Guides
Elevated CA 15-3: It Is Not a Breast Cancer Screening Test
CA 15-3 is not a breast cancer screening test. In Türkiye, screening is done with mammography every 2 years at ages 40–69; CA 15-3 is used to follow up patients already diagnosed.
Translated from the Turkish original by DoktorClub. The Turkish version is the reference text; this English translation has not been separately reviewed by a physician. Read the Turkish original.
Key takeaway
CA 15-3 is not a breast cancer screening test; its result does not show whether or not you have cancer. In Türkiye, under the program of the Turkish Ministry of Health (HSGM), breast cancer screening is done with mammography every 2 years in women aged 40–69. According to the NACB 2008 guideline, CA 15-3 can be used to monitor treatment in advanced breast cancer. Evaluate your result against the laboratory reference range on your report.
Short Answer
CA 15-3 is not a breast cancer screening test; its result does not show whether or not you have cancer. In Türkiye, under the program of the Turkish Ministry of Health (HSGM), breast cancer screening is done with mammography every 2 years in women aged 40–69. According to the NACB 2008 guideline, CA 15-3 can be used to monitor treatment in advanced breast cancer. Evaluate your result against the laboratory reference range on your report.
How does it appear on your report?
On reports, the test is written as "CA 15-3", "CA15-3" or "Cancer antigen 15-3". Another test used for a similar purpose is called "CA 27.29". In the Ministry of Health's list of Test Measurement Units, the unit for CA 15-3 is U/mL.
The "Tahlillerim" (My Tests) screen in e-Nabız (Türkiye's national health record app) shows the result with its reference value and marks out-of-range values in color. You can see your previous results with the chart icon. For a patient under follow-up, the direction of change matters more than a single value.
A single number or a range? On the report you usually see a single upper limit. Under the Ministry of Health procedure, decision limits are marked with an asterisk (*) to distinguish them from the reference range.
Laboratory differences: In a 2024 external quality assessment, a difference of up to 107% was found for CA 15-3 between the methods measuring highest and lowest. So do not directly compare results from two different laboratories.
Normal value and reference range
The upper limit varies by laboratory and method; the limit on your report is the one that applies. The values below are example data that affect interpretation.
| Situation | Value | What does it mean? | Source |
|---|---|---|---|
| Healthy women, day 7 of the menstrual cycle | Mean 19.27 U/mL | First half of the cycle | Gaziantep study, 1999 |
| Healthy women, day 21 of the menstrual cycle | Mean 26.33 U/mL | Significantly higher in the second half of the cycle | Gaziantep study, 1999 |
| 1220 people with benign disease | Above 40 U/mL in 3.1% | Can rise without cancer | Colomer et al., 1989 |
| Different test methods | Up to 107% difference between methods | Follow-up should be done at the same laboratory | Kremser et al., 2024 |
The reference range covers 95% of healthy people; about 1 in 20 healthy people may fall slightly outside the range. So, in the absence of symptoms, a mild elevation means nothing on its own.
What does it mean if it is high?
Causes are listed from common and harmless to serious.
1. Menstrual cycle. In a study of 23 healthy women in Gaziantep, CA 15-3 was found to be markedly higher in the second half of the cycle. The authors recommended taking the cycle day into account when interpreting the result.
2. Laboratory and method differences. Different analyzers can give different results for the same blood. An increase seen when you change laboratories may not be real.
3. Liver diseases. In a study of 1220 patients with benign disease, CA 15-3 was elevated in 42.9% of those with chronic hepatitis. This rate was 13.3% in liver cirrhosis.
4. Lung and immune system diseases. In the same study, elevation was seen in 16.7% of sarcoidosis, 9.7% of tuberculosis and 6.7% of lupus cases.
5. Breast cancer. CA 15-3 may rise, but a normal value does not rule out cancer. According to the US National Cancer Institute (NCI), not everyone with a particular cancer has an elevated marker for that cancer. According to NACB 2008, CA 15-3 can be used to monitor the course of treatment in advanced breast cancer. In diagnosed patients, consecutive rises are more meaningful than a single high value.
