cancer genetics

Cancer genetics asks a simple question with a complicated answer: what goes wrong in the instructions of a cell so that it starts to grow when it should not? Think of a cell as a worker that normally follows a careful rulebook about when to divide, when to pause, and when to die. Cancer happens when enough rules in that book get rewritten that the cell ignores the team and grows for itself.

More precisely, cancer is a genetic disease of the body's own cells. Mutations and other changes accumulate in the DNA, switching on growth-promoting genes called oncogenes and switching off protective genes called tumor-suppressor genes. Most of these changes are somatic, meaning they arise in ordinary body cells during a lifetime and are not inherited; a smaller fraction are inherited and run in families.

The field studies which genes are involved, how their changes drive tumor growth, and how this knowledge guides diagnosis, risk prediction, and treatment. It is important to separate two ideas: nearly all cancer is genetic at the cellular level, but only some cancer is hereditary in the sense of being passed from parent to child.