What is Skin Cancer?
Your skin is your body's largest organ. It covers and protects your body and helps regulate your body temperature. Your skin has three main layers: the epidermis, the dermis, and the subcutis (a layer of fatty tissue). Skin cancer usually forms in your epidermis, which is the outermost layer of skin. Your epidermis has two main types of cells: keratiniocytes and melanocytes. Keratinocytes make an important protein called keratin which provides water-proofing for the body. These cells begin as round, basal-layer keratinocytes whose function is to divide to grow new skin. As these cells mature, they take on a flattened, squamous shape and the ability to make keratin. For every 36 keratinocytes, there is a population of special cells called melanocytes that produces pigment. These melanocytes transfer their pigment packets to the surrounding keratinocytes to protect your skin from sun damage and are responsible for your skin color.
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The two most common forms of skin cancer are basal and squamous cell carcinomas:
Basal cell carcinomas
(BCC) are the most common type of skin cancer, accounting for about 80% to 90% of all cases. Basal cell carcinomas grow from the basal-layer keratinocytes and are usually slow-growing. Basal cell carcinomasrarely spread to your lymph nodes or organs. These tumors, however, can eventually enlarge and invade nearby tissues if left untreated. Basal cell cancers are very common in the Caucasian population. It is estimated that there are as many BCC’s diagnosed each year as all other forms of cancer combined. Fortunately, the overwhelming majority of BCC’s are diagnosed at an early stage when treatment is straightforward and long-term outcomes are excellent.
Squamous cell carcinomas
(SCC) are the second most common type of skin cancer, accounting for about 10% to 20% of all skin cancers. Squamous cell carcinomas arise from the squamous cells of the epidermis. These cancers are more aggressive than basal cell carcinomas but not as aggressive as melanomas. Squamous cell carcinomas are more likely to invade deeper layers of your skin and have a 5% risk of spreading to nearby lymph nodes or distant organs. As with BCC, if diagnosed early, the treatment of SCC is quite straightforward and long-term outcomes are excellent.
