Tumor Marker – Part 9 – CA 15-3 , CA 27-29 (Cancer Antigen 15-3 and 27-29)

CA 15-3 and CA 27-29 are the markers for breast cancer.

Sample

1. Venous blood needed to prepare the serum.
2. Citrated plasma can be used.
3. < 5 days can be stored at 2 to 8 °C.
4. If more than 5 days then store at -20 °C.

Purpose of the test (Indication)

• These tumor markers are used to monitor the treatment of breast cancer.

Pathophysiology

1. This is also known as the cancer antigen breast.
   1. This is a glycoprotein, 400 KD, and is membrane -enriched breast cancer extract.
   2. CA 27-29 is a high molecular weight glycoprotein.
2. Both CA 15-3 and CA 27-29 are the markers for breast cancer.
   1. These are not as sensitive as other breast tumor markers.
3. The raised level of CA 15-3 indicates advanced breast cancer or bulky tumor.
   1. Only 50% of the patients show a high level of localized breast cancer or a small tumor.
   2. But 80% of the patient with metastatic cancer shows a high level of CA 15-3 and 65% has CA 27-29.
4. Other causes of the raised level of CA 15-3 and CA 27-29 are:
   1. Benign breast diseases.
   2. Cancers of lung, pancreas, ovary, and prostate.
5. These markers are good markers for the treatment of metastatic breast cancer.
   1. Remission will show a decreasing level.
   2. Persistently raised levels indicate progressive disease.
6. CA 15-3 was the first tumor marker of breast cancer.
7. These are not used for the screening of breast cancer.
   1. Most useful following the therapy response in metastatic breast cancers.

Normal

• CA 15-3 = <31 U/mL or <31 k units /L.
• CA 27-29 = <38 U/mL or <38 k units /L.
  • In healthy subjects, the upper limit is 25 kU/L.
    • 5.5% of the normal subjects.
    • 23% of the primary breast disease.
    • 69% with metastasis to the liver.
• Source 2
  • CA 15-3 = <22 units/mL  (<22 kU/L).
  • CA 27-29 = <38 units/mL (<38 kU/L).

The raised level is seen in:

1. Metastatic breast cancer.
2. CA- 15-3 is raised in other malignancies like:
   • Pancreatic cancer.
   • Colorectal carcinoma.
   • Liver.
3. The raised level also was seen in benign diseases like;
   • liver diseases.
   • Benign breast diseases.
4. Both CA 15-3 and CA 27-29 not needed to do at the same time.  CA 15-3 is enough to perform.  Both have the same purpose.
5. Other benign and malignant conditions are:
   1. Lung cancer.
   2. Cirrhosis.
   3. Hepatitis.
   4. Fibrocystic diseases of the breast.
   5. Diseases of prostate, pancreas, and colon.

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