Improving Malignancy Detection Rates in Body Fluids Submitted to the Hematology Laboratory for Nucleated Cell Count and Differential: A Quality Improvement Study.

CONTEXT.­: Body fluid specimens are regularly submitted to the hematology laboratory for cell count and differential. Unless there is high clinical suspicion for malignancy, most cases lack concurrent cytology review and may not benefit from more focused examination for malignancy. OBJECTIVE.­: To compare rates of malignancy detection before and after fluid-focused training for hematology technologists as part of a quality improvement initiative. DESIGN.­: During an 8-week pretraining period, body fluids submitted to the cytology laboratory were correlated with concurrent hematology specimens. After slide review and training sessions for the hematology technologists, the same data were collected for a 4-week period. Discrepant cases were reviewed by hematology laboratory supervisors and pathologists. RESULTS.­: We collected 465 pretraining and 249 posttraining body fluids with concurrent cytology and hematology evaluation. In the pretraining cohort, 48 cases (10.3%) were diagnosed as malignant by cytology; of those, 33 were detected by hematology. In the posttraining cohort, 30 cases (12.0%) were diagnosed as malignant by cytology of which 27 were detected by hematology. Of the 18 discrepant cases (all carcinomas), hematology slide review showed definite features of malignancy in 15 and no tumor cells in 3. The malignancy detection rate by the hematology laboratory significantly improved after training (68.8% versus 90.0%, P = .01). CONCLUSIONS.­: We demonstrate the comparatively lower malignancy detection rate for body fluid specimens processed in our hematology laboratory, particularly for carcinomas. Hematology technologist education/training improved the malignancy detection rate, an important quality improvement given the large proportion of body fluids undergoing hematology evaluation without concurrent cytology reviews.

The Difference Between Unfixed and Postfixation Placental Weight.

OBJECTIVES: Reference values for placental weights correlated with gestational age are used in surgical pathology. Most reference values were established for fresh placentas. Some laboratories routinely fix all placentas, bringing into question the accuracy of the reference weight values. We wanted to determine the impact of fixation on placental weight. METHODS: One hundred placentas from uncomplicated pregnancies were weighed in the fresh state, after removal of the cord and membranes. After fixation in formalin for 1 day and 5 days, the placentas were reweighed. The change in weight for each placenta was analyzed by a two-tailed paired t test. RESULTS: Statistically, a small but significant gain in weight occurred after 24 hours (3.7%, P << .001), and there was no significant change identified in the additional 4 days (P = .51). Nine placentas lost weight with fixation; the weight of four was unchanged. CONCLUSIONS: We consider formalin fixation to add a statistically significant but clinically negligible amount of weight to the placenta.

Modified Plasma-Thrombin Method of Cell Block Preparation for Fine-Needle Aspiration Biopsies in Resource-Limited Settings.

OBJECTIVES: The plasma-thrombin method is commonly used to make cell blocks from fine-needle aspiration (FNA) samples but requires centrifugation. We describe a modification to this method that does not require centrifugation for use in resource-limited settings. METHODS: Pooled fresh plasma is aliquoted into 2-mL Eppendorf tubes and the FNA sample directly rinsed into the plasma. Two drops of reconstituted thrombin are added and gently mixed. A cell clot is transferred to a tissue bag, fixed in formalin, and processed. This method was applied to FNA samples from 44 patients presenting to the Mbarara University of Science and Technology FNA clinic. RESULTS: The cell blocks were less cellular than the smears but contained adequate material to confirm morphologic impression or perform immunocytochemistry in 36 of 44 cases (82% adequacy rate). CONCLUSIONS: The modified plasma-thrombin method is a reliable cell block preparation method that can be easily applied in resource-limited settings.

Integrated genomic analysis of clear cell ovarian cancers identified PRKCI as a potential therapeutic target.

Clear cell ovarian cancer (CCOC) is an epithelial ovarian cancer histotype with unique pathologic, biologic and clinical features. Despite its worse prognosis than serous ovarian cancer (SOC), the genomic landscape of CCOC is less well defined. Integrated genomic analysis of CCOC allows the identification of potential therapeutic targets to improve the treatment of this tumor. Using comparative genomic hybridization and gene expression profiling, we have screened 12 CCOC cell lines and 40 tumors to identify 45 amplified and overexpressed genes. Pathways analysis of these genes identified 19 genes with cancer-related functions. Of these, PRKCI is one of the most frequently amplified and overexpressed genes and its expression induced cancer cell proliferation and migration/invasion in vitro as well as tumor growth in vivo. Targeting PRKCI by small molecule inhibitor, sodium aurothiomalate (ATM), significantly reduced the in vivo tumor growth and may be a new therapeutic strategy to improve the treatment of CCOC.

