High Percentage Of False-positive Results Research Articles

Abstract PO2-28-11: How to improve margins in breast cancer surgery: a

Abstract Objective: Intraoperative specimen mammography (ISM) is a diffuse technique that allows surgeons to check specimens immediately after lumpectomy, instead of intraoperative frozen sections, definitely abandoned. in Italy and Europe, because it is regarded as too expensive and time-consuming examination. Although the specimen is slightly compressed, the radiological image can be distorted by tissue overlap, and this may affect the evaluation of tumor borders, resulting in extension of the lumpectomy. As ISM may be less precise due to inadequate compression, a vacuum effect was applied to the specimen to increase the precision of margin detection. Study design: This study was conducted at St. Anna Hospital Breast Unit, Turin, Italy. Women who underwent lumpectomy for cancer were eligible for inclusion. BCS resection was performed with a free margin, and the surgical specimen was imaged immediately by SSM and evaluated by an expert radiologist and surgeon.Inclusion criteria were: breast cancer detected by a screening test, and treatment with surgical lumpectomy. Both standard ISM (sISM) and vacuum ISM (vISM) were performed. A dedicated breast surgeon at the study institution performed both surgery and radiological scans, and their interpretation. A dedicated radiologist reviewed all of the images. ISM was performed by a digital specimen mammography system (Faxitron, Bioptics Inc., Tucson, AZ, USA) in the operating room. Specimen registration and ISM analysis took 3 min. sISM (two orthogonal projections) was performed. Specimens were sealed in plastic bags in the vacuum apparatus (TissueSAFE Milestone Medical, Sorisole, Italy); this process took a few seconds. 152 specimens obtained after lumpectomy from 1 April 2021 to 31 April 2022 were scanned. sISM (two orthogonal projections) was performed. Next, the specimen was placed in a vacuum bag, and vISM was performed. Additional tissue was removed if the surgeon considered that excision was inadequate. Finally, the specimen was sent for definitive histopathological analysis, which is the gold standard for the assessment of surgical margins. Intraoperative histological margin assessment was not performed. The sISM and vISM images and final histopathology reports were compared. A first experience on a limited number of patients to demonstrate feasibility of the technique, is reported in table 1 and 2. Results: For sISM, specificity was 43,85% [95 % confidence interval (CI) 35.96-51.73], sensitivity was 40.91% (95 % CI 33.09-48.73), positive predictive value (PPV) 10.98% (95 % CI 6.01-15.95) and negative predictive value (NPV) 81.43% (95 % CI 75.25-87.61). For vISM, specificity 92,31% (95 % CI 88,07-96.54), sensitivity 72.73% (95 % CI 65.65-79.81), PPV 61.54% (95 % CI 53.80-69.27) and NPV 95.24% (95 % CI 91.85-98.62). Conclusion: ISM is a valid, safe and quicker alternative to intraoperative histopathological study, but has been reported to be limited due to less compression than standard SSM. Consequently, ISM may result in a high percentage of false-positive results, meaning unnecessary wider resections that lead to increased operative times and worse aesthetic results. A vacuum effect was performed on the specimen to increase the precision of margin detection. vISM images seem to be easier to interpret than sISM images (Figs. 1–3) as they are characterized by a vacuum-created radiolucent rim that better defines the tumor margins. These data suggest that the vacuum technique is feasible, cost-saving and yields results that are similar to those from frozen sections but without the limitations, such as prolonged operating time, high variability in sensitivity due to pathologists abilities, risk of compromising the histology, and unreliability for small lumps and ductal carcinoma in situ. Keywords: Breast cancer; Intraoperative mammography; Lumpectomy; Specimen mammography; Vacuum intraoperative mammography. Table 1. Clinical Data IC, invasive cancer; DCIS ductal carcinoma in situ; ADH, atypical ductal hyperplasia; ILC, invasive lobular cancer; B3, lesions of uncertain malignant potential; IMPC, invasive micropapillary carcinoma; NST, no special type; sISM, standard intraoperative specimen mammography; vISM, vacuum intraoperative specimen mammography. ª Margin: 0, involved; 1, free Table 2. Figure 1 - 2 - 3 Standard intraoperative specimen mammography (left) and vacuum intraoperative specimen mammography (right). Citation Format: Maria Grazia Baù, Vincenzo Marra, Alessandra Surace, Donatella Tota, Maria Piera Mano, Aurelia Mondino, Alessandro Bottero, Elisabetta Robba. How to improve margins in breast cancer surgery: a [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-28-11.

