Tumor Markers

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Tumor Markers

What are they……?:

What are they……? They are substances usually proteins . Produced by the body in response to cancer growth or by cancer tissue itself. found in the blood , urine , or body tissues that can be elevated in cancer . can be produced directly by the tumor or by non-tumor cells as a response to the presence of a tumor.

Classification:

Classification 1.Cancer-specific markers . Cancer-specific markers are related to the presence of certain cancerous tissue. there is a large overlap between the many different tumor tissue types and the markers produced these markers might not be specific in making a diagnosis. examples of these markers are CEA , CA19-9 , CA125 .

.Tissue-specific markers :

. Tissue-specific markers Tissue-specific markers are related to specific tissues which have developed cancer. Examples include PSA , beta-HCG - ( Human chorionic gonadotropin ).

Ideal Tumor Markers…….:

Ideal Tumor Markers……. Highly Specific To The Tumor. Highly Sensetive :non-detectable in Physiological or benign disease states. Level Should Change in Response To Tumor Size. Abnormoal Level should be obtained in the presence of micrometastases .

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Predict recurrence before they are clinically detectable. relatively short half-life, reflecting temporal changes in tumor burden and response to therapy. applicati.on of low cost.

Why are they done…….? :

Why are they done…….? Screen. Most markers are not suited for general screening, but some may be used in people with a strong family history of a particular cancer. PSA testing may be used to screen for prostate cancer . Diagnose. In a person who has symptoms, tumor markers may be used to help identify the source of the cancer, such as CA-125 for ovarian cancer , and to help differentiate it from other conditions. Remember that tumor markers cannot diagnose cancer by themselves but aid in this process.

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Stage . If a person does have cancer, tumor marker elevations can be used to help determine how far the cancer has spread into other tissues and organs. Determine Prognosis . Some tumor markers can be used to help doctors determine how aggressive a cancer is likely to be. Guide Treatment . A few tumor markers, such as Her2/ neu , will give doctors information about what treatments their patients may respond to (for instance, breast cancer patients who are Her2/ neu positive are more likely to respond to Herceptin treatment).

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Monitor Treatment . Tumor markers can be used to monitor the effectiveness of treatment, especially in advanced cancers. If the marker level drops, the treatment is working; if it stays elevated, adjustments are needed. The information must be used with care, however, since other conditions can sometimes cause tumor markers to rise or fall. Determine Recurrence . Currently, one of the most important uses for tumor markers is to monitor for cancer recurrence. If a tumor marker is elevated before treatment, low after treatment, and then begins to rise over time, then it is likely that the cancer is returning. (If it remains elevated after surgery, then chances are that not all of the cancer was removed.)

Examples………….:

Examples………….

Alpha-fetoprotein (AFP):

Alpha-fetoprotein (AFP) Alpha-Fetoprotein is a normal fetal serum protein synthesized by the liver, yolk sac, and gastrointestinal tract that shares sequence homology with albumin. AFP can help diagnose and guide the treatment of liver cancer ( hepatocellular carcinoma). Normal levels of AFP are usually less than 10 ng / mL .

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also elevated in acute and chronic hepatitis. also higher in certain germ cell tumors. It is a glycoprotein produced in large amounts during fetal life and is homologous to albumin. elevated in normal pregnancy, benign liver disease (hepatitis, cirrhosis), as well as in cancer.

Carcinoembryonic antigen (CEA) :

Carcinoembryonic antigen (CEA) glycoprotein involved in cell adhesion . It is normally produced during fetal development, but the production of CEA stops before birth. CEA is not used to diagnose or screen for colorectal cancer, but it is the preferred tumor marker to help predict outlook in patients with colorectal cancer. CEA is also the standard marker used to follow patients with colorectal cancer during and after treatment.

Prostate-specific antigen:

Prostate-specific antigen Is a protein (It is a serine protease ) produced by the cells of the prostate gland. PSA is produced for the ejaculate where it liquifies the semen in the seminal coagulum and allows sperm to swim freely. It is also believed to be instrumental in dissolving the cervical mucous , allowing the entry of sperm. present in small quantities in the serum of men with healthy prostates, but is often elevated in the presence of prostate cancer .

CA 125 :

CA 125 CA125 is an antigen present on 80 percent of nonmucinous ovarian carcinomas. It is defined by a monoclonal antibody ( OC125 ) that was generated by immunizing laboratory mice with a cell line established from human ovarian carcinoma. CA125 is often elevated in patients with ovarian cancer.

CA19-9 :

CA19-9 CA19-9 is a monoclonal antibody generated against a colon carcinoma cell line . It is found it to be elevated in 21 to 42 percent of cases of gastric cancer. 20 to 40 percent of colon cancer, and 71 to 93 percent of pancreatic cancer. has been proposed to differentiate benign from malignant pancreatic disease.

Human Chorionic Gonadotropin :

Human Chorionic Gonadotropin HCG is a glycoprotein consisting of subunits a e b, which are nonconvalently linked. The hormone is normally produced by the syncytiotrophoblastic cells of the placenta and is elevated in pregnancy. Its most important uses as a tumor marker are in gestational trophoblastic disease and germ cell tumors.

Acid Phosphatase :

Acid Phosphatase This enzyme is found in high concentraitions in the normal prostate as well as in primary and metastatic prostate cancers. it may also be elevated in up to 6 percent of cases of benign prostatic hypertrophy and other conditions.

..............Detection:

.............. Detection

What`s new in tumor marker research? :

What`s new in tumor marker research? Genomics The study of patterns of DNA changes (or mutations) is called genomics . We know that most cancers have changes in their DNA, the molecules that direct the functions of all cells. It is these changes that turn a normal cell into a cancer cell. By looking for DNA changes in blood, or urine, scientists may be able to find cancers very early. Looking at the patterns of changes is likely to prove more useful than looking for single DNA changes.

Proteomics:

Proteomics Another newer approach is called proteomics . This technology looks at the patterns of all the proteins in the blood instead of looking at individual protein levels. New testing equipment allows doctors to look at thousands of proteins at one time. It's unlikely that such a test would be used in a doctor's office, but it may help researchers narrow down which protein levels are important in a certain type of cancer. This information could then be used to develop a blood test that might look only at these important proteins. Then, blood or a tissue sample could be checked for the protein pattern as a way to find cancer.

Prof.Dr. El.Shahat A.Toson:

Prof.Dr . El.Shahat A.Toson Supervised By Prepared by Adel Ezzat Abed