Aorta-Lesion-Attenuation-Difference (ALAD) on contrast-enhanced CT: a potential imaging biomarker for differentiating malignant from benign oncocytic neoplasms.

OBJECTIVE: To evaluate whether the Aorta-Lesion-Attenuation-Difference on contrast-enhanced CT can aid in the differentiation of malignant and benign oncocytic renal neoplasms. MATERIALS AND METHODS: Two independent cohorts-an initial (biopsy) dataset and a validation (surgical) dataset-with oncocytomas and chromophobe renal cell carcinomas (chRCC) were included in this IRB-approved retrospective study. A region of interest was placed on the renal mass and abdominal aorta on the same CT image slice to calculate an Aorta-Lesion-Attenuation-Difference (ALAD). ROC curves were plotted for different enhancement phases, and diagnostic performance of ALAD for differentiating chRCC from oncocytomas was calculated. RESULTS: Seventy-nine renal masses (56 oncocytomas, 23 chRCC) were analyzed in the initial (biopsy) dataset. Thirty-six renal masses (16 oncocytomas, 20 chRCC) were reviewed in the validation (surgical) cohort. ALAD showed a statistically significant difference between oncocytomas and chromophobes during the nephrographic phase (p < 0.001), early excretory phase (p < 0.001), and excretory phase (p = 0.029). The area under the ROC curve for the nephrographic phase was 1.00 (95% CI: 1.00-1.00) for the biopsy dataset and showed the narrowest confidence interval. At a threshold value of 25.5 HU, sensitivity was 100 (82.2%-100%) and specificity was 81.5 (61.9%-93.7%). When tested on the validation dataset on measurements made by an independent reader, the AUROC was 0.93 (95% CI: 0.84-1.00) with a sensitivity of 100 (80.0%-100%) and a specificity of 87.5 (60.4%-97.8%). CONCLUSIONS: Nephrographic phase ALAD has potential to differentiate benign and malignant oncocytic renal neoplasms on contrast-enhanced CT if histologic evaluation on biopsy is indeterminate.

Smears are important for adequate cytologic diagnosis of kidney lesions.

INTRODUCTION: Traditionally at our institution, smears with or without liquid-based cytology (LBC) and core biopsies (CBs) have been obtained by radiologists performing image-guided fine-needle aspiration biopsies (FNABs) of deep organs. Since 2015, however, there has been a shift to providing cytology with samples for LBC only when obtaining CBs. The impression among our institution's cytologists is that LBC alone is less often adequate for diagnosis compared with smears and LBC together. We examined a series of kidney FNABs pre- and post-"LBC only" to evaluate this impression. MATERIALS AND METHODS: With institutional review board approval, we compared all kidney FNABs from 2012 to those from 2015. We recorded the type(s) of cytology preparation(s), the number of cytology slides, the cytology diagnosis, the concurrent CB diagnosis, and whether there was a subsequent excision and the excision diagnosis. We examined cytology and CB slides as needed. RESULTS: In 2012, 105 patients underwent 111 kidney biopsies, 109 with smears made. In 2015, 58 patients underwent 62 kidney biopsies, 7 with smears made. In 2012, there were 13 (12%) nondiagnostic (ND) cytology cases and 19 (17%) cases where the cytology and CB diagnoses were discrepant. By comparison, in 2015, there were 20 (32%) ND cytology cases and 21 (33%) discrepant cases. CONCLUSIONS: There were more cytology slides per case and fewer ND diagnoses in 2012 compared with 2015 (12% versus 32%, respectively, P = 0.001). Concordance was also better in 2012 (83% versus 67%, P = 0.015). We believe that our metrics would improve if we returned to the procedures followed in 2012.

Touch Preps of Products of Conception for Rule-Out Ectopic Pregnancy: A Viable Alternative to Frozen Section.

