Non-melanoma skin cancers are the most common cancers
of the skin, and the two types that are most
common are basal cell carcinoma and squamous
cell carcinoma.
Basal cell carcinoma begins in the lowest layer of
the epidermis, the basal cell layer. About 75% of
all skin cancers are basal cell carcinomas. They
usually begin on areas exposed to the sun such as
the head
and neck and grow slowly. It is highly unusual for
a basal cell cancer to spread to distant parts of
the body. After treatment, basal cell carcinoma can
recur in the same place on the skin or start elsewhere
on the skin.
Squamous cell carcinomas begin in the upper part
of the epidermis and account for about 20% of all
skin cancers. They usually appear on sun-exposed
areas such as the face, ear, neck, lips and hands,
though
they can also begin within scars or skin ulcers elsewhere
on the body. Compared to basal cell carcinomas, squamous
cell carcinomas are more likely to invade tissues
beneath the skin, and slightly more likely to spread
to distant parts of the body. Even so, very few squamous
cell skin carcinomas spread to lymph nodes and/or
other organs.
Cancer of the skin (including melanoma and non-melanoma
skin cancer) is the most common form cancer. It accounts
for nearly half of all cancers.
Source: American Cancer Society
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