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PubMed2001

Concordance in judgments among c-erbB-2 (HER2/neu) overexpression detected by two immunohistochemical tests and gene amplification detected by Southern blot hybridization in breast carcinoma.

We compared the c-erbB-2 protein overexpression status detected by the HercepTestTM (DAKO A/S, Grostrup, Denmark) with another conventional immunohistochemistry system using an anti-c-erbB-2 rabbit polyclonal antibody (Nichirei Co., Tokyo, Japan) and with the c-erbB-2 gene amplification status detected by Southern blot hybridization in 101 surgically resected breast carcinomas. According to the criteria for overexpression, recommended by the manufacturer, c-erbB-2 overexpression by HercepTestTM was detected in 24 cancers (24%), comprising six score-2 tumors and 18 score-3 tumors. The level of agreement in judgment of the HercepTestTM, among three independent observers, was excellent (kappa = 0.845). C-erbB-2 overexpression by Nichirei's antibody and c-erbB-2 gene amplification were detected in 21% and 16% of cases, respectively, and their concordance with HercepTestTM scores of 2-3 was 89% and 90%, respectively. In the score-3 cases by Hercep TestTM only, the concordance rates with overexpression by Nichirei's immunohistochemistry and with gene amplification were slightly higher, 94% and 93%, respectively. Score-2 cases by HercepTestTM were mostly judged as negative overexpression by Nichirei's antibody and as no amplification by Southern blot hybridization. The present results showed that HercepTestTM score-3 detected c-erbB-2 overexpression almost optimally as well as the conventional methods and the score-3 breast carcinomas had clinical and biological implications. Further examination would be necessary to decide the significance of breast cancers of HercepTestTM score 2.

Blotting, Southern↗

PubMed2001

Detection of Salmonella and simultaneous detection of Salmonella and Shiga-like toxin-producing Escherichia coli using the magnetic capture hybridization polymerase chain reaction.

The magnetic capture hybridization polymerase chain reaction (MCH-PCR) was used to detect Salmonella and also to simultaneously detect Salmonella and Shiga-like toxin-producing Escherichia coli (SLTEC). Fifty-seven Salmonella and 41 SLTEC were included in the study. Salmonella were detected either individually by a single MCH-PCR assay targeting the inv gene or simultaneously with SLTEC by a multiplex MCH-PCR in which SLTEC were detected using primers for the slt genes. Both single and multiplex assays were found to be specific for tested pathogens. The results indicate that MCH-PCR can be used as means of detecting single or multiple bacterial pathogen(s).

Adhesins, Bacterial↗

PubMed2003

Detection of Legionella pneumophila in water samples by quantitative culture and an antigen detection assay.

We evaluated the new Legionella pneumophila antigen detection assay Binax Equate for quantitative determination of legionellae in potable water samples. Seventy-seven water samples from different sources were investigated by Binax Equate and quantitative culture. Our culture assay is able to detect 20 to 40 cfu per 100 ml water. The rates of detection of legionellae were 1% (1 of 77) for the antigen detection assay and 25% (19 of 77) by culture. We were able to detect antigen in one water sample with 28 cfu per ml L. pneumophila serogroup 1. In in-vitro experiments the antigen assay had a sensitivity of about 333 cfu per ml when the bacteria were added directly to the test tubes and about 1000 cfu per ml when a simulated water sample was investigated. None of the water samples positive for L. pneumophila serogroup 2 to 14 was positive in the Binax Equate. The new antigen assay proved to be a valuable tool for investigating heavy L. pneumophila Serogroup 1 contamination in potable water systems but lacks sufficient sensitivity to be used in the surveillance of water supplies.

Antigens, Bacterial↗

PubMed1995

Multi-element detection of organometals by supercritical fluid chromatography with inductively coupled plasma mass spectrometric detection.

Organometal compounds of arsenic, antimony, and mercury are speciated using supercritical fluid chromatography with inductively coupled plasma mass spectrometric (ICP-MS) detection. The multi-element capability of ICP-MS for transient signals is examined by detecting five compounds containing all three elements in a single chromatographic injection. The results obtained are compared with those obtained from flame-ionization detection (FID). Trimethyl arsine is not distinguished from the solvent peak when FID is used because it coelutes with the solvent, whereas trimethyl arsine is detected when ICP-MS is used because of its element-selective nature. The detection limits obtained by ICP-MS are 2-3 orders of magnitude lower than those obtained by FID. Determination of isotope abundance is also demonstrated for triphenyl antimony and diphenyl mercury compounds.

