A Classifier for Improving Early Lung Cancer Diagnosis Incorporating Artificial Intelligence and Liquid Biopsy.

Lung cancer is the leading cause of cancer-related deaths worldwide and in China. Screening for lung cancer by low dose computed tomography (LDCT) can reduce mortality but has resulted in a dramatic rise in the incidence of indeterminate pulmonary nodules, which presents a major diagnostic challenge for clinicians regarding their underlying pathology and can lead to overdiagnosis. To address the significant gap in evaluating pulmonary nodules, we conducted a prospective study to develop a prediction model for individuals at intermediate to high risk of developing lung cancer. Univariate and multivariate logistic analyses were applied to the training cohort (n = 560) to develop an early lung cancer prediction model. The results indicated that a model integrating clinical characteristics (age and smoking history), radiological characteristics of pulmonary nodules (nodule diameter, nodule count, upper lobe location, malignant sign at the nodule edge, subsolid status), artificial intelligence analysis of LDCT data, and liquid biopsy achieved the best diagnostic performance in the training cohort (sensitivity 89.53%, specificity 81.31%, area under the curve [AUC] = 0.880). In the independent validation cohort (n = 168), this model had an AUC of 0.895, which was greater than that of the Mayo Clinic Model (AUC = 0.772) and Veterans' Affairs Model (AUC = 0.740). These results were significantly better for predicting the presence of cancer than radiological features and artificial intelligence risk scores alone. Applying this classifier prospectively may lead to improved early lung cancer diagnosis and early treatment for patients with malignant nodules while sparing patients with benign entities from unnecessary and potentially harmful surgery. Clinical Trial Registration Number: ChiCTR1900026233, URL: http://www.chictr.org.cn/showproj.aspx?proj=43370.

The presence of tumour-infiltrating neutrophils is an independent adverse prognostic feature in clear cell renal cell carcinoma.

Tumour-promoting inflammation is an emerging hallmark of cancer that is increasingly recognised as a therapeutic target. As a constituent measure of inflammation, tumour-infiltrating neutrophils (TINs) have been associated with inferior prognosis in several cancers. We analysed clinically annotated cohorts of clear cell renal cell carcinoma (ccRCC) to assess the presence of neutrophils within the tumour microenvironment as a function of outcome. We centrally reviewed ccRCC surgical resection and fine-needle aspiration (FNA) specimens, including primary and metastatic sites, from three centres. TINs were scored based on the presence of neutrophils in resection and FNA specimens by two pathologists. TIN count was correlated with tumour characteristics including stage, WHO/ISUP grade, and immunohistochemistry (IHC). In parallel, we performed CIBERSORT analysis of the tumour microenvironment in a cohort of 516 ccRCCs from The Cancer Genome Atlas (TCGA). We included 102 ccRCC cases comprising 65 resection specimens (37 primary and 28 metastatic resection specimens) and 37 FNAs from primary lesions. High TINs were significantly associated with worse overall survival (p = 0.009) independent of tumour grade and stage. In ccRCCs sampled via FNA, all cases with high TINs had distant metastasis, whereas they were seen in only 19% of cases with low TINs (p = 0.0003). IHC analysis showed loss of E-cadherin in viable tumour cells in areas with high TINs, and neutrophil activation was associated with elastase and citrullinated histone H3 expression (cit-H3). In the TCGA cohort, neutrophilic markers were also associated with worse survival (p < 0.0001). TINs are an independent predictor of worse prognosis in ccRCC, which have the potential to be assessed at the time of first biopsy or FNA. Neutrophils act directly on tumour tissue by releasing elastase, a factor that contributes to the breakdown of cell-cell adhesion and to facilitate tumour dissemination.

Detection of circulating genetically abnormal cells using 4-color fluorescence in situ hybridization for the early detection of lung cancer.

