Pathology
Neoplasia and Tumour Markers
Neoplasia for MBBS and NEET-PG: benign versus malignant, oncogenes and tumour suppressors, routes of spread, tumour markers and paraneoplastic syndromes, mapped to NMC codes.
MedNext Academy | 3 min read
Neoplasia and Tumour Markers
Neoplasia for MBBS and NEET-PG: benign versus malignant, oncogenes and tumour suppressors, routes of spread, tumour markers and paraneoplastic syndromes, mapped to NMC codes.
The neoplasia chapter underpins oncology across every clinical subject. It covers the difference between benign and malignant tumours, the molecular basis of cancer through oncogenes and tumour suppressor genes, the routes of spread, and the tumour markers and paraneoplastic syndromes that examiners test heavily.
High-yield: Neoplasia and Tumour Markers
- A benign tumour is well differentiated, slow growing and non-invasive and does not metastasise; a malignant tumour is the opposite.
- Anaplasia is the hallmark of malignancy: loss of differentiation, pleomorphism, hyperchromatic nuclei and a high nucleus-to-cytoplasm ratio.
- Carcinoma is a malignant tumour of epithelial origin; sarcoma is of mesenchymal origin.
- Metastasis is the single most reliable feature that defines a tumour as malignant.
- Carcinomas spread mainly by lymphatics; sarcomas spread mainly by the bloodstream.
- Grading describes the degree of differentiation; TNM staging describes anatomical extent and guides prognosis better.
- Oncogenes act dominantly after activation (RAS, MYC, HER2); tumour suppressor genes need both alleles lost (p53, RB).
- p53, the guardian of the genome, is the most commonly mutated gene in human cancer.
- Alpha-fetoprotein is raised in hepatocellular carcinoma and non-seminomatous germ cell tumours.
- CA-125 marks ovarian carcinoma, CA 19-9 pancreatic carcinoma, and CA 15-3 breast carcinoma.
- Carcinoembryonic antigen is raised in colorectal carcinoma and is used for follow-up, not screening.
- Prostate-specific antigen is used for prostate carcinoma; beta-hCG for choriocarcinoma and germ cell tumours.
- Psammoma bodies, laminated calcifications, are seen in papillary thyroid carcinoma, serous ovarian tumours and meningioma.
- Small cell lung cancer causes SIADH and ectopic ACTH; squamous cell lung cancer causes hypercalcaemia through PTHrP.
Tumour markers to memorise
- **AFP:** Hepatocellular carcinoma, non-seminomatous germ cell tumours.
- **CA-125 / CA 19-9 / CA 15-3:** Ovarian, pancreatic and breast carcinoma respectively.
- **CEA:** Colorectal carcinoma, used for follow-up not screening.
- **PSA / beta-hCG:** Prostate carcinoma; choriocarcinoma and germ cell tumours.
NMC competencies in this chapter
- **PA7.1:** Definitions and characteristics of benign and malignant neoplasms
- **PA7.2:** Molecular basis of cancer: oncogenes and tumour suppressor genes
- **PA7.3:** Routes of tumour spread and metastasis
- **PA7.4:** Grading, staging and tumour markers
- **PA7.5:** Paraneoplastic syndromes
Frequently Asked Questions
What single feature defines malignancy?
Metastasis is the most reliable feature. A tumour that has spread to a distant site is by definition malignant, whatever its microscopic appearance.
What is the difference between grading and staging?
Grading describes how differentiated the tumour cells are, while staging (usually TNM) describes the anatomical extent. Staging is the stronger guide to prognosis.
Which tumour marker goes with which cancer?
AFP with hepatocellular and germ cell tumours, CA-125 with ovary, CA 19-9 with pancreas, CEA with colorectal, PSA with prostate and beta-hCG with choriocarcinoma.
What are psammoma bodies?
Laminated calcifications seen in papillary thyroid carcinoma, serous ovarian tumours and meningioma, a classic pattern-recognition point.
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