Introduction

Skin cancers are the most common type of cancer in the United States. The skin is the largest organ in the body. Its job is to control body temperature and protect the body from light, heat, infection, and injury. The skin’s outermost layer, the epidermis, is mostly made of flat cells (squamous cells). Round cells (basal cells) are found under the squamous cells in the deepest part of the epidermis. About 1 million people are diagnosed with non-melanoma skin cancer each year in the United States, according to the American Cancer Society.

Most skin cancers are non-melanoma cancers. They usually start in the basal or squamous cells. Most of these cancers start on parts of the body that have been exposed to the sun, including the face, ears, neck, lips, and backs of the hands. However, these cancers can start anywhere on the skin. These cancers grow slowly and rarely spread (metastasize) to other parts of the body.

The main warning sign for non-melanoma skin cancer is a change in the skin. The disease may start as a sore or lump that develops a scab and does not heal; a flat red or brownish patch that is scaly and may begin to itch; or a shiny, pale, or waxy lump.

Most non-melanoma skin cancers are caused by exposure to ultraviolet (UV) radiation in the part of the skin where the cancer starts. This radiation usually comes from sunlight, but it can also come from artificial sources, such as tanning salons. About twice as many men develop this kind of cancer as women. The number of non-melanoma cancers has increased in recent years.

This content has been reviewed and approved by Myo Thant, MD.