پاورپوینت Bio Marker
دانلود پاورپوینت Bio Marker
Biomarker
Detection of biomarker
Detection of biomarker – diagnosis
Self properties, e.g enzymatic activities
Antibodies, IHC, ELISA
Detection of biomarker
Quantitative
a link between quantity of the marker and disease
Qualitative
a link between exist of a marker and disease
Biomarker & Diagnosis
Ideal Marker for diagnosis
Should have great sensitivity, specificity, and accuracy in reflecting total disease burden. A tumor marker should also be prognostic of outcome and treatment
Biomarker for Screening
- The marker must be highly specific, minimize false positive and negative
- The marker must be able to clearly reflect the different stages of the disease (early)
- The marker must be easily detected without complicated medical
procedures. The disease markers released to serum and urine are good
targets for application of early screening.
- The method for screening should be cost effective.
Samples for biomarker detection
Blood, urine, or other body fluids samples
Tissue samples
Prostate Cancer marker PSA
PSA is a protein normally made in the prostate gland in ductal cells that make some of the semen. PSA helps to keep the semen liquid. PSA, also known as kallikrein III, seminin, semenogelase, γ-seminoprotein and P-30 antigen, is a glycoprotein, a serine protease
Prostate Cancer Diagnosis with PSA
Cancer of the prostate does not cause any symptoms until it is locally advanced or metastatic.
There is a correlation between elevated PSA and prostate cancer.
Detection of PSA is a surrogate for early detection of prostate cancer.
Large screening trials have shown that PSA nearly doubles the rate of detection when combined with other methods. Based on these data, PSA testing was approved by the US FDA for the screening and early detection of prostate cancer.
PSA is also found in the cytoplasm of benign prostate cells.
“I never dreamed that my discovery four decades ago would lead to such a profit-driven public health disaster." -Richard Ablin (inventor of the PSA test)
PSA screening generates ~$1.7 billion annually in the U.S. alone.
Sensitivity = the ability of the test to detect the disease (True positive rate)
Specificity = the likelihood that your test will be normal if you are disease free
(True Negative)
A brief aside about Statistics and Probability
-Statistics are the formalization of common sense
-because they have to handle many different
situations, they can be really complicated
-they should make you feel really good or really
bad about your data
-People are inherently bad at statisitics and probability
Case Study: rate for being HIV positive: 1:10000
false positive rate of HIV test: 1:1000
If I test positive, what is the chance that I am really HIV negative?
