Hi Liz,
Just saw your post. When you had a recurrence, did you have other genetic testing? Usually they now test for a full panel of genes vs BRCA only. I know they are finding many more genes besides the BRCA gene that are associated with hereditary breast and ovarian cancers.
Regarding tumor marking testing, I know many oncologists don't believe in them unless it's in the metastatic treatment setting. When I was first diagnosed in 2009, my oncologist used the CA 27.29 tumor marker test. My levels were always in the normal range, even when I found out I had a recurrence. I had a friend who had metastatic ovarian cancer and the tumor marker tests were very accurate in determining when her cancer was active again. It may be a valuable tool in the metastatic treatment setting, but not sure if it's highly effective as a screening tool (just my two cents).
What Is the Cancer Antigen 15-3 Blood Test?
A tumor marker test used to monitor metastatic breast cancer
The cancer antigen 15-3 (CA 15-3) biomarker test is used to monitor breast cancer.
The CA 15-3 antigen is a protein released into the bloodstream by
certain types of cancer. Although breast cancer is closely linked to the
CA 15-3 antigen, it is associated with other cancerous and
non-cancerous conditions as well.
CA 15-3 is one of several substances classified as
tumor markers, which may increase as a malignancy progresses and decrease as a tumor responds to
cancer therapy. The CA 15-3 is one of several tumor markers used to monitor people with
stage 4 breast cancer (also known as metastatic breast cancer).
1 While some
oncologists will use the test to detect
breast cancer recurrence, it is not endorsed for this use.
Purpose
CA 15-3 is an antigen found normally in breast tissue. Antigens are
Y-shaped proteins that identify a cell to the body, acting as its unique
"signature."
While the CA 15-3 antigen does not cause cancer, it can increase in
number as cancer cells rapidly divide. Because cancer cells do not
undergo apoptosis (programmed cell death), the number of CA 15-3 antigens will increase in tandem with a tumor's growth.
With that said, not all breast cancers shed CA 15-3 antigens. This is
especially true with early-stage breast cancer, in which fewer than half
of patients will show elevations in CA 15-3 values. By contrast, up to
80% of people with metastatic breast cancer will have increased CA 15-3
levels.2
These dynamics make the CA 15-3 useful for monitoring stage 4 breast cancer in which a primary breast tumor has spread (metastasized),
establishing secondary tumors in other parts of the body. If your
oncologist orders a CA 15-3 test, it may be for one of two reasons:3
- By regularly tracking your CA 15-3 values, the oncologist can assess how effectively a cancer treatment is working.
- If CA 15-3 antigens rise over a certain level, it may indicate a
worsening of the disease and warrant the investigation of metastasis in
other parts of the body (most often the bone or liver).
Limitations
Although the CA 15-3 test is valuable for monitoring breast cancer, it
is less reliable when used for cancer screening. This is partly due to
the fact that the CA 15-3 is
specific to breast cancer but not
exclusive to it.