Cancer risk is primarily determined by somatic mutations, not germline mutations, making genotype testing generally unhelpful except for rare outliers.

Whole-body MRI screening in healthy adults produces more incidentaloma harm than cancer-mortality benefit.

Starting colonoscopy screening at 45 (vs 50) prevents enough early-onset cancers to justify the population cost.

Multi-cancer liquid-biopsy tests like Galleri detect early cancers at a stage that meaningfully improves survival.