PURPOSE: Available biomarkers lack sensitivity for an early lung cancer. Circulating genetically abnormal cells (CACs) occur early in tumorigenesis. To determine the diagnostic value of CACs in blood detected by 4-color fluorescence in situ hybridization (FISH) for lung cancer. METHODS: This was a prospective study of patients with pulmonary nodules ≤ 30 mm detected between 10/2019 and 01/2020 at four tertiary hospitals in China. All patients underwent a pathological examination of lung nodules found by imaging and were grouped as malignant and benign. CACs were detected by 4-color FISH. Patients were divided into the training and validation cohorts. Receiver operating characteristics analysis was used to analyze the diagnosis value of CACs. RESULTS: A total of 205 participants were enrolled. Using a cut-off value of ≥ 3, blood CACs achieved areas under the curve (AUCs) of 0.887, 0.823, and 0.823 for lung cancer in the training and validation cohorts, and all patients, respectively. CACs had high diagnostic values across all tumor sizes and imaging lesion types. CACs were decreased after surgery (median, 4 vs. 1, P < 0.001) in the validation set. The CAC status between blood and tissues was highly consistent (kappa = 0.909, P < 0.001). The AUC of CAC (0.823) was higher than that of CEA (0.478), SCC (0.516), NSE (0.506), ProGRP (0.519), and CYFRA21-1 (0.535) (all P < 0.001). CONCLUSION: CACs might have a high value for the early diagnosis of lung cancer. These findings might need to be validated in future studies. Evidence suggested homology in genetic aberrations between the CACs and the tumor cells.

A Proposal for the Performance, Classification, and Reporting of Lymph Node Fine-Needle Aspiration Cytopathology: The Sydney System.

BACKGROUND: The evaluation of lymph nodes (LN) by fine-needle aspiration cytology (FNAC) is routinely used in many institutions but it is not uniformly accepted mainly because of the lack of guidelines and a cytopathological diagnostic classification. A committee of cytopathologists has developed a system of performance, classification, and reporting for LN-FNAC. METHODS: The committee members prepared a document that has circulated among them five times; the final text has been approved by all the participants. It is based on a review of the international literature and on the expertise of the members. The system integrates clinical and imaging data with cytopathological features and ancillary techniques. The project has received the endorsement and patronage of the International Academy of Cytology and the European Federation of the Cytology Societies. RESULTS: Clinical, imaging, and serological data of lymphadenopathies, indications for LN-FNAC, technical procedures, and ancillary techniques are evaluated with specific recommendations. The reporting system includes two diagnostic levels. The first should provide basic diagnostic information and includes five categories: inadequate/insufficient, benign, atypical lymphoid cells of undetermined/uncertain significance, suspicious, and malignant. For each category, specific recommendations are provided. The second diagnostic level, when achievable, should produce the identification of specific benign or malignant entities and additional information by utilizing ancillary testing. CONCLUSION: The authors believe that the introduction of this system for performing and reporting LN-FNAC may improve the quality of the procedure, the report, and the communication between cytopathologists and the clinicians. This system may lead to a greater acceptance and utilization of LN-FNAC and to a better interdisciplinary understanding of the results of this procedure.

Identification of circulating tumor cells using 4-color fluorescence in situ hybridization: Validation of a noninvasive aid for ruling out lung cancer in patients with low-dose computed tomography-detected lung nodules.

BACKGROUND: Approximately one third of needle biopsies that are performed to rule out malignancy of indeterminate pulmonary nodules detected radiologically during lung cancer screening are negative, thus exposing cancer-free patients to risks of pneumothorax, bleeding, and infection. A noninvasive confirmatory tool (eg, liquid biopsy) is urgently needed in the lung cancer diagnosis setting to stratify patients who should receive biopsy versus those who should be monitored. METHODS: A novel antigen-independent, 4-color fluorescence in situ hybridization (FISH)-based method was developed to detect circulating tumor cells (CTCs) with abnormalities in gene copy numbers in mononuclear cell-enriched peripheral blood samples from patients with (n = 107) and without (n = 100) lung cancer. RESULTS: Identification of CTCs using FISH probes at 10q22.3/CEP10 and 3p22.1/3q29 detected lung cancer cases with 94.2% accuracy, 89% sensitivity, and 100% specificity compared with biopsy. CONCLUSION: The high accuracy of this liquid biopsy method suggests that it may be used as a noninvasive decision tool to reduce the frequency of unnecessary needle biopsy in patients with benign pulmonary lesions.

Cytologic features, immunocytochemical findings, and DNA ploidy in four rare cases of epithelioid hemangioendothelioma involving effusions.

