Skin Cancer
Sunlight has a profound effect on the skin causing premature skin
aging, skin cancer and a host of skin changes. Effective protection
towards the damaging effects of UVB & UVA radiation through
protective measures as avoiding sunshine, protective clothing and
efficient use of sunscreens is the best way to avoid the damaging
effects. Sun protection has become a major issue in most Western
countries because of the general increase of skin cancers and
especially melanoma, but also because of the role in premature skin
aging and the deterioration of various skin diseases.
Skin Cancer caused by the Sun
The ability of the sun to cause skin cancer is a well-known fact. UV radiation can damage DNA (Deoxyribonucleic acid, contains the genetic instructions) directly (by striking the DNA molecule) or indirectly (by causing the formation of highly reactive molecules which attack DNA and other cell components). Although every cell has mechanisms for repairing damaged DNA, these mechanisms can be overwhelmed or inactivated by UV, allowing UV damage to accumulate.
The three main skin cancers are melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC). BCC and SCC are also referred to as non-melanoma skin cancer (NMSC)
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Melanoma
Melanoma is the most dangerous skin cancer because it metastasizes more
readily than the other skin cancers and can cause people to die from
it. It appears as an irregular brown spot or changing mole and can
arise from normal skin or from a mole, which has turned bad. If caught
early, melanoma is usually curable. |
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Basal Cell Carcinoma
Basal Cell Carcinoma is the most common in the general population. This
type of cancer usually presents as a pinkish small tumour on the head
or the neck. If not treated, it may change to ulceration, bleeding, and
formation of crust. Basal cell carcinoma increases slowly and rarely
spreads to other parts of the body invading muscle and bones.
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Actinic Keratosis
UV radiation causes an increased number of moles in sun-exposed areas.
Sun exposure also causes early still benign cancerous lesions called
actinic keratoses that develop especially on the face, ears, and backs
of the hands. They are small crusty bumps that can often be felt better
than they can be seen. Actinic keratoses are considered to be the first
appearance of squamous cell carcinoma because they may develop into
squamous cell carcinoma. Early treatment of actinic keratoses can
prevent their transformation into serious squamous cell carcinomas.
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Squamous Cell Carcinoma
The appearance of Squamous Cell Carcinoma may be close to the one of
basal cell carcinoma but its relief is generally higher and crustier.
It may look like an irritated wart. It occurs most often on the head,
neck, ears, lips, back of the hands and forearms. This tumour may
spread to lymphatic nodes and other organs (metastases). Squamous cell
carcinoma may be easily cured if treated early. The risk of getting
squamous cell carcinoma is determined by a person's lifetime exposure
to UV radiation and the person's pigment protection.
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Evidence on Sun Screens and Skin Cancer
Regular sunscreen use benefits “normal” populations. Researchers in
Australia have shown that daily application of a broad-spectrum (UVA
and UVB) sunscreen can reduce the number of sun-exposure associated
skin lesions (actinic keratoses, AKs) in people aged 40 or over.1
Transplant patients benefit particularly from effective sun protection.
These patients are at increased risk of skin cancer because their
immune defences have been artificially lowered to prevent organ
rejection (so called immuno suppression). A recent study in Germany
has shown that transplant patients using a very high protection broad
spectrum (UVA and UVB) liposomal sunscreen are protected from the
development of both actinic keratoses and squamous cell carcinoma (SCC).2
1 Thompson SC, Jolley D, Marks R. Reduction of solar keratoses by regular sunscreen use. N Engl J Med 1993;329(16):1147-51
2 Ulrich C., et al., Prevention of non-melanoma skin cancer in organ transplant patients by regular use of a sunscreen: a 24 months, prospective, case-control study. British Journal of Dermatology 2009; 161 (Suppl. 3): 78-84
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