There are three main layers of the skin. From the outside to the inside they are: the epidermis, the dermis and the subcutaneous.

The epidermis, which is the outer most layer and is approximately 1/100 of an inch thick. It is made up of squamous cells. These squamous cells form a protein known as keratin that helps to protect the underlayer. Melanocytes, which are the pigmented cells in the body, are found in this layer. The skin cancer known as squamous cell also can arise from this layer.

The dermis is the middle layer of the skin. It contains hair follicles, sweat glands, blood vessels and nerve endings. It also contains collagen, which holds together all other parts of the tissue. The collagen is derived from a cell known as a fibroblast. These fibroblasts can be responsible for developing skin cancers known as dermatofibrosarcomas.

The most inside layer is called the subcutis. It helps to maintain temperature regulation and is composed mostly of cells and fat.

Approximately 500,000 people per year will be diagnosed with a non-melanoma skin cancer. About 1,900 people will die as a direct result of a non-melanoma skin cancer. The most common types of cancer of the skin are called squamous cell carcinomas (10% to 20%) and basal cell carcinomas (65% to 80%). Lesser-known types of skin cancer include Kaposi sarcoma, primary cutaneous lymphoma (also known as mycosis fungoides) and dermatofibrosarcoma. There has been a 20% increase of basal cell and squamous cell skin cancers in the last decade.