BACKGROUND: Epithelioid hemangioendothelioma (EHE) involving serous effusion is extremely rare, and the diagnosis can be challenging. DNA ploidy quantitation of EHE in effusion fluids has not been previously described in the English-language literature. METHODS: Specimens of cytological diagnosed with EHE in effusion fluids between 2002 and 2009 were retrieved from the pathology files at MD Anderson Cancer Center. A total of four cases of EHE involving or arising from effusion fluids were found, and we reviewed cytospin, smears, cell block sections, and immunostained slides. DNA image analysis for ploidy and proliferation evaluation was performed on a destained, papanicolaou-stained slide from each case. RESULTS: The tumor cells were epithelioid with prominent cytoplasmic vacuolization and intracytoplasmic inclusions, which could resemble reactive mesothelial cells, mesothelioma, or adenocarcinoma. The tumor cells were positive for endothelial markers. DNA image analysis in three of the four cases revealed predominantly diploid and tetraploid subpopulations, with few aneuploid cells and fairly low proliferation indices, and these patients had fairly prolonged survival. CONCLUSIONS: DNA image analysis is useful for differentiating EHE from reactive mesothelial cells and high-grade carcinoma. For accurate diagnosis of EHE in effusion fluids, cytologic features should be considered together with clinical history and ancillary studies.

Novel fluorescence in situ hybridization-based definition of bacille Calmette-Guérin (BCG) failure for use in enhancing recruitment into clinical trials of intravesical therapies.

OBJECTIVES: To present a molecular definition of bacille Calmette-Guérin (BCG) failure that incorporates fluorescence in situ hybridization (FISH) testing to predict BCG failure before it becomes clinically evident, which can be used to enhance trial designs for patients with non-muscle-invasive bladder cancer. PATIENTS AND METHODS: We used data from 143 patients who were followed prospectively for 2 years during intravesical BCG therapy, during which time FISH assays were collected and correlated to clinical outcomes. RESULTS: Of the 95 patients with no evidence of tumour at 3-month cystoscopy, 23 developed tumour recurrence and 17 developed disease progression by 2 years. Patients with a positive FISH test at both 6 weeks and 3 months were more likely to develop tumour recurrence (17/37 patients [46%] and 16/28 patients [57%], respectively) than patients with a negative FISH test (6/58 patients [10%] and 3/39 patients [8%], respectively; both P < 0.001). Using hazard ratios for recurrence with positive 6-week and 3-month FISH results, we constructed clinical trial scenarios whereby patients with a negative 3-month cystoscopy and positive FISH result could be considered to have 'molecular BCG failure' and could be enrolled in prospective, randomized clinical trials comparing BCG therapy (control) with an experimental intravesical therapy. CONCLUSIONS: Patients with positive early FISH and negative 3-month cystoscopy results can be considered to have molecular BCG failure based on their high rates of recurrence and progression. This definition is intended for use in designing clinical trials, thus potentially allowing continued use of BCG as an ethical comparator arm.

Epithelioid hemangioendothelioma: a study of 14 cytopathology cases.

INTRODUCTION: The cytopathologic diagnosis of the rare vascular tumor epithelioid hemangioendothelioma (EHE) in patients who have no previous history of EHE or who have a complicated and/or misleading disease history is challenging. Furthermore, few studies have described the cytopathology of EHE. Herein, we identify 14 cases of EHE from 10 patients, some of whom had a history of epithelial tumor, and provide a detailed report of the cytomorphology of EHE, discuss the tumor's differential diagnoses, and describe ancillary examinations that may be helpful in diagnosing EHE cytologically, especially in patients with a complex disease history. MATERIALS AND METHODS: We retrieved the slides of 14 cases of EHE archived between 2002 and 2009 in our institution's cytology section. Conventional direct smears and cell block sections were prepared from most fine-needle aspiration samples and from all effusion samples. Cell block sections were subjected to immunostaining for vascular, mesothelial, and epithelial markers. RESULTS: EHE shared many morphologic features with other, more common tumors such as adenocarcinoma and mesothelioma. The defining cytologic feature of EHE was an intracellular lumen containing entrapped intact and degenerating erythrocytes, which was not present in every case. EHE cells were positive for the vascular markers CD34, CD31, factor VIII, and friend leukemia integration 1 transcription factor (FLI-1) and negative for epithelial and mesothelial markers. Clinicians provided information important to the diagnosis of EHE. CONCLUSIONS: Carefully examining the smear and cell block sections for morphologic features indicative of EHE (eg, prominent cytoplasmic vacuolization, intranuclear cytoplasmic inclusions, and intracellular lumen containing entrapped intact and degenerating erythrocytes), confirming these findings with immunocytochemical staining, and communicating with clinicians are all important to correctly diagnosing EHE.

Cervista HPV assays for fine-needle aspiration specimens are a valid option for human papillomavirus testing in patients with oropharyngeal carcinoma.

