Cancer is best defined as?

• A. Uncontrolled growth of abnormal cells.
• B. Infection of healthy tissue.
• C. A temporary swelling that resolves on its own.
• D. A benign growth that does not spread.

Answer: (A)

Uncontrolled growth of abnormal cells is the defining feature of cancer. This happens when genetic changes disrupt the normal controls of the cell cycle, so cells divide without the usual checks and often don't die when they should. These abnormal cells can form tumors and invade nearby tissues or spread to other parts of the body through the blood or lymph system. Infections involve pathogens and immune responses, not uncontrolled cell growth; a temporary swelling is usually inflammation that goes away, not cancer; and a benign growth stays localized and does not spread. So the best description is uncontrolled growth of abnormal cells.