DNA Mutations and Cancer: The Genetic Foundation of Malignancy

Cancer is fundamentally a genetic disease driven by mutations that disrupt normal cellular controls, leading to uncontrolled growth and invasion.

Mutation Categories

• Driver mutations: Confer selective growth advantage (e.g., KRAS, EGFR, TP53). These are the "engine" of cancer development.
• Passenger mutations: Neutral changes that accumulate randomly but don't drive malignancy.

Origins of Mutations

• Inherited (germline): Present in every cell. Examples include BRCA1/2 (breast/ovarian cancer) and Lynch syndrome genes (colorectal/endometrial cancer). These predispose to specific cancers but don't guarantee them.
• Acquired (somatic): Arise during life from environmental exposures (UV radiation, tobacco, chemicals), random DNA replication errors, or viral integration (HPV, HBV/HCV).

Functional Consequences

• Oncogene activation: Mutated genes drive uncontrolled proliferation (e.g., EGFR mutations in lung cancer).
• Tumor suppressor loss: Inactivation of genes like TP53 removes critical brakes on cell division and apoptosis.
• DNA repair defects: Mutations in repair genes (e.g., BRCA1/2, mismatch repair genes) cause genomic instability, accelerating further mutations.

Clinical Translation

Precision oncology targets driver mutations with matched therapies (e.g., EGFR inhibitors, PARP inhibitors). Prevention focuses on reducing mutagen exposures (sun protection, smoking cessation) and genetic counseling for hereditary syndromes.