Why is it not a screening test? According to the NCI, circulating tumor markers do not work well for screening. They cannot catch everyone who has the disease, and they can also rise in people without cancer. That is why national programs use mammography, not a blood test, for breast screening.
Read together
- CA 15-3 mildly high + no symptoms + normal mammogram: This result is not interpreted as a screening finding; continue your mammography program.
- CA 15-3 high + abnormal liver tests or hepatitis: The elevation may be due to liver disease.
- CA 15-3 high + blood drawn in the second half of the menstrual cycle: The value may be high because of the cycle.
- Breast lump + normal CA 15-3: A normal value does not rule out cancer; imaging and examination are needed.
- CA 15-3 falling during breast cancer treatment: May support a response to treatment; decisions are made together with imaging.
- CA 15-3 rising on consecutive tests after treatment: Your oncologist evaluates this with imaging.
Preparation before the test
- Cycle day: Note which day of your menstrual cycle you are on and tell your doctor.
- Biotin: According to the Ministry of Health's 2024 guide, high-dose biotin can make immunological tests show falsely low or falsely high results, depending on the method. If you take supplements, tell the laboratory.
- Same laboratory: Have follow-up measurements done at the same laboratory and with the same method.
- Liver disease: If you have been diagnosed with hepatitis or cirrhosis, tell your doctor.
- Testing on your own initiative: If you have no symptoms, do not have CA 15-3 done for screening purposes; follow the mammography program.
Which doctor, which test?
- If you are of screening age (40–69): See your family physician or a KETEM (Cancer Early Diagnosis, Screening and Training Center); a free mammogram is taken every 2 years.
- Breast lump, nipple discharge or skin dimpling: General surgery or breast surgery; examination and breast imaging.
- Those who have been treated for breast cancer: Medical oncology; follow-up is done with regular examination and mammography.
- If liver tests are abnormal: Internal medicine or gastroenterology.
- If there is breast or ovarian cancer in the family: Talk to your doctor about a risk assessment and screening plan.
In Türkiye
- National breast screening: According to the standard of the Ministry of Health General Directorate of Public Health (HSGM), women aged 40–69 have a mammogram every 2 years. CA 15-3 is not part of the program.
- KETEMs and family physicians: Cancer Early Diagnosis, Screening and Training Centers and family physicians carry out screenings free of charge.
- Other programs: There is an HPV test every 5 years at ages 30–65 for cervical cancer, and a fecal occult blood test every 2 years at ages 50–70 for colorectal cancer.
- Data from Türkiye: A 1999 study from Gaziantep University showed that CA 15-3 changes with the menstrual cycle in healthy women.
- Units: In the national list of units, CA 15-3 is reported in U/mL.
When should you seek urgent care?
- If you have a breast cancer diagnosis and develop sudden shortness of breath, chest pain or swelling in one leg, call 112 (the emergency number in Türkiye).
- If sudden back pain is accompanied by weakness in the legs or loss of bladder or bowel control, call 112.
- If you have a new, very severe headache, a seizure or a change in consciousness, call 112.
- If there is a rapidly growing, red and painful swelling in the breast with fever, see a doctor the same day.
- If the laboratory has called you about a critical value, see your doctor or go to the emergency department the same day.
Related tests
- Lab Test Guide: all tests
- Does elevated CEA mean cancer?
- Elevated CA 125: cyst or cancer?
- When should liver enzymes be taken seriously?
- How to read a complete blood count (CBC)
What has changed? (October 2026)
- The HSGM national breast cancer screening standard was used as the basis: ages 40–69, mammography every 2 years.
- NCI tumor marker information reviewed in December 2023 and the ASCO follow-up recommendation were added.
- 2024 external quality data showing differences between methods were added.
