scholarly journals On the information hidden in a classifier distribution

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Farrokh Habibzadeh ◽  
Parham Habibzadeh ◽  
Mahboobeh Yadollahie ◽  
Hooman Roozbehi
Keyword(s):  
Prostate Cancer ◽  
Probability Density ◽  
Frequency Distribution ◽  
Relative Frequency ◽  
Specific Antigen ◽  
Performance Indices ◽  
Likelihood Ratios ◽  
Wide Range ◽  
Relative Frequency Distribution ◽  
Sensitivity Specificity

AbstractClassification tasks are a common challenge to every field of science. To correctly interpret the results provided by a classifier, we need to know the performance indices of the classifier including its sensitivity, specificity, the most appropriate cut-off value (for continuous classifiers), etc. Typically, several studies should be conducted to find all these indices. Herein, we show that they already exist, hidden in the distribution of the variable used to classify, and can readily be harvested. An educated guess about the distribution of the variable used to classify in each class would help us to decompose the frequency distribution of the variable in population into its components—the probability density function of the variable in each class. Based on the harvested parameters, we can then calculate the performance indices of the classifier. As a case study, we applied the technique to the relative frequency distribution of prostate-specific antigen, a biomarker commonly used in medicine for the diagnosis of prostate cancer. We used nonlinear curve fitting to decompose the variable relative frequency distribution into the probability density functions of the non-diseased and diseased people. The functions were then used to determine the performance indices of the classifier. Sensitivity, specificity, the most appropriate cut-off value, and likelihood ratios were calculated. The reference range of the biomarker and the prevalence of prostate cancer for various age groups were also calculated. The indices obtained were in good agreement with the values reported in previous studies. All these were done without being aware of the real health status of the individuals studied. The method is even applicable for conditions with no definite definitions (e.g., hypertension). We believe the method has a wide range of applications in many scientific fields.

scholarly journals Screening for Prostate Cancer: To Screen or Not To Screen? A Review of The State-of-The Art

2019 ◽  
pp. 19-24
Author(s):  
Lajos Döbrőssy
Keyword(s):  
Prostate Cancer ◽  
State Of The Art ◽  
Specific Antigen ◽  
Digital Rectal Examination ◽  
Conclusive Evidence ◽  
Screening Tests ◽  
Health Concern ◽  
Average Risk ◽  
Randomized Controlled ◽  
Sensitivity Specificity

Prostate cancer is a major public health concern, particularly in the welfare countries, for this reason, screening should be considered to reduce the number of deaths. Screening tests are available, i.e. digital rectal examination; trans-rectal ultrasonography and prostate specific antigen, nevertheless their sensitivity, specificity and positive predictive value are far from being perfect. Evidences from randomized screening trials are still indebted for conclusive evidence. The screening might cause more harm than good due to over diagnosis and over-treatment as a result of limited specificity of the screening tests. According to our point a view, opportunistic screening as part of diagnostics of patients having suspicion for uncertain symptoms of prostatic disorder is fully justified but mass screening of the population of average risk should not be introduced until supportive evidence from randomized controlled trials would be available.

An Estimate of Prostate Cancer Prevalence in Italy

2002 ◽  
Vol 88 (5) ◽  
pp. 367-369 ◽  
Author(s):  
Carlo La Vecchia ◽  
Paolo Bruzzi ◽  
Adriano Decadi ◽  
Franco Gaboardi ◽  
Peter Boyle
Keyword(s):  
Prostate Cancer ◽  
Advanced Disease ◽  
Specific Antigen ◽  
Cancer Prevalence ◽  
Previous Diagnosis ◽  
Wide Range ◽  
Range Of Variation

Estimates of the total number of men with a previous diagnosis of prostate cancer in Italy range from 55,000 to 135,000. This wide range of variation is largely due to uncertainties on the number of protein-specific antigen-detected, asymptomatic cases. The number of clinically detected cases, including cases with advanced disease, is less subject to uncertainty, with reasonable estimates ranging from 45,000 to 60,000.

scholarly journals Fragmented Rockfall Volume Distribution from Photogrammetry-Based Structural Mapping and Discrete Fracture Networks

