Cancer Development: Role of Genetic Mutations

Cancer begins with mutations in a single cell. Key concepts:

• Somatic mutations (acquired): Environmental (UV, chemicals, radiation) or spontaneous replication errors. Most common.
• Germline mutations (inherited): Present in all cells; rare but high penetrance.

Critical Gene Classes

• Oncogenes: Normally promote growth; mutations cause constitutive activation (e.g., RAS, MYC).
• Tumor suppressor genes: Normally restrain growth/repair DNA; mutations cause loss of function (e.g., TP53, RB1).

Multiple hits across these genes drive malignant transformation.