What is Cancer?

The human body consists of living cells. Normal body cells grow, divide, and die in a systematic way. Cells become cancer cells when the deoxyribonucleic acid (DNA) inside of them is damaged. DNA is found inside of every cell and controls the cell's functions. Normal cells can repair their damaged DNA, or they die. Cancer cells do not repair their damaged DNA nor die; they continue to replicate and create more cancer cells. Damaged DNA can be inherited or caused by a mutation or mistake that occurs when a normal cell is replicating.

Cells are the building blocks of tissues. When cell growth becomes abnormal, new cells form when the body doesn't need them, and damaged cells do not die when they are supposed to. This replication of abnormal cells often results in a mass of tissue called a lump, or tumor.

Not all tumors cause cancer. Tumors that are not cancerous are called benign and are rarely life-threatening. Tumors that are cancerous are called malignant. Malignant tumors can grow into different parts of the body. When cancer has invaded surrounding tissues, it has metastasized.