Tumour markers: CA-125: practice question

A Biochemistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Biochemistry · Tumour markers: CA-125

Sample item

A 58-year-old postmenopausal woman has a complex adnexal mass and ascites, with serum CA-125 of 850 U/mL. After surgery for serous epithelial ovarian carcinoma and chemotherapy, what is the most appropriate use of CA-125?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Monitoring response to treatment and detecting recurrence

CA-125 is raised in most epithelial serous ovarian cancers and falls with effective therapy, so serial values help follow response and recurrence. It is also raised in endometriosis, menstruation, pelvic inflammation and peritoneal irritation, so it lacks specificity for screening or diagnosis. Histology remains the basis of diagnosis.

Option by option

  • A. Monitoring response to treatment and detecting recurrence (correct)

    Correct. Serial values track tumour burden and response.

  • B. Replacing histology for the diagnosis

    Tissue diagnosis cannot be replaced by a marker.

  • C. Population screening of asymptomatic women

    Poor sensitivity in early disease and low specificity make it unsuitable for screening.

  • D. Distinguishing ovarian carcinoma from all other causes of raised levels

    Benign conditions also raise it, so it cannot discriminate all causes.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is A, Monitoring response to treatment and detecting recurrence. CA-125 is raised in most epithelial serous ovarian cancers and falls with effective therapy, so serial values help follow response and recurrence.

Why is "Replacing histology for the diagnosis" not the answer?

Tissue diagnosis cannot be replaced by a marker.

Why is "Population screening of asymptomatic women" not the answer?

Poor sensitivity in early disease and low specificity make it unsuitable for screening.

Why is "Distinguishing ovarian carcinoma from all other causes of raised leve…" not the answer?

Benign conditions also raise it, so it cannot discriminate all causes.

What concept does this question test?

It tests Tumour markers: CA-125 in Biochemistry. It is also raised in endometriosis, menstruation, pelvic inflammation and peritoneal irritation, so it lacks specificity for screening or diagnosis. Histology remains the basis of diagnosis.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Tumour markers: CA-125?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.