Antimony↗

PubMed2006

A new detection algorithm (NDA) based on fuzzy cellular neural networks for white blood cell detection.

White blood cell detection is one of the most basic and key steps in the automatic recognition system of white blood cells in microscopic blood images. Its accuracy and stability greatly affect the operating speed and recognition accuracy of the whole system. But there are only a few methods available for cell detection or segmentation due to the complexity of the microscopic images. This paper focuses on this issue. Based on the detailed analysis of the existing two methods--threshold segmentation followed by mathematical morphology (TSMM), and the fuzzy logic method--a new detection algorithm (NDA) based on fuzzy cellular neural networks is proposed. NDA combines the advantages of TSMM and the fuzzy logic method, and overcomes their drawbacks. With NDA, we can detect almost all white blood cells, and the contour of each detected cell is nearly complete. Its adaptability is strong and the running speed is expected to be comparatively high due to the easy hardware implementation of FCN. Experimental results show good performance.

Algorithms↗

PubMed2006

Analysis of the kinestatic charge detection system as a high detective quantum efficiency electronic portal imaging device.

Megavoltage x-ray imaging suffers from reduced image quality due to low differential x-ray attenuation and large Compton scatter compared with kilovoltage imaging. Notwithstanding this, electronic portal imaging devices (EPIDs) are now widely used in portal verification in radiotherapy as they offer significant advantages over film, including immediate digital imaging and superior contrast range. However video-camera-based EPIDs (VEPIDs) are limited by problems of low light collection efficiency and significant light scatter, leading to reduced contrast and spatial resolution. Indirect and direct detection-based flat-panel EPIDs have been developed to overcome these limitations. While flat-panel image quality has been reported to exceed that achieved with portal film, these systems have detective quantum efficiency (DQE) limited by the thin detection medium and are sensitive to radiation damage to peripheral read-out electronics. An alternative technology for high-quality portal imaging is presented here: kinesatic charge detection (KCD). The KCD is a scanning tri-electrode ion-chamber containing high-pressure noble gas (xenon at 100 atm) used in conjunction with a strip-collimated photon beam. The chamber is scanned across the patient, and an external electric field is used to regulate the cation drift velocity. By matching the scanning velocity with that of the cation (i.e., ion) drift velocity, the cations remain static in the object frame of reference, allowing temporal integration of the signal. The KCD offers several advantages as a portal imaging system. It has a thick detector geometry with an active detection depth of 6.1 cm, compared to the sub-millimeter thickness of the phosphor layer in conventional phosphor screens, leading to an order of magnitude advantage in quantum efficiency (>0.3). The unique principle of and the use of the scanning strip-collimated x-ray beam provide further integration of charges in time, reduced scatter, and a significantly reduced imaging dose, enhancing the imaging signal-to-noise ratio (SNR) and leading to high DQE. While thick detectors usually suffer from reduced spatial resolution, the KCD provides good spatial resolution due to high gas pressure that limits the spread of scattered electrons, and a strip-collimated beam that significantly reduces the inclusion of scatter in the imaging signal. A 10 cm wide small-field-of-view (SFOV) prototype of the KCD is presented with a complete analysis of its imaging performance. Measurements of modulation transfer function (MTF), noise power spectrum (NPS), and DQE were in good agreement with Monte Carlo simulations. Imaging signal loss from recombination within the KCD chamber was measured at different gas pressures, ion drift velocities, and strip-collimation widths. Image quality for the prototype KCD was also observed with anthropomorphic phantom imaging in comparison with various commercial and research portal imaging systems, including VEPID, flat-panel imager, and conventional and high contrast film systems. KCD-based imaging provided very good contrast and good spatial resolution at very low imaging dose (0.1 cGy per image). For the prototype KCD, measurements yielded DQE(0)=0.19 and DQE(1 cy/mm)=0.004.

Computer-Aided Design↗

PubMedDate not supplied

Computerized detection of pulmonary nodules in digital chest images: use of morphological filters in reducing false-positive detections.

