DIBH (11.37 vs. 4.81 Gy, p = 0.004). Maximum heart dose BED was similar between WBI-DIBH and IORT, 16.63 vs. 19.36 Gy (p = 0.64), respectively. No difference was found in mean left anterior descending artery dose: 2.18 Gy with WBI-DIBH and 1.89 Gy with IORT (p = 0.446). The maximum left anterior descending doses were 9.63 Gy and 3.62 Gy with WBI-DIBH and IORT, respectively (p = 0.016). Distance from the heart to the lumpectomy cavity was inversely associated with heart dose for PB-IORT, but not for WBI-IORT. CONCLUSIONS Heart doses were low in both groups. Expected increase in cardiac risk at these doses is minimal. It is unlikely that there will be a clinically significant difference in cardiac toxicity in patients treated with WBI-DIBH or PB-IORT. Further research is needed to evaluate the actual clinical impact of the observed cardiac doses delivered with these modalities.


Clinical Breast Cancer | 2017

The Effect of Receptor Status on Mastectomy and Contralateral Prophylactic Mastectomy Rates in Early Stage Invasive Breast Carcinoma

Sunil W. Dutta; Daniel M. Trifiletti; Surbhi Grover; Kara D. Romano; Einsley-Marie Janowski; Shayna L. Showalter

Background: There is an established relationship between hormone receptor (HR; estrogen and/or progesterone receptors) status, HER2 status, and locoregional recurrence. The purpose of this study was to analyze how HR and HER2 receptor status have influenced the surgical management trends among patients with early stage breast cancer. Patients and Methods: The National Cancer Database was queried for patients with cT1 to cT3, cN0, and cM0 breast carcinoma from 2004 to 2012. Patients were grouped on the basis of receptor status and surgical management (mastectomy or breast‐conserving surgery [BCS]). Multivariable analyses were performed to investigate factors associated with increased odds of receiving mastectomy over BCS. Among a subgroup of patients who underwent ipsilateral mastectomy, analyses were performed to determine any association between contralateral prophylactic mastectomy (CPM) and receptor status. Results: We found 280,241 patients who met inclusion criteria for analyzing mastectomy or BCS surgical decision. Patients with HER2‐positive (HER2+) tumors (HR+/HER+ and HR−/HER2+) were the most likely to undergo mastectomy (odds ratio [OR], 1.212 and 1.499 respectively, compared with HR+/HER2− patients, each P < .001). HR status alone did not affect ipsilateral surgical management as patients with HR+/HER2− and HR−/HER2− tumors demonstrated similar mastectomy rates (P = .391). Among the 108,018 who underwent mastectomy, 20% underwent CPM. After adjustment, patients with HR+/HER2+, HR−/HER2+, and HR−/HER2− were all more likely to undergo CPM (OR 1.356, 1.608, and 1.358, respectively compared with HR+/HER2− patients, each P < .001). Conclusion: This analysis indicates that patients with early stage breast cancer are more likely to undergo a mastectomy and CPM if they have HER2+ tumors.


Clinical Journal of Oncology Nursing | 2014

Malignant Phyllodes Tumor of the Breast: A Case Study

Jessica Keim-Malpass; Anne M. Mills; Shayna L. Showalter

Malignant phyllodes tumors of the breast are rare, fast-growing tumors that can be difficult to diagnose. A case study is featured about a young adult patient who lacked insurance and received a delayed diagnosis of malignant phyllodes tumor of the breast. This article includes pertinent clinical and age-specific considerations for comprehensive management.


International Journal of Radiation Oncology Biology Physics | 2016

A Novel Form of Breast Intraoperative Radiation Therapy With CT-Guided High-Dose-Rate Brachytherapy: Results of a Prospective Phase 1 Clinical Trial.

Shayna L. Showalter; Gina R. Petroni; Daniel M. Trifiletti; Bruce Libby; Anneke T. Schroen; David R. Brenin; Parchayi Dalal; Mark E. Smolkin; Kelli A. Reardon; Timothy N. Showalter


Brachytherapy | 2014

Dosimetric comparison of 192Ir high-dose-rate brachytherapy vs. 50 kV x-rays as techniques for breast intraoperative radiation therapy: Conceptual development of image-guided intraoperative brachytherapy using a multilumen balloon applicator and in-room CT imaging

Ryan Jones; Bruce Libby; Shayna L. Showalter; David R. Brenin; David D. Wilson; Anneke T. Schroen; Monica M. Morris; Kelli A. Reardon; John Morrison; Timothy N. Showalter


International Journal of Radiation Oncology Biology Physics | 2018

Time-Driven Activity-Based Cost Analysis of CT-Guided Intraoperative High-Dose Rate Brachytherapy Versus Whole Breast Irradiation in the Treatment of Early Stage Breast Cancer

J. Sanders; Sunil W. Dutta; Bruce Libby; Constance Hodge; Timothy N. Showalter; Shayna L. Showalter; E.M. Janowski

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Bruce Libby

University of Virginia

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Surbhi Grover

University of Pennsylvania

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Gary M. Freedman

University of Pennsylvania

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