SU9.1-3 | Surgical Investigations and Cancer Detection — Practice Quiz

Correct. An investigation is justified only when its result could change what you do — confirm or exclude a diagnosis, stage disease, or alter the operative plan. There is no place for ordering a test 'just to check'.

Order a test only if a positive or negative result would change what you do for the patient.

The clinical indication for any investigation is a specific, answerable clinical question. A test is worth ordering only when its result could change management.

Correct. Sensitivity is the proportion of people WITH the disease who test positive. A highly sensitive test, when negative, is good for ruling a disease OUT (SnNout).

Sensitivity = detection of disease when present; a very sensitive test that is negative helps rule disease OUT.

Sensitivity = true positives / all people with the disease. The proportion of test-positives who truly have the disease is the positive predictive value, not sensitivity.

Correct. A highly specific test rarely gives false positives, so when it is positive it helps rule the disease IN (SpPin).

SpPin — a Specific test, when Positive, rules disease IN.

High specificity means few false positives, so a positive result rules the disease IN (SpPin). Ruling OUT on a negative result is the property of a sensitive test.

Correct. PPV depends on prevalence. In a low-prevalence population most positives are false positives, so PPV falls — a key reason screening tests need very high specificity.

PPV and NPV are prevalence-dependent; sensitivity and specificity are not.

Sensitivity and specificity are intrinsic to the test, but PPV and NPV depend on prevalence. As prevalence falls, a larger share of positives are false positives, so PPV falls.

Correct. Tumour markers are for monitoring (and supporting diagnosis in context), not screening. CA 19-9 rises in benign biliary obstruction, and a normal CEA does not exclude colorectal cancer.

Tumour markers monitor known disease — they neither screen nor exclude cancer.

Tumour markers are for monitoring, not screening. CA 19-9 can be raised by benign biliary obstruction; a normal CEA does not exclude colorectal cancer.

Correct. For the great majority of solid cancers, stage at diagnosis is the strongest determinant of curability — a small tumour confined to its organ of origin is far more often curable.

Stage at diagnosis drives curability — the rationale for finding cancer early.

The clinical value of early detection rests on the robust fact that stage at diagnosis is the strongest determinant of curability for most solid cancers.

Correct. Most carcinomas evolve normal epithelium → dysplasia → carcinoma-in-situ (confined above the basement membrane) → invasive carcinoma. This slow natural history creates the detection window.

Dysplasia → carcinoma-in-situ → invasion: the pre-invasive window is when detection cures.

The sequence is normal epithelium → dysplasia → carcinoma-in-situ → invasive carcinoma. Carcinoma-in-situ is still confined above the basement membrane, which is why early detection can be curative.

Correct. Screening is for the WELL (asymptomatic); a symptomatic patient (rectal bleeding) needs a prompt diagnostic work-up, not a screening test.

Symptomatic = diagnose promptly; asymptomatic well population = screen.

Never blur screening and early diagnosis. Screening is for asymptomatic people; a symptom such as rectal bleeding mandates a prompt diagnostic work-up.

Correct. Wilson-Jungner requires an important condition with a recognisable latent/early stage, a suitable acceptable test, and an accepted effective treatment whose early application improves outcome.

Screen only when there is a detectable early stage AND early treatment improves outcome.

Wilson-Jungner criteria require an important condition with a detectable early/latent stage and an accepted, effective treatment that works better when applied early. Rarity and high cost are not requirements.

Correct. In SPIKES, S = Setting, P = Perception, I = Invitation (how much the patient wants to know), K = Knowledge, E = Emotions/empathy, S = Strategy/summary.

SPIKES: Setting, Perception, Invitation, Knowledge, Emotions, Strategy.

SPIKES: Setting, Perception, Invitation, Knowledge, Emotions (empathy), Strategy/Summary. The 'I' is the Invitation — eliciting how much the patient wishes to know.

Correct. Responding to emotion before moving to the plan is the most skipped yet most important step. A patient in shock cannot absorb a treatment schedule until the emotion is acknowledged.

Address emotion first; only then discuss the management plan.

The most important and most often skipped step is responding to EMOTION before the plan. A patient who has just heard 'cancer' cannot take in chemotherapy details until their emotion is addressed.