Cancer

Cancer: Lab Tests

By Fornia ⋅ January 17, 2010 ⋅  Print This Post ⋅ Post a comment

Below, I will present — for those new to them — the significance in the broadest sense of each of the following tumor markers.

General Marker CEA:

CEA (Carcinoembryonic antigen) is an inadequate marker — as a diagnostic tool, an elevated CEA too often provides false positives. Most elevated levels that are true positive appear at late stage. For colon cancer though, preoperative CEA values have been positively correlated with stage and negatively correlated with disease free survival — so elevated CEA levels with colon cancer are not a good sign. CEA is elevated in non-colonic cancers, but not as useful.

High CEA levels may also hint of recurrence, and for this reason CEA testing is useful one every 1-3 months. This applies post-operatively: CEA levels should normalize within 1-2 months of surgery, if it does not, the malignant cancer might still be present.

Ovarian Cancer Marker CA125:

This antigen presents itself in 80% of nonmucinous ovarian carcinomas. CA125 is often elevated in patients with ovarian cancer. It correlates to severity of cancer in the patient, and hence is a better marker than CEA is. It is also elevated in other cancers. Ovarian cancer is not so commonly seen, and hence the test is not useful in screening.

Breast Cancer Markers CA 15-3 and CA 27-29

CA15-3:

CA 15-3 is a protein that is a normal product of your breast tissue. When a carcinoma is present in the breast, CA 15-3 levels rise with an increase in the number of cancer cells — these tumor cells shed copies of the CA 15-3 protein.

Other conditions may elevate CA 15-3 levels, e.g. pregnancy and lactation, benign breast disease, endometriosis, pelvic inflammatory disease, hepatitis, benign ovarian disease as well as ovarian, lung and prostate cancers.

CA 27-29:

This antigen is shed by breast cancer cells. It is a mucus-containing protein produced by the MUC-1 gene. Blood CA 27-29 can also appear in benign breast and ovarian diseases, as well as cancers of the colon, liver, lung, pancreatic, ovarian and prostate.

Established TMs for gastrointestinal Cancers include CA 50, CA 19-9 and CA 24-2

CA 50:
CA 50 is found mainly in gastrointestinal carcinomas e.g. gastric, colorectal, pancreatic and hepatic carcinomas.

CA19-9:

This monoclonal antibody is found to be elevated mostly in pancreatic cancer (71-93%). Next in line are gastric and colon cancer (about 20-40%).

CA 72-4:
CA 72-4 has been demonstrated to be highly sensitive and specific in cases of gastric cancer.

CA 242:

This latest marker is very specific for pancreatic cancer.

For the Lungs CYFRA 21-1 and NSE:

CYFRA 21-1: Applicable to NSCC (non-small cell carcinoma) of the lungs, in particular squamous cell carcinoma (鳞癌) of the lung.

NSE: More applicable to SCC (small cell carcinoma) of the lungs

For the Liver, AFP (alpha-fetoprotein)

It is particularly useful for post-treatment follow-up of hepatocellular carcinomas (HCC). It is also applicable in liver metastases, especially those originating from cancers of the digestive tract. However, its not so useful in diagnosing liver carcinoma, because AFP levels are also high with liver cirrhosis (肝硬化) and Hepatitis C (丙肝).

Elevated AFP levels (in serum or amniotic fluid) are also possible in a pregnant person.

Resources:

• A list: http://www.ria-cis.com/an/product.php4?p=98&f=2
• On CA 242: http://www3.interscience.wiley.com/journal/112676274/abstract?CRETRY=1&SRETRY=0

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