BACKGROUND: The objectives of this study were to evaluate the validity of Cervista human papillomavirus (HPV) assays in head and neck fine-needle aspiration (FNA) specimens from patients with head and neck squamous carcinomas and to verify that the Cervista assay in FNA specimens is a valid option for determining HPV status in patients with oropharyngeal carcinomas. METHODS: The authors retrospectively retrieved 64 head and neck FNA specimens from patients who had head and neck squamous carcinoma. The specimens were tested for HPV types 16 and 18 (HPV16/18) and for high-risk (HR) HPV DNA using the Cervista HPV16/18 and HPV HR assays, respectively. The results from those assays were compared with the results from polymerase chain reaction (PCR)-based HPV assays in the same tissues and with the results from HPV in situ hybridization assays/p16 immunostaining in the corresponding primary tumors. RESULTS: In total, 64 FNA specimens were analyzed. The Cervista HPV16/18 and/or HPV HR assays were positive in 48 of 64 specimens (75%), and there was a predominance of HPV16 (42 of 48 specimens; 88%). In the 49 specimens that had PCR-based test results, overall agreement with Cervista assay results was 96% (47 of 49 specimens; κ = 0.883). In the 49 specimens that had PCR-based HPV16/18 genotyping results, overall agreement with the Cervista HPV16/18 results was 94% (46 of 49 specimens; κ = 0.847). In the 36 primary carcinoma specimens that had valid HPV in situ hybridization/p16 immunostaining results, overall agreement with the Cervista assay results was 92% (33 of 36 specimens; κ = 0.679). CONCLUSIONS: Cervista HPV16/18 and Cervista HPV HR testing of head and neck FNA specimens is a valid option for determining HPV16/18 status in patients with oropharyngeal carcinoma.

Fine-needle aspiration diagnosis of lymphomas with signet ring cell features: potential pitfalls and solutions.

BACKGROUND: Lymphoma with signet ring cell features (LSF) is a rare morphologic variant of non-Hodgkin lymphoma. Although it has been well documented in the surgical pathology literature, to the best of the authors's knowledge, the features of LSF in fine-needle aspiration (FNA) samples have rarely been reported. An accurate cytologic diagnosis of LSF is of important therapeutic significance. METHODS: The authors retrospectively reviewed 7 FNA cases of LSF for cytologic features, ancillary studies, corresponding histologic findings, and the patients' clinical and radiologic information to illustrate the diagnostic clues and potential pitfalls. RESULTS: The final diagnoses, based on a multidisciplinary approach, were follicular lymphoma (5 patients), large B-cell lymphoma of follicular center cell origin (1 patient), and low-grade B-cell lymphoma with plasmacytoid features (1 patient). FNAs were obtained from both lymph node and extranodal sites. Common cytologic features included various percentages of signet ring cells in a background of nonvacuolated lymphomatous cells, lymphoglandular bodies, and cytoplasmic rings. The majority of signet ring cells contained a single, large, clear intracytoplasmic vacuole that pushed the nucleus laterally whereas fewer cells contained ≥ 2 vacuoles that indented the nucleus into a scalloped or stellate configuration. These cells resemble, to some degree, other lesions with signet ring cell features. One of the diagnostic clues of LSF was the similarity in nuclear details between signet ring cells and surrounding nonvacuolated lymphoid cells. CONCLUSIONS: Familiarity with cytologic features, correlation with clinical/radiologic information, and ancillary studies are important for an accurate diagnosis of LSF and for distinguishing it from other lesions with signet ring cell features in FNA samples.

Use of fluorescence in situ hybridization to predict response to bacillus Calmette-Guérin therapy for bladder cancer: results of a prospective trial.

