Guides
High CA 125: Ovarian Cyst or Cancer?
An elevated CA 125 is most often due to benign causes such as menstruation, endometriosis, fibroids or inflammation. It is not a screening test; it is interpreted with age and ultrasound.
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
An elevated CA 125 does not by itself mean ovarian cancer. Menstruation, endometriosis, fibroids, pelvic infection and liver disease also raise the value. According to the 2018 recommendation of the US Preventive Services Task Force (USPSTF), women without symptoms should not be screened for ovarian cancer. Evaluate your result according to the laboratory reference range on your report, your age and the ultrasound findings.
Short Answer
An elevated CA 125 does not by itself mean ovarian cancer. Menstruation, endometriosis, fibroids, pelvic infection and liver disease also raise the value. According to the 2018 recommendation of the US Preventive Services Task Force (USPSTF), women without symptoms should not be screened for ovarian cancer. Evaluate your result according to the laboratory reference range on your report, your age and the ultrasound findings.
How does it appear on your report?
On reports, the test is written as "CA 125," "CA-125" or "Cancer antigen 125" (Turkish: "Kanser antijeni 125"). In the Turkish Ministry of Health's Test Measurement Units list, its unit is U/mL. On some reports you may see kU/L; the two are numerically identical.
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 results in color. You can see your previous results with the chart icon. With CA 125, the direction of change matters more than a single value.
A single number or a range? The report often shows a single upper limit such as "below 35." According to the Ministry of Health procedure, decision limits are marked with an asterisk (*) to distinguish them from the reference range.
Laboratory differences: Laboratories may use different test methods. So, if possible, have follow-up done at the same laboratory with the same method.
Normal values and reference range
| Condition | Value | What does it mean? | Source |
|---|---|---|---|
| Traditional upper limit | 35 U/mL | In the original study, about 1% of healthy women were above this limit | Charkhchi et al., 2020 |
| With symptoms, ages 40–49 | 35 IU/mL and above | Urgent ultrasound is recommended | NICE NG12, 2026 |
| With symptoms, ages 50–59 | 31 IU/mL and above | Urgent ultrasound is recommended | NICE NG12, 2026 |
| With symptoms, ages 60–69 | 24 IU/mL and above | Urgent ultrasound is recommended | NICE NG12, 2026 |
| With symptoms, ages 70–79 | 25 IU/mL and above | Urgent ultrasound is recommended | NICE NG12, 2026 |
| With symptoms, age 80 and over | 31 IU/mL and above | Urgent ultrasound is recommended | NICE NG12, 2026 |
| With symptoms, age 39 and under | Not used on its own for decisions | Ultrasound is considered | NICE NG12, 2026 |
| Premenopausal ovarian mass | Above 200 U/mL | A gynecologic oncologist is consulted | RCOG, 2011 |
A reference range covers 95% of healthy people; about 1 in 20 healthy people may fall slightly outside the range. CA 125 naturally decreases with age. According to a comprehensive review, between ages 45 and 55 the average value falls by 30% over 10 years. Values are markedly higher in healthy premenopausal women.
What does a high value mean?
The causes are listed from common and harmless to serious. In one study, 80% of people found to have a high CA 125 did not have ovarian cancer.
1. Menstruation. CA 125 increases during menstruation and begins to rise in the premenstrual period.
2. Endometriosis and adenomyosis. Endometrioma, known as a chocolate cyst, is also in this group. According to the RCOG guideline, CA 125 rising to hundreds or thousands of units is generally expected only in advanced-stage endometriosis.
3. Fibroids and pelvic infection. According to RCOG, fibroids and pelvic infection raise CA 125. In general, irritation or inflammation of the lining of the abdomen and pelvis increases CA 125.
4. Pregnancy and childbirth. CA 125 can be high in the first weeks of pregnancy. In one study, the median value at weeks 5–8 was 36.2 U/mL, and values up to 251 U/mL were seen. The value then usually falls below 35 U/mL. It rises again during delivery and continues to rise until 48 hours after birth. A single CA 125 result cannot be reliably interpreted during these periods.