OBJECTIVES: Tissue confirmation of the intrauterine location of a pregnancy can be difficult grossly, necessitating a frozen section diagnosis. First-trimester tissue is often scant and can be exhausted by frozen section. We examined 39 endometrial curettings performed for rule-out ectopic pregnancy by touch prep to examine the utility of cytopathology in documenting trophoblast or chorionic villi (products of conception [POC]). METHODS: First-trimester curettage specimens sent to the Massachusetts General Hospital Pathology Departmentreceived a gross examination followed by a touch prep of the area most suspicious for villi. Touch preps were reviewed blinded to the final diagnosis and then compared. RESULTS: Thirty-three of the 39 touch preps and histology specimens were concordant, including all 11 negative histology specimens and 22 of the 28 positive histology specimens. CONCLUSIONS: POC can be diagnosed by touch prep and may offer confirmation of grossly identified villi. Positive predictive value is 100%. Negative touch preps should receive further evaluation.

Trends in Cervical Cytology Screening and Reporting Practices: Results From the College of American Pathologists 2011 PAP Education Supplemental Questionnaire.

CONTEXT: The College of American Pathologists periodically surveys laboratories to determine changes in cytopathology practices. We report the results of a 2011 gynecologic cytology survey. OBJECTIVE: To provide a cross-sectional survey of gynecologic cytology practices in 2010. DESIGN: In 2011, a survey was sent to 1604 laboratories participating in the College of American Pathologists gynecologic cytology interlaboratory comparison education program and proficiency testing programs requesting data from 2010 on the following topics: terminology/reporting, cytotechnologist workload, quality assurance, reagents, and ancillary testing. RESULTS: Six hundred and twenty-five laboratories (39%) replied to the survey. The nonstandard use of "low-grade squamous intraepithelial lesion cannot exclude high-grade squamous intraepithelial lesion" is used by most laboratories to report the presence of low-grade squamous intraepithelial lesion with possibility of high-grade squamous intraepithelial lesion. Most laboratories also report the presence or absence of cells from the transformation zone. Most respondents do not limit cytotechnologist screening workload during the work shift. Only about one-third of laboratories (188 of 582; 32%) use image-assisted screening devices. Rapid prescreening as a quality assurance measure is used by only 3.5% (21 of 594) of the laboratories. When used for screening, most laboratories use the imager for retrospective review of slides to detect human locator and interpretive errors. Most laboratories receive both liquid-based cytology samples (mainly ThinPrep, Hologic, Marlborough, Massachusetts) and conventional Papanicolaou tests. Expiration dates of liquid-based cytology test vials are not usually recorded. CONCLUSIONS: The field of gynecologic cytology is evolving rapidly. These survey results offer a snapshot of national gynecologic cytology practices in 2010.

Young investigator challenge: The accuracy of the nuclear-to-cytoplasmic ratio estimation among trained morphologists.

BACKGROUND: The estimation of the nuclear-to-cytoplasmic ratio (N:C ratio) is an important factor in diagnosing atypia and malignancy in pathological specimens, particularly in cytology. Many algorithms for determining malignant potential make reference to specific, decimal N:C ratios without specifying how the ratio should be measured, with the implication that the observer is intended to estimate this ratio by eye. The authors wanted to determine how accurate trained morphologists (including attending pathologists, pathology residents, and cytotechnologists) are at estimating the N:C ratio without a measuring device. METHODS: Two surveys were prepared containing ideal and real cell images of various N:C ratios. Participants were instructed to select their best estimate from a list of decimal ratios. The data were tabulated and analyzed to determine how accurate the estimates were and whether there was any performance difference between ideal and real images. RESULTS: The absolute and percentage deviation from the actual N:C ratio decreased steadily with increasing N:C ratio. Aggregate performance was found to be closely correlated between real and ideal images, although interobserver variation was not significantly different among participants in the real images quiz, but was significantly different on the ideal images quiz. CONCLUSIONS: Trained morphologists make relatively accurate estimations of the N:C ratio and become increasingly more accurate as the depicted N:C ratio increases. This suggests that including N:C ratio decimals as a criteria for the diagnosis of atypia is valid for high N:C ratios.

Digital diffraction analysis enables low-cost molecular diagnostics on a smartphone.