2020 ◽  
Vol 10 (19) ◽  
pp. 6977
Author(s):  
Renato Macciotta ◽  
Chris Gräpel ◽  
Roger Skirrow
Keyword(s):  
Frequency Distribution ◽  
Relative Frequency ◽  
Fracture Network ◽  
Discrete Fracture Network ◽  
Volume Distribution ◽  
Structural Mapping ◽  
Discrete Fracture ◽  
Relative Frequency Distribution ◽  
Rockfall Protection Structures ◽  
Rockfall Protection

The design of rockfall protection structures requires information about the falling block volumes. Computational tools for rockfall trajectory simulation are now capable of modeling block fragmentation, requiring the fragmented volume-relative frequency distribution of rockfalls as input. This can be challenging at locations with scarce or nonexistent rockfall records and where block surveys are not feasible. The work in this paper shows that simple discrete fracture network realizations from structural mapping based on photogrammetric techniques can be used to reliably estimate rock fall block volumes. These estimates can be used for dimensioning rockfall protection structures in cases where data is scarce or not available. The methodology is tested at two sites in the Canadian Cordillera where limestone outcrops have been the source of recurrent rockfalls. The results suggest that fragmentation will largely tend to occur through weak planes and expansion of non-persistent discontinuities, while other block breakage mechanisms exert less influence in the fragmented volume-relative frequency distribution of rockfalls. Therefore, block volume distribution can be estimated using a simple discrete fracture network (DFN) with fully persistent discontinuities. Limitations of the methods are also discussed, as well as potential future research to address such limitations.

ECONOMIC EVALUATION OF DIAGNOSTIC LOCALIZATION FOLLOWING BIOCHEMICAL PROSTATE CANCER RECURRENCE

2014 ◽  
Vol 30 (4) ◽  
pp. 345-353 ◽  
Author(s):  
Daniel A. Barocas ◽  
Mark E. Bensink ◽  
Kristin Berry ◽  
Zahra Musa ◽  
Carolyn Bodnar ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cost Effectiveness ◽  
Radical Prostatectomy ◽  
Metastatic Disease ◽  
Specific Antigen ◽  
Base Case ◽  
Diagnostic Strategy ◽  
Potential Cost ◽  
Life Years ◽  
Wide Range

Objectives: The aim of this study was to assess potential cost-effectiveness of using a prostate cancer specific functional imaging technology capable of identifying residual localized disease versus small volume metastatic disease for asymptomatic men with low but detectable prostate specific antigen (PSA) elevation following radical prostatectomy.Methods: Markov modeling was used to estimate the incremental impact on healthcare system costs (2012 USD) and quality-adjusted life-years (QALYs) of two alternative strategies: (i) using the new diagnostic to guide therapy versus (ii) current usual care—using a combination of computed tomography, magnetic resonance imaging, and bone scan to guide therapy. Costs were based on estimates from literature and Medicare reimbursement. Prostate cancer progression, survival, utilities, and background risk of all-cause mortality were obtained from literature. Base-case diagnostic sensitivity (75 percent), specificity (90 percent), and cost (USD 2,500) were provided by our industry partner GE Healthcare.Results: The new diagnostic strategy provided an average gain of 1.83 (95 percent uncertainty interval [UI]: 1.24–2.64) QALYs with added costs of USD 15,595 (95 percent UI: USD -6,330–44,402) over 35 years. The resulting incremental cost-effectiveness ratio was USD 8,516/QALY (95 percent UI: USD -2,947–22,372). Results were most influenced by the utility discounting rate and test performance characteristics; however, the new diagnostic provided clinical benefits over a wide range of sensitivity and specificity.Conclusion: This analysis suggests a diagnostic technology capable of identifying whether men with biochemical recurrence after radical prostatectomy have localized versus metastatic disease would be a cost-effective alternative to current standard work-up. The results support additional investment in development and validation of such a diagnostic.

Assessing Curriculum Efficiency Through Monte Carlo Simulation

2018 ◽  
Vol 22 (4) ◽  
pp. 597-610
Author(s):  
David Torres ◽  
Jorge Crichigno ◽  
Carmella Sanchez
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Frequency Distribution ◽  
Relative Frequency ◽  
Monte Carlo Algorithm ◽  
Pass Rate ◽  
Random Numbers ◽  
Pass Rates ◽  
Low Pass ◽  
Relative Frequency Distribution

