Reference — Oncology
Tumor Markers Reference
Tumor markers are substances (often proteins) made by cancer cells or by the body in response to cancer. Their main job is monitoring treatment response and recurrence — most are not specific enough to screen the general population.
Educational use only. Tumor markers are interpreted by the provider alongside imaging and biopsy; a single value rarely confirms or excludes cancer. This reference is an educational aid. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Common Tumor Markers
| Marker | Associated cancer | Notes |
|---|---|---|
| PSA | Prostate | Screening (shared decision) + monitoring; also rises with BPH, prostatitis, recent manipulation |
| CEA | Colorectal (also lung, breast, pancreatic) | Monitors treatment response/recurrence; not for screening; elevated in smokers |
| CA 15-3 / CA 27-29 | Breast | Monitor metastatic/recurrent breast cancer treatment |
| CA 125 | Ovarian | Monitor treatment/recurrence; can rise in benign conditions (endometriosis, menses, pregnancy) |
| CA 19-9 | Pancreatic (also biliary) | Monitor disease; not specific enough for screening |
| AFP (alpha-fetoprotein) | Hepatocellular (liver), testicular (germ cell) | Also elevated in pregnancy and some liver disease |
| Beta-hCG | Testicular/germ cell, gestational trophoblastic disease | Also positive in pregnancy |
How Markers Are Used
The most reliable use is trending a marker in a patient with known cancer: a falling level suggests the treatment is working, and a rising level can signal recurrence. Markers can be elevated in benign conditions (CA 125 in endometriosis/menses, AFP/beta-hCG in pregnancy, PSA in BPH, CEA in smokers), so a single elevated value does not diagnose cancer. PSA is the notable marker also used in screening (as a shared decision).
NCLEX Pearls
- ✦PSA → prostate; CEA → colorectal; CA 15-3/27-29 → breast; CA 125 → ovarian; CA 19-9 → pancreatic; AFP → liver/germ cell; beta-hCG → testicular/trophoblastic.
- ✦Tumor markers mainly MONITOR treatment response and recurrence — most are NOT screening tests.
- ✦A trend matters more than a single value — falling = responding, rising = possible recurrence.
- ✦Markers rise in benign states too (CA 125 in menses/endometriosis; AFP/beta-hCG in pregnancy; PSA in BPH).
- ✦PSA is the exception used in screening — and only via shared decision-making.
Related Resources
Standards & sources
Fact-checked Jun 21, 2026This page is written to align with Oncology Nursing Society (ONS) · National Comprehensive Cancer Network (NCCN) · American Society of Clinical Oncology (ASCO). It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →