Cells that refuse to stop dividing threaten the whole organism. Cancer is a group of diseases characterized by uncontrolled growth and spread of abnormal cells that can invade surrounding tissue and metastasize to distant sites.

Causes include genetic mutations, environmental exposures, infections, and aging. Different cancers behave differently; some grow slowly and remain localized, while others progress rapidly. Diagnosis typically requires tissue biopsy, imaging, and staging to determine extent.

Treatment may combine surgery, radiation, chemotherapy, immunotherapy, and targeted drugs. Early detection through screening improves outcomes for several common cancers. Research continues to refine molecular classification so that therapy matches the biology of each tumor.

• Uncontrolled growth and spread of abnormal cells
• Can invade locally and metastasize
• Diagnosed by biopsy and staging investigations
• Treated with multimodal, increasingly targeted approaches