If a mutation provides a cellular benefit, such as increased growth, that cell and its daughters will proliferate, potentially leading to cancer with further mutations.

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.