.avif&w=256&q=75){kind=logo}
Tumor markers are proteins in your blood linked to certain cancers. They work best for two jobs. First, they track a cancer you already have. Second, they watch a small group of people at known high risk. Using them to screen healthy adults often causes more harm than good. This guide explains each major tumor marker. You will learn what it measures. You will learn what a high result can and cannot mean, and when it is the right test.
Tumor Markers: What CEA, AFP, CA-125, and CA 19-9 Reveal
Written by &you Labs Team
Updated September 15, 2026
Quick answer
Tumor markers detect proteins linked to specific cancers. Most have poor screening value, since many harmless conditions raise them too. Their best uses are tracking a known cancer and watching a defined high-risk group. They also help sort out a suspicious symptom or scan. One example: AFP for people with long-term hepatitis.
CEA (carcinoembryonic antigen)
CEA is a protein your body makes in small amounts as an adult. Cancer can push it higher.
Normal: under 3 ng/mL if you do not smoke, under 5 ng/mL if you do.
CEA most often rises with colon cancer. It can also rise with lung, breast, pancreatic, and stomach cancers. It rises for harmless reasons too. This includes smoking, gut swelling, pancreatitis, cirrhosis, ulcers, and low thyroid function.
Doctors use CEA to track known colon cancer. They check a baseline before treatment, then recheck over time to catch a return. They also use it to help sort out a suspicious finding.
CEA is not built for routine screening. A normal CEA does not rule out cancer. A high CEA does not confirm it.
AFP (alpha-fetoprotein)
AFP is a protein made by a growing baby's liver. Adults make very little of it. Some cancers push it up.
Normal in adults: under 10 ng/mL.
AFP rises mainly in liver cancer, called hepatocellular carcinoma. It also rises in some rare tumors called germ cell tumors. It rises hugely and normally in pregnancy too.
AFP has real value for watching people with long-term hepatitis B or C. Doctors check AFP and an ultrasound together, usually every 6 months. This is one of the clearer, well-supported uses of a tumor marker. It matters, since hepatitis B is common in the Philippines. AFP also helps track known liver tumors and germ cell tumors.
CA-125 (cancer antigen 125)
CA-125 is a protein that rises with some ovarian cancers.
Normal: under 35 U/mL.
CA-125 rises most with cancer of the ovary lining, called epithelial ovarian cancer. It also rises with some other cancers, like uterine, fallopian tube, and lung cancer. Harmless causes include endometriosis, fibroids, pelvic infection, pregnancy, your period, recent surgery, and liver disease. Even 1 to 2% of healthy women without any disease show a mild rise.
CA-125 helps track known ovarian cancer. It also helps sort out a pelvic mass found on ultrasound. It also has a role for women with a known BRCA gene change. This is under a specialist's care.
CA-125 is not built for routine screening. Large studies found no drop in deaths from screening average-risk women. They also found real harm from false alarms. It is not an "annual ovarian cancer check."
CA 19-9
CA 19-9 is a marker. It rises with some pancreatic and bile duct cancers.
Normal: under 37 U/mL.
CA 19-9 rises most with pancreatic cancer. It also rises with cholangiocarcinoma, a bile duct cancer, and with some colon and stomach cancers. Harmless causes include pancreatitis, a blocked bile duct, hepatitis, cirrhosis, and diabetes.
Doctors use CA 19-9 to track known pancreatic cancer. It also helps sort out a pancreatic mass found on imaging. It is not built for screening healthy adults. About 1 in 10 healthy adults cannot make this marker at all. This is due to their blood type, even if they do have cancer.
CA 15-3 and CA 27-29
These two markers rise with some breast cancers.
Normal: CA 15-3 under 30 U/mL. CA 27-29 under 40 U/mL.
Doctors use these to track known breast cancer, mostly when it has spread. Mammograms remain the tool for breast cancer screening, not these blood tests.
Beta-hCG
Beta-hCG is the pregnancy hormone. It also rises with some rare tumors.
Doctors use it for pregnancy tests. They also use it to track germ cell tumors. It also tracks a rare condition called gestational trophoblastic disease.
Calcitonin
Calcitonin is a hormone made by special thyroid cells. It rises with a rare cancer called medullary thyroid cancer.
Doctors use it to screen family members with a rare inherited condition called MEN2. They also use it to track known medullary thyroid cancer. It is not part of routine thyroid screening.
Thyroglobulin
Thyroglobulin is a protein made by thyroid tissue.
Doctors use it after thyroid cancer surgery. A rising level can point to the cancer coming back. Doctors also check a related antibody test alongside it. That antibody can throw off the result otherwise.
Why a "full tumor marker panel" often backfires
Many clinics sell a bundle of markers together, often CEA, AFP, CA-125, and CA 19-9. They sell it as part of an executive checkup. Here is the problem:
- Each marker has several harmless causes of a high result. Running many at once raises your odds of a false alarm.
- Most early cancers do not raise these markers at all.
- A high result often leads to scans and sometimes biopsies, each with its own risk.
- The worry from an unclear result is real.
- Large studies of routine screening have not shown fewer cancer deaths.
When tumor markers do make sense
Situation | Example |
|---|---|
Watching a defined high-risk group | AFP plus ultrasound for hepatitis carriers |
Sorting out a symptom or scan finding | CA-125 for an unexplained pelvic mass |
Tracking a cancer you already have | CEA after colon cancer treatment |
A specific inherited condition | Calcitonin for MEN2 family members |
Want to know which tests actually fit your situation? Book your &you Labs panel and talk it through with a doctor.
How &you Labs handles tumor markers
A &you Labs panel includes hepatitis B and C screening. This is common among Filipino adults. It includes AFP for confirmed hepatitis carriers, as part of ongoing watching. It includes PSA for men 40 and up, framed as a conversation with your doctor. It does not include a routine tumor marker bundle by default. CEA, CA-125, CA 19-9, and other markers are available too. They fit when your specific situation calls for them. For breast, cervical, colon, and lung cancer, imaging and specialist care remain the right screening path.
Frequently asked questions
Should I add tumor markers to my executive checkup?
Usually not, unless you have a real risk factor or symptom. Most checkup bundles that include tumor markers cause more worry than useful early answers.
My company checkup found a high tumor marker. What now?
Talk to a doctor first. Most high results turn out to be harmless. What happens next depends on a few things. This includes which marker is high, how high it is, your symptoms, and your other results.
Are there any tumor markers I should test routinely?
For Filipino adults, hepatitis B and C screening matters. It decides if AFP watching applies to you. For men over 50, PSA is worth a conversation. Beyond that, routine tumor marker testing does not fit most healthy adults.
What about the newer multi-cancer blood tests?
These are promising, but not yet standard care. Our full guide to cancer screening blood tests covers where the science stands today.
Are tumor markers useful for cancer survivors?
Yes. This is where tumor markers do their best work. They watch for a cancer's return and track how well treatment works.
Key takeaways
- Tumor markers detect proteins linked to specific cancers, but they have limited value for screening.
- Their best uses are tracking a known cancer and watching a defined high-risk group. They also help sort out a suspicious finding.
- A routine tumor marker bundle often causes more false alarms than useful answers in a healthy adult.
- One clear exception: AFP plus ultrasound for people with long-term hepatitis B or C.
- Imaging and tissue tests still do most of the real work in cancer screening.
