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SU9.1-3 | Surgical Investigations and Cancer Detection — Graded Quiz
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A 70-year-old woman has a clinical picture making the pretest probability of a surgical condition very low. A test with high sensitivity but only moderate specificity returns POSITIVE. What is the most appropriate interpretation?
Correct. A result updates pretest probability, it does not replace clinical judgement. With low pretest probability and only moderate specificity, a positive result is more likely a false positive and should be confirmed.
Interpret every result against pretest probability; do not let one test override clinical judgement.
A test result modifies — but does not replace — pretest probability. With low pretest probability and modest specificity, a positive result is probably a false positive and must be confirmed.
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Which of the following correctly pairs a test property with its clinical use?
Correct. SnNout — a Sensitive test, when Negative, rules disease OUT. Specific tests rule in on a positive (SpPin), and NPV is prevalence-dependent.
SnNout for ruling out; SpPin for ruling in.
SnNout: a Sensitive test that is Negative rules disease OUT. Specificity rules in on a positive (SpPin), and both PPV and NPV vary with prevalence.
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A patient with treated colorectal cancer is on surveillance. The single most appropriate use of serum CEA in this patient is to:
Correct. Tumour markers such as CEA are for monitoring known disease — a rising CEA on follow-up suggests recurrence. They do not screen and a normal value does not exclude cancer.
Tumour markers monitor known disease, most usefully detecting recurrence.
CEA is a monitoring marker: it tracks recurrence in patients with known colorectal cancer. It cannot screen the population, exclude cancer, or replace colonoscopy.
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A cancer is detected while still confined above the basement membrane, with no stromal invasion. This describes which stage, and why is it clinically important?
Correct. Carcinoma-in-situ is malignant cells that have not breached the basement membrane; without access to lymphatics/vessels it cannot metastasise and is potentially curable by local treatment.
Carcinoma-in-situ has not breached the basement membrane — no metastasis, high curability.
Carcinoma-in-situ means malignant cells still confined above the basement membrane — no invasion, hence no metastatic potential, hence potentially curable. Invasion defines invasive carcinoma.
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Modern cancer management is described as a multidisciplinary team (MDT) activity. What is the primary rationale for the MDT approach to a newly diagnosed cancer?
Correct. The MDT pools surgical, oncological, radiological and pathological expertise so the treatment plan is stage-appropriate, evidence-based and tailored to the patient — not the decision of any single doctor.
The MDT delivers stage-appropriate, evidence-based, individualised cancer care.
The MDT exists precisely because modern cancer care should not be one doctor's decision: it combines the relevant specialties to plan stage-appropriate, individualised, evidence-based treatment.
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A screening programme for a particular cancer detects many small, indolent lesions that would never have caused harm, leading to unnecessary surgery. This phenomenon is best described as:
Correct. Overdiagnosis — detecting disease that would never have caused harm — is a key potential harm of screening, leading to unnecessary treatment. This is why screening can do net harm despite seeming sensible.
Screening can cause net harm through overdiagnosis and overtreatment.
Detecting harmless lesions that prompt unnecessary treatment is overdiagnosis, a recognised harm of screening. Lead-time bias relates to apparent survival, not unnecessary treatment.
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In the SPIKES protocol, which step comes BEFORE delivering the actual medical facts (Knowledge)?
Correct. Perception ('ask before you tell') precedes Knowledge in SPIKES, so the explanation can be pitched to what the patient already understands. Emotions and Strategy follow the giving of knowledge.
Assess Perception before giving Knowledge — ask before you tell.
SPIKES order: Setting → Perception → Invitation → Knowledge → Emotions → Strategy. Perception ('ask before you tell') comes before delivering the facts.
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A junior doctor must communicate a serious investigation result to a patient. Which single principle should guide HOW the news is delivered?
Correct. Plain language, small chunks, and checking understanding are core principles — alongside protecting confidentiality and consent. How news is delivered affects understanding, trust and harm.
Plain language, small chunks, check understanding — confidentiality always protected.
Good result communication uses plain language in small chunks with checks of understanding, while always protecting confidentiality. Jargon and speed harm understanding; confidentiality is never relaxed.
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