Keeney, Michael

ABSTRACT Purpose We studied histologic Ewing sarcoma (ES) tumor response at local control surgery to explore associations between histologic response and chemotherapy practice changes over time and confirm its prognostic significance in the modern era. Methods We reviewed clinical data for 126 patients with ES treated at Mayo Clinic from 1977 to 2022, analyzing the percentage necrosis as a prognostic factor across chemotherapy regimens (including modern interval‐compressed VDC‐IE). Results In the historical cohort, 5‐year event‐free survival (EFS) and overall survival (OS) for patients with ≤5% versus greater than 5% viable tumor were 76% versus 59% ( p = 0.01) and 83% versus 62% ( p = 0.01). Review of 104 specimens by two pathologists identified the percentage remaining viable tumor as more reproducible than the percentage necrosis and/or fibrosis. On multivariable analysis of patients with localized disease ( n = 87), pelvic tumors and greater than 5% viable tumor remained independent risk factors for poor survival (EFS: hazard ratio [HR] 3.1, p < 0.01; OS: HR 2.1, p = 0.048). The modern cohort consisted of 22 patients. No patients with tumor size less than 8 cm at diagnosis and 100% necrosis after surgery had events; four of seven with tumors greater than 8 cm had events despite 100% necrosis. Conclusions Our results validate the historical threshold of greater than 5% viable tumor with older chemotherapy regimens but not with modern interval‐compressed VDC‐IE. In addition, inter‐rater reliability for the percentage viable is more reproducible than the percentage necrosis. Although numbers are small, tumors less than 8 cm with no viable tumor appear to be a favorable subgroup and suggest risk stratification using a combination of tumor size and any viable tumor should be evaluated in ES.

ABSTRACT Imaging mass spectrometry has made significant advancements in recent years owing to its ability to study the spatial localization and abundance of proteins, peptides, lipids, glycans, metabolites, and drugs. In this study, we employed an imaging mass spectrometry‐based workflow called MALDI‐IHC, which uses antibodies conjugated with photocleavable mass‐tags, to investigate the detection of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) along with pan‐cytokeratin in formalin‐fixed paraffin‐embedded (FFPE) sections from cases with breast cancer. The expression of ER, PR, and HER2 was consistent with the clinical diagnosis based on conventional immunohistochemistry, lacking signal in triple‐negative cases and concordant signals in the cases that were classified as ER+/PR+/HER2+, ER+/PR+/HER2−, and ER−/PR−/HER2+ groups, respectively. In addition, the potential utility of a seconday antibody‐based MALDI‐IHC approach for HER2 expression was evaluated. In agreement with immunohistochemistry results, HER2 expression co‐localized within tumor regions in a HER2+ breast cancer case, while no expression was observed in a HER2− case. Collectively, these results highlight the potential of imaging mass spectrometry‐based MALDI‐IHC workflow for multiplexed detection of proteins in clinically relevant tissue sections.

529 Background: Neoadjuvant chemotherapy (NAC) is commonly administered to patients (pts) with estrogen receptor alpha (ER) negative (immunohistochemistry [IHC] 0%) and ER-low (IHC 1-10%) breast cancer (BC). For pts without pathological complete response (pCR), ER expression may differ between baseline and residual BC following NAC. We previously demonstrated adjuvant endocrine therapy (ET) omission in ER-low early-stage BC was associated with significantly worse overall survival (OS); however, this effect was restricted to pts with residual BC following NAC and those with higher baseline ER levels (IHC 6-10%) (Choong et al., ASCO 2024). Here, we assessed how often ER was expressed in residual invasive BC for pts treated with NAC for ER-negative and ER-low BC. Methods: Weidentified pts with pre-treatment (tx) ER-negative and ER-low (regardless of HER2 expression) stage I-III BC treated with NAC who underwent BC surgery at Mayo Clinic Rochester between 2009 and 2023. ER IHC was performed in a CAP/CLIA laboratory. We evaluated ER expression in residual invasive BC for pts without pCR. The percent of pts with a post-tx change in ER status was estimated and reported with 95% Wilson confidence intervals. Results: 955 pts (838 [88%] pre-tx ER-negative; 117 [12%] pre-tx ER-low) met inclusion criteria, of whom 69% had HER2-negative and 31% HER2-positive BC. The median age at diagnosis was 52 (range: 24-86). 496 (52%) had residual BC. Residual BC was more common in HER2-negative versus (vs) positive tumors (56% vs 42%, p < 0.001) but did not differ significantly by ER status (ER-negative 51% vs ER-low 57%, p = 0.22). Of those with residual BC, 277/496 (56%) had ER re-testing. Rates of ER re-testing did not vary for pre-tx ER-negative vs -low (57% vs 51%, p = 0.37) but were significantly lower for HER2-positive vs HER2-negative tumors (39% vs 62%, p < 0.001). Among those with post-tx testing, 31/277 (11%, 95% CI: 8-15%) had an increase in ER expression from pretreatment levels (defined as ER IHC < 1% to either 1-10% or > 10%; or ER IHC 1-10% to > 10%). In these 31 pts, the original NAC was for either TNBC (21/31; 68%) or HER2+ BC (10/31; 32%). In pts with pre-tx ER-negative BC, 27/243 (11%, 95% CI: 8-16%) had ER expression in the residual BC including 14/243 (6%, 95% CI: 3-9%) with ER > 10% and 13/243 (5%, 95% CI: 3-9%) with ER 1-10%. For pts with baseline ER-low BC, 4/34 (12%, 95% CI: 5-27%) had ER > 10% in the residual BC. Among the 31 pts where ER increased following NAC, 21/31 (68%) received adjuvant ET, including 17/18 if ER was > 10% in the residual disease and 4/13 in those with ER 1-10%. Conclusions: In pts treated with NAC for ER-negative or ER-low BC not achieving pCR, we identified higher ER expression in the residual breast cancer in > 10% of pts. Given that omission of ET in ER-low BC with residual cancer following NAC is associated with worse survival, repeat biomarker testing should be considered in those without pCR, and ET individualized according to ER expression.