The BlueScreen HC assay to predict the genotoxic potential of fragrance materials

BlueScreen HC is a mammalian cell-based assay for measuring the genotoxicity and cytotoxicity of chemical compounds and mixtures. The BlueScreen HC assay has been utilized at the Research Institute for Fragrance Materials in a safety assessment program as a screening tool to prioritize fragrance materials for higher-tier testing, as supporting evidence when using a read-across approach, and as evidence to adjust the threshold of toxicological concern. Predictive values for the BlueScreen HC assay were evaluated based on the ability of the assay to predict the outcome of in vitro and in vivo mutagenicity and chromosomal damage genotoxicity assays. A set of 371 fragrance materials was assessed in the BlueScreen HC assay along with existing or newly generated in vitro and in vivo genotoxicity data. Based on a weight-of-evidence approach, the majority of materials in the data set were deemed negative and concluded not to have the potential to be genotoxic, while only a small proportion of materials were determined to show genotoxic effects in these assays. Analysis of the data set showed a combination of high positive agreement but low negative agreement between BlueScreen HC results, in vitro regulatory genotoxicity assays, and higher-tier test results. The BlueScreen HC assay did not generate any false negatives, thereby providing robustness when utilizing it as a high-throughput screening tool to evaluate the large inventory of fragrance materials. From the perspective of protecting public health, it is desirable to have no or minimal false negatives, as a false-negative result may incorrectly indicate the lack of a genotoxicity hazard. However, the assay did have a high percentage of false-positive results, resulting in poor positive predictivity of the in vitro genotoxicity test battery outcome. Overall, the assay generated 100% negative predictivity and 3.9% positive predictivity. In addition to the data set of 371 fragrance materials, 30 natural complex substances were evaluated for BlueScreen HC, Ames, and in vitro micronucleus assay, and a good correlation in all three assays was observed. Overall, while a positive result may have to be further investigated, these findings suggest that the BlueScreen HC assay can be a valuable screening tool to detect the genotoxic potential of fragrance materials and mixtures.

Clinical Impact of Preoperative Magnetic Resonance Imaging in the Evaluation of Myometrial Infiltration and Lymph-Node Metastases in Stage I Endometrial Cancer.

: Purpose: In the developed world, endometrial cancer is one of the most common malignant gynecological cancer types. Due to the highly available diagnostic modalities and patient education, the early detection of the tumor leads to high overall survival. Methods: In this study we analyzed the reliability of preoperative MRI findings in the staging of early stage endometrial cancer, as well as the clinical characteristics of patients underwent radical hysterectomy and the histopathologic evaluation of their tumor, with the retrospective data of radical hysterectomies performed in our hospital between 2010 and 2019. Results: The accuracy, sensitivity, specificity, negative- and positive predictive value of MRI regarding stage were 94.7, 63.3, 94.8, 83.8, and 83.8%, respectively. The accuracy, sensitivity, specificity, negative- and positive predictive value of MRI for the detection of the myometrial invasion were 69.8, 80.0, 60.8, 64.3, and 77.5%, respectively. The accuracy, sensitivity, specificity, negative- and positive predictive value of MRI for the detection of lymph node metastases were 78.1, 28.6, 82, 11.1, and 93.6%, respectively. Conclusions: Based on our results, MRI is the method of choice in terms of evaluating overall staging, as well as myometrial invasion, as its specificity and negative predictive value are relatively high. However, systematic lymphadenectomy showed improved cancer-related survival and recurrence-free survival. Our studies showed that the diagnosis of lymph node metastases is difficult with MRI modality since hyperplastic and metastatic nodes cannot easily differentiate, leading to a high percentage of false-positive results. Therefore, other imaging modalities may be used for more accurate evaluation. New findings of our study were that the role of the radiologist’s expertise in the evaluation of MR imaging plays an essential role in lowering false-negative and false-positive results. Therefore, findings evaluated by a radiologist with high-level expertise in gynecological imaging can complement the clinical findings and help substantially define the needed treatment.