A Monte Carlo algorithm is designed to predict the average time to graduate by enrolling virtual students in a degree plan. The algorithm can be used to improve graduation rates by identifying bottlenecks in a degree plan (e.g., low pass rate courses and prerequisites). Random numbers are used to determine whether students pass or fail classes by comparing them to institutional pass rates. Courses cannot be taken unless prerequisites and corequisites are satisfied. The output of the algorithm generates a relative frequency distribution which plots the number of students who graduate by semester. Pass rates of courses can be changed to determine the courses that have the greatest impact on the time to graduate. Prerequisites can also be removed to determine whether certain prerequisites significantly affect the time to graduate.

scholarly journals Glycans as Biomarkers in Prostate Cancer

2019 ◽  
Vol 20 (6) ◽  
pp. 1389 ◽  
Author(s):  
Emma Scott ◽  
Jennifer Munkley
Keyword(s):  
Prostate Cancer ◽  
Specific Antigen ◽  
Liquid Biopsies ◽  
Multifaceted Approach ◽  
Disease Biomarkers ◽  
High Profile ◽  
Psa Testing ◽  
Wide Range ◽  
Multifocal Disease ◽  
Core Fucosylation

Prostate cancer is the most commonly diagnosed malignancy in men, claiming over350,000 lives worldwide annually. Current diagnosis relies on prostate-specific antigen (PSA)testing, but this misses some aggressive tumours, and leads to the overtreatment of non-harmfuldisease. Hence, there is an urgent unmet clinical need to identify new diagnostic and prognosticbiomarkers. As prostate cancer is a heterogeneous and multifocal disease, it is likely that multiplebiomarkers will be needed to guide clinical decisions. Fluid-based biomarkers would be ideal, andattention is now turning to minimally invasive liquid biopsies, which enable the analysis oftumour components in patient blood or urine. Effective diagnostics using liquid biopsies willrequire a multifaceted approach, and a recent high-profile review discussed combining multipleanalytes, including changes to the tumour transcriptome, epigenome, proteome, and metabolome.However, the concentration on genomics-based paramaters for analysing liquid biopsies ispotentially missing a goldmine. Glycans have shown huge promise as disease biomarkers, anddata suggests that integrating biomarkers across multi-omic platforms (including changes to theglycome) can improve the stratification of patients with prostate cancer. A wide range ofalterations to glycans have been observed in prostate cancer, including changes to PSAglycosylation, increased sialylation and core fucosylation, increased O-GlcNacylation, theemergence of cryptic and branched N-glyans, and changes to galectins and proteoglycans. In thisreview, we discuss the huge potential to exploit glycans as diagnostic and prognostic biomarkersfor prostate cancer, and argue that the inclusion of glycans in a multi-analyte liquid biopsy test forprostate cancer will help maximise clinical utility.

Utility and limits of serum prostate specific antigen determinations in prostatic cancer staging in view of surgical treatment

1992 ◽  
Vol 59 (4) ◽  
pp. 65-67 ◽  
Author(s):  
S. Rocca Rossetti ◽  
D.F. Randone ◽  
C. Terrone ◽  
M. Pasquale ◽  
F. Pecchio
Keyword(s):  
Prostate Cancer ◽  
Prostate Specific Antigen ◽  
Specific Antigen ◽  
Cancer Staging ◽  
Pathological Stage ◽  
Clinical Value ◽  
Predictive Values ◽  
Serum Prostate Specific Antigen ◽  
Wide Range ◽  
Retropubic Radical Prostatectomy

We investigated the clinical value of serum prostate specific antigen in 35 patients with apparently localized prostate cancer who underwent retropubic radical prostatectomy at our Department. In this series preoperative prostate specific antigen levels tended to increase with the increasing severity of pathological stage. The positive and negative predictive values were 68.1% and 63.6% respectively, accuracy was 66.6%. In the case of lymph node involvment, PSA values were lower than 10 nanog./ml in 20% of cases. Prostate specific antigen values not useful to predict preoperatively the final pathological stage of the prostate cancer because of the wide range of values among patients within each stage.

Prediction of postoperative histology in patients with prostate cancer using preoperative Ga-68-PSMA-PET/CT.