Background: Papillary fibroelastomas (PFE) arising between the left upper pulmonary vein and left atrial appendage, commonly referred to as the coumadin ridge or Q-tip, are extremely rare and best detected by transesophageal echocardiography (TEE). Although PFEs are benign, they have been associated with a range of serious embolic events. Objective: To analyze the characteristics, clinical findings, and diagnostic techniques of PFEs originating from the coumadin ridge. Methods: We describe 13 cases of pathology proven papillary fibroelastomas uniquely attached to the Q-tip. Patient data, including demographics, mass characteristics and diagnostic imaging were collected and analyzed. Results: Thirteen patients with pathology-proven PFEs attached to the coumadin ridge were included in the study. The median age of the cohort is 73 (IQR 67-77), and 54% of the patients were male. Tumor sizes ranged from 2mm to 20mm with a median of 5mm (IQR 3.5-8.5). Twelve (92%) of the PFEs were initially visualized on TEE, and one case was diagnosed postoperatively by pathologists after the excision of the left atrial appendage. The majority of cases were incidental diagnoses, with 46% of cases incidentally discovered intraoperatively by routine TEE, and 30% visualized on TEE done for diverse reasons including valvular assessment, exclusion of infective endocarditis, and coronary artery disease (CAD) assessment. One case was incidentally detected on CMR performed as part of a metastatic tumor workup. Four (30%) patients presented with symptoms of stroke/TIA, of which 2 had a previous history of stroke. One patient had symptoms of both TIA and angina pectoris. Cardiovascular disease risk factors were prevalent: 69% had hyperlipidemia, 46% had atrial fibrillation (Afib), 31% had CAD, 54% had hypertension, and 46% were former smokers. Conclusions: Masses on the Q-tip are rare but significant intracardiac sources of embolism. Accurate identification and categorization of these masses are challenging, yet critical, to guide appropriate surgical intervention and improve patient outcomes. Further studies are needed to establish standardized diagnostic and treatment protocols for this unique presentation of PFEs.

For patients with ductal carcinoma in situ (DCIS), sentinel lymph node (SLN) surgery is generally reserved for patients at high risk of being upstaged to invasive disease. The use of frozen section (FS) pathologic analysis of the primary tumor may allow for selective surgical nodal staging within one procedure. We sought to define the reliability of FS for detection of upstaging. Eight hundred and twenty-seven patients were identified with DCIS on core needle biopsy that underwent 834 operations at our institution between January 2004 and October 2014. We calculated the rate of upstage from DCIS to invasive cancer on both intraoperative FS and final pathology to determine the performance of FS. Upstage rate on final pathology was 118/834 (14.1%) 95 per cent confidence interval 11.8 to 16.7 per cent. FS identified 88/118 (74.6%) of the upstages. Specificity was 99.3 per cent (711/716). Overall accuracy was 95.8 per cent (799/834) and the positive predictive value was 96.0 per cent (711/741 patients). Mean size of invasive cancers identifiedon FS was 5.6 mm, versus 3.5 mm for those identified only on permanent section, P = 0.11. Intraoperative FS analysis of DCIS is useful for identification of upstage to invasive disease. This may facilitate a selective approach to SLN surgery that both decreases unnecessary SLN surgery and the need for a second operation.

Background and ObjectivesAdenoid cystic carcinoma (ACC) is a rare, typically triple‐negative, breast cancer reported to have a favorable prognosis and low rate of nodal metastasis. No consensus guidelines exist for axillary staging and treatment.MethodsWe identified all patients with ACC evaluated at our institution from January 1994 to August 2016. Patient, tumor, and treatment variables were abstracted and analyzed.ResultsWe identified 20 pure ACCs (0.13% of all invasive breast cancers) with size range 0.2‐4.8 cm, in 19 women, median age 59 years. Preoperative axillary ultrasound was normal in 10/13 women and suspicious in 3/13 who had a subsequent negative lymph node fine needle aspiration (FNA). Fifteen patients (75%) had sentinel lymph node surgery and were pathologically node‐negative, while the remaining five had no axillary surgery. With 3.6 years median follow‐up (range 0.2‐38.6 years), three patients experienced an in‐breast recurrence at 2, 16, and 17 years, respectively, while none recurred in regional nodes.ConclusionsWe observed no cases of nodal metastasis in 20 consecutive cases of ACC of the breast. Preoperative axillary ultrasound with FNA of suspicious nodes accurately predicted pathologic nodal stage. These data suggest axillary surgery might be omitted safely in patients with pure ACC and a clinically negative axilla.