Currently, radiologists can fail to detect lung nodules in up to 30% of actually positive cases. If a computerized scheme could alert the radiologist to locations of suspected nodules, then potentially the number of missed nodules could be reduced. We are developing such a computerized scheme that involves a difference-image approach and various feature-extraction techniques. In this paper, we describe our use of digital morphological processing in the reduction of computer-identified false-positive detections. A feature-extraction technique, which includes the sequential application of nonlinear filters of erosion and dilation, is employed to reduce the camouflaging effect of ribs and vessels on nodule detection. This additional feature-extraction technique reduced the true-positive rate of the computerized scheme by 13% and the false-positive rate by 50%. In a comparison of the scheme with and without the additional feature-extraction technique, inclusion of the additional technique increased the detection sensitivity by about half at the level of three to four false-positive detections per chest image.

False Positive Reactions↗

PubMed1996

Detection of serum immunoglobulin M to human cytomegalovirus by western blotting correlates better with virological data than detection by conventional enzyme immunoassay.

Western blotting (immunoblotting) with proteins separated from purified human cytomegalovirus (HCMV) particles (viral WB) has repeatedly been shown to be a reliable and sensitive method for detecting HCMV-specific immunoglobulin M (IgM). The aim of the present work was to determine whether IgM detected by viral WB correlates with virological diagnosis better than conventional enzyme immunoassay (conv-EIA). The presence of an active HCMV infection was documented on the basis of isolation of virus from urine and/or saliva and on the basis of antigenemia and/or PCR with polymorphonuclear leukocytes for immunocompetent and immunocompromised subjects, respectively. The agreement observed between IgM detected by viral WB and the results obtained by virological detection of HCMV was significantly higher (88.7%) than the agreement of IgM detected by conv-EIA and virological results (67.5%).

Antibodies, Viral↗

PubMed1978

Increased Escherichia coli enterotoxin detection after concentrating culture supernatants: possible new enterotoxin detectable in dogs but not in infant mice.

The heat-stable enterotoxin (ST) of Escherichia coli can be detected by infant mouse or dog intestinal loop tests. These tests differ in that the dog assay uses concentrated culture supernatants and is based on measurements of net intestinal absorption, whereas the mouse test uses unconcentrated supernatants and depends on gross fluid accumulation. To compare the relative sensitivities of these assays, culture supernatants of randomly selected E. coli isolates from 34 Bangalee diarrhea patients were tested for ST in dog loops and infant mice. Supernatants were also tested for heat-labile enterotoxin (LT) in dog loops, Y-1 adrenal cells, and Chinese hamster ovary cells. E. coli supernatants that produced positive responses for both ST and LT in the dog loop assay (ST+/LT+) also produced positive responses when tested for ST in infant mice and for LT in cell lines. Supernatants of strains negative for ST and LT in dog loop (ST-/LT) were also negative in other assays. Of 10 strains positive for just ST in the dog loop test (ST+/LT-), only 5 were ST positive in the standard infant mouse test. Supernatants of the other five strains (dog loop positive, mouse test negative) were then concentrated 100-fold and retested in mice. Three of these five gave consistently positive results after concentration, and two were only intermittently positive. Concentrated supernatants of negative control strains (ST-/LT-) were all negative in mice. The dog assay detects more strains producing ST than the infant mouse test. The infant mouse test, which detects only gross fluid accumulation, failed to detect approximately half of the 10 strains which produced ST alone (ST+/LT-; P = 0.025). Concentrating supernatants for the mouse assay increases sensitivity for detection of ST, but certain E. coli strains produce a variety of ST to which infant mice do not respond.

Animals↗

PubMed1991

Rapid detection of hepatitis B virus DNA in liver tissue by in situ hybridisation and its combination with immunohistochemistry for simultaneous detection of HBV antigens.

A rapid technique using a non-radioactive receptor molecule (digoxigenin) for intrahepatic hepatitis B virus (HBV) DNA detection using in situ hybridisation was developed. It can be adapted for use in combination with standard immunohistochemistry for simultaneous detection of both HBV DNA and HBV antigens. The total time required for dual detection of HBV antigens and HBV DNA starting from paraffin wax liver sections was two working days. A good signal to background ratio for the detection of HBV DNA was always obtained using this labelling. This technique is cheap, safe, and relatively simple which makes it an ideal tool for the detection of intrahepatic HBV DNA for both routine diagnostic purposes and in research.

DNA, Viral↗

PubMed2003

Accurate molecular detection of melanoma nodal metastases: an assessment of multimarker assay specificity, sensitivity, and detection rate.

