Describe tumour markers in gynaecology — its aetiology, clinical features and management.

Definition

Tumour markers are substances (usually proteins) produced by tumour cells or by the body in response to a tumour, measurable in blood and used mainly to monitor treatment response and detect recurrence (and to support diagnosis), rather than for screening.

Important Gynaecological Markers

Principle and Limitations

An ideal marker is both specific and sensitive; in practice most gynaecological markers lack the specificity needed for screening (CA-125 is raised in many benign conditions) and are used chiefly for supporting a diagnosis, monitoring the response to treatment and detecting recurrence of a known tumour.

A Note on WHY Tumour Markers Are for Monitoring, Not Screening

A useful and important principle is understanding why CA-125 is invaluable in a woman known to have ovarian cancer, yet useless as a screening test in the general population — a distinction that explains the correct use of every tumour marker. CA-125 is neither specific nor sensitive enough for screening: it is raised in many benign and physiological conditions — endometriosis, fibroids, pelvic inflammatory disease, menstruation, pregnancy, ascites of any cause, and even peritoneal irritation — so in a screening programme the vast majority of positives would be false, subjecting healthy women to needless anxiety and laparotomy; and it is normal in a substantial proportion of early ovarian cancers, so it would falsely reassure exactly those women whom screening is meant to save. Its real value is quite different. In a woman already diagnosed with epithelial ovarian cancer, the level reflects her tumour burden — so it is used to monitor the response to chemotherapy (a falling level means the treatment is working) and to detect recurrence during follow-up (a rising level heralds relapse before it is clinically apparent). Understanding the difference between screening a healthy population and monitoring a known tumour explains the proper place of every marker in this list.

CA-125 for epithelial ovarian; AFP and hCG for germ cell tumours.

• CA-125: epithelial ovarian cancer — used to monitor response and detect recurrence, not to screen (raised also in endometriosis, fibroids, PID, pregnancy, ascites).
• AFP: yolk sac (endodermal sinus) tumour; β-hCG: choriocarcinoma and germ cell tumours (and molar pregnancy); LDH: dysgerminoma.
• CEA: mucinous ovarian tumours and gastrointestinal primaries; inhibin: granulosa cell tumour.
• SCC antigen: squamous cell carcinoma of the cervix; HE4 (with CA-125, in the ROMA index) improves specificity for ovarian cancer.
• Principle: tumour markers are for monitoring a known tumour and detecting recurrence — not for screening healthy populations.