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Principles of screening programmes
Screening is the offer of a test to people without symptoms in order to detect disease or risk earlier – and it is justified only when the disease is important, has a detectable latent stage, there is an acceptable test and early treatment improves the outcome, and the benefit exceeds the harm and cost.
Why it matters in the exam
Items on this topic ask which condition justifies population screening, how screening differs from diagnosis, and which measure shows a programme works: a fall in disease-specific mortality in a randomized trial, not longer "survival from diagnosis", which may result from lead-time bias, length-time bias or overdiagnosis. Also tested are the Israeli recommendations – a faecal immunochemical test (FIT) every year at ages 50–74, mammography every two years at ages 50–74, and no recommendation for population screening with PSA – and items on changing the cut-off of a screening test and its effect on sensitivity, specificity and the number referred for work-up. Remember that a screening programme is a whole process – invitation, testing, work-up of positives, treatment and quality monitoring – not a single test, and that any weak link in the chain cancels the benefit and leaves only the harm. Another item asks you to distinguish mass screening of the whole population, targeted screening of risk groups, and opportunistic case-finding during a visit to the doctor for another reason. Each has advantages and drawbacks, but all require a work-up pathway, records and quality measures such as uptake and referral rates.
Key points
- Screening targets people without symptoms and requires an important disease with a latent stage.
- The best proof is a fall in disease-specific mortality in a randomized trial.
- Lead time, length time and overdiagnosis bias survival in favour of screening.
- In Israel: FIT every year and mammography every two years at ages 50–74.
- There is no recommendation for population screening with PSA.
Summary table
| Principle | Meaning | Example |
|---|---|---|
| An important health problem | Common or serious, with a significant burden | Colorectal cancer |
| A detectable latent stage | A time window between disease onset and symptoms | An adenomatous polyp before cancer |
| A suitable and acceptable test | Sensitive, specific enough, safe and cheap | FIT every year, mammography every two years |
| Early treatment that improves outcome | Early detection changes the prognosis | Removing a polyp during colonoscopy |
| Available work-up and treatment | Colonoscopy and clinics exist for all positives | Short waits for work-up |
| Benefit greater than harm and cost | Shown in a randomized trial; overdiagnosis is weighed | No recommendation for population PSA screening |
Free exam questions
( מדענית יצאה בפרסום כי היא פיתחה בדיקת סיקור screening ) לסרטן הלבלב, סרטן קטלני שעדיין אין לו טיפול יעיל. לתבחין יש רגישות וסגוליות של 90% . במשרד הבריאות הוחלט לסרוק את כל המבוגרים במדינת ישראל בני 45-84 שנים , ובשלב זה עדיין לא הוחלט על תדירות הבדיקות. מה צפוי שימצא לגבי המאפיינים של המחלה בתום השנה הראשונה לביצוע הבדיקה? (the question as examined, in Hebrew)
- א. ( עליה בהשרדות לשנה one year survival) בחולי סרטן לבלב
- ב. ירידה בהארעות סרטן הלבלב בשנה שבה בוצעה הסריקה
- ג. ירידה בשיעורי המצאות סרטן הלבלב בשנה לאחר ביצוע הסריקה
- ד. עליה בהארעות של פנקראטיטיס, שמהווה גורם סיכון לסרטן הלבלב
בן 74 , בריא בדרך כלל. מגיע אליך עם בקשה להוסיף לבדיקות הדם הבאות שלו גם בדיקה לגילוי מוקדם של סרטן הערמונית. מה ההמלצה לגבי בצוע הבדיקה? (the question as examined, in Hebrew)
- א. מעל גיל 70 אין המלצה לבדיקת סקר עם PSA
- ב. ערך PSA .גבוה חד פעמי אינו אינדיקציה להמשך בירור
- ג. בדיקת DRE ( Digital Rectal Examination ) עדיפה על PSA .כבדיקת סקר
- ד. אצל מעשנים מומלץ לעשות בדיקת סקר עם PSA
In the full version for subscribers
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Sources
- Wilson & Jungner, Principles and Practice of Screening for Disease (WHO Public Health Papers), 1968 — Principles of early disease detection
- WHO Regional Office for Europe, Screening programmes: a short guide, 2020 — Increase effectiveness, maximize benefits and minimize harm
- Israel Ministry of Health, national cancer screening programmes, current — Colorectal and breast cancer early detection
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.