PURPOSE: No reliable methods currently exist to predict patient response to intravesical immunotherapy with bacillus Calmette-Guérin given after transurethral resection for high risk nonmuscle invasive bladder cancer. We initiated a prospective clinical trial to determine whether fluorescence in situ hybridization results during bacillus Calmette-Guérin immunotherapy can predict therapy failure. MATERIALS AND METHODS: Candidates for standard of care bacillus Calmette-Guérin were offered participation in a clinical trial. Fluorescence in situ hybridization was performed before bacillus Calmette-Guérin, and at 6 weeks, 3 months and 6 months during bacillus Calmette-Guérin therapy with maintenance. Cox proportional hazards regression was used to assess the relationship between fluorescence in situ hybridization results and tumor recurrence or progression. The Kaplan-Meier product limit method was used to estimate recurrence-free and progression-free survival. RESULTS: A total of 126 patients participated in the study. At a median followup of 24 months 31% of patients had recurrent tumors and 14% experienced disease progression. Patients who had positive fluorescence in situ hybridization results during bacillus Calmette-Guérin therapy were 3 to 5 times more likely than those who had negative fluorescence in situ hybridization results to experience recurrent tumors and 5 to 13 times more likely to have disease progression (p <0.01). The timing of positive fluorescence in situ hybridization results also affected outcomes. For example, patients with a negative fluorescence in situ hybridization result at baseline, 6 weeks and 3 months demonstrated an 8.3% recurrence rate compared to 48.1% for those with a positive result at all 3 points. CONCLUSIONS: Fluorescence in situ hybridization results can identify patients at risk for tumor recurrence and progression during bacillus Calmette-Guérin immunotherapy. This information may be used to counsel patients about alternative treatment strategies.

Activating enhancer-binding protein-2ß nucleolar localization predicts poor survival after stage I non-small cell lung cancer resection.

BACKGROUND: Activating enhancer-binding protein-2ß (AP2ß) is a transcription factor involved in apoptosis. The purpose of the current study was to assess the cellular location and level of AP2ß in non-small cell lung cancer (NSCLC) and normal lung tissue and investigate whether the level and localization of AP2ß expression is predictive of overall survival in patients with stage I NSCLC. METHODS: We performed immunohistochemical analysis of tissue microarrays (TMAs) prepared from stage I NSCLC specimens with adjacent normal lung tissue from two independent sets of patients who underwent lung resection with curative intent at our institution. The AP2ß intensity was assessed in TMAs, and AP2ß staining patterns were classified as either diffuse or nucleolar in the TMAs. The AP2ß intensity and localization were analyzed for correlation with patients' survival. RESULTS: Immunohistochemical analysis of TMAs showed that the intensity of AP2ß immunohistochemical staining did not correlate with overall survival. When location of AP2ß was analyzed in TMAs, all of the normal lung tissue had diffuse pattern of AP2ß. In the first set of NSCLC, patients with nucleolar pattern had a significantly lower 5-year survival rate than patients with diffuse pattern (67% versus 100%; p=0.004); this finding was confirmed in the second set (64% versus 91%; p=0.02). Multivariate analysis revealed that nucleolar pattern was an independent predictor of poor overall survival in both sets. CONCLUSIONS: The AP2ß, which is located in the nucleoplasm in normal lung tissue, is found in either nucleoplasm or nucleoli in NSCLC. The patients with AP2ß in the nucleoli had poor survival compared with patients with AP2ß in the cytoplasm.

Expression and relevance of TRPS-1: a new GATA transcription factor in breast cancer.

GATA transcription factor family members have been found to play a critical role in the differentiation of many tissue types. For example, GATA-3 has been found to be highly correlated with estrogen receptor α (ER) expression and is emerging as one of the "master regulators" in breast ductal epithelial cell differentiation. Recently, we discovered another GATA family member highly prevalent in breast cancer called the trichorhinophalangeal syndrome-1 gene (TRPS-1). Using a quantitative immunohistochemistry (qIHC) approach, we found that TRPS-1 was significantly correlated with ER, PR, GATA-3, as well as HER2 expression. However, TRPS-1 was also found to be expressed in a high proportion of ER(-) ductal epithelial breast cancers (BCs), indicating that it may act as a ductal epithelial cell-specific transcription factor regulating cell fate at some point in the epithelial cell differentiation pathway. In keeping with this hypothesis, we found that TRPS-1 protein expression in BC above a certain threshold using qIHC correlated with markedly improved overall survival. Cox proportional hazards analysis found that both TRPS-1 and ER expression above critical threshold equally predicted for improved survival. Thus, TRPS-1 may be a powerful new positive prognostic marker in BC, and further IHC studies, as well as examination of its molecular function in ductal epithelial cell differentiation in the breast, are warranted. In this regard, data on the role of TRPS-1 in the differentiation of cells from mesenchymal precursors in other tissues, such as kidney metanephric mesenchymal cells, columnar chondrocytes, and osteoblasts, in mouse models may be useful. Indeed, these studies have found that TRPS-1 is a critical regulator of mesenchymal-to-epithelial cell transition. In the mammary gland, the restricted expression of TRPS-1 in human, mouse, and rat ductal epithelial cells suggests that it may also play a similar role during ductal luminal progenitor/stem cell differentiation. We present a model of TRPS-1 action in which it may act upstream of GATA-3 and ER on an earlier ductal epithelial progenitor cell or mammary stem cell during mammary gland development and also helps prevent reversion of ER(+) BC cells back into mesenchymal-like cells. This model predicts that BCs with low or no TRPS-1 expression may inherently be much less differentiated and more aggressive tumors with less favorable prognosis.

