Tumor Markers for Ovarian Mass Evaluation

Primary Recommendation: CA-125

• The American College of Radiology recommends measuring CA-125 before surgery in all patients with suspected ovarian cancer, with a specificity of 98.5% in women over 50 years old when using a threshold of 35 U/mL 1
• CA-125 is elevated in approximately 80-90% of serous carcinomas, the most common type of epithelial ovarian cancer, in patients with ovarian masses 1
• The combination of CA-125 with ultrasound imaging provides better diagnostic accuracy than either test alone for differentiating benign from malignant ovarian masses in patients with suspected ovarian cancer 2, 3

Critical Limitations of CA-125

• CA-125 only detects 50% of stage I ovarian cancers, so a normal level does not exclude early malignancy in patients with ovarian masses 1
• CA-125 performed worse than ultrasound alone in distinguishing benign from malignant lesions and only improved specificity for lesions already suspected to be malignant on imaging in patients with ovarian masses 3

Additional Markers When CA-125 is Not Elevated

• The Society of Gynecologic Oncologists recommends measuring CA 19-9 when CA-125 is normal, particularly if imaging suggests clear cell, mucinous, or endometrioid tumors in patients with ovarian masses 1

Special Populations Requiring Additional Markers

• In young women, particularly under age 35, the American College of Obstetricians and Gynecologists also recommends measuring alpha-fetoprotein (AFP) and beta-hCG to exclude germ cell tumors in patients with ovarian masses 1

Clinical Integration

• The American College of Radiology recommends always interpreting CA-125 results in conjunction with imaging findings, such as transvaginal ultrasound with color Doppler, in patients with suspected ovarian cancer 2, 3
• A progressively elevated CA-125 level over time, even within the normal range, should prompt further evaluation as it may indicate malignancy in patients with ovarian masses 1
• When CA-125 is elevated with imaging showing an indeterminate mass, the American College of Radiology recommends MRI with IV contrast as the next best step for further characterization in patients with ovarian masses 2, 3

Common Pitfalls to Avoid

• The Society of Gynecologic Oncologists recommends not relying on CA-125 alone to make surgical decisions, as it lacks sufficient sensitivity for early disease, and not testing CA-125 in patients with ascites from any cause, as it is universally elevated and nonspecific in this setting 4
• The American College of Obstetricians and Gynecologists recommends not assuming a normal CA-125 excludes ovarian cancer, particularly in premenopausal women or early-stage disease, in patients with ovarian masses 1

CA125:CEA Ratio Interpretation in Postmenopausal Women with Adnexal Masses

Primary Clinical Application

• The American College of Radiology suggests that a high CA125:CEA ratio indicates ovarian origin, while a low ratio suggests gastrointestinal malignancy in postmenopausal women with adnexal masses 5
• The CA125:CEA ratio is used to differentiate ovarian epithelial neoplasms from gastrointestinal primary cancers that have metastasized to the ovaries, as both can present with elevated tumor markers and pelvic masses 5

Understanding the Individual Markers

• The American College of Radiology states that a high CA125:CEA ratio strongly suggests an ovarian primary malignancy rather than a gastrointestinal primary tumor, optimizing specificity for distinguishing between these two cancer origins 5

Practical Interpretation Algorithm

• A high CA125 level with a normal CEA level suggests a high ratio, which strongly suggests ovarian primary malignancy, particularly serous histology, in postmenopausal women with adnexal masses 5
• The ratio calculation becomes critical when both CA125 and CEA are elevated; a higher CA125 level relative to CEA still favors ovarian origin 5

Clinical Context and Limitations

• The CA125:CEA ratio optimizes specificity specifically for distinguishing ovarian versus gastrointestinal primary neoplasms, which is clinically relevant when imaging shows features that could represent either entity 5
• The ratio does not help differentiate benign from malignant ovarian masses, its specific utility is distinguishing ovarian primary from metastatic gastrointestinal cancer 5

CA‑125 Clinical Utility and Limitations

Serial Measurement Interpretation

Specificity by Menopausal Status

Benign Conditions Causing Elevated CA‑125

Use of CA‑125 in the Evaluation of Suspected Adnexal Masses

Indications for Ordering CA‑125

• The American College of Radiology recommends measuring CA‑125 pre‑operatively in every patient with a suspected ovarian malignancy, particularly when trans‑vaginal ultrasound shows solid components, papillary projections, or abnormal vascular flow. 7

Diagnostic Performance When Combined with Imaging

• Combining CA‑125 results with ultrasound findings yields higher diagnostic accuracy than either test alone. 8
• CA‑125 improves specificity only after ultrasound has already identified a lesion as suspicious; it is not suitable as a stand‑alone screening test. 8

Limitations of CA‑125

• CA‑125 detects only about 50 % of stage I ovarian cancers; a normal value does not rule out early‑stage disease. 7
• False‑positive elevations occur in many benign conditions, including endometriosis, benign ovarian cysts, pelvic inflammatory disease, menstrual bleeding, pregnancy, any cause of ascites, and liver cirrhosis. 7

Interpretation in the Context of Ultrasound

• CA‑125 results should always be interpreted together with trans‑vaginal Doppler ultrasound findings, as ultrasound is superior to CA‑125 for distinguishing benign from malignant adnexal lesions. 8

Follow‑up and Further Imaging

• In cases of an indeterminate adnexal mass with an elevated CA‑125, the next recommended step is pelvic magnetic resonance imaging with intravenous contrast. 9

Use of CA‑125/CEA Ratio for Differential Diagnosis

• A high CA‑125/CEA ratio increases specificity for primary ovarian neoplasms versus gastrointestinal metastases to the ovary; a low ratio suggests a gastrointestinal origin. 7

Non‑gynecologic Causes of False‑Positive CA‑125 Elevations

Specificity Issues

• In women undergoing CA‑125 testing, elevations can occur due to non‑gynecologic conditions such as liver cirrhosis, hepatitis, renal failure, heart failure, peritonitis, pleural effusion, any cause of ascites, and pregnancy, which may lead to false‑positive results and reduce test specificity. 10