molecular diagnostics in cancer screening Flashcards
Why is it important to detect tumor early and to screen for them?
- to improve the survival rates
- improve quality of life
- reduce cost and complexity of cancer treatment
Name examples of preventive examinations
- PAP cytology screening
- palpation of the breat
- colonoscopy
- mole screening
- vaginal ultrasound
define biomarker
biomarker are measured as an indicator of normal biological processes, pathogenic processes or reponses to an exposure or intervention, including therapeutic interventions
Name 5 types of biomarkers regarding cancer
- prognostic
- diagnostic
- predictive
- pharmacodynamics
- recurrence
Why is the translation of biomarkers from publication to clinical practice a challenge?
- disintegrated pipeline
- lack of quality control and standardization
- lack of data availibility
What type of marker is prostate specific antigen? How does it work?
prognostic marker
- secreted by the epithelial cells of the prostate gland
- normally: active, bound PSA and free, unbound PSA diffuses into serum
- in cancer cells: disruption of the basal cell layer and membrane leads to increasing level of complexed PSA and proPSA in serum –> decreased levels of free PSA
What is analytical validity?
measure of how well the test measures what it purports to measure
What are the two types of validity?
specificity (correctly identify paitent without cancer) and sensitivity (identify patients with cancer)
What is the effect of a higher cutoff setting?
results in higher specificity and lower sensitivity (and vice versa)
Are high levels of PSA specific for prostate cancer?
No –> PSA test lack specificity
What is faecl calprotectin and for what can it be used as a biomarker?
calprotectin can in the presence of calcium sequester transition metals iron, manganese and zinc via chelation
–> feacal calprotectin correlates significantly with disease activity e.g. colon cancer
What is needed for a ROC curve?
true positive rate and the false positive rate
How would the best predicition method look like in a ROC curve?
method would yield a point in the upper left corner (coordinate 0,1) of the ROC space –> 100 % sensitivity and 100 % specificity
points below the line of discriminations represent bad results
