Tumor markers• What are tumor markers?
• Tumor markers are substances that can be found
• in the body when cancer is present.
• They are usually found in the blood or urine.
• They can be products of the cancer cells
• themselves or of the body in response to cancer or other conditions.
• Most tumor markers are proteins.
For many reasons, tumor markers by themselves are usually not enough to diagnose or rule out cancer.
Most tumor markers can be made by normal cells as well as by cancer cells. Sometimes, non-cancerous diseases can also cause levels of certain tumor markers to be higher than normal.
And not every person with cancer may have higher levels of a tumor marker.
For these reasons, only a handful of tumor markers are commonly used by most doctors
• Uses of tumor markers• 1-Screening and Early Detection of Cancer
• Screening refers to looking for cancer in people who have no symptoms of the disease.
Early detection is finding cancer at an early stage, when it is less likely to have spread and is more likely to respond well to treatment.
The most widely accepted tumor marker is the prostate-specific antigen (PSA) blood test, which is used (along with the digital rectal exam) to screen for prostate cancer.
• 2-Diagnosing Cancer• Tumor markers are usually not used to diagnose cancer.
markers can help determine if a cancer is likely. They can also help diagnose the source of widespread cancer in a patient when the origin of the cancer is unknown.
The presence of a high level of the tumor marker CA 125 will strongly suggest ovarian cancer, even if surgery can't identify the source.
3-Determining the Prognosis (Outlook) for Certain CancersSome types of cancer grow and spread faster than other types.
Some newer tumor markers help show how aggressive a person's cancer is likely to be, or even how well it might respond to certain drugs.
4-Determining the Effectiveness of Cancer TreatmentIf the tumor marker level in the blood goes down, it is almost always a sign that the treatment is having an effect.
On the other hand, if the marker level goes up, then the treatment probably should be changed.
5-Detecting Recurrent CancerMarkers are also used to look for cancer that may come back (recur) after initial treatment.
These include PSA (for prostate cancer),
human chorionic gonadotropin (HCG)
Some women who have been treated for breast cancer have yearly blood tests for levels of the tumor marker CA 15-3.
This can sometimes detect cancer recurrence before the woman has symptoms or evidence of cancer on imaging tests.