The widespread distribution of smartphones, with their integrated sensors and communication capabilities, makes them an ideal platform for point-of-care (POC) diagnosis, especially in resource-limited settings. Molecular diagnostics, however, have been difficult to implement in smartphones. We herein report a diffraction-based approach that enables molecular and cellular diagnostics. The D3 (digital diffraction diagnosis) system uses microbeads to generate unique diffraction patterns which can be acquired by smartphones and processed by a remote server. We applied the D3 platform to screen for precancerous or cancerous cells in cervical specimens and to detect human papillomavirus (HPV) DNA. The D3 assay generated readouts within 45 min and showed excellent agreement with gold-standard pathology or HPV testing, respectively. This approach could have favorable global health applications where medical access is limited or when pathology bottlenecks challenge prompt diagnostic readouts.

HER2 over-expressing high grade endometrial cancer expresses high levels of p95HER2 variant.

BACKGROUND: Subsets of high grade endometrial cancer (EnCa) over-express HER2 (ERBB2), yet clinical trials have failed to demonstrate any anti-tumor activity utilizing trastuzumab, an approved platform for HER2 positive breast cancer (BrCa). A truncated p95HER2 variant lacking the trastuzumab binding site may confer resistance. The objective of this investigation was to characterize the expression of the p95HER2 truncated variant in EnCa. MATERIALS AND METHODS: With institutional approval, 86 high grade EnCa tumors were identified with tumor specimens from surgeries performed between 2000 and 2011. Clinical data were collected and all specimens underwent tumor genotyping, HER2 immunohistochemistry (IHC, HercepTest®), HER2 fluorescent in situ hybridization (FISH), along with total HER2 (H2T) and p95HER2 assessment with VeraTag® testing. Regression models were used to compare a cohort of 86 breast tumors selected for equivalent HER2 protein expression. RESULTS: We identified 44 high grade endometrioid and 42 uterine serous carcinomas (USC). IHC identified high HER2 expression (2+ or 3+) in 59% of the tumors. HER2 gene amplification was observed in 16 tumors (12 USC, 4 endometrioid). Both HER2 gene amplification and protein expression correlated with H2T values. High p95HER2 expression above 2.8RF/mm2 was observed in 53% (n=54) with significant correlation with H2T levels. When matched to a cohort of 107 breast tumors based on HercepTest HER2 expression, high grade EnCa presented with higher p95 levels (p<0.001). CONCLUSIONS: These data demonstrate that compared to BrCa, high grade EnCa expresses higher levels of p95HER2 possibly providing rationale for the trastuzumab resistance observed in EnCa.

Non-16/non-18 high-risk human papillomavirus types predominate in anal cytology categories of negative for intraepithelial lesion and atypical cells of undetermined significance.

INTRODUCTION: Screening for anal carcinoma continues to grow despite controversy regarding its efficacy. High-risk human papillomavirus (HR-HPV) has been adopted as a cotest with anal Papanicolaou tests. We sought to identify the prevalence of HR-HPV types in the most common anal cytology specimens: negative for intraepithelial lesion or malignancy (NILM) and atypical squamous cell of undetermined significance (ASC-US). MATERIALS AND METHODS: Anal cytology specimens were identified and tested for HR-HPV using Roche cobas 4800 HR-HPV analysis (Roche Molecular Systems, Inc., Indianapolis, Ind) and, if positive, typed further for: HPV-16, -18, and/or non-16/non-18 "other" HR-HPV type. RESULTS: There were 642 specimens from 538 patients. The most common interpretation was NILM (48.6%) and ASC-US (25.7%). Of NILM cases, 47% were HR-HPV+ (53% in men, 33% in women, P = 0.03, χ2). In ASC-US cases, 73% were HR-HPV+ (74% in male patients, 70% in female patients). The most common HPV subtype was non-16/non-18 HR-HPV "other" types in 89% of cases. HPV-16 and HPV-18 were positive in 35% and 18% of cases, respectively. In patients with non-16/non-18 HR-HPV+ anal cytology, 16 of 79 had biopsies histologically diagnosed as at least high-grade squamous intraepithelial lesion (HSIL+). However, the relative risk of having HSIL+ was 2.3-times higher for anal cytology positive for HPV-16, -18, with/without coinfection with non-16/non-18 HR-HPV than those positive for non-16/non-18 "other" HR-HPV types alone. CONCLUSIONS: Non-16/non-18 "other" HR-HPV types are most prevalent in anal cytology interpretations of NILM and ASC-US. Patients with HR-HPV+ NILM or ASC-US, negative for HPV-16/-18, are at lower relative risk of having subsequent histologic HSIL+, but a percentage of these patients still harbor HSIL+ on biopsy.