BACKGROUND: The application of lymphoscintigraphy followed by sentinel lymph node (SN) biopsy to patients with primary melanoma has revolutionised the ability to identify accurately, yet conservatively, those patients who harbour occult nodal metastases. The molecular detection of SN micrometastases facilitates the cost effective analysis of the entire SN using multiple markers. Currently, a lack of marker specificity is the main barrier preventing the molecular evaluation of SN tissue from becoming clinically applicable. AIMS: To develop a reproducible multimarker reverse transcription-polymerase chain reaction (RT-PCR) assay, with the emphasis on achieving high specificity for the accurate detection of melanoma metastases in nodal tissue. METHODS: Three pigment cell specific (PCS) markers-tyrosinase, Pmel-17, and MART-1-and one cancer testis antigen (CTA)-MAGE-3-were selected for use in a multimarker RT-PCR assay. The conditions for this assay were optimised. RESULTS: High specificity was achievable for each marker by optimising the PCR cycle number such that unwanted transcripts (that is, illegitimate transcripts and/or specific transcripts from other low abundance nodal cell types) remained undetectable in appropriate controls (normal visceral nodes). Tyrosinase was 100% specific at 40 PCR cycles, MAGE-3 and MART-1 at 35 PCR cycles, and Pmel-17 at 30 PCR cycles. Tyrosinase proved to be the most sensitive marker, detecting 10 melanoma cells in 0.1 g of nodal tissue. CONCLUSIONS: Excellent reproducibility of the entire nodal processing and RT-PCR protocol for the detection of very low numbers of melanoma cells in nodal tissue was shown, although there is a risk of false positives using the PCS markers alone, because of an approximate 4-8.5% incidence rate of nodal nevi in melanoma draining SNs (these nevi being absent in all other normal nodes). MAGE-3 was shown to be the only marker that is not expressed by melanocytes. However, because not all melanomas express MAGE-3, it is recommended that more emphasis should be placed on the development of a panel of CTA markers to ensure a zero false positive rate and to provide optimum detection.

Antigens, Neoplasm↗

PubMed2003

Detection of monitoring materials on bedside chest radiographs with the most recent generation of storage phosphor plates: dose increase does not improve detection performance.

PURPOSE: To evaluate the performance of the most recent generation of storage phosphor plates for the detection of low-contrast catheter material on bedside chest radiographs. MATERIALS AND METHODS: In 10 patients in the intensive care unit, bedside chest radiographs were obtained with a 400-speed conventional screen-film system and with storage phosphor plates with exposure levels comparable to a 200-, 400-, or 800-speed conventional system. The chest radiograph was divided into 20 regions, 60% of which were superimposed with low-contrast catheter fragments. Six observers independently assessed the presence of catheter fragments by using a receiver operating characteristic (ROC) methodology. RESULTS: Detection performance (mean area under the ROC curve [Az]) with the storage phosphor plates was significantly superior to that with the screen-film system (Az = 0.76) at all three dose levels (Az = 0.88, 0.87, and 0.83 for 200-, 400-, and 800-speed doses, respectively; P <.05). Increasing the dose to a 200-speed system did not significantly increase detection performance compared with that with the 400-speed digital radiographs (Az = 0.88 vs 0.87). Dose reduction to 800 speed significantly deteriorated the detection performance (Az = 0.83) compared with that with the 400- and 200-speed digital radiographs, respectively. CONCLUSION: The most recent generation of storage phosphor plates is superior to a 400-speed screen-film system for the detection of catheter material, even at an exposure level of 800 speed.

Adult↗

PubMed2004

Sensitivity of noncommercial computer-aided detection system for mammographic breast cancer detection: pilot clinical trial.

PURPOSE: To evaluate a noncommercial computer-aided detection (CAD) program for breast cancer detection with screening mammography. MATERIALS AND METHODS: A CAD program was developed for mammographic breast cancer detection. The program was applied to 2,389 patients' screening mammograms at two geographically remote academic institutions (institutions A and B). Thirteen radiologists who specialized in breast imaging participated in this pilot study. For each case, the individual radiologist performed a prospective Breast Imaging Reporting and Data System (BI-RADS) assessment after viewing of the screening mammogram. Subsequently, the radiologist was shown CAD results and rendered a second BI-RADS assessment by using knowledge of both mammographic appearance and CAD results. Outcome analysis of results of examination in patients recalled for a repeat examination, of biopsy, and of 1-year follow-up examination was recorded. Correct detection with CAD included a computer-generated mark indicating a possible malignancy on craniocaudal or mediolateral oblique views or both. RESULTS: Eleven (0.46%) of 2,389 patients had mammographically detected nonpalpable breast cancers. Ten (91%) of 11 (95% CI: 74%, 100%) cancers were correctly identified with CAD. Radiologist sensitivity without CAD was 91% (10 of 11; 95% CI: 74%, 100%). In 1,077 patients, follow-up findings were documented at 1 year. Five (0.46%) patients developed cancers, which were found on subsequent screening mammograms. The area where the cancers developed in two (40%) of these five patients was marked (true-positive finding) by the computer in the preceding year. Because of CAD results, a 9.7% increase in recall rate from 14.4% (344 of 2,389) to 15.8% (378 of 2,389) occurred. Radiologists' recall rate of study patients prior to use of CAD was 31% higher than the average rate for nonstudy cases (10.3%) during the same time period at institution A. CONCLUSION: Performance of the CAD program had a very high sensitivity of 91% (95% CI: 74%, 100%).