Validation of Diaporthe toxica resistance markers in European Lupinus angustifolius germplasm and identification of novel resistance donors for marker-assisted selection

The fungus, Diaporthe toxica, anamorph Phomopsis sp., previously classified as P. leptostromiformis, is a plant endophyte and occasional pathogen, causing Phomopsis stem blight. This disease is damaging not only to lupins but also to the animals grazing on infected plants, due to the toxic secondary metabolites called phomopsins. The aim of this work was to validate markers for resistance to Phomopsis stem blight in narrow-leafed lupins and identify novel germplasm with increased levels of resistance to the disease. Plant inoculations were performed using ten isolates of D. toxica, originating from Australia and Poland. The European core collection of L. angustifolius was evaluated both in a controlled environment and with field experiments to classify the accessions based on their resistance to the disease. Simultaneously, the accessions were assayed with disease resistance markers to identify donors of hypothetical resistance alleles. We have found that the European lupin germplasm collection preserves wild and domesticated donors of at least two resistance genes to Phomopsis stem blight, including Phr1 and PhtjR. Molecular markers PhtjM7, InDel2, and InDel10, tagging PhtjR gene, were applicable for marker-assisted selection targeting the European gene pool with an expected accuracy of 95%. None of diagnostic markers for the Phr1 locus was found useful for European breeding programs; two existing markers Ph258M1 and Ph258M2 were unreliable, due to a high percentage of false-positive results (up to 58%) and a high recombination rate between markers (~ 30%).

Low-dose computer tomography as a screening tool for lung cancer in a high risk population.

The aim of the study was to evaluate the usefulness of low-dose computer tomography as a screening tool for early stage lung cancer. The study was performed in 332 individuals aged 55-70 who were asymptomatic, who had not previously suffered from cancer, and who smoked at least ten packs of cigarettes a year. Baseline and repeated LD-CT scans were performed. Pulmonary nodules were classified according to the size and morphology, and the results were categorized as negative (no nodules observed), semi-positive (nodules of 4 mm or smaller in diameter) and positive (nodules 5 mm or larger). Based on the category of the patient, either a repeat low-dose CT, a bronchoscopy with or without a biopsy, or a PET-CT was performed. The baseline screening showed 59 positive results. Eighteen patients were hospitalized and underwent bronchoscopy and biopsy. One of these patients had Stage I non small cell lung carcinoma (NSCLC) and a lobectomy was performed. Three patients had Stage IV NSCLC and were referred for chemotherapy. We identified 103 semi-positive results. Only 25 of those patients had a repeat scan because of noncompliance. We observed no significant growth of diagnosed nodules in a semi-positive group. Low-dose CT can be used as a screening tool for early stage lung cancer. A high percentage of false-positive results are observed. There are difficulties in diagnosing nodules in patients with post-tuberculosis changes. A high rate of noncompliance was noticed.

The comparative assessment of the effectiveness of immunoanalysis and tandem mass spectrometry applied for re-testing the children with suspected congenital adrenal cortical hyperplasia

Congenital adrenal cortical hyperplasia (CAH) is one of the commonest endocrine pathologies in the children. Screening newborn infants for CAH is currently based on the measurement of 17-hydroxyprogesterone (17-OHP) levels in blood spots using the immunoenzymatic assay. However, this techniques is known to suffer relatively low specificity accounting for the high percentage of false-positive results. We compared two 17-OHP measurement tecniques, immunoenzymatic assay and liquid chromatography-tandem mass spectrometry (LC-MS/MS) employed for the additional examination of the children in whom screening for CAH revealed the enhanced blood 17-OHP levels. The study included 50 patients at the age from 7 days to 1.5 months born at different gestational ages. 17-OHP levels were measured in all of them using the immunoenzymatic assay and LC-MS/MS. The results of the study indicate that the latter technique should be regarded as the method of choice for the confirmation of diagnosis of CAH. The absence of clinical manifestations of 21-hydroxylase deficiency in the patients in whom the immunoenzymatic assay reveals the enhanced levels of 17-OHP whereas the LC-MS/MS method demonstrates the normal or only slightly elevated concentrations of 17-OHP allows to exclude diagnosis of CAH. The gestational age of the infant is the key factor in the choice of the upper threshold level of 17-OHP for the purpose of screening; the child's body weight is of low diagnostic value. The 17-OHP levels measured by LC-MS/MS in the boys may be slightly higher than the reference values compared with the girls.

