Squamous Cell Carcinoma
Squamous cell carcinoma, the second most common skin cancer after basal
cell carcinoma, afflicts more than 200,000 Americans each year. It arises
from the epidermis and resembles the squamous cells that comprise most
of the upper layers of skin. Squamous cell cancers may occur on all areas
of the body including the mucous membranes, but are most common in areas
exposed to the sun.
Although squamous cell carcinomas usually remain confined to the epidermis
for some time, they eventually penetrate the underlying tissues if not
treated. In a small percentage of cases, they spread (metastasize) to
distant tissues and organs. When this happens, they can be fatal. Squamous
cell carcinomas that metastasize most often arise on sites of chronic
inflammatory skin conditions or on the mucous membranes or lips.
What Causes It?
Chronic exposure to sunlight causes most cases of squamous cell carcinoma.
That is why tumors appear most frequently on sun-exposed parts of the
body: the face, neck, bald scalp, hands, shoulders, arms, and back. The
rim of the ear and the lower lip are especially vulnerable to the development
of these cancers.
Squamous cell carcinomas may also occur where skin has suffered certain
kinds of injury: burns, scars, long-standing sores, sites previously exposed
to X-rays or certain chemicals (such as arsenic and petroleum by-products).
In addition, chronic skin inflammation or medical conditions that suppress
the immune system over an extended period of time may encourage development
of squamous cell carcinoma.
Who Gets It?
Anyone with a substantial history of sun exposure can develop squamous
cell carcinoma. But people who have fair skin, light hair, and blue, green,
or gray eyes are at highest risk. Those whose occupations require long
hours outdoors or who spend extensive leisure time in the sun are in particular
jeopardy. Dark-skinned individuals of African descent are far less likely
than fair-skinned individuals to develop skin cancer. More than two thirds
of the skin cancers that they do develop, however, are squamous cell carcinomas,
usually arising on the sites of preexisting inflammatory skin conditions
or burn injuries.
Warning Signs of Squamous Cell Carcinoma
-A wart-like growth that crusts and occasionally bleeds.
-A persistent, scaly red patch with irregular borders that sometimes crusts
or bleeds.
-An open sore that bleeds and crusts and persists for weeks.
-An elevated growth with a central depression that occasionally bleeds.
A growth of this type may rapidly increase in size.
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