What Are Tumor Markers? - Definition & Functions

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  • 0:09 Marking Things Off
  • 0:37 What Are Tumor Markers?
  • 1:36 Prostate Specific Antigen
  • 2:35 Alpha-Fetoprotein
  • 3:31 Carcinoembryonic Antigen
  • 4:14 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson will discuss the concept of tumor markers. You'll learn what they are, where they are found, and what they are used for. We'll also go into three specific and famous tumors markers known as PSA, CEA, and AFP.

Marking Things Off

Try and remember what it was like in elementary school. I remember one thing in particular: lots of colorful markers. I used them to draw, mark off things that were important in my little notebook, or mark other people's arms just for the fun of it. Marking off something in a notebook, or on a wall like graffiti often does, identifies important points, locations, and memories. While marking may seem like fun and games, it actually plays a very important role with regard to cancer.

What Are Tumor Markers?

Tumor markers are substances found in body tissues and fluids that help to show the presence and type of cancer. Usually these tumor markers are found in bodily fluids such as blood or urine, but they do not have to be. The reason these tumor markers, often proteins, can be found is because they are either produced by cancer cells themselves or produced by the body in response to the cancer's presence in abnormally large quantities.

Therefore, when a sample of bodily fluid is taken and sent off to the lab for analysis, the presence of tumor markers may indicate a potentially malignant process and even a specific type of malignant tumor. You can think of these tumor markers as forensic evidence left in a crime scene by a criminal. Be it DNA that links police to the exact criminal or footprints that show the potential that a criminal was there, these markers are indicators of some kind of 'criminal' act, shall we say, occurring within your body.

Prostate Specific Antigen

Since there's a ton of these different markers, I'll just focus on three big ones for this lesson as to not overwhelm you with too much information. One of them is known as PSA, or prostate-specific antigen. As you can tell by its full name, this tumor marker helps your doctor detect the presence of prostate cancer - if you are a man, that is.

PSA is made by cells of the prostate gland and is present in abnormally large amounts in men with prostate cancer. But medicine is never that simple, and therefore its elevation can be caused by non-malignant processes such as BPH, or benign prostatic hyperplasia. Therefore, to be sure about the diagnosis of cancer, it's sometimes advised that men with high levels of PSA have a biopsy taken in order to confirm the diagnosis of cancer or even rule it out.

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