Define the term cancer biomarker
A substance or process that is indicative of the presence of cancer in the body
What are the uses of cancer biomarkers in practice?
- Prediction (response to treatment)
What are the categories of biomolecules that can be cancer biomarkers
What are the genetic cancer biomarkers?
- DNA mutations
- mRNA expression
What are the epigenetic cancer biomarkers?
- DNA methylation
- Histone methylation
- miRNA gene silencing
What are the proteomic cancer biomarkers?
- Protein levels
What are the glycomic cancer biomarkers?
What sources can be tested for cancer biomarkers?
- Fine-needle aspirates
- Fresh tissue
- Frozen tissue
What are the features of an ideal cancer biomarker?
- Reflect kinetics
- Minimally invasive
- Clinical importance
What should a cancer biomarker be specific to?
- Disease type
- Disease stage
How sensitive should the ideal biomarker be?
Ideally should detect a single molecule
What should the ideal biomarker be predictive of?
- Treatment response
What factors are considered when deciding if a biomarker is robust?
What features must biomarkers have if they are to be used for cancer screening?
- Must be highly specific
- Must be able to clearly reflect different stages of the disease
- Must be easily detected without complicated medical procedures
- Method of screening must be cost effective
Why must cancer biomarkers used for screening be highly specific?
To minimise false positives and negatives
What markers are good targets for application of early screening?
Markers released to the serum and urine
What is prostate specific antigen produced by?
Epithelial cells of the prostate
What levels of PSA are considered suspicious?
What is required when PSA is 4-10ng/ml?
How is PSA used in risk stratification?
Used to stratify patients into low, intermediate, or high risk for having/developing metastatic disease, or dying of prostate cancer. It is used in conjunction with two other parameters - grade (Gleason grading) and stage (imaging)
Where is HPV detected?
Almost all cases of cervical cancer
How are cervical cells collected?
Using a Pap smear
Who is screened for cervical cancer in the UK?
Women aged 25 to 64 years - 25-49 years screened every 3 years, 50-64 screened every 5 years
How is cancer traditionally diagnosed?
Using tissue biopsy, on which immunohistochemistry and pathological evaluation are performed
What is the problem with using biopsy to diagnose cancer?
- Highly invasive
Define diagnostic biomarkers
Substances that are produced by cancer, or by other cells of the body, in response to cancer or certain benign conditions.
Are tumour markers made by normal cells?
Most are, however are produced much higher levels in cancerous conditions
Give 6 examples of diagnostic biomarkers
- Alpha-fetoprotein in liver cancer
- Cancer antigen 125 in ovarian cancer
- CA15-3 in metastatic breast cancer
- Carbohydrate antigen 19-9 in colorectal cancer
- Carcinoembryonic antigen in pancreatic cancer
- Prostate specific antigen in prostate cancer
Give an example of a genetic diagnostic biomaker
BCR-ABL in CML (chronic myelogenous leukaemia)
What % of patients with CML harbour a BCR-ABL translocation?