Cancer Prevention, Outreach, and Research
Core concepts
Prevention has three levels: primary (reduce incidence-vaccination, tobacco control, lifestyle), secondary (early detection-screening), and tertiary (reduce recurrence/complications after treatment).
Know evidence-based screening: cervical (HPV vaccination plus cytology/HPV testing), colorectal (FIT, colonoscopy, stool DNA), breast (mammography in defined age groups), and lung (low-dose CT in high-risk smokers). Screening must meet criteria: important disease, acceptable test, effective treatment, and favorable benefit-harm balance.
Outreach and equity
Outreach addresses access barriers: rurality, cost, language, health literacy, and cultural mistrust. Community health workers, patient navigation, and reminder systems improve uptake. Overdiagnosis and false positives are real harms that must be discussed in shared decision-making.
Research literacy
Understand study designs: RCTs (causal inference), cohort (incidence/risk), case-control (rare outcomes), and the meaning of absolute vs relative risk reduction, number needed to screen/treat, and confidence intervals. Recognize bias types (selection, lead-time, length-time).
Traps in questions
- Confusing relative and absolute risk reduction-a 50% relative reduction may be a tiny absolute benefit.
- Ignoring lead-time bias when screening appears to prolong survival.
- Assuming screening is universally beneficial regardless of risk group.
Rule of thumb
Match the screening test to the risk group and the disease's natural history; when in doubt, use shared decision-making and quantify absolute benefit.