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E C Burton

Publications and source records attributed to E C Burton.

11 recordsLinked to original sources
PubMed2005

Overestimation of clinical diagnostic performance caused by low necropsy rates.

BACKGROUND: Diagnostic sensitivity is calculated as the number of correct diagnoses divided by the sum of correct diagnoses plus the number of missed or false negative diagnoses. Because missed diagnoses are generally detected during clinical follow up or at necropsy, the low necropsy rates seen in current practice may result in overestimates of diagnostic performance. Using three target conditions (aortic dissection, pulmonary embolism, and active tuberculosis), the prevalence of clinically missed cases among necropsied and non-necropsied deaths was estimated and the impact of low necropsy rates on the apparent sensitivity of antemortem diagnosis determined. METHODS: After reviewing case series for each target condition, the most recent study that included cases first detected at necropsy was selected and the reported sensitivity of clinical diagnosis adjusted by estimating the total number of cases that would have been detected had all decedents undergone necropsy. These estimates were based on available data for necropsy rates, time period, country (US v non-US), and case mix. RESULTS: For all three target diagnoses, adjusting for the estimated prevalence of clinically missed cases among non-necropsied deaths produced sensitivity values outside the 95% confidence interval for the originally reported values, and well below sensitivities reported for the diagnostic tests that are usually used to detect these conditions. For active tuberculosis the sensitivity of antemortem diagnosis decreased from an apparent value of 96% to a corrected value of 83%, with a plausible range of 42-91%; for aortic dissection the sensitivity decreased from 86% to 74%; and for pulmonary embolism the reduction fell only modestly from 97% to 91% but was still lower than generally reported values of 98% or more. CONCLUSIONS: Failure to adjust for the prevalence of missed cases among non-necropsied deaths may substantially overstate the performance of diagnostic tests and antemortem diagnosis in general, especially for conditions with high early case fatality.

Aortic Dissection↗
PubMed2000

Malignant gliomas.

Gliomas are a heterogeneous group of neoplasms that comprise the majority of tumors originating in the central nervous system (CNS). In adults, the most frequently encountered of these are high-grade or malignant neoplasms of astrocytic and oligodendrocytic lineage, ie, anaplastic astrocytoma (AA), glioblastoma multiforme (GBM), and anaplastic oligodendroglioma (AO), respectively. Tumors of mixed lineage are also seen, the most common of which is designated anaplastic oligoastrocytoma (AOA). Standard treatment for these tumors is typically surgery, followed by radiation then chemotherapy. Surgery is required for a definitive histopathologic diagnosis, which in turn will dictate subsequent therapy options. Moreover, aggressive tumor resection improves survival outcomes, and in many cases, the patient's neurologic function. We generally advocate the safest, maximal resection attainable for patients with these tumors as a way to improve prognosis. In almost all cases, surgery is followed by radiation therapy. Postsurgical irradiation is the most effective treatment currently available for improving survival. There is also mounting evidence to suggest that additional radiation, given in the form of brachytherapy or radiosurgery, at initial diagnosis as a "boost" to standard radiation or at tumor recurrence, may provide added improvement in survival outcome. Radiosurgery and brachytherapy are therapies often used to treat eligible patients at this institution. Adjuvant chemotherapy, conventionally given after radiation, may offer a modest survival benefit in some patients with GBM. Bischloroethylnitrosourea (BCNU) is the typical first-line agent used, but chemotherapy seems to be most beneficial in young patients, with little if any impact on survival for patients over 60 years old. At this institution, we often defer treatment with adjuvant chemotherapy for elderly patients with GBM due to lack of efficacy and the attendant risk with chemotherapy. For anaplastic astrocytomas, oligodendrogliomas, and oligoastrocytomas, a commonly accepted standard is adjuvant chemotherapy following irradiation with the three-drug regimen--procarbazine, CCNU, and vincristine (PCV). This is due to an earlier clinical trial that showed a survival advantage in patients treated with adjuvant PCV compared with patients that received BCNU. However, recent data suggest that treatment with either PCV or BCNU may be appropriate. Both regimens now appear to have equal efficacy for anaplastic gliomas in light of a more recent analysis done with larger numbers of patients. AOs are a unique case with respect to tumor chemosensitivity and patient survival. Molecular studies have identified a subpopulation of patients with AO whose tumors have lost chromosomes 1p and 19q. Patients with this molecular pattern have an exceptional responsiveness to PCV chemotherapy and have prolonged survival. Currently, trials are being conducted to confirm this finding and to determine the best treatment regimen for these patients, with particular regard to the timing of radiation and chemotherapy.