Background and ObjectivesCurrent randomized controlled trials are investigating the outcomes of non‐surgical treatment for patients with ductal carcinoma in situ (DCIS). We sought to evaluate pre‐operative factors associated with no residual disease at definitive resection following a core needle biopsy (CNB) diagnosis of DCIS.MethodsEight hundred and thirty‐four operations for DCIS were performed at our institution between January 2004 and October 2014. We evaluated patient and biopsy tumor characteristics to determine pre‐operative factors associated with no residual disease at surgical resection using uni‐ and multivariable analyses.ResultsSixty‐nine patients (8%) had no residual disease on final pathology. On multivariable analysis, low‐ or intermediate‐grade lesions, <1 cm in size on mammography, and lesions where ≥90% of calcifications were removed correlated with finding no residual disease on final pathology, c‐statistic 0.84. Of the 14 patients with all three low‐risk factors, 36% had no residual disease on final pathology.ConclusionsAlthough our multivariable analysis performed well, its clinical utility would be limited as we were unable to identify a subset of patients with DCIS in whom the probability of finding no residual disease is low enough to consider routine use of non‐surgical management.

ObjectiveHuman adipose‐derived mesenchymal stem cells (ADSCs) were used to rehabilitate bone damaged by osteoradionecrosis (ORN) in an established animal model.Study DesignProspective animal study.SettingAcademic department laboratory.Subjects and MethodsAfter institutional review board and Institutional Animal Care and Use Committee approval, 24 athymic nude rats were divided into 5 groups: 4 groups irradiated (20 Gy) by brachytherapy catheter placed at the left hemimandible and 1 mock irradiation control (n = 4). For all groups, ORN was initiated by extraction of the central molar 1 week later. After 28 days, animals (n = 5/group) received injection at the extraction site with saline (SAL), ADSCs, platelet‐rich plasma and collagen (PRP/COL), or ADSCs + PRP/COL. Rats were sacrificed 28 days later and their mandibles harvested for histopathology analysis (osteoblasts, osteoclasts, and fibrosis) and bone volume measurement using 3‐dimensional micro–computed tomography.ResultsAll but 1 rat survived the experiment period (23/24). Radiographic and histological analysis revealed 60% bone loss in the SAL group compared with the nonirradiated control. Injection of ADSCs increased jaw region bone volume by up to 36% (P <. 01). All experimental groups (ADSC, PRP/COL, and ADSC + PRP/COL) showed dramatically decreased osteoclast counts (P <. 001) while injection of PRP/COL with or without ADSCs increased osteoblasts. Increased fibrosis was observed after ADSC injection (P <. 05).ConclusionThe application of human ADSCs to an induced mandibular osteoradionecrosis model in athymic rats results in increased deposition or preservation of bone, demonstrated both histologically and radiographically. This offers an encouraging possible treatment option for translational research in this difficult disease.

ObjectiveWe aim to create a model of mandibular osteoradionecrosis in athymic rats. Athymic rats provide an immunosuppressed environment whereby human stem cells and biomaterials can be used to investigate regenerative solutions for osteoradionecrosis, bridging the gap between in vivo testing and clinical application.Study DesignProspective animal study.SettingAcademic otolaryngology department laboratory.Subjects and MethodsAfter Institutional Animal Care and Use Committee approval, 10 athymic nude rats were divided into 2 groups. The experimental group (n = 6) underwent irradiation (20 Gy), while the control group (n = 4) underwent sham irradiation catheter placement only. All 10 rats underwent extraction of the second mandibular molar 7 days later. The rats were sacrificed 28 days after dental extraction, and their mandibles were harvested. The mandibles were examined with histologic analysis and bone volume analysis based on 3‐dimensional micro–computed tomography.ResultsAll 10 rats survived the experiment period. Radiographic and histologic analysis revealed decreased bone formation in the experimental group compared with the control group. Jaw region volume ratio was 0.83 for the experimental group versus 0.97 in the control group (P =. 003). The region‐of‐interest volume ratio was 0.75 in the experimental group and 0.97 in the control group (P =. 005). Histologically, there were increased osteoclasts (P =. 02) and decreased osteoblasts (P =. 001) as well as increased fibrosis in the experimental group versus the control group.ConclusionMandibular osteoradionecrosis can be effectively and reproducibly produced in an athymic rat model. This will allow further research to study regenerative medicine in an athymic rat model.