Updated on: Sep 14, 2022

So what is cancer?

Cancer is a disease where your normal cells become damaged and start to grow very fast. These fast growing cells can make tumors that are benign (not cancer) or cancerous (malignant). These cancer cells can also spread to other parts of your body, this is a process called metastasis.

Cells that make up a metastasis are the same type of cells as in the primary cancer. They are not a new type of cancer. For instance, breast cancer cells that spread to the lungs are still breast cancer and NOT lung cancer. And colon cancer cells that spread to the liver are still colon cancer.

Cancer can start to grow almost anywhere in the body. Many cancers form solid tumors, but cancers of the blood, such as leukemias, generally do not.

What is Cancer? - Canadian Cancer Society

The Canadian Cancer Society states:

All types of cancer start in our cells. Our bodies are made up of trillions of cells grouped together to form tissues and organs such as muscles, bones, the lungs and the liver. Genes inside each cell tell it when to grow, work, divide and die. Normally, our cells follow these instructions and we stay healthy. But sometimes the instructions get mixed up, causing our cells to grow and divide out of control or not die when they should. As more and more of these abnormal cells grow and divide, they can form a lump in the body called a tumour.

About Cancer and Cancer Treatment - Online class from Princess Margaret Cancer Centre

Cancer 101 - Cancer Care Ontario