Title: Cancer Antigen 15-3 Test: Uses, Procedure, Results
Headings: What Is the Cancer Antigen 15-3 Blood Test?
What Is the Cancer Antigen 15-3 Blood Test?
A tumor marker test used to monitor metastatic breast cancer
Purpose
Limitations
Risks and Contraindications
Before the Test
Timing
Location
What to Wear
Food and Drink
Medication Use
Cost and Health Insurance
What to Bring
During the Test
Throughout the Test
Post-Test
After the Test
Interpreting Results
Follow-Up
A Word From Verywell

Content: Location
The CA 15-3 test can often be performed at the oncologist's office during your visit. Alternately, you may be referred to a nearby lab. What to Wear
You should choose a top that is either short-sleeved or has sleeves that can be easily rolled up. If you plan to return to work after the test, you may want to wear long sleeves to cover the bandage or puncture mark on your arm. Food and Drink
There are no food or drink restrictions for the CA 15-3 test. If you have small veins, it often helps to drink a couple of glasses of water before the test. Doing so won't affect the results but may plump your veins and make the blood draw easier. Medication Use
Certain medications and supplements can interfere with the CA 15-3 test. Among them is biotin (also known as vitamin B7, vitamin B8, vitamin H, or coenzyme R). The CA 15-3 test relies on biotin to bind to the CA-153 antigen and may be affected if too much biotin is consumed.