The skin is the largest organ in
the body, protecting against germs and the loss of too much water and other
Skin sends messages to the brain
about heat, cold, touch, and pain.
The skin has three layers. From the
outside in, they are epidermis, dermis and subcutis.
The top layer of the skin, the
epidermis, is very thin and protects the deeper layers of skin and the organs.
It also has three layers.
The bottom layer is made up of
basal cells, which divide to form keratinocytes that make a protein called
keratin. Keratin helps the skin protect the body.
The outermost part of the epidermis
is made of dead keratinocytes that are shed as new ones form. The cells in this
layer are called squamous cells.
Melanocyte is another type of cell
also found in the epidermis. These cells make the brown pigment called melanin,
which makes the skin tan or brown and help protect the deeper layers of the
skin from some of the harmful effects of the sun.
The basement membrane is a layer
that separates the epidermis from the deeper layers of the skin. It is
important because when a cancer becomes more advanced, it grows through this
Types of skin cancer
Because they behave differently,
skin cancers are divided into two major groups. The first is melanomas –
cancers that start from the pigment-making cells of the skin (the melanocytes),
which are also responsible for moles or noncancerous growths.
The other is keratinocyte
carcinomas or keratinocyte cancers. There are many types of keratinocyte
cancers, but two types are most common – basal cell carcinoma, which begins in
the lowest part of the epidermis and accounts for about eight of 10 skin cancers
and usually begins on skin exposed to the sun; and squamous cell carcinoma,
which begins in the upper part of the epidermis and accounts for about two of
10 skin cancers. Squamous cell carcinoma also starts most often on skin exposed
to the sun, but can also start within scars or skin ulcers.
Carcinoma is a medical word for a
cancer that starts in a lining layer of cells, like the skin or the lining
cells of the digestive system.
In addition to melanomas and
keratinocyte cancers, there are also some other types of skin cancers that are
less common. These account for less than 1 per cent of skin cancers.
According to the World Health
Organisation, the incidence of skin cancers has been increasing over the past
decades. Currently, between 2 million and 3 million non-melanoma skin cancers
and 132,000 melanoma skin cancers occur globally each year. One in every three
cancers diagnosed is a skin cancer.
Cayman Islands Cancer Society is observing the month of June as skin cancer
Muniz Ferreira is the project coordinator of the Cayman Islands Cancer Society.