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Staging (TNM), performance status and tumour markers
TNM describes the tumour (T), the nodes (N) and the metastases (M), and performance status (ECOG) describes the patient — together they set the goal of treatment; blood tumour markers are used for follow-up and prognosis, and almost never for screening.
Why it matters in the exam
Almost every clinical question in the bank rests on the TNM stage and ECOG, so the principles must be known: the difference between clinical stage, pathological stage and stage after neoadjuvant therapy, and the difference between ECOG 2 and ECOG 3. Further questions cover tumour markers — which marker suits which tumour, when it rises without a tumour, and what a temporary rise after starting treatment means.
Common distractors are using CA-125 or CEA for screening in the general population, or reading a raised CA 19-9 in a patient with biliary obstruction as proof of a tumour. Remember too that in the AJCC eighth edition some stages include biological markers — for example hormone receptors and HER2 in the breast and HPV in the oropharynx.
Key points
- TNM describes tumour, nodes and metastases, and prefixes distinguish clinical stage, pathological stage and stage after neoadjuvant therapy.
- ECOG describes performance status: ECOG 2 — in bed less than half the day, ECOG 3 — more than half the day.
- Tumour markers are used for follow-up and prognosis, not for screening the general population, except in defined cases.
- CEA, CA 19-9 and CA-125 also rise in benign conditions, so they must be read in the clinical context.
- AFP and β-hCG matter in germ cell tumours, and a slower fall than expected from the half-life suggests residual disease.
Summary table
| Concept or marker | Use | Trap or detail |
|---|---|---|
| TNM and prefixes | c — clinical; p — pathological; yp — after neoadjuvant therapy; r — recurrence | The eighth edition builds biological markers into the stage of some tumours |
| ECOG | 0 — fully active; 1 — limited on exertion; 2 — self-caring, not working, in bed less than half the day; 3 — in bed or chair more than half the day; 4 — bedbound | Performance status 0 to 1 is usually needed for intensive chemotherapy |
| CEA | Follow-up after colon cancer surgery and detecting relapse | Also raised in smokers, inflammation and liver disease |
| CA 19-9 | Follow-up in pancreatic and biliary cancer | Rises with biliary obstruction; not produced by about 5% to 10% of people (Lewis-negative) |
| CA-125 | Follow-up in ovarian cancer | Rises in endometriosis, ascites, heart failure and any peritoneal irritation |
| AFP and β-hCG | Germ cell tumours and HCC; choriocarcinoma | Half-life: AFP about 5 to 7 days, β-hCG about 1 to 3 days; LDH adds prognostic information |
| Other markers | PSA — prostate; calcitonin — medullary; thyroglobulin — differentiated thyroid; chromogranin A — neuroendocrine tumours | Chromogranin A also rises on proton pump inhibitors |
In the full version for subscribers
- A simple algorithm
- Memory aid
- Exam traps
- 5 review cards
- Enough for IMLE
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Sources
- AJCC Cancer Staging Manual, 8th ed. (2017) — Principles of cancer staging
- Oken et al., Toxicity and response criteria of the Eastern Cooperative Oncology Group, 1982 — ECOG performance status
- NACB/ESMO recommendations on the use of tumour markers, 2008 to 2023 — Clinical use of serum tumour markers
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.