Skin Cancer is a common and locally destructive cancerous (malignant) growth of the skin. It originates from the cells that line up along the membrane that separates the superficial layer of skin from the deeper layers.
What are the risk factors for skin cancer?
The most common risk factors for skin cancer are as follows.
- Ultraviolet light exposure, either from the sun or from tanning beds. Fair-skinned individuals, with hazel or blue eyes, and people with blond or red hair are particularly vulnerable. The problem is worse in areas of high elevation or near the equator where sunlight exposure is more intense.
- A chronically suppressed immune system (immunosuppression) from underlying diseases such as HIV/AIDS infection or cancer, or from some medications such as prednisone or chemotherapy
- Exposure to ionizing radiation (X-rays) or chemicals known to predispose to cancer such as arsenic
- Certain types of sexually acquired wart virus infections
- People who have a history of one skin cancer have a 20% chance of developing a second skin cancer in the next two years.
- Elderly patients have more skin cancers.
Is skin cancer hereditary?
Since most skin cancers are caused by ultraviolet light exposure, skin cancers are generally not considered to be inherited. But the fact that skin cancer is much more common among poorly pigmented individuals and that skin color is inherited does support the proposition that genetics are very important. There are some very rare genetic syndromes that result in an increased number of skin cancers in those affected.
What causes skin cancer?
It appears basal cell skin cancers arise from DNA mutations in the basaloid cells in the upper layer of the skin. Many of these early cancers seem to be controlled by natural immune surveillance, which when compromised may permit the development of masses of malignant cells that begin to grow into tumors.
In squamous cell cancers, the tumors arise from normal squamous cells in the higher layers of the skin of the epidermis. As with basal cell cancers, these cells are prevented from growing wildly by natural mutational repair mechanisms. When there is an alteration in these genes or the immune surveillance system that controls it, these skin cancers start to grow. In most instances, the genes are altered by ultraviolet exposure.
What are the different types of skin cancer?
- Basal cell carcinoma is the most common cancer in humans. Over 1 million new cases of basal cell carcinoma are diagnosed in the U.S. each year. There are several different types of basal cell carcinoma, including the superficial type, the least worrisome variety; the nodular type, the most common; and the morpheaform, the most challenging to treat because the tumors often grow into the surrounding tissue (infiltrate) without a well-defined border.
- Squamous cell carcinoma accounts for about 20% of all skin cancers but is more common in immunosuppressed people. In most instances, its biologic behavior is much like basal cell carcinoma with a small but significant chance of distant spread.
- Less common skin cancers include melanoma, Merkel cell carcinoma, atypical fibroxanthoma, cutaneous lymphoma, and dermatofibrosarcoma.