How skin cancer forms

Cancer of the skin, like other cancers, is a disease of cells, which are tiny structures that make up all parts of the body. Although they differ in shape and function in various organs, all cells reproduce themselves by dividing. Normal growth and repair of tissue takes place in this orderly fashion.

When cell division is not orderly and controlled, abnormal growth occurs. Masses of tissue called tumors build up. Tumors can be benign or malignant. A malignant tumor is a cancer.

Benign tumors do not spread. But cancerous or malignant tumors invade and destroy surrounding normal tissue as they grow. Occasionally, cancer cells may break away from the tumor and spread (metastasize) through either the blood or lymphatic vessels to distant parts of the body, where they form additional tumors.