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SU9.1-3 | Surgical Investigations and Cancer Detection — PBL Case

CLINICAL SETTING

Mrs L is a 48-year-old schoolteacher with no symptoms who attended a community health camp where a 'cancer screening package' was being offered. She had several blood tests including tumour markers and an abdominal ultrasound. She now arrives at your surgical clinic, frightened, holding a report that says her CA-125 is 'mildly elevated'. She has no gynaecological or abdominal complaints. Her sister died of ovarian cancer two years ago. She asks you whether she has cancer and whether she needs surgery.

Trigger 1: The frightened well patient and the 'screening' tumour marker

Mrs L is completely asymptomatic. The camp marketed tumour markers as a way to 'catch cancer early'. Her CA-125 is mildly raised. She has a strong family history. You must decide how to think about this result before you say anything to her.

DISCUSSION POINTS

  • Why are tumour markers such as CA-125 inappropriate as screening tests in asymptomatic people? Use the concepts of sensitivity, specificity and predictive value.
  • How does Mrs L's low pretest probability (asymptomatic, no clinical findings) affect the meaning of a mildly raised CA-125? What does a 'mildly elevated' result actually tell you?
  • What benign causes could explain a raised CA-125, and why does this matter for interpretation?
Click to reveal Trigger 2: Screening for the well versus diagnosis for the symptomatic (discuss previous trigger first!)

Trigger 2: Screening for the well versus diagnosis for the symptomatic

Mrs L's family history makes her anxious that she 'must be screened more'. You consider what a defensible, evidence-based approach to her risk looks like, drawing on the principles that decide when screening is worthwhile.

DISCUSSION POINTS

  • Distinguish screening (for the well) from early diagnosis (for the symptomatic). Into which category does Mrs L fall, and how should that shape your plan?
  • Apply the Wilson-Jungner criteria: what conditions must be met before a cancer is worth screening for? How well does population CA-125 screening meet them?
  • What harms could arise from acting on this result — for example overdiagnosis, unnecessary surgery, or sustained anxiety? How do you weigh these against the family history?
Click to reveal Trigger 3: Communicating uncertainty and planning next steps (discuss previous trigger first!)

Trigger 3: Communicating uncertainty and planning next steps

You must now talk to Mrs L. She is expecting either reassurance or a cancer diagnosis, and the truth is genuinely uncertain. You also need to decide what, if anything, to do next and how to involve other specialists.

DISCUSSION POINTS

  • How would you communicate an uncertain result to an anxious patient using the principles of good result communication (plain language, small chunks, checking understanding, responding to emotion)?
  • What would a sensible next step be — for example referral to a specialist or family-history risk clinic, an appropriate diagnostic pathway, or planned non-intervention with safety-netting — and how would the multidisciplinary team contribute?
  • How do you balance honesty about uncertainty with avoiding both false reassurance and unnecessary alarm?

Group Task Assignments

  • Group A: Prepare a one-page explainer, in plain patient-friendly language, of why a raised tumour marker in a well person is not the same as a cancer diagnosis.
  • Group B: Draw a flow chart distinguishing the correct pathway for an ASYMPTOMATIC person with a family history versus a SYMPTOMATIC person, showing where screening, diagnosis and the MDT each belong.
  • Group C: Role-play and then critique the consultation in which the result is explained to Mrs L, marking each other against the principles of good result communication.

Learning Issues

Research these questions and bring your findings to the discussion.

  1. [SU9.1] How do sensitivity, specificity, PPV and NPV behave when a test is applied to a low-prevalence (asymptomatic) population, and why does this make tumour markers poor screening tools?
  2. [SU9.2] What are the Wilson-Jungner criteria, and how do screening and early diagnosis differ in their target populations and aims?
  3. [SU9.2] What is overdiagnosis, and what harms can result from screening asymptomatic people for cancer?
  4. [SU9.3] How should an uncertain or anxiety-provoking investigation result be communicated to a worried but well patient?