Sources
- T.C. Sağlık Bakanlığı Halk Sağlığı Genel Müdürlüğü (HSGM). Kanser Taramaları (national screening standards). Current version. https://hsgm.saglik.gov.tr/tr/kanser-taramalari (accessed October 2, 2026)
- T.C. Sağlık Bakanlığı. e-Nabız Kullanım Kılavuzu V2.1. 2025. https://enabiz.gov.tr/document/User_Manual.pdf (accessed October 2, 2026)
- T.C. Sağlık Bakanlığı SHGM. Test Ölçüm Birimleri, Versiyon 2. 15.09.2021. https://dosyamerkez.saglik.gov.tr/Eklenti/41467/0/test-olcum-birimleri-versiyon-2-pdfpdf.pdf (accessed October 2, 2026)
- T.C. Sağlık Bakanlığı SHGM. Tıbbi Biyokimya Toplam Test Süreci Rehberi, Publication No 1287. May 2024. https://dosyamerkez.saglik.gov.tr/Eklenti/48692/0/tibbi-biyokimya-toplam-test-sureci-rehberipdf.pdf (accessed October 2, 2026)
- Erbağcı AB, Yılmaz N, Kutlar I. Menstrual cycle dependent variability for serum tumor markers CEA, AFP, CA 19-9, CA 125 and CA 15-3 in healthy women. Dis Markers. 1999;15:259-267. https://doi.org/10.1155/1999/960934 (accessed October 2, 2026)
- Sturgeon CM et al. National Academy of Clinical Biochemistry laboratory medicine practice guidelines for use of tumor markers. Clin Chem. 2008;54:e11-79. https://doi.org/10.1373/clinchem.2008.105601 (accessed October 2, 2026)
- Khatcheressian JL et al. Breast Cancer Follow-Up and Management After Primary Treatment: ASCO Clinical Practice Guideline Update. J Clin Oncol. 2013;31:961-965. https://doi.org/10.1200/JCO.2012.45.9859 (accessed October 2, 2026)
- National Cancer Institute (NCI). Tumor Markers (reviewed December 7, 2023). https://www.cancer.gov/about-cancer/diagnosis-staging/diagnosis/tumor-markers-fact-sheet (accessed October 2, 2026)
- Colomer R et al. Circulating CA 15-3 levels in the postsurgical follow-up of breast cancer patients and in non-malignant diseases. Breast Cancer Res Treat. 1989;13:123-133. https://doi.org/10.1007/BF01806524 (accessed October 2, 2026)
- Kremser M et al. Longitudinal evaluation of external quality assessment results for CA 15-3, CA 19-9, and CA 125. Front Mol Biosci. 2024;11:1401619. https://doi.org/10.3389/fmolb.2024.1401619 (accessed October 2, 2026)
Frequently asked questions
Does elevated CA 15-3 mean breast cancer?
No. CA 15-3 can also rise in non-cancer conditions such as liver diseases, sarcoidosis, tuberculosis and lupus. It can also measure higher in the second half of the menstrual cycle. Breast cancer is diagnosed by examination, imaging and biopsy.
Should I have CA 15-3 done for breast cancer screening?
No. According to the NCI, tumor markers do not work well for screening. In Türkiye, breast cancer screening is done with mammography every 2 years in women aged 40–69. If you are of screening age, make an appointment with your family physician or a KETEM (Cancer Early Diagnosis, Screening and Training Center).
My CA 15-3 showed up red in e-Nabız but my mammogram is clear. What should I do?
Show the result to your family physician. Your doctor will evaluate your cycle day, your liver tests and any other diseases. If you have no symptoms and your examination is normal, this value alone is not considered a reason for further tests. If you notice a new change in your breast, seek care without waiting.
My breast cancer treatment has ended. How often should CA 15-3 be checked?
According to the ASCO guideline, CA 15-3, CA 27.29 and CEA are not recommended for routine follow-up in patients without symptoms. Follow-up is done with regular history, examination and mammography. Visits are every 3–6 months for the first 3 years, every 6–12 months in years 4 and 5, and yearly after that. Your oncologist may make a different plan for you.
Does CA 15-3 change during the menstrual cycle?
Yes. In the study conducted in Gaziantep, the mean value was 19.27 U/mL on day 7 of the cycle and 26.33 U/mL on day 21. The difference was statistically significant. So the cycle day on which blood is drawn can affect interpretation.
