All You Need To Know About Cancer Markers
If you have been asked to take a blood test for cancer markers, you may have questions about what these tests measure and what your results mean. Understanding tumour markers can help you make sense of your medical care and have more informed conversations with your doctor.
This guide explains what markers in cancer are, how they are used in clinical practice, and what you should know about specific markers like CA-125.
What Are Cancer Markers?
Cancer markers, also called tumour markers or biomarkers, are substances produced by cancer cells or by normal cells in response to cancer. These substances, usually proteins, can be detected in blood, urine, or tissue samples. When present at elevated levels, they may indicate the presence of cancer or provide information about how a cancer is responding to treatment.
It is important to understand that tumour markers are not definitive diagnostic tools on their own. Many markers can be elevated due to non-cancerous conditions, and some cancers do not produce detectable levels of markers at all. For this reason, cancer markers on blood test results are always interpreted alongside other diagnostic methods, including imaging studies, physical examinations, and biopsies.
How Cancer Markers Are Used
Tumour markers serve several purposes in cancer care. Your doctor may order these tests to monitor treatment response in patients undergoing cancer therapy, detect recurrence after successful treatment, help evaluate a suspicious mass or growth when combined with imaging, assess prognosis and guide treatment decisions, and screen high-risk individuals for certain cancers.
Most tumour markers are not sensitive or specific enough to be used for general screening in the healthy population. The main exception is prostate-specific antigen (PSA) for prostate cancer, though even this use remains debated among medical professionals.
CA-125: The Ovarian Cancer Marker
CA 125, or cancer antigen 125, is one of the most well-known cancer markers for ovarian cancer. This protein is found on the surface of ovarian cancer cells and can be measured in the blood when shed by tumours.
Normal Range and Interpretation
The reference range for CA-125 is 0 to 35 units per millilitre (U/mL). Values above this threshold may warrant further investigation, though an elevated result does not automatically indicate cancer.
CA-125 is elevated in approximately 80% of women with epithelial ovarian cancer. However, sensitivity varies by stage. Only about 50% of women with early-stage ovarian cancer have elevated CA-125 levels, while approximately 85% of those with advanced disease show elevated levels. This limitation means CA-125 cannot reliably detect ovarian cancer in its earliest, most treatable stages.
Limitations of CA-125
Several non-cancerous conditions can cause elevated CA-125 levels, including menstruation, pregnancy, endometriosis, pelvic inflammatory disease, uterine fibroids, liver disease such as cirrhosis or hepatitis, and heart failure.
Because of these limitations, CA-125 is not recommended for routine screening in women at average risk of ovarian cancer. Instead, it is most useful for monitoring treatment response in women already diagnosed with ovarian cancer and detecting recurrence after treatment.
Who Should Be Tested
CA-125 testing may be appropriate for postmenopausal women with a pelvic mass, women with symptoms suggestive of ovarian cancer combined with abnormal imaging findings, women at high risk due to family history or genetic mutations such as BRCA1 or BRCA2, and women previously treated for ovarian cancer who require ongoing surveillance.
An ultrasound clinic can provide transvaginal ultrasound imaging, which is often used alongside CA-125 testing to evaluate pelvic masses and assess ovarian health.
HE4 and the ROMA Algorithm
Human epididymis protein 4 (HE4) is another tumour marker used in ovarian cancer assessment. Research shows that HE4 has a specificity of approximately 94% and, unlike CA-125, is not typically elevated in endometriosis.
The Risk of Ovarian Malignancy Algorithm (ROMA) combines CA-125 and HE4 results with menopausal status to calculate a woman’s risk of having epithelial ovarian cancer. Studies indicate that ROMA achieves sensitivity of approximately 90% for detecting ovarian cancer while maintaining high specificity. This algorithm helps doctors determine whether a woman with a pelvic mass should be referred to a gynaecological oncologist.
Breast Cancer Markers
For breast cancer, the most commonly used tumour markers are CA 15-3 and CA 27-29, which measure similar antigens. The normal range for CA 15-3 is less than 30 U/mL, while CA 27-29 should be less than 38 U/mL.
These markers are not used for screening or early detection because they are elevated in fewer than 50% of women with early-stage breast cancer. However, CA 15-3 is elevated in approximately 80% of women with metastatic breast cancer, making it useful for monitoring advanced disease and treatment response.
Imaging remains the cornerstone of breast cancer detection. Ultrasound breast screening is particularly valuable for evaluating breast lumps and is often used alongside mammography, especially in women with dense breast tissue.
Other Common Cancer Markers
Carcinoembryonic Antigen (CEA)
CEA is primarily used to monitor colorectal cancer. Normal levels are typically less than 2.5 ng/mL in non-smokers. Levels above 10 ng/mL suggest extensive disease, while levels above 20 ng/mL may indicate metastatic spread. CEA is also used to monitor cancers of the lung, breast, pancreas, and stomach.
Alpha-Fetoprotein (AFP)
AFP is the primary marker for hepatocellular carcinoma (liver cancer) and certain testicular cancers. Normal adult levels are less than 15 to 20 ng/mL. Elevated AFP can also occur in chronic liver disease, hepatitis, and cirrhosis, which can complicate interpretation.
CA 19-9
CA 19-9 is used primarily for pancreatic cancer, with normal levels below 37 U/mL. This marker has a sensitivity and specificity of 80 to 90% for pancreatic cancer. It may also be elevated in biliary tract cancer and some benign conditions affecting the liver and bile ducts.