VALUTATION OF OFFICIAL MOUSE BIOASSAY FOR THE DETECTION OF LIPOPHILIC MARINE TOXINS

The official biotoxicological (MBA) method for the determination of lipophilic marine toxins shows important gaps with regard to reproducibility, specificity and quality of the data provided and serious ethical contraindications. The Commission Regulation (EU) No 15/2011 establishes the date of December 31, 2014 as the deadline for replacement of the mouse test with a LC-MS/MS method by the laboratories of the member states responsible for the monitoring of marine biotoxins. In order to facilitate the interpretation of the MBA during this transition period, we further evaluated the specificity and selectivity of this assay in comparison with a LC-MS/MS method in detecting lipophilic marine toxins on mussels of the middle Adriatic Sea. Data show a high percentage of false-positive results on MBA due to interference by yessotoxins. It was also possible to evaluate the toxic profile of the samples analyzed

VALUTATION OF OFFICIAL MOUSE BIOASSAY FOR THE DETECTION OF LIPOPHILIC MARINE TOXINS

The official biotoxicological (MBA) method for the determination of lipophilic marine toxins shows important gaps with regard to reproducibility, specificity and quality of the data provided and serious ethical contraindications. The Commission Regulation (EU) No 15/2011 establishes the date of December 31, 2014 as the deadline for replacement of the mouse test with a LC-MS/MS method by the laboratories of the member states responsible for the monitoring of marine biotoxins. In order to facilitate the interpretation of the MBA during this transition period, we further evaluated the specificity and selectivity of this assay in comparison with a LC-MS/MS method in detecting lipophilic marine toxins on mussels of the middle Adriatic Sea. Data show a high percentage of false-positive results on MBA due to interference by yessotoxins. It was also possible to evaluate the toxic profile of the samples analyzed.

Avaliação do teste do anel em leite na vigilância epidemiológica da brucelose bovina em rebanhos e em laticínios

Analisaram-se 464 amostras individuais de leite e 54 amostras de leite de latões, oriundos de leite dos mesmos animais, por meio do teste do anel do leite (TAL) visando à sua aplicação no diagnóstico individual e de rebanhos da brucelose bovina. Foram também avaliadas 464 amostras de soro sangüíneo por meio de provas do antígeno tamponado acidificado (ATA), soroaglutinação lenta em tubos (SAL) e 2-mercaptoetanol (2-ME), todas para brucelose. Cento e vinte e três amostras (26,5%) testadas pelo TAL apresentaram resultados positivos. Dessas, 30 resultaram positivas ao ATA, 28 ao ATA, à SAL e ao 2-ME e 18 à SAL. Das amostras positivas ao TAL, 95 pertenciam a animais sorologicamente negativos ao 2-ME, caracterizando 77,2% (95/123) das reações falso-positivas; dos resultados negativos ao TAL, 4 pertenciam a animais sorologicamente positivos, caracterizando 1,2% (4/341) de reações falso-negativas no TAL individual. Das 54 amostras de leite de latões analisadas pelo TAL, 17 foram consideradas positivas, das quais uma foi caracterizada como falso-positivo, pois todos os animais que a compunham foram negativos ao 2-ME. De 37 latões considerados negativos ao TAL, três continham leite de animais positivos ao 2-ME, caracterizando 8,1% de falso-negativos. O TAL individual demonstrou elevado percentual de resultados falso-positivos, enquanto o TAL em amostras de leite obtidas em latões detectou 84,2% de latões contaminados e 75% de rebanhos infectados.

Validity of Plasma Aldosterone-to-Renin Activity Ratio in African American and White Subjects With Resistant Hypertension

Recent reports suggesting that primary aldosteronism (PA) is more common than historically thought have often relied on use of the plasma aldosterone concentration (PAC) to plasma renin activity (PRA) ratio (ARR) to identify patients with PA. Prior determinations of the validity of the ARR had been generally limited to subjects that could be withdrawn from antihypertensive therapy and to non-African American subjects. The current study was designed to evaluate prospectively the diagnostic value of the ARR in treated African American and white subjects with resistant hypertension. Consecutive subjects referred to a university hypertension clinic for resistant hypertension were evaluated with an early morning ARR and a 24-h urinary aldosterone and sodium. The presence of PA was defined as a suppressed PRA (<1.0 ng/mL/h) and elevated urinary aldosterone excretion (>12 microg/24 h) during high dietary sodium ingestion (>200 mEq/24 h). In 58 subjects, PA was confirmed. The ARR was elevated (>20) in 45 of 58 subjects with PA and in 35 of the 207 patients without PA, resulting in a sensitivity of 78% and specificity of 83% with a corresponding positive predictive value of 56% and a negative predictive value of 93%. Among African American subjects, the ARR was less sensitive than in white subjects (75% v 80%), but it still had a high negative predictive value (92% v 94%). These data indicate that the ARR is valid as a screening test for PA in African American and white patients on stable antihypertensive treatments, but a high percentage of false-positive results precludes using it for accurate diagnosis of PA.