Interinstitutional whole slide imaging teleconsultation service development: assessment using internal training and clinical consultation cases.

CONTEXT: Assessment of accuracy and feasibility of whole slide imaging (WSI) for interinstitutional consultation in surgical pathology. OBJECTIVES: To train technical and pathologist staff in WSI technology, establish and evaluate a WSI workflow using training cases and second-opinion consultations, and assess diagnostic accuracy. DESIGN: First, WSI training and evaluation using selected subspecialty service cases were performed and compared with the clinical glass slide (GS) diagnosis. Second, WSI and GS diagnoses of consecutive, second-opinion consultation cases were compared. Discrepancies underwent adjudication to determine a reference diagnosis. Participant observations on WSI initiation to practice were gathered. RESULTS: There were 130 cases evaluated, with 123 correlations (94.6%) and 6 minor (4.6%) and 1 major (0.8%) discrepancies. The 74 consultation cases interpreted had 52 correlations (70.3%), and 18 minor (24.3%) and 4 major (5.4%) discrepancies. The WSI and GS adjusted major discrepancy rates in second-opinion consultations were 2.7% (2 of 74) and 4.1% (3 of 74), respectively. Statistical analysis showed that WSI was not inferior to GS interpretation. Pathologists agreed the software was easy to use and the images were adequate, but more time was spent rendering WSI interpretations. CONCLUSIONS: A significant learning curve was observed in the transition from the training set to clinical consultation cases associated both with WSI interpretation and adjustments to the digital analogs of routine GS workflow. Results from second-opinion consultations indicated that WSI interpretation was as accurate as GS interpretation among properly trained and experienced users. Overall, WSI-based practice appears feasible for second-opinion consultations.

Human papillomavirus testing and reporting rates in 2012: results of a College of American Pathologists national survey.

CONTEXT: College of American Pathologists (CAP) surveys are used to establish national benchmarks for laboratory parameters. OBJECTIVE: To evaluate changes in laboratory human papillomavirus (HPV) testing patterns in laboratories incorporating HPV testing with Papanicolaou tests in 2012. DESIGN: Data were analyzed from the CAP HPV Supplemental Questionnaire distributed to 1771 laboratories participating in either CAP HPV or CAP Papanicolaou proficiency testing in 2013. RESULTS: A total of 1022 laboratories (58%) responded. There were more high-risk (HR) HPV tests performed per institution as compared to previous surveys. There were more HPV tests performed within an institution as compared to previous surveys. Hybrid Capture 2 (HC2) remains the most common method (42.4%, 239 of 564); Cervista and cobas methods are used in 37.2% (210 of 564) and 14.9% (84 of 564) of laboratories, respectively. Human papillomavirus testing is offered as a reflex test after a Papanicolaou test result of atypical squamous cells of undetermined significance (ASC-US) in 89.6% of laboratories (476 of 531); as a cotest for women aged 30 years and older in 60.3% (404 of 531); as reflex testing after atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion (ASC-H) in 42.7% (320 of 531); and as reflex testing after atypical glandular cells (AGC) in 27.3% (145 of 531). The HPV-positive rates for ASC-US and ASC-H were similar in 2012 and 2006. Cervista (49.2%, 88 of 179) and Roche cobas (27.4%, 49 of 179) are the most common methods used for genotyping. Most laboratories use the CAP Human Papillomavirus for Cytology Program for proficiency testing. CONCLUSIONS: There was an increase in annual volume of HR-HPV testing with a shift toward in-house HR-HPV testing. Genotyping volumes also increased. HC2 and Cervista are most commonly used, with an increasing volume of Roche cobas testing. The most common indication for HPV testing among all laboratories was ASC-US reflex testing, but an increase in HPV cotesting was observed. The data provide an update into persisting and newer trends in HPV testing practices.

Dual HER2 targeting impedes growth of HER2 gene-amplified uterine serous carcinoma xenografts.