Prostate-Specific Antigen (PSA)
PSA is used to screen for and monitor prostate cancer in men. While it is the most widely used cancer screening marker, elevated PSA can also result from benign prostatic hyperplasia, prostatitis, and other non-cancerous conditions.
Cancer Markers Reference Table
| Marker | Normal Range | Primary Cancer Association | Key Limitations |
| CA-125 | <35 U/mL | Ovarian cancer | Elevated in endometriosis, menstruation, pregnancy |
| HE4 | <150 pmol/L | Ovarian cancer | May be affected by smoking, kidney function |
| CA 15-3 | <30 U/mL | Breast cancer | Low sensitivity in early-stage disease |
| CA 27-29 | <38 U/mL | Breast cancer | Similar limitations to CA 15-3 |
| CEA | <2.5 ng/mL | Colorectal cancer | Elevated in smokers and some benign conditions |
| AFP | <15-20 ng/mL | Liver cancer, testicular cancer | Elevated in chronic liver disease |
| CA 19-9 | <37 U/mL | Pancreatic cancer | Not produced by individuals with Lewis-null blood type |
Cancer in Malaysia: Why Early Detection Matters
Cancer is now the third most common cause of death in Malaysia, accounting for 15,200 deaths in 2022 and moving up from fourth position in 2021. The proportion of deaths attributed to cancer increased from 10.5% in 2021 to 12.6% in 2022, according to the Department of Statistics Malaysia.
The Malaysia National Cancer Registry Report 2017-2021 recorded 168,822 new cancer cases over the five-year period. The ten most commonly diagnosed cancers among Malaysians are breast cancer, colorectal cancer, lung cancer, lymphoma, liver cancer, prostate cancer, leukaemia, nasopharyngeal cancer, uterine corpus cancer, and ovarian cancer.
Ovarian cancer is the fifth most common cancer affecting Malaysian women, with an incidence rate of 6.2 per 100,000 people. Research indicates that ovarian cancer incidence rises sharply after the age of 40 years.
The registry report highlights a concerning trend: the proportion of cancers detected at Stage 3 and 4 has increased to 65.1%, up from 63.7% in the previous reporting period. Late-stage detection is associated with lower survival rates, underscoring the importance of awareness, regular health screenings, and prompt medical attention when symptoms arise.
When to Discuss Cancer Markers with Your Doctor
Consider speaking with your doctor about tumour marker testing if you have a family history of cancer, particularly ovarian, breast, or colorectal cancer. Testing may also be appropriate if you carry known genetic mutations such as BRCA1 or BRCA2, have persistent unexplained symptoms such as bloating, pelvic pain, or changes in bowel habits, have been diagnosed with cancer and are undergoing treatment, or have completed cancer treatment and require ongoing surveillance.
For women planning pregnancy or concerned about reproductive health, a fertility test in Malaysia can provide insight into how certain conditions affecting tumour marker levels, such as endometriosis or ovarian cysts, may impact fertility and what options are available.
Emerging Research
Stem cell therapy is showing promising research in treatment of cancer. Scientists are exploring how stem cells might be used to regenerate healthy tissue damaged by chemotherapy or radiation, deliver targeted treatments directly to tumour sites, and support bone marrow recovery following intensive cancer treatment.
While most stem cell applications in oncology remain experimental, bone marrow transplants using haematopoietic stem cells are already an established treatment for certain blood cancers such as leukaemia and lymphoma.
At SpringHill Clinic, our team provides compassionate, evidence-based care for women at every stage of life. Whether you need guidance on screening options, have concerns about symptoms, or simply want to be proactive about your wellbeing, we are here to help. Book an appointment today.
References
Department of Statistics Malaysia (DOSM). Statistics on Causes of Death, Malaysia 2023. https://www.dosm.gov.my
Ministry of Health Malaysia. Malaysia National Cancer Registry Report 2017-2021. KKM. https://www.moh.gov.my
National Institutes of Health. Tumor Markers Fact Sheet. National Cancer Institute. https://www.cancer.gov
Dochez V, Caillon H, Vaucel E, et al. Biomarkers and algorithms for diagnosis of ovarian cancer: CA125, HE4, RMI and ROMA, a review. Journal of Ovarian Research. 2019;12:28. https://ovarianresearch.biomedcentral.com
FAQ
Most cancer markers are not sensitive enough to detect cancer in its earliest stages. Many markers, including CA-125 for ovarian cancer, are elevated in only about 50% of early-stage cases. This is why tumour markers are typically used for monitoring rather than screening in average-risk individuals.
An elevated CA-125 (above 35 U/mL) does not necessarily mean you have cancer. Many benign conditions, including endometriosis, menstruation, and pelvic inflammatory disease, can cause elevated levels. Your doctor will interpret the result alongside your symptoms, medical history, and imaging findings.
For cancer surveillance, markers are typically tested every three to six months during the first few years after treatment, then less frequently over time. The schedule depends on the type of cancer, stage at diagnosis, and your individual risk factors. Your oncologist will recommend an appropriate testing schedule.
Cancer marker tests require only a standard blood draw. You may feel a brief pinch when the needle is inserted, and some people experience mild bruising at the site afterward. The procedure takes just a few minutes.
Most cancer marker tests do not require fasting. However, if your doctor has ordered additional blood tests alongside the tumour markers, fasting may be necessary. Always follow your doctor’s specific instructions before your appointment.