Page 130 - Clinical Biochemistry

PSA in Prostatic cancer
5- Genetic markers: They have great potential for diagnosis of cancer by gene analysis to
detect mutations or alterations.
Genetic changes (mutations) in:
• Oncogenes
• Apoptosis-related genes
• Tumor suppressor genes
• DNA repair genes
The most common example mutations in the BRCA1 and BRCA2 genes
• They are tumor suppressors normally play a role in protecting the body against the
development of cancer.
• Individuals with mutations in either of these genes have increased cancer risks, breast and
ovarian cancer.

Figure 76: mutations in the BRCA1 and BRCA2 genes

Ideal Tumor Marker
An “ideal” tumor marker, which include the following:
1. Detectable only in a given malignancy and absent in non-malignant conditions (ie, with

clinical specificity and sensitivity).
2. Present at concentrations proportional to tumor burden.
3. Conveniently measured by a readily available, simple, reproducible, and inexpensive

procedure.
4. Beneficial to clinical care with a measurable effect on patient outcome.
No such tumor marker has yet been identified. However, measurement of hCG approaches
ideal in the screening and monitoring of women who have had a molar pregnancy and are at
risk of developing choriocarcinoma.