Source: Colon Cancer Cells, Wellcome Library

Cancer is a disease of the cell cycle. Cancer cells don't respond to the signals and safeguards that are in place. Because they don't respond to the signals and regulators, they grow uncontrollably and eventually damage the tissues that are around them.

If the cancer cells continue to grow, they will form a mass called a tumor.

Some tumors are benign and may be harmless. Malignant tumors are very dangerous and even cause death. Malignant tumors have the ability to leave their original growth site and move through the bloodstream to other areas of the body. This process is called metastasis. If this occurs, the tumor invades the new tissue and can continue to grow uncontrollably in the surrounding tissue.

Directions: Watch the following video to better understand how cancer spreads.