Antineoplastic Agents↗
PubMed1998

Autopsy diagnoses of malignant neoplasms: how often are clinical diagnoses incorrect?

CONTEXT: Autopsy often reveals new diagnoses of malignant neoplasms, but as technological advances to improve diagnosis during life have improved, autopsy rates have declined dramatically. OBJECTIVE: To determine if there is still a high discordance rate between clinical and autopsy diagnoses of malignant neoplasms despite increasing technological advances in diagnostic methods. DESIGN AND SETTING: A 10-year retrospective study (1986-1995) of all autopsies performed at the Medical Center of Louisiana at New Orleans. PARTICIPANTS: All patients autopsied, excluding preterm fetuses, at the Medical Center of Louisiana at New Orleans, by both Tulane and Louisiana State University Schools of Medicine in which consent was obtained or authorization given from the Orleans Parish Coroner's Office. MAIN OUTCOME MEASURES: Discordance between clinical and autopsy diagnoses of malignant neoplasms. RESULTS: A total of 1625 cases were reviewed of which 520 preterm fetuses were excluded. Of the remaining 1105 cases, 654 were male and 451 were female. The mean age was 48.3 years (range, 1-98 years). A total of 433 neoplasms were diagnosed, 250 of which were malignant. One hundred eleven malignant neoplasms in 100 patients had been either undiagnosed or misdiagnosed, and in 57 patients, the immediate cause of death could be attributed to the malignant neoplasm. The discordance between clinical and autopsy diagnoses of malignant neoplasms in this study is 44%, which is similar to previously reported studies. CONCLUSION: The discordance rate between clinical and autopsy diagnoses of malignant neoplasms is large and confirms the importance of the postmortem examination.

Adolescent↗
PubMed1991

Divergent patterns of incorporation of bromodeoxyuridine and iododeoxyuridine in human colorectal tumor cell lines.

Using a panel of four human colorectal tumor (HCT) cell lines, we have quantitatively characterized the incorporation of bromodeoxyuridine (BrdUrd) and iododeoxyuridine (IdUrd) into DNA, both as individual agents and in combination with fluoropyrimidines. The intrinsic ability of these cell lines to incorporate BrdUrd, as reflected by the concentration required to achieve half-maximal incorporation, varied almost 4-fold across this panel, from 1.6 microM for HuTu80 cells to 6.1 microM for HT29 cells. Three of the four cell lines (HT29, SW480, SW620) responded to fluoropyrimidines as expected, displaying 100-150% increases in BrdUrd incorporation when combined with growth inhibitory concentrations of fluorouracil (FUra). In contrast, neither FUra nor fluorodeoxyuridine (FdUrd) was able to increase BrdUrd incorporation in HuTu80 cells by more than 25%, even in the presence of 100 microM leucovorin. IdUrd incorporation was modulated to a substantially higher degree in both HT29 and HuTu80 cell lines. Finally we demonstrate the feasibility of a technique for evaluating the net effect of fluoropyrimidine treatments on de novo thymidine nucleotide production in a single specimen, using a combination of normotopic and stable-isotope labeled BrdUrd. We propose that this approach may be useful in evaluating the response of an individual tumor to fluoropyrimidines in vivo.

Bromodeoxyuridine↗
PubMed1989

Response of human HT-29 colorectal tumor cells to extended exposure to bromodeoxyuridine.

Effects of the extended exposure of a human colorectal tumor-cell line (HT-29) to bromodeoxyuridine (BrdUrd) were studied in anticipation of the clinical use of that agent to treat colorectal cancer, particularly as a regionally delivered radiosensitizer. We found that 72-h exposure to a concentration of BrdUrd that is estimated to be locally maintained in the liver (100 microM) was significantly cytotoxic with a 3-log reduction in survival. As measured by GC/MS-SIM method, incorporation of BrdUrd into DNA followed an unexpected time course in that continuous exposure to 10 microM BrdUrd resulted in maximal incorporation at 3 days, after which the extent of incorporated analog fell significantly (despite daily changes of the medium). This finding was apparently due to a greater rate of loss of BrdUrd from the medium at later time points. Flow cytometric analysis using an anti-BrdUrd antibody (IU-4) revealed that antibody binding also peaked and fell off with time. However, at exposure times of greater than 24 h, the timing and extent of this decline were significantly different than had been indicated by the GC/MS method. These results indicate that the quantitative relationship between antibody staining and BrdUrd incorporation changes as drug-exposure time increases and that quantitative studies of anti-BrdUrd antibody binding must be interpreted with caution, especially when extended drug-treatment protocols have been used.

Bromodeoxyuridine↗