Skin cancer is a disease condition in which the skin cells lose their ability to divide and grow in regular controlled manner resulting in tumor of cells. Cells in different layers of skin can get involved in skin cancer.
Skin cancer is caused by the mutations in the DNA-genetic material of cells responsible for cell division. The cells having such mutated DNA divide rapidly resulting in accumulation of cells in a specific location.
These cancerous cells first start forming in top most layer of the skin called epidermis. From there it can spread to different layers of the skin.
Potential causes of Skin Cancer:
The agents or substances causing cancer are called carcinogens. The main cause of skin cancer is damage to DNA in the cells of skin.
The most common factor responsible for this damage to DNA in the cells of skin is Ultraviolet radiation (UV radiation). UV radiation is a part of electromagnetic radiation, having wavelength less than that of visible light. It is mainly comprised of UVA and UVB radiations which are important carcinogens. UVA radiation causes long term damage to the cells while UVB radiation causes direct damage to the DNA.
The principal source of UV radiation is the light coming from the sun. Most of the UV radiation coming from the sun is prevented from reaching the earth by the filtering action of ozone layer surrounding the earth. But in the recent years due to the depletion of ozone layer, the amount of UV radiation reaching the earth surface increased alarmingly resulting in enhanced number of skin cancer cases.
Apart from ozone depletion other factors also contribute to increased UV exposure. These factors include high altitudes where ozone layer is thin, places near equator, low density of clouds. Due to the exposure to the sun, the DNA present in the skin cells gets damaged, making such cells to divide in rapid disorderly fashion.
Type of skin:
The other important risk factor causing skin cancer is type of skin, which is genetically determined. People having fair skin are more susceptible to skin cancer because the levels of melanin pigment which offers protection against UV radiation, in their skin is low. This explains the fact that the Caucasians are more prone to skin cancer than African-americans.
Radiation used in treatment of other diseases:
Radiation is a frequently employed method of treatment for diseases like cancer and psoriasis. Now-a-days most commonly used radiation for cancer treatment is ionizing radiation. This radiation can remove atoms from atoms, changing the cell bio-molecular structure and affecting its division process as the molecular changes damage the DNA of the cell. Radiation used in psoriasis treatment also poses risk of developing skin cancer. Hence, skin cancer can be termed as one of the side-effects of this treatment too!
Exposure to arsenic:
Arsenic is an inorganic element which if enters the body in toxic amounts, affects DNA by hypermethylation of tumor suppressor genes thereby resulting in increased risk of skin cancer
The scientists found a link between smoking and squamous cell carcinoma-dangerous type of skin cancer. The risk of developing skin cancer is 3.3 times higher in smokers than in non-smokers. This risk increases with the amount of tobacco smoked or cigarettes consumed. Although the reason for this strong association is not yet known, it is assumed that smoking damages DNA in skin cells.
Hereditary of skin cancers:
Family history of skin cancer increases risk of developing skin cancer. As skin cancer results due to damage to the cell genetic material-DNA which can be inherited by the off-springs, heredity plays an important role in skin cancer transmission. Other rarely inherited diseases like xeroderma pigmentosum, in which there is deficiency in repair of sun damaged DNA, also pose a risk factor for developing skin cancer.
Weakened immune system:
The immune system of the body fights with skin cancer cells. But in certain cases like organ transplants, the immune system is weakened by the drugs to decrease the denial of transplants by the immune system. In such situation the risk of skin cancer increases by 70% within 20 years to transplant and may result in fatal cases of skin cancer.
Long term use of corticosteroids also weaken the immune system increasing the risk of developing skin cancer.
Moles and freckles:
These are common in most of the humans. But if these grow in size or bleed or else if the number of moles increase, skin cancer could be suspected.
Skin tanning in solariums can be a potential cause of skin cancer as they tan the skin using much intense sunlight compared to the natural sunlight thereby increasing damage to the skin cell DNA.
Apart from these previous history of skin cancers, old age, male gender (2 times more likely to develop skin cancer than females), long term or severe skin injury or inflammation, human papilloma virus infection also increase chances of developing skin cancer.