Skin Cancer
Did you know that there are about one million new cases of skin
cancer
diagnosed each year in the United States? Every year
the number of cases
increases due to the overexposure of UVA and UVB light. Cancer,
as
defined by the National Cancer Institute, is the abnormally quick
growth and
division of cells without control. There are two major types of skin
cancer,
non-melanomas and melanomas. Non-melanomas, the less severe group, are
divided
into two subcategories, basal cell and squamous cell cancers accounting
for
seventy-five and twenty percent of all skin cancers respectively.
Melanomas,
although less common only accounting for five percent of all cases, are
deadly.
The survival rates depend on type, detection, and treatment plans.
Most basal
cell and squamous cell cancers if detected early and are treated can be
treated
with ninety-five to one hundred percent survival. Relatively quick and
mild
treatments for non-melanoma cancers include surgery, radiation or laser
therapy, and electrodissection. Malignant melanoma can spread to other
parts of
the body quickly. If detected and treated early the five year survival
rates
range from ninety-five percent if localized to sixty-one percent if
regionally
metastasized to only sixteen percent if distant metastasized. Malignant
melanoma requires longer and more intense treatments which can include:
chemotherapy, biotherapy and wide excision surgery.
How does the suns’ radiant energy cause skin damage? Overexposure
to UVB
light can cause direct or indirect DNA damage. Photocarcinogenesis, or
the
light induced formation of melanoma, is considered to be the cause of
direct
DNA damage. The DNA directly absorbs the UVB light. Although DNA
transforms
ninety-nine point nine percent of the light into heat quickly, the last
fraction causes extreme damage to the skin including sunburn and
increased melanin
production. The absorption spectrum of DNA and action spectrum of
sunburn are
almost identical; therefore, it is said that sunburn is caused by
direct DNA damage of UVB radiation.
The DNA’s nitrogen bases of thymine are then combine causing
thymine-thymine
dimers. The more sun exposure the more dimer production causing higher
risk of
melanoma. DNA is also indirectly damaged
by the absorption of UVB light by chromophores which can not convert
the energy
quick or efficiently. This inefficient transfer of energy in turn
creates
hydroxyl radicals which hook onto the nitrogen bases of DNA.
Direct damage of DNA by the thymine-thymine dimer. Creating bonds
between nitrogen bases.
Indirect DNA damage caused by the slow energy dispursion from the
chromophores creating hydroxyl radicals. The radicals then attach to
the nitrogen bases.
How can we identify if we have skin cancer? For non-melanomas you
can look
for a few distinguishing characteristics. Basal cell cancer often takes
on the
form of a pale, waxy, pearly nodule. Squamous cell cancers look like a
red scaly
outlined patch of dry skin.
To identify melanoma an ABCD rule, first devised by a group of
dermatologists at NYU, was instituted. The letter E was added in 2004
by the
same group as well as new member of the dermatological team.
ABCDE Rule
|
What to Look For:
|
Asymmetry
|
One half of the mole does not match the other half
|
Boarder Irregularities
|
The edges of the mole ar ragged, notched, or blurred
|
Color
|
The pigmentation is not unifor or it is intensely black
|
Diameter
|
The size of the mole is grater than 6 mm, the size of a
pencil eraser
|
Evolving
|
Size, Shape, Symptoms, Surface Bleeding, Shades of Color
|
How can we help prevent skin cancer? Each person can be responsible
for
protecting themselves from the sun. Limit the amount of sun exposure
during the
day to ten to fifteen minutes during non-peak sun hours (that means
avoiding
midday sun 10 a.m. to 4p.m.) will greatly reduce your risk. Wearing at
least a
15 SPF sunscreen during extended hours in the sun and protective
clothing such
as wide brim hats and eye protection will increase your sun safety.
Lastly but
most importantly avoid sunlamps and artificial tanning in salons and
check your
skin regularly for any changes.