How Does Skin Cancer Occur?
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What Causes Skin Cancer?
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Most cases of skin cancer are caused by exposure to ultraviolet light, or UV radiation. UV radiation is found in sunlight, so this means everyone is at risk of developing the condition unless they wear sunscreen or take other measures to avoid UV exposure. Ultraviolet light rays create a chemical reaction with melanin, the chemical that causes pigmentation in the skin. Melanin's job is to protect the body from radiation by absorbing UV radiation when it comes in contact with the skin. When the melanin absorbs too much UV radiation, you will get a sunburn. Increased exposure to UV radiation can cause permanent damage to the melanin and the skin cells, eventually leading to cancer.
How Basal Cell Carcinoma Develops
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Basal cell carcinoma, the most prevalent type of skin cancer, rarely causes death, but can disfigure the area of the body where it is found. It looks like a firm, red growth that extends below the skin. The cancer begins in the skin's basal cell layer. When this layer of the skin is exposed to too much sunlight, a form of DNA damage known as thymine dimer occurs. When the skin cells attempt to repair the thymine dimers, they sometimes fail to remove all of the damage completely. Over time, the mutations are replicated along with the skin cells, and this causes the development of a cancerous tumor.
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How Squamous Cell Carcinoma Develops
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Squamous cell carcinoma, the second most prevalent skin cancer, resembles scaly, red patches on the skin. These patches can become crusted, usually cause pain, and tend to show up on the areas that are exposed to the sun. This cancer develops just below the outer skin layer, known as the epidermis. The basal cells are the bottom of the epidermis, and these cells are responsible for creating new skin cells. The squamous cells are just above the basal cells, and the cancer develops in the squamous cells when they stop dying and then renewing as they normally do. In healthy skin, old skin cells die and are pushed towards the epidermis by new skin cells. At the surface of the skin, the old skin cells are shed. When UV radiation damages the DNA of the squamous cells, the old cells are not shed as they should be, and they begin to grow into a cancerous lesion.
How Melanoma Develops
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Melanoma, the type of skin cancer that leads to the most skin cancer deaths, usually appears as a mole or dark patch on the skin that begins growing and changing. This cancer occurs when the cells that produce melanin, which are known as melanocytes, are damaged. Melanin is the chemical that gives the skin its pigmentation, and melanocytes are always reproducing and shedding, just like squamous basal cells. Exposure to UV radiation can cause the DNA in the skin cells to activate oncogenes, which are genes that make the cell cancerous. It can also damage the DNA itself, causing the cells' renewal and shedding cycle to be disrupted. This causes the cells to grow in an abnormal manner, leading to a tumor or lesion. Melanoma can spread into the body, which is what makes it a deadly form of skin cancer.
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