|MadSci Network: Medicine|
Skin cancer occurs as a variety of different microscopic types having several known, as well as unknown, causes.
But most of the time when we speak of SKIN CANCER we refer to either:
1) squamous and basal cell cancer, which are cancers derived from
the round to flattened keratin-making cells that compose almost all of
our protective body layer called skin.
2) malignant melanoma, arising from the melanin pigment producing cells of our skin, which can produce harmless brown moles (nevi) on most of us. (These are not the same as "freckles", however).
Squamous carcinoma and a close relative, basal cell carcinoma are by far the most common of the two types and both are readily cured, if treated before they become to large, because they virtually never metastasize (spread by the blood and lymphatics to distant body locations) and respond to simple surgical excision or even irradiation if surgery might produce destructive scarring. These cancers usually result from cumulative sun exposure (solar radiation) particulary in pale blond-haired individuals of northern European descent (Celtic backgrounds for example). Thus, if your ethnic background is of a high risk type such as these, you will have a somewhat increased chance of eventually developing the type #1 cancer described above. But remember that it is not fatal and is readily cured if handled early! Try to reduce this genetic risk by wearing sun-protective clothing (hat, long sleeves, and long pants) and skin lotions (sun barriers with an SPF-rating of at least 30-40) to minimize the sun's damaging ultra-violet rays.
Malignant melanoma is far more serious because it will METASTASIZE if left untreated!! Cure is certainly possible if the lesions are small, flat, shallow in depth, and are WIDELY EXCISED by an experienced physician. Common warning signs include: a) a change in color, size, or shape of a previously inactive pigmented skin lesion, b) lesion ulceration or bleeding, c) failure of a skin lesion to heal after an insignificant injury, and d) the appearance of satellite skin lesions resembling the apparently inactive "parent". There are families with related members having "atypical nevi" (skin moles) and these individuals have a definite risk of melanoma developing in such nevi. But the vast majority of our skin moles (nevi) are not atypical and are no cause for alarm. A dermatologist is the most skilled at recognition of possible atypical nevi, but the definite diagnosis of this type of nevus (singular for nevi) requires examination of a skin biopsy by a skilled skin pathologist or dermatologist with pathological diagnostic experience. The cause of melanoma is less well understood than type #1 above, but sun exposure does play a definite role!! It seems, for example, that those with weekend exposures to the sun, who otherwise work indoors, are more likely to develop melanoma, while those working outdoors in the sun all day tend to end up with the squamous cell type of cancer!! Puzzling isn't it; we just don't know enough to answer all your questions with confidence.
You have raised an extremely important issue with your questions: the increasing loss of the earth's ozone layer is now directly linked with increasing skin cancer; particularly the more dangerous type #2 above: the malignant melanoma type of cancer. The desire to eliminate the ozone-damaging fluorohydrocarbons from our environment has a real basis in public health protection.
Good luck in your life-long learning; and thank you for this complex and most important health question!
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