Cancer registries: population-based and hospital-based: practice question

A PSM 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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PSM · Cancer registries: population-based and hospital-based

Sample item

A health officer takes the 300 new oral cancer patients registered in the cancer hospital's registry in one year and divides by the district population to report the district incidence. What is the main flaw?

ADividing new cases by the population gives prevalence rather than incidenceBHospital patients do not form a defined population, so the denominator does not matchCIncidence can be derived only from mortality dataDHospital registries record only advanced cancers

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

The answer and the reasoning

B. Hospital patients do not form a defined population, so the denominator does not match

A hospital-based registry records patients attending one institution and has no defined catchment, so it cannot give incidence. A population-based registry collects all new cases from a defined geographic population, giving a valid numerator and denominator. Hospital registries are best for case mix, treatment outcomes and survival.

Option by option

A. Dividing new cases by the population gives prevalence rather than incidence
New cases in a period divided by the population at risk is incidence; the flaw lies in the numerator source.
B. Hospital patients do not form a defined population, so the denominator does not match (correct)
Correct. Without a defined population the numerator does not match the denominator.
C. Incidence can be derived only from mortality data
Incidence is derived from newly diagnosed cases, and mortality data are used for death rates.
D. Hospital registries record only advanced cancers
Hospital registries include all stages of patients attending, so the stage is not the central flaw.

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.

Questions about this PSM question

What is the answer to this PSM question?

The best answer is B, Hospital patients do not form a defined population, so the denominator does not match. A hospital-based registry records patients attending one institution and has no defined catchment, so it cannot give incidence.

Why is "Dividing new cases by the population gives prevalence rather than inc…" not the answer?

New cases in a period divided by the population at risk is incidence; the flaw lies in the numerator source.

Why is "Incidence can be derived only from mortality data" not the answer?

Incidence is derived from newly diagnosed cases, and mortality data are used for death rates.

Why is "Hospital registries record only advanced cancers" not the answer?

Hospital registries include all stages of patients attending, so the stage is not the central flaw.

What concept does this question test?

It tests Cancer registries: population-based and hospital-based in PSM. A population-based registry collects all new cases from a defined geographic population, giving a valid numerator and denominator. Hospital registries are best for case mix, treatment outcomes and survival.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Cancer registries: population-based and hospital-based?

Practise biostatistics with small calculations until sensitivity, predictive values and risk measures are automatic. Then use the flashcards and the other PSM 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.