5. Body weight. CA 125 tends to increase as body mass index increases.
6. Diseases of the liver, heart and lining of the lungs. CA 125 is high in 85% of patients with cirrhosis. Fluid buildup in the abdomen (ascites) or in the lining of the lungs also raises the value. In heart failure, CA 125 has also been proposed as a marker that predicts the course of the disease.
7. Ovarian cancer and other cancers. According to RCOG, CA 125 is raised in only 50% of early-stage ovarian cancers. About 20% of ovarian cancers do not produce CA 125. It can also rise in breast, lung, pancreatic, colorectal and uterine cancers.
Cyst or cancer? According to RCOG, CA 125 cannot reliably distinguish benign from malignant masses in premenopausal women. If a simple cyst is seen on ultrasound, CA 125 may not be needed. Simple cysts smaller than 50 mm usually disappear on their own within 2–3 menstrual cycles. According to NACB 2008, CA 125 is recommended in the differential diagnosis of suspicious pelvic masses after menopause. Specialists also use a risk score (RMI) that combines CA 125 with ultrasound and menopausal status.
When read together
- Mildly high CA 125 + menstruation: Interpretation is adjusted accordingly; your doctor may repeat the test outside your period.
- Mildly high CA 125 + simple cyst on ultrasound: Monitoring is usually sufficient; the cyst may disappear within a few cycles.
- High CA 125 + endometrioma appearance: Endometriosis becomes the leading possibility.
- CA 125 rising quickly on serial measurements: According to RCOG, the likelihood of malignancy is higher than with a stable high value.
- Postmenopausal + ovarian mass + high CA 125: Gynecologic oncology evaluation is required.
- High CA 125 + fluid in the abdomen or a palpable mass: According to NICE, rapid referral via the suspected cancer pathway is required.
- High CA 125 + cirrhosis or heart failure: The elevation may be due to these diseases.
Preparing for the test
- Menstrual day: Tell your doctor and the laboratory if you are on your period.
- Pregnancy and childbirth: Mention it if you are pregnant or have recently given birth.
- Same laboratory: If possible, have follow-up measurements done at the same laboratory with the same method.
- No decision on a single measurement: A borderline value is interpreted together with ultrasound and clinical findings.
- Note your symptoms: Write down how long you have had bloating, early satiety, abdominal pain and frequent urination.
Which doctor, which test?
- First step: An obstetrician-gynecologist; examination and abdominal-pelvic ultrasound.
- Gynecologic oncology: If ultrasound suggests cancer, if premenopausal CA 125 is above 200 U/mL, or if there is a suspicious mass after menopause.
- Complex mass under age 40: According to RCOG, AFP, hCG and LDH should also be measured.
- Internal medicine or gastroenterology: If liver disease, fluid in the abdomen or heart failure is suspected.
- Genetic counseling: If there is ovarian or breast cancer in the family or a known BRCA mutation, monitoring is planned with a specialist.
- If symptoms persist: Even if CA 125 and ultrasound are normal, see a doctor again if complaints increase.
In Türkiye
- National screening program: The Ministry of Health's HSGM (General Directorate of Public Health) program includes breast, cervical and colorectal cancer screening. There is no national screening program for ovarian cancer; CA 125 is not used as a screening test.
- Cervical screening: According to HSGM, it is done with an HPV test every 5 years in women aged 30–65. This screening should not be confused with CA 125.
- Breast screening: Done with mammography every 2 years in women aged 40–69.
- KETEM: Cancer Early Diagnosis, Screening and Education Centers and family doctors perform these screenings free of charge.
- Units: In the national units list, CA 125 is reported in U/mL.
When should you seek emergency care?
- If sudden, very severe groin or abdominal pain occurs together with vomiting or fainting, call 112 (the emergency number in Türkiye).
- If there is bleeding and one-sided groin pain when pregnancy is possible, call 112.
