What labs are included in a tumor marker workup?

Tumor Marker Workup Labs

The specific tumor markers ordered depend entirely on the clinical context and suspected malignancy, but a basic tumor marker workup should include AFP and β-hCG in males with suspected germ cell tumors, PSA in males with possible prostate cancer, CA15-3 and CA125 in females with suspected gynecological primaries, CEA, CA19-9, and CA72-4 when a gastrointestinal primary is suspected, and chromogranin A in patients with possible neuroendocrine malignancy. 1

Context-Dependent Tumor Marker Selection

Tumor markers are not used for cancer screening or diagnosis in isolation, but rather as adjuncts to clinical evaluation and imaging. 2, 3 The selection of which markers to order must be guided by:

For Males with Suspected Germ Cell Tumors

• α-fetoprotein (AFP) 1
• β-human chorionic gonadotropin (β-hCG) 1
• These markers are particularly valuable in non-seminomatous germ cell testicular tumors, where they suggest diagnosis, stage, confirm response to therapy, and predict relapse 4

For Males with Possible Prostate Cancer

• Prostate-specific antigen (PSA) 1
• PSA is used to identify hormone-sensitive tumors amenable to specific therapy 1

For Females with Suspected Gynecological Primary

• Cancer antigen 15-3 (CA15-3) 1
• Cancer antigen 125 (CA125) 1
• CA125 is particularly useful for monitoring therapy in patients with ovarian cancer 5
• In females with axillary node metastases, estrogen and progesterone receptor testing should be performed to rule out hormone-sensitive breast tumors 1

For Suspected Gastrointestinal Primary

• Carcinoembryonic antigen (CEA) 1
• Carbohydrate antigen 19-9 (CA19-9) 1
• Cancer antigen 72-4 (CA72-4) 1
• Despite frequent non-tumor type-specific elevations, these markers may be used to determine disease course and monitor treatment response 1

For Suspected Neuroendocrine Malignancy

• Chromogranin A 1
• This marker is essential when neuroendocrine tumors are suspected based on histology or clinical presentation 1

Basic Laboratory Panel Accompanying Tumor Markers

Beyond specific tumor markers, the workup should include:

• Complete blood count (CBC) 1
• Comprehensive metabolic panel including serum calcium, liver function studies, lactate dehydrogenase (LDH), and serum creatinine 1
• Alkaline phosphatase 1
• Urinalysis 1

Critical Limitations and Pitfalls

A positive tumor marker result alone does not confirm malignancy and must be corroborated with imaging and/or pathological confirmation. 2, 3 Key limitations include:

• Most tumor markers lack sufficient sensitivity and specificity for cancer screening 2, 3, 4
• Tumor markers can be elevated in benign conditions 2, 3
• A single elevated result should not establish diagnosis; serial measurements are more informative 2
• The primary clinical utility of tumor markers is in monitoring disease course and detecting recurrence after treatment, not in initial diagnosis 2, 4, 5

Monitoring and Follow-up Considerations

When using tumor markers for monitoring:

• Sampling should ideally be repeated after 5-6 half-lives of the marker in question 2
• If elevated, repeat sampling after 2-4 weeks for additional evidence 2
• Rising trends may detect recurrence before clinical or radiological evidence ("biochemical recurrence") 2
• CEA, CA19-9, CA15-3, and CA125 may be used to determine disease course and monitor treatment response despite non-specific elevations 1