Iron-oxide-enhanced magnetic resonance imaging of atherosclerotic plaques: postmortem analysis of accuracy, inter-observer agreement, and pitfalls.

Contrast-enhanced magnetic resonance (MR) imaging using ultra small superparamagnetic iron oxide (USPIO) particles is a new noninvasive modality for imaging inflammatory atherosclerotic plaques. We determined the accuracy, interobserver agreement, and potential sources of error of this technique by means of postmortem MR imaging of aortic preparations. Anesthetized atherosclerotic Watanabe heritable hyperlipidemic (WHHL) rabbits were studied after administration of different dosages of intravenous USPIO (DDM 43/34, IDF Berlin, Germany) and different postcontrast time intervals. A (n = 5) received 0 micromol Fe/kg. B (n = 5) received 50 micromol Fe/kg, 8-hour postcontrast interval. C (n = 5) received 50 micromol, 24 hours. D received 200 micromol, 48 hours. The aortas were removed and 3-mm segments prepared for postmortem examination by MR imaging using a T2-weighted gradient-echo sequence (TR/TE/FA; 41 milliseconds/11 milliseconds/15 degrees ), radiography (mammography), and histology (iron staining). USPIO accumulation was defined as the presence of 20 iron-positive cells per microscopic view (x100 magnification). Two independent readers analyzed the MR images and rated their confidence level for a positive MRI finding, defined as a focal signal loss, on a 5-point scale. The results were evaluated by receiver-operator characteristic (ROC) analysis. Of a total of 621 vessel segments technically acceptable for evaluation, 534 were histologically negative and 87 positive. Accuracy, expressed as the area under the ROC curve, was 0.85 for reader 1 and 0.88 for reader 2. Interobserver agreement was 0.67. False-positive findings were established by at least one reader for 121 of the 621 segments, false-negative findings for only 15 segments. Calcifications and mural thrombi were identified as potential sources of error of the method. Postmortem USPIO-enhanced MR imaging of atherosclerotic plaques showed a high accuracy and good interobserver agreement in the animal model used here. Further optimization of the method should aim at reducing the rather high percentage of false-positive results.

Clinical significance of placenta previa detected at early routine transvaginal scan.

Transvaginal ultrasonography in early pregnancy was used to determine the prevalence of placenta previa and the rate of persistence until delivery. The location of the placenta was registered systematically in 2342 pregnant women who underwent transvaginal ultrasonography at 10 to 16 weeks' gestation as a primary examination. The outcome of pregnancy as well as the presence or absence of placenta previa at delivery was noted in a total of 2158 cases. A receiver operating characteristic curve was generated for the different measurements from the edge of the placenta to the internal cervical os versus placenta previa at delivery. In 105 of the 2158 women screened in the early stages of pregnancy (4.9%) the placenta extended to or over the internal cervical os, and in 34 of 2158 patients (1.6%) the distance to the placental edge beyond the internal cervical os was equal to or greater than 14 mm. Of the eight cases of placenta previa at delivery, six (75%) were identified in our study, and two cases were missed. When a cutoff value of greater than 14 mm is used for the receiver operating characteristic curve the likelihood is 17.6% (95% confidence interval = 6.8 to 34.5) for placenta previa at delivery. Although a high percentage of false-positive results occur owing to the low prevalence at delivery, this screening procedure can identify high-risk patients who should be rescanned later in pregnancy.

High Percentage of False-Positive Results of Cytokeratin 19 RT-PCR in Blood: A Model for the Analysis of Illegitimate Gene Expression

Cytokeratin 19 (CK19) RT-PCR is widely used in order to detect circulating tumor cells in peripheral blood and bone marrow. However, increasing amounts of information support the fact that it is also associated with a high percentage of false-positive results. In our study, we not only managed to demonstrate the significant limitations of this method, but were also able to clarify the reasons behind these limitations. We developed a completely novel RT-PCR for CK19 and sequenced an intron at nucleotide (nt) 980 of the CK19 mRNA to exclude DNA contamination. Tumor dilution experiments were performed in order to analyze the specificity and sensitivity of the method. Control experiments using the blood of healthy donors were performed. Tumor cell dilution experiments gave a detection limit of one tumor cell. If tumor cells were mixed with an equal volume of pure mononuclear cells, the detection limit was 1 tumor cell in 10⁵ mononuclear cells. RT-PCR of mononuclear cells from healthy blood donors gave false-positive results in 29% of the cases. We conclude that a significant decrease in the sensitivity of CK19 RT-PCR occurs if it is performed in blood cells and that the illegitimate CK19 gene expression in normal cells can lead to false-positive results. These limitations have to be taken into account if RT-PCR is to be used for the detection of tumor cells either in blood or in bone marrow in clinical practice.

