Stomach cancer tumor markers are substances found in the blood of patients and can be used to aid management of the condition.
Some people thought of their use as a diagnostic tool, but the problem with them is that they are not generally specific enough to do this.
That aside, they can be used to help monitor the disease during and after treatment and also used as a research tool too.
There are a few types and I will go through these individually for you:
CA 19-9 or Cancer Antigen 19-9 is a carbohydrate antigen or modified Lewis blood group antigen picked up in some sufferer’s blood.
It is primarily used in the management of pancreatic tumors, but can also be raised in a variety of other tumors including gastric malignancies.
It isn't very specific for gastric tumors and also 10% of sufferers don’t express the Lewis antigen on their blood cells.
As a result, a negative test doesn't exclude a tumor in the same way as a positive test doesn't confirm it either.
CEA or Cancer embryonic antigen is a glycoprotein found in blood. It’s normal role is in cell binding or adhesion.
It is often used as a tumor marker in colorectal cancer, but can also be raised in gastric malignancy too.
It is actually a poor predictive finding if it is found to be elevated prior to surgery.
The problem again arises with this marker as it can be elevated in normal people and smokers too so results need to be interpreted with caution.
Pepsinogen (PG) 1 and 2 levels have been studied as a marker of gastric malignancies, produced by mucus cells in the stomach.
Low PG1 and low PG1/PG2 ratios can be found in atrophic gastritis, a pre-cancer condition in some people.
Elevated PG2 levels are a seen with approx 78% sensitivity in picking up disease, although specificity for gastric malignancies is slightly lower at 71%.
Pepsinogen has a potential for use with other markers as a screening tool.
The Trefoil family factors (TFF) are a group of factors with a 3 loop structure, that are secreted in to the gut.
There are 3 TFF's and TFF3 seems to be the best marker with relatively high sensitivity and specificity (around 81%).
Its stability makes it quite a good stomach cancer tumor marker which can be measured in your blood and studies are currently looking at combining it with other markers such as Pepsinogen to improve its power further.
CA 50 is another cancer antigen or carbohydrate antigen that can be raised in gastric malignancies.
The CA 50 in combination with the CEA and CA 19-9 before surgery have been shown to be a predictor of poor prognostic surgical outcome.
Studies have shown an increased number of lymph nodes at surgery and deeper tissue infiltration within the stomach.