Plasma microRNAs as potential biomarkers for non-small-cell lung cancer.

Non-small-cell lung cancer (NSCLC) is the leading cause of cancer-related death. Developing minimally invasive techniques that can diagnose NSCLC, particularly at an early stage, may improve its outcome. Using microarray platforms, we previously identified 12 microRNAs (miRNAs) the aberrant expressions of which in primary lung tumors are associated with early-stage NSCLC. Here, we extend our previous research by investigating whether the miRNAs could be used as potential plasma biomarkers for NSCLC. We initially validated expressions of the miRNAs in paired lung tumor tissues and plasma specimens from 28 stage I NSCLC patients by real-time quantitative reverse transcription PCR, and then evaluated diagnostic value of the plasma miRNAs in a cohort of 58 NSCLC patients and 29 healthy individuals. The altered miRNA expressions were reproducibly confirmed in the tumor tissues. The miRNAs were stably present and reliably measurable in plasma. Of the 12 miRNAs, five displayed significant concordance of the expression levels in plasma and the corresponding tumor tissues (all r>0.850, all P<0.05). A logistic regression model with the best prediction was defined on the basis of the four genes (miRNA-21, -126, -210, and 486-5p), yielding 86.22% sensitivity and 96.55% specificity in distinguishing NSCLC patients from the healthy controls. Furthermore, the panel of miRNAs produced 73.33% sensitivity and 96.55% specificity in identifying stage I NSCLC patients. In addition, the genes have higher sensitivity (91.67%) in diagnosis of lung adenocarcinomas compared with squamous cell carcinomas (82.35%) (P<0.05). Altered expressions of the miRNAs in plasma would provide potential blood-based biomarkers for NSCLC.

Prospective isolation of clonogenic mantle cell lymphoma-initiating cells.

Here, we have prospectively isolated and characterized, for the first time, clonogenic cells with self-renewal capacities from mantle cell lymphoma (MCL), a particularly deadly form of non-Hodgkin's lymphoma (NHL). Self-renewal and tumorigenic activities were enriched in MCL cell fractions that lacked expression of the prototypic B-cell surface marker, CD19. CD45+CD19- cells represented a relatively small fraction of the total MCL tumor cells; however, they recapitulated the heterogeneity of original patient tumors on transplantation into immunodeficient mice. As few as 100 of these cells displayed self-renewal capacities in secondary and tertiary recipient mice by in vivo limiting dilution assays. Similar to leukemic stem cells, CD45+CD19- MCL cells also displayed a quiescent status as determined by dye efflux assays. In summary, this study is the first to isolate subpopulations of MCL cells that have self-renewal and tumorigenic capacities. Identification and characterization of MCL-ICs are important first steps toward understanding how self-renewal and tumorigenicity are regulated in MCL and designing targeted therapies against MCL-ICs will ultimately lead to improved outcomes for MCL patients.

A review on the current state of urine cytology emphasizing the role of fluorescence in situ hybridization as an adjunct to diagnosis.

Urinary cytology has a significant role in the detection and surveillance of patients with urothelial carcinoma (UC), which has a high morbidity rate in the United States. Examination of the urine is a comprehensive screen of both the upper and lower urinary tract and is ideal for detecting both primary bladder UC and synchronous or metachronous, multifocal UCs that commonly occur because of a "field effect." This field effect is the result of both clonal and random genetic abnormalities that have resulted from exposure to carcinogens (most frequently in tobacco smoke) in conjunction with the individual's ability to repair DNA damage. Although urinary cytology has high specificity for the detection of UC, its sensitivity is relatively low, especially for more prevalent low-grade tumors. Consequently, several urine-based tests have been investigated, some of which are available commercially and approved by the US Food and Drug Administration. However, these tests also have their limitations and often have lower specificity than urinary cytology. Consequently, urinary cytology, which is a noninvasive, cost-effective test, continues in mainstream use because of its ability to detect high-grade, flat lesions that can be difficult to detect clinically and that often have more aggressive biologic behavior.