PURPOSE: Uterine serous carcinoma (USC) is an aggressive subtype of endometrial cancer that commonly harbors HER2 gene amplification. We investigated the effectiveness of HER2 inhibition using lapatinib and trastuzumab in vitro and in xenografts derived from USC cell lines and USC patient-derived xenografts. EXPERIMENTAL DESIGN: Immunohistochemistry and FISH were performed to assess HER2 expression in 42 primary USC specimens. ARK1, ARK2, and SPEC2 cell lines were treated with trastuzumab or lapatinib. Cohorts of mice harboring xenografts derived from ARK2 and SPEC2 cell lines and EnCa1 and EnCa2 primary human USC samples were treated with either vehicle, trastuzumab, lapatinib, or the combination of trastuzumab and lapatinib. Acute and chronic posttreatment tumor samples were assessed for downstream signaling alterations and examined for apoptosis and proliferation. RESULTS: HER2 gene amplification (24%) correlated significantly with HER2 protein overexpression (55%). All models were impervious to single-agent trastuzumab treatment. Lapatinib decreased in vitro proliferation of all cell lines and in vivo growth of HER2-amplified xenografts (ARK2, EnCa1). In addition, dual therapy with trastuzumab and lapatinib resulted in significant antitumor activity only in ARK2 and EnCa1 tumors. Dual HER2 therapy induced on target alteration of downstream MAPK and PI3K pathway mediators only in HER2-amplified models, and was associated with increased apoptosis and decreased proliferation. CONCLUSIONS: Although trastuzumab alone did not impact USC growth, dual anti-HER2 therapy with lapatinib led to improved inhibition of tumor growth in HER2-amplified USC and may be a promising avenue for future investigation.

Clear vision through the haze: a practical approach to ground-glass opacity.

Ground-glass opacity (GGO) is a common, nonspecific imaging finding on chest computed tomography that may occur in a variety of pulmonary diseases. GGO may be the result of partial filling of alveolar spaces, thickening of the alveolar walls or septal interstitium, or a combination of partial filling of alveolar spaces and thickening of the alveolar walls and septal interstitium at the histopathologic level. Diseases that commonly manifest on chest computed tomography as GGO include pulmonary edema, alveolar hemorrhage, nonspecific interstitial pneumonia, hypersensitivity pneumonitis, and pulmonary alveolar proteinosis. Generating an extensive list of possible causes of GGO in radiologic reports would not be helpful to referring physicians. Preferably, a more concise and focused list of differential diagnostic possibilities may be constructed using a systematic approach to further classify GGO based on morphology, distribution, and ancillary imaging findings, such as the presence of cysts, traction bronchiectasis, and air trapping. Correlation with clinical history, such as the chronicity of symptoms, the patient's immune status, and preexisting medical conditions is vital. By thorough analysis of imaging patterns and consideration of relevant clinical information, the radiologist can generate a succinct and useful imaging differential diagnosis when confronted with the nonspecific finding of GGO.

Inhibition of gamma-secretase activity impedes uterine serous carcinoma growth in a human xenograft model.

OBJECTIVE: Uterine serous carcinoma (USC) represents an aggressive subtype of endometrial cancer. We sought to understand Notch pathway activity in USC and determine if pathway inhibition has anti-tumor activity. METHODS: Patient USC tissue blocks were obtained and used to correlate clinical outcomes with Notch1 expression. Three established USC cell lines were treated with gamma-secretase inhibitor (GSI) in vitro. Mice harboring cell line derived or patient derived USC xenografts (PDXs) were treated with vehicle, GSI, paclitaxel and carboplatin (P/C), or combination GSI and P/C. Levels of cleaved Notch1 protein and Hes1 mRNA were determined in GSI treated samples. Statistical analysis was performed using the Wilcoxon rank sum and Kaplan-Meier methods. RESULTS: High nuclear Notch1 protein expression was observed in 58% of USC samples with no correlation with overall survival. GSI induced dose-dependent reductions in cell number and decreased levels of cleaved Notch1 protein and Hes1 mRNA in vitro. Treatment of mice with GSI led to decreased Hes1 mRNA expression in USC xenografts. In addition, GSI impeded tumor growth of cell line xenografts as well as UT1 USC PDXs. When GSI and P/C were combined, synergistic anti-tumor activity was observed in UT1 xenografts. CONCLUSIONS: Notch1 is expressed in a large subset of USC. GSI-mediated Notch pathway inhibition led to both reduced cell numbers in vitro and decreased tumor growth of USC some xenograft models. When combined with conventional chemotherapy, GSI augmented anti-tumor activity in one USC PDX line suggesting that targeting of the Notch signaling pathway is a potential therapeutic strategy for future investigation.