2016 ◽  
Vol 34 (2_suppl) ◽  
pp. 144-144
Author(s):  
Martin Boegemann ◽  
Axel Semjonow ◽  
Hans-Joerg Breyholz ◽  
Andres Jan Schrader ◽  
Laura-Maria Krabbe ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Standard Uptake Value ◽  
Whole Body ◽  
Diagnostic Tools ◽  
Likelihood Ratios ◽  
Psma Pet ◽  
Pet Ct ◽  
Detect Prostate Cancer ◽  
Sensitivity Specificity ◽  
Specific Membrane

144 Background: Recently developed 68Ga labeled prostate specific membrane antigen (PSMA) ligands were introduced as diagnostic tools to detect prostate cancer (PCa), PCa relapse and metastases with high accuracy. In this study we assessed the usability of preoperative PSMA-PET/CT information on congruency of spread of PCA compared with postoperative PCa-maps derived from radical prostatectomy (RPE) specimens. Methods: We referred 6 patients with biopsy proven high risk PCa to PSMA-PET/CT prior to RPE. Whole body PET/CT (Biograph mCT with 128 slice CT, Siemens) was performed 62±8 minutes after injection of 160±31 MBq [68Ga]-PSMA-HBED-CC (DKFZ-Ga-PSMA-11) as described by routine acquisition protocol. After RPE, prostate specimens were processed in the local pathology department. Topographical analysis of extension of PCa was reconstructed from representative slides on a schematic diagram resulting in a PCa-map of the prostate. After aligning the cutting planes of the PSMA-PET/CT to the PCa-map we defined 20 segments of the prostate and the seminal vesicles. We measured the maximum standard uptake value (SUV) of PSMA activity of the respective segments and compared the concordance of PSMA-positive and -negative areas with those of PCa and no PCa on the PCa-maps. We calculated sensitivity, specificity, positive and negative likelihood ratios (LR) taking available segments into account. Results: 106/112 segments were analyzed. 8 segments were excluded due to spillover of PSMA-activity in bladder urine. All but 3 segments with no PCa on the PCa-maps showed no uptake in PSMA-PET/CT (Specificity = 92%). The sensitivity of PSMA-PET/CT for showing PCa areas was equally 92%. The positive and negative LR for PSMA-PET/CT detecting or ruling out PCa was 11.5 and 0.09, respectively. Conclusions: This preliminary proof of concept study shows that prediction of later pathologic results in RPE-specimens could be estimated by preoperative PSMA-PET/CT. With optimized acquisition protocols it may be possible to improve our preliminary results. Perspectively PSMA-PET/CT may be helpful for identifying PCa suspicious lesions prior to prostate biopsy and support decision making prior to RPE or radiation therapy.

The multi-cancer marker, rs6983267, located at region 3 of chromosome 8q24, is associated with prostate cancer in Greek patients but does not contribute to the aggressiveness of the disease

2012 ◽  
Vol 50 (2) ◽  
Author(s):  
Amalia Papanikolopoulou ◽  
Olfert Landt ◽  
Konstantinos Ntoumas ◽  
Stefanos Bolomitis ◽  
Stavros I. Tyritzis ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Specific Antigen ◽  
Prostate Cancer Risk ◽  
Greek Population ◽  
Cancer Case ◽  
P Value ◽  
Total Blood ◽  
Predictive Values ◽  
Sensitivity Specificity ◽  
Chromosome 8Q24

AbstractRecently, several polymorphisms located on human chromosome 8q24 were found to be associated with prostate cancer risk with different frequency and incidence among the investigated populations. The authors conducted a prostate cancer case-control study in the Greek population to evaluate the association of the single nucleotide polymorphism (SNP) rs6983267, located at region 3 of chromosome 8q24, with this type of cancer.Samples of total blood from 86 patients with histologically confirmed prostate cancer and 99 healthy individuals were genotyped using real time polymerase chain reaction (PCR). Tumor-node-metastasis (TNM) stage, Gleason score and levels of prostate-specific antigen (PSA) at diagnosis were included in the analysis.A highly significant association (odds ratio=2.84 and p-value=0.002) was found between rs6983267 and prostate cancer in the Greek population. The sensitivity, specificity, negative and positive predictive values of the presence of G allele for the discrimination between patients and controls were 81.40%, 39.4%, 53.9% and 70.9%, respectively. A lower proportion of homozygotes was found in patients with PSA level <4 ng/mL compared to those with PSA level more than 4 ng/mL (p=0.019). None of the other clinical factors nor the aggressiveness of the disease were found to be significantly associated with rs6983267 genotype.The SNP rs6983267 is an established marker for a range of cancers. In prostate cancer, it indicates an enhanced risk for carriers to develop the disease in general. In our study it showed no association with aggressive forms or familial and early-onset prostate cancer families.

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