Phase 1 · Understand the Body — Why the disease behaves the way it does.
The One-Line Truth
The whole disease in one chain
Everything on this page exists to explain this line.
Lung cancer kills more people than any other cancer — and most cases start with cigarette smoke damaging the DNA in lung cells until one cell breaks free and multiplies without stopping.
A Factory Losing Its Quality Control
Your airway lining is like a factory assembly line where each worker (airway lining cell) has a strict job: make one copy of yourself when your neighbor wears out, then stop. Cigarette smoke is like acid spilled on the factory floor — it damages the instruction manual (DNA) in thousands of workers over decades. Most workers either fix the damage or walk off the job (die). But if smoke damages the master switch in the manual (oncogenes like KRAS, EGFR) or the emergency shutdown button (tumor suppressors like TP53), one worker loses the signal to stop — it keeps copying itself endlessly, crowding out normal workers and eventually choking the whole factory line. The tumor is that one rogue worker and all its clones, and metastasis is when some of them sneak out through the warehouse doors (blood vessels) and set up illegal factories in the liver, brain, and bones.
NCCN Clinical Practice Guidelines in Oncology: Non-Small Cell Lung Cancer 2024 · American Cancer Society Lung Cancer Guidelines · CHEST Guideline and Expert Panel Report on Lung Cancer Screening 2021 · ASCO Clinical Practice Guideline on Systemic Therapy for Stage IV Non-Small Cell Lung Cancer · reviewed 2026-07-07