Adult↗

PubMed2000

Frequency and spectrum of HPV types detected in cutaneous squamous-cell carcinomas depend on the HPV detection system: a comparison of four PCR assays.

BACKGROUND: The association of human papillomavirus (HPV) with cutaneous squamous-cell carcinomas (SCCs) has been described recently, but the frequency and spectrum of HPV types identified differed substantially in distinct studies. OBJECTIVE: Comparison of different PCR assays with respect to sensitivity and range of HPV types detected. METHOD: Cutaneous SCC were analyzed for HPV DNA using both consensus PCR assays with degenerate primers and PCR assays with nondegenerate primers derived from HPV types 5 and 8. RESULTS: HPV DNA was found in 50% of SCC specimens using degenerate primers. The rate of HPV-DNA-positive specimens increased to 69% when PCR assays with nondegenerate primers were applied in addition. The spectrum of HPV types detected with each of the PCR assays differed considerably. CONCLUSIONS: The frequency and spectrum of HPV types detected in cutaneous SCC strongly depends on the HPV detection system used and urges the need for standardization of HPV detection and typing in skin lesions in order to characterize HPV types predominating in distinct tumors.

Aged↗

PubMed2003

Detection of Escherichia coli O157:H7 in cattle feces using a polymerase chain reaction-based fluorogenic 5' nuclease (TaqMan) detection assay after secondary enrichment.

Currently, methods for recovering and identifying Escherichia coli O157:H7 from cattle feces are inconsistent and hindered by their inability to specifically and rapidly detect small numbers of organisms from this complex and highly variable matrix. A standard approach for isolating and characterizing E. coli O157:H7 from cattle feces was compared with a polymerase chain reaction (PCR)-based 5' nuclease assay specific for E. coli O157:H7 that included a secondary enrichment step. The PCR-based method proved a better indicator of the presence of the organism than the culture procedure. Retests indicated that the inclusion of a secondary enrichment step and the subsequent analysis by the 5' nuclease assay were reproducible and specific. Escherichia coli O157:H7 could be detected in fecal samples that were otherwise negative after a primary enrichment step, immunomagnetic separation, and plating onto sorbitol MacConkey agar plates containing cefixime and tellurite (CT-SMAC). In samples that were initially identified as culture positive but PCR negative, retesting of the culture isolates on CT-SMAC indicated that the sorbitol fermentation interpretations could frequently not be repeated in retests, whereas retesting using the 5' nuclease assay on the original samples demonstrated a high level of agreement with the initial PCR conclusions. These results indicate the necessity of confirmatory evaluation of isolates culturally recovered by standard cultural methods that involve the interpretation of CT-SMAC. The high level of disagreement between initial culture results and retests, and the high level of agreement between initial PCR results and retests, indicates the advantages of a gene-based detection system for identifying E. coli O157:H7 in cattle feces. Screening large numbers of fecal samples for E. coli O157:H7 would appear to be feasible by integrating the use of enrichment media in serial rounds of incubation with a PCR-based fluorogenic detection procedure in high throughput detection systems that had automated liquid-handling capabilities.

5'-Nucleotidase↗

PubMed2003

Computer-aided detection (CAD) in screening mammography: sensitivity of commercial CAD systems for detecting architectural distortion.