- If there is rapidly increasing abdominal swelling and shortness of breath, go to the emergency department the same day.
- If there is fever, groin pain and foul-smelling discharge, see a doctor the same day; it may be a pelvic infection.
- 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 a high CEA mean cancer?
- High CA 15-3: not a breast cancer screening test
- Sexually transmitted infection tests
- When should liver enzymes be taken seriously?
- CRP, ESR and procalcitonin: inflammation tests
What changed? (October 2026)
- The age-based CA 125 thresholds and the warning for under-39s from the April 15, 2026 update of NICE NG12 were added.
- Screening information was updated with USPSTF 2018 (grade D) and the UKCTOCS 2021 long-term results.
- HSGM national screening programs were used as the basis; ovarian cancer is not included in these programs.
Sources
- T.C. Sağlık Bakanlığı Halk Sağlığı Genel Müdürlüğü (HSGM). Kanser Taramaları (ulusal tarama standartları). 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)
- US Preventive Services Task Force. Ovarian Cancer: Screening. Final Recommendation Statement, grade D. February 13, 2018. https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/ovarian-cancer-screening (accessed October 2, 2026)
- Menon U et al. Ovarian cancer population screening and mortality after long-term follow-up in UKCTOCS. Lancet. 2021;397:2182-2193. https://doi.org/10.1016/S0140-6736(21)00731-5 (accessed October 2, 2026)
- NICE. NG12 Suspected cancer: recognition and referral (ovarian cancer, last updated April 15, 2026). https://www.nice.org.uk/guidance/ng12/chapter/Recommendations-organised-by-site-of-cancer (accessed October 2, 2026)
- RCOG/BSGE. Management of Suspected Ovarian Masses in Premenopausal Women, Green-top Guideline No. 62. November 2011. https://www.rcog.org.uk/media/0mebp0mv/gtg_62.pdf (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)
- Charkhchi P et al. CA125 and Ovarian Cancer: A Comprehensive Review. Cancers. 2020;12:3730. https://doi.org/10.3390/cancers12123730 (accessed October 2, 2026)
- Spitzer M, Kaushal N, Benjamin F. Maternal CA-125 levels in pregnancy and the puerperium. J Reprod Med. 1998;43:387-392. https://pubmed.ncbi.nlm.nih.gov/9583073/ (accessed October 2, 2026)
Frequently asked questions
Is a high CA 125 an ovarian cyst or cancer?
CA 125 alone cannot tell them apart. According to RCOG, in premenopausal women fibroids, endometriosis and pelvic infection are common causes of false elevation. The decision is made together with the ultrasound appearance, age, menopausal status and the trend in CA 125. After menopause, a high CA 125 is evaluated more carefully.
My CA 125 came back high in e-Nabız but my ultrasound is normal; what does this mean?
According to NICE NG12, in this situation other causes of the symptoms are investigated. If no other cause is found and complaints become more frequent, you should see a doctor again. Causes such as menstruation, endometriosis or liver disease are also reviewed.
Does CA 125 rise during menstruation?
Yes. CA 125 increases during menstruation and begins to rise before the period. So a mild elevation may be seen in blood drawn during a period. If needed, your doctor will have the test repeated outside your period.
Should I have a CA 125 test to screen for ovarian cancer?
Not if you have no symptoms and no high inherited risk. USPSTF 2018 gives a grade D recommendation against screening in women without symptoms. In the UKCTOCS study in the UK, 202,638 women were followed for a median of 16.3 years; screening did not significantly reduce deaths. If there is ovarian cancer or a BRCA mutation in your family, talk to a specialist.
At what level is CA 125 dangerous?
There is no single danger threshold. For women with symptoms, NICE 2026 uses age-based thresholds for ultrasound ranging from 24 to 35 IU/mL. According to RCOG, a value above 200 U/mL with a premenopausal mass requires consulting a gynecologic oncologist. Rapidly rising values are also important.
