Skin cancer is a disease in which malignant, or cancerous, cells form in the tissues of the skin. There are three main types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. Basal cell carcinoma is the most common type of skin cancer. Basal cell carcinoma accounts for approximately 80 percent of all skin cancers. This highly treatable cancer starts in the epidermis (the top layer of skin) and grows very slowly. Basal cell carcinoma usually appears as a small, shiny bump or nodule on the skin. It mainly affects those areas exposed to the sun, such as the head, neck, hands, and face. It commonly occurs among people with light-colored eyes, hair, and complexion. Squamous cell carcinoma is less common but still highly treatable. Squamous cell carcinoma accounts for about 20 percent of all cases. Although more aggressive than basal cell carcinoma, this cancer is highly treatable. Squamous cell carcinoma may appear as nodules or red, scaly patches of skin. It may be found on the face, ears, lips, and mouth. But it can spread to other parts of the body. This type of skin cancer is usually found in fair-skinned people. Melanoma is the most dangerous type of skin cancer. Malignant melanoma accounts for a small percentage of all skin cancers, but it causes the most skin cancer deaths. Malignant melanoma starts in the melanocytes, which are cells that produce pigment in the skin. Malignant melanomas usually begin as a mole that then turns cancerous. This cancer may spread quickly. It affects people with all skin types but most often appears on fair-skinned men and women. The key to prevention is to check your skin on a regular basis. To prevent skin cancer, it is important to examine your skin on a regular basis. Become familiar with moles and other skin conditions to better identify changes. Finding suspicious moles or skin cancer early is the key to treating skin cancer successfully. A skin self-exam is usually the first step in detecting skin cancer. Certain moles are at higher risk for changing into malignant melanoma. Moles that are present at birth and atypical moles have a greater chance of becoming malignant. Recognizing changes in moles is crucial in detecting malignant melanoma at its earliest stage. Melanomas vary greatly in appearance. Always consult your doctor for a diagnosis. Fair skin is one of several skin cancer risk factors. Skin cancer is more common in fair-skinned people -- especially those with blond or red hair, who have light-colored eyes. Skin cancer is rare in children. However, no one is safe from skin cancer. Other risk factors include: family history of melanoma, amount of time spent unprotected in the sun, early childhood sunburns, many freckles, many ordinary moles (more than 50), and dysplastic nevi (unusual benign moles that may resemble melanoma). Skin cancer treatment is highly effective in the majority of cases. There are several kinds of treatments for skin cancer, including surgery, laser surgery, radiation therapy, immunotherapy, and chemotherapy. Immunotherapy is a complex type of treatment involving various approaches to boost the body's immune system, helping it to slow the growth of the cancer. You can prevent skin cancer by following these steps: Wear protective clothing, including a hat with a four-inch brim and sunglasses. Apply sunscreen all over your body and avoid the midday sun from 10 a.m. to 4 p.m. Regularly use a broad-spectrum sunscreen with an SPF of 15 or higher, even on cloudy days.