Cervical analgesic discography. A new test for the definitive diagnosis of the painful-disk syndrome

The cervical discogenic (painful-disk) syndrome consists of scapular pain radiating into the head, shoulder, and upper arm, often associated with paresthesias but without neurologic deficit. Plain roentgenograms or myelograms are normal or show degenerative changes. Positive-contrast discography has been useful but is subject to a high percentage of false-positive results roentgenographically and nonspecific pain patterns clinically. Analgesic discography more precisely confirms the diagnosis and more accurately locates the pain-producing disk. Injection of a local anesthetic into a painful disk produces transient symptomatic relief and full neck mobility. Its use during a two-year period in 71 consecutive discogenic patients followed by anterior cervical fusion resulted in a 93% excellent or good recovery rate. Analgesic discography is the most effective test for diagnosis and location in the painful-disk syndrome.

Cervical Analgesic Discography

The cervical discogenic (painful-disk) syndrome consists of scapular pain radiating into the head, shoulder, and upper arm, often associated with paresthesias but without neurologic deficit. Plain roentgenograms or myelograms are normal or show degenerative changes. Positive-contrast discography has been useful but is subject to a high percentage of false-positive results roentgenographically and nonspecific pain patterns clinically. Analgesic discography more precisely confirms the diagnosis and more accurately locates the pain-producing disk. Injection of a local anesthetic into a painful disk produces transient symptomatic relief and full neck mobility. Its use during a two-year period in 71 consecutive discogenic patients followed by anterior cervical fusion resulted in a 93% excellent or good recovery rate. Analgesic discography is the most effective test for diagnosis and location in the painful-disk syndrome.

Endometrial lavage as an aid in the cytochemical detection of adenocarcinomata.

In 59 patients with malignant neoplasias of the uterine cavity and/or the upper portion of the cervical canal an evaluation was made of the diagnostic accuracy of a cytochemical method based on the demonstration of a high SDH or DPND content in the neoplastic cells. These exfoliated cells were collected by lavage in a solution of a tetrazolium salt. The neoplastic cells were recognizable in the sediment of the lavage fluid by microscopic examination, because the cytoplasm exhibited an intense red-stained reaction due to the oxidative enzymes present in a much higher quantity than it is usually found in rapidly proliferating non-neoplastic cells. The cervico-vaginal lavage method was not sufficiently accurate for the detection of endometrial carcinoma since it gave poorer results than cytologic smears from the pool. The endometrial lavage method, used in 32 patients plus 61 controls free from malignant tumors of the genital organs had a satisfactory diagnostic accuracy although the control group gave a high percentage of false-positive results.

The two-step exercise electrocardiogram. A double-blind evaluation of its use in the diagnosis of angina dectoris.

A double-blind study was made to evaluate the two-step exercise electrocardiographic test (Master) as a means of differentiating between anginal and nonanginal chest pain in 100 consecutive patients. A high percentage of false-positive results in nonanginal cases and a number of false negatives in anginal cases greatly impaired the usefulness of the test for this purpose. When Master's criterion of an ST depression of 0.5 mm. or more was employed, there were 39 per cent false positives and 12 per cent false negatives. Stricter criteria progressively diminished the number of false positives, but resulted in increasing numbers of false negatives. Even if 1 mm. or more of ST depression was required, there were 8 per cent false positives and 43 per cent false negatives. There were no false positives only when the ST segment was depressed 2 mm. or more. Although an ischemic type of ST depression may be more significant for angina pectoris than the J type, in our series ischemic ST depressions also occurred more frequently than the J type in false-positive tests in nonanginal patients. The new criteria of Master and Rosenfeld were not more satisfactory than the previous criteria recommended. There are relatively few cases in which an objective two-step test is necessary to aid in the differentiation of anginal and nonanginal pain, since an unequivocal diagnosis of angina pectoris or nonanginal pain was made in 86 per cent of cases independently by at least two observers, on the basis of a single interview, and since this percentage could undoubtedly have been increased by further interviews concerning the effect of effort and of nitroglycerin. Insofar as confirmation of a clinical diagnosis of angina pectoris by an objective exercise test is desirable, an ST-segment depression of at least 1 mm. usually offers such confirmation. However, this degree of ST-segment depression is often absent in unequivocal cases of angina pectoris and conversely may be occasionally present in patients with nonanginal pain.