Tumor Marker for Ovarian Mass
Order CA-125 as the primary tumor marker for evaluating an ovarian mass, as it is the most widely used and clinically validated marker for epithelial ovarian cancer. 1
Primary Recommendation: CA-125
CA-125 should be measured 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) 1
The combination of CA-125 with ultrasound imaging provides better diagnostic accuracy than either test alone for differentiating benign from malignant ovarian masses 2
Critical Limitations of CA-125
CA-125 only detects 50% of stage I ovarian cancers, so a normal level does not exclude early malignancy 1
False-positive elevations occur commonly with benign conditions including endometriosis, adenomyosis, pelvic inflammatory disease, benign ovarian cysts, and cirrhosis 1, 3
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 2
Additional Markers When CA-125 is Not Elevated
Measure CA 19-9 when CA-125 is normal, particularly if imaging suggests clear cell, mucinous, or endometrioid tumors 1
These tumor subtypes may not produce elevated CA-125 levels, making alternative markers essential for proper evaluation 1
Special Populations Requiring Additional Markers
In young women (particularly under age 35), also measure alpha-fetoprotein (AFP) and beta-hCG to exclude germ cell tumors 1
Germ cell tumors represent a distinct category of ovarian malignancy that requires different tumor markers for detection 1
Markers NOT Recommended
Do not order OVA1 or multimarker panels as screening tools, as they are not recommended by the Society of Gynecologic Oncologists or FDA for this purpose 1
HE4 and other emerging markers (mesothelin, B7-H4) do not increase early enough to be useful in detecting early-stage ovarian cancer 1
Clinical Integration
Always interpret CA-125 results in conjunction with imaging findings (transvaginal ultrasound with color Doppler is the primary imaging modality) 2
A progressively elevated CA-125 level over time, even within the normal range, should prompt further evaluation as it may indicate malignancy 1
When CA-125 is elevated with imaging showing an indeterminate mass, MRI with IV contrast is the next best step for further characterization 2
Common Pitfalls to Avoid
Do not rely on CA-125 alone to make surgical decisions, as it lacks sufficient sensitivity for early disease 4
Do not test CA-125 in patients with ascites from any cause (especially cirrhosis), as it is universally elevated and nonspecific in this setting 5, 3
Do not assume a normal CA-125 excludes ovarian cancer, particularly in premenopausal women or early-stage disease 1, 4