# Cancer Antigen (CA) 15-3

> This test measures the amount of CA 15-3, a protein often released into the blood by breast cancer cells. It is primarily used to monitor how well treatment is working for invasive breast cancer or to check if the disease has returned. Tracking these levels helps show whether the cancer is responding to therapy or progressing. However, this test cannot be used alone to diagnose breast cancer or screen for it, as some non-cancerous conditions can also cause elevated levels.

- Labcorp code: 143404
- Category: [Cancer Detection](https://app.picardo.health/labs/tests/cancer-detection.md)
- Price: shown at checkout, before payment.
- Blood draw: free at a Labcorp location, or $75.00 at home.
- Order link: https://app.picardo.health/labs/order?tests=143404&ref=assistant

## About ordering

A licensed physician reviews every order before any test is run, and results arrive in the person's Picardo account. Ordering is open to adults 18 and over in the US, except New York, New Jersey, Rhode Island, Pennsylvania, Maryland, Massachusetts, Hawaii and Maine. General health information, not medical advice.