CA-125 Should Not Be Ordered to Screen for Cancer in Patients with DVT and PE
CA-125 is not recommended as part of occult cancer screening in patients presenting with deep vein thrombosis and pulmonary embolism, as it lacks specificity and is not included in guideline-recommended screening protocols for VTE-associated malignancy. 1
Guideline-Recommended Cancer Screening for VTE Patients
The International Society on Thrombosis and Haemostasis (ISTH) provides clear guidance on appropriate cancer screening in VTE patients, which does not include CA-125 testing 1:
For Unprovoked VTE (First Episode)
Patients should undergo limited cancer screening consisting of 1:
- Thorough medical history and physical examination
- Complete blood count
- Serum calcium
- Liver function tests
- Urinalysis
- Chest X-ray
- Age-specific and gender-specific cancer screening (colon, breast, cervix, prostate) per national recommendations
For Provoked VTE
Routine cancer screening is not recommended in patients with provoked VTE, as the absolute cancer detection rate is <2% over 12-24 months of follow-up 1
Why CA-125 Is Not Appropriate
Poor Specificity in This Context
CA-125 has extremely high false-positive rates that make it unsuitable for cancer screening in VTE patients 1, 2, 3:
- Only 50% of early-stage ovarian cancers have elevated CA-125 1, 4
- False positives occur with endometriosis, benign ovarian cysts, pelvic inflammatory disease, pregnancy, menstruation, peritonitis, pleural effusion, and ascites 1, 2
- CA-125 can be elevated up to 1000-5000 kU/L in benign conditions 2
- In one audit, only 20% of abnormal CA-125 results in patients being evaluated for malignancy were actually due to ovarian cancer 3
Not Validated for VTE-Associated Cancer Screening
CA-125 is FDA-approved only for monitoring response to therapy in known epithelial ovarian cancer and detecting recurrence in patients who have undergone first-line therapy—not for screening 5. The marker has never been validated or recommended for occult cancer detection in the VTE population 1.
Cost and Clinical Uncertainty
Inappropriate CA-125 testing leads to 3:
- Results that are clinically useless
- Significant cost implications
- Increased patient anxiety
- Clinical uncertainty requiring additional unnecessary workup
Clinical Algorithm for Cancer Screening in Your Patient
Step 1: Classify the VTE
- Determine if DVT/PE is provoked (surgery, trauma, immobilization, estrogen therapy) or unprovoked (no clear precipitating factor) 1
Step 2: Apply Appropriate Screening
- If provoked: No routine cancer screening beyond standard age/gender-appropriate screening 1
- If unprovoked: Perform limited screening as outlined above (CBC, calcium, LFTs, urinalysis, chest X-ray) plus age/gender-appropriate screening 1
Step 3: Consider Special Circumstances
- Recurrent unprovoked VTE: Maintain lower threshold for cancer detection; consider more extensive screening 1
- Unusual site VTE (splanchnic, cerebral): The diagnostic imaging used to confirm the thrombosis typically identifies any associated malignancy 1
Common Pitfalls to Avoid
- Do not order tumor markers (including CA-125, CEA, CA 19-9) as part of routine occult cancer screening in VTE patients—they are not guideline-recommended and have poor specificity 1
- Do not pursue extensive imaging (CT abdomen/pelvis) in unprovoked VTE unless limited screening reveals abnormalities, as extensive screening is not cost-effective and may lead to unnecessary anticoagulation withdrawal 1
- Do not overlook age-appropriate screening: Ensure colon, breast, cervical, and prostate cancer screening is up to date per national guidelines 1