In an organised breast cancer screening programme, a woman has a normal mammogram in January and presents eight months later with a palpable lump confirmed as carcinoma. Such a tumour is called an interval cancer. Its main significance in programme evaluation is that it:
- A Confirms the programme has adequate sensitivity
- B Proves the woman developed an entirely new fast-growing tumour unrelated to screening quality
- C Serves as an indicator of false negative results and reflects the sensitivity of the screening test ✓
- D Indicates the screening interval should be shortened in every participant
Correct answer: C. Serves as an indicator of false negative results and reflects the sensitivity of the screening test
Explanation
Interval cancers are those diagnosed between scheduled screening rounds after a negative result. They arise either from false negative readings or from genuinely rapidly progressive tumours, and their rate is the standard proxy for screening sensitivity: the lower the interval cancer rate, the better the test performance. They do not validate the programme, and while a rising rate may prompt review of intervals, it does not mandate shortening for everyone.
Reference: Gordis Epidemiology, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.