Learning Objective
By the end of this section, learners should be able to identify key serum tumor markers, their associated cancers, and their clinical utility in monitoring treatment or recurrence, while understanding that diagnosis requires tissue confirmation.
Key Points
- Tumor markers should not be used as the primary diagnostic or screening tool.
- They are primarily used for:
- Monitoring tumor recurrence
- Assessing response to therapy
- Definitive diagnosis always requires a biopsy.
- Some markers may be elevated in non-neoplastic conditions, so interpretation must be contextual.
Major Tumor Markers and Clinical Associations
| Marker | Key Associations | Notes / High-Yield Points |
|---|---|---|
| Alkaline phosphatase (ALP) | Bone or liver metastases, Paget disease of bone, seminoma (PLAP) | Rule out hepatic origin with LFTs and GGT |
| α-Fetoprotein (AFP) | Hepatocellular carcinoma, endodermal sinus (yolk sac) tumor, mixed germ cell tumor | Produced by fetus; transiently elevated in pregnancy; high levels → neural tube defects, low levels → Down syndrome |
| hCG | Hydatidiform mole, choriocarcinoma, testicular cancer, mixed germ cell tumor | Produced by syncytiotrophoblasts |
| CA 15-3 / CA 27-29 | Breast cancer | Useful for monitoring recurrence |
| CA 19-9 | Pancreatic adenocarcinoma | May also be elevated in biliary disease |
| CA 125 | Epithelial ovarian cancer | Useful for monitoring response and recurrence |
| Calcitonin | Medullary thyroid carcinoma (sporadic or MEN2A/2B) | Monitors post-surgical recurrence |
| CEA (Carcinoembryonic antigen) | Colorectal, pancreatic; minor: gastric, breast, medullary thyroid | Nonspecific; valuable for monitoring recurrence |
| Chromogranin | Neuroendocrine tumors | Marker of secretory activity |
| LDH | Testicular germ cell tumors, ovarian dysgerminoma, and other cancers | Correlates with tumor burden |
| Neuron-specific enolase (NSE) | Neuroendocrine tumors: small cell lung cancer, carcinoid, neuroblastoma | Reflects tumor activity |
| PSA (Prostate-Specific Antigen) | Prostate cancer, also known as BPH, prostatitis | Best for monitoring recurrence; screening controversial |
Activity
High-Yield Pearls
- AFP → Hepatocellular carcinoma, yolk sac tumors
- hCG → Gestational trophoblastic disease, testicular tumors
- CEA → Recurrence monitoring in colorectal cancer
- PSA → Post-treatment monitoring; screening is controversial
- LDH → Tumor burden indicator, not specific for diagnosis
