Article Medically Reviewed By:
Diane S. Berson, MD
Assistant Professor of Dermatology Cornell University Weill Medical College New York, NY
Overview
What Is It?
Skin cancer is the most common type of cancer, probably making up more than half of all diagnosed cases of cancer.
Skin cancer is the most common type of cancer, probably making up more than half of all diagnosed cases of cancer, according to the American Cancer Society (ACS). The incidence of skin cancer is rising dramatically in the United States. More than one million cases of non-melanoma are diagnosed each year, leading to about 2,000 deaths. And the ACS estimates that in 2009, there will be 68,720 new cases of melanoma and 8,650 deaths from the disease. In fact, between 40 percent and 50 percent of people in the United States over age 65 will develop non-melanoma skin cancer. This type of cancer is highly treatable when diagnosed in its early stages, and is usually relatively easy to diagnose.
The majority of lifetime sun exposure occurs before age 20, and skin cancer can take 20 years or more to develop. In fact, very young children who experience as few as two to three severe sunburns are believed to have an increased risk of developing skin cancer later in life. That's not to say you should ignore your risk of developing skin cancer. You need to be concerned about skin cancer, whether your sunbathing days are over or you still spend time pursuing the perfect tan.
The Structure of Skin
The skin is the largest organ in your body and is the body's first defense against disease and infection. It also protects your internal organs from injuries. The skin regulates body temperature, prevents excess fluid loss and helps to remove excess water and salt from your body.
Skin is composed of two layers: the epidermis (the outermost layer of skin) and the dermis (the lower layer). The epidermis itself has four layers: the stratum corneum, the granular layer, the squamous cell layer and the basal cell layer. Keratin (dead, dense protein cells) makes up the stratum corneum or outer layer of the epidermis—the skin layer that can be seen and felt.
The granular layer moves the dead keratin cells to the surface of the epidermis. The squamous cell layer produces keratin for the stratum corneum and also transports water. The basal cell layer is the lowest layer of the epidermis. This is where squamous cells are produced and where the cells that produce melanin, or skin pigment, reside.
The dermis is the deeper layer of skin. It is a diverse combination of blood vessels, hair follicles and sebaceous glands or oil glands. The proteins collagen and elastin are found in the dermis. They provide support and elasticity to the skin. The sun's rays eventually break down these proteins. With age, the skin naturally begins to wrinkle and sag.
The subcutaneous level, or subcutis, is a layer of fatty tissue that provides nourishment to the dermis and upper layers of skin....
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