OBJECTIVE: Computer-aided detection (CAD) algorithms have successfully revealed breast masses and microcalcifications on screening mammography. The purpose of our study was to evaluate the sensitivity of commercially available CAD systems for revealing architectural distortion, the third most common appearance of breast cancer. MATERIALS AND METHODS: Two commercially available CAD systems were used to evaluate screening mammograms obtained in 43 patients with 45 mammographically detected regions of architectural distortion. For each CAD system, we determined the sensitivity for revealing architectural distortion on at least one image of the two-view mammographic examination (case sensitivity) and for each individual mammogram (image sensitivity). Surgical biopsy results were available for each case of architectural distortion. RESULTS: Architectural distortion was deemed present and actionable by a panel of expert breast imagers in 80 views of the 45 cases. One CAD system detected distortion in 22 of 45 cases of distortion (case sensitivity, 49%) and in 30 of 80 mammograms (image sensitivity, 38%); it displayed 0.7 false-positive marks per image. Another CAD system identified distortion in 15 of 45 cases (case sensitivity, 33%) and 17 of 80 mammograms (image sensitivity, 21%); it displayed 1.27 false-positive marks per image. Sensitivity for malignancy-caused distortion was similar to or lower than sensitivity for all causes of distortion. CONCLUSION: Fewer than one half of the cases of architectural distortion were detected by the two most widely available CAD systems used for interpretations of screening mammograms. Considerable improvement in the sensitivity of CAD systems is needed for detecting this type of lesion. Practicing breast imagers who use CAD systems should remain vigilant for architectural distortion.

Adult↗

PubMed2004

Computer-aided detection in diagnostic mammography: detection of clinically unsuspected cancers.

OBJECTIVE: We had two objectives: to determine the percentage of women presenting with clinical findings whose diagnostic mammogram led to detection of a breast cancer at a site distant from the original clinical complaint and to assess the performance of computer-aided detection (CAD) on diagnostic mammography. MATERIALS AND METHODS: Three institutions contributed consecutive cases in which a mammogram was obtained to evaluate a clinical finding, after which a histologic diagnosis of breast cancer was made. Clinical data and the mammograms were reviewed to determine the nature of the clinical findings and to document the location and characteristics of 212 biopsy-proven cancers in 197 patients who met the study criteria. Standard four-view breast mammograms were then analyzed by a CAD system. RESULTS: The most common clinical finding was a palpable mass (90%, 177/197), with nipple discharge (5%, 9/197), focal tenderness or pain (2%, 5/197), and miscellaneous complaints (3%, 6/197) also noted. Two separate cancers were found in 7.6% (15/197) of the cases. In another 7.6% (15/197) of the cases, the single diagnosed cancer was not at the location of the specific clinical finding. The CAD system correctly marked 87% (26/30) of those cancers that were clinically unsuspected (i.e., not at the location of the clinical finding). CONCLUSION: Breast cancers occurred at locations other than the site of the presenting clinical finding in 15% (30/197) of patients undergoing diagnostic mammography in whom a cancer was detected. CAD identified 87% of these incidentally detected cancers and may therefore be useful as a detection aid to the radiologist when interpreting diagnostic mammograms.

Breast Neoplasms↗

PubMedDate not supplied

The benefit and cost of prostate cancer early detection. The Investigators of the American Cancer Society-National Prostate Cancer Detection Project.

Cost-effectiveness calculations of prostate cancer early detection have not been possible due to the lack of any data demonstrating reduction in mortality from any test or procedure. Prior analyses focused only on cost assessments without consideration of any possible benefits. We used current data from three consecutive years of the American Cancer Society-National Prostate Cancer Detection Project to assess different economic perspectives of test performance, marginal costs, and benefit-cost analysis. The marginal cost, or cost per cancer, of digital rectal examination (DRE) markedly increased by the third year relative to several proposed prostate-specific antigen (PSA) scenarios. Sensitivity analysis for average cost showed that at 4 ng/ml, pricing PSA below $30 would be the most potent factor in potentially lowering costs. Analysis of receiver operator characteristic curves suggested that optimal performance for PSA may be at 3 ng/ml when combined with DRE or between 2 to 3 ng/ml when used alone. Benefit-cost calculations demonstrated that DRE when performed by highly skilled examiners had the lowest cost. However, DRE became one of the most costly detection scenarios when a minor decrease in performance was assumed. Sensitivity analysis demonstrated that the three most determinant parameters of net benefit, in decreasing order, are: specificity, benefits from earlier therapy, and prevalence. If a slightly more specific PSA assay is developed, the higher prevalence of clinically detectable prostate cancer could also make screening less costly than breast cancer screening. Under the assumptions of these analyses, the combination of PSA and DRE appears to represent an ethical and economical detection choice for individual patients in consultation with their physicians. Additional research is needed to quantify the significance of differences between different screening strategies.

American Cancer Society↗