Skin Cancer Causes Skin has two main layers and skin cancer starts in the epidermis - the top layer of the skin.
This is a thin layer, as thin as a hair and provides protection to the skin cells which are constantly shed by the body. The top layer or epidermis contains three major types of cells -
- Squamous cells - These are flat, scaly cells below the outer surface of the skin.
- Basal cells - They are located beneath the squamous cells and they function to produce new skin cells.
- Melanocytes - These cells are located in the lower portion of epidermis and are responsible to produce melanin - skin pigment which gives color to the skin.
More melanin is produced from the melanocytes when the skin is exposed to the ultraviolet (UV) radiation of the sun for long periods. This function has a protective effect on the deeper layers of the skin; dark color of tanned skin is a result of excess melanin production.
Causes of Skin Cancer
Under normal situation the skin cells in the top layer slough off the old cells and produce new cells continuously.
This process is effectively controlled in an orderly way by our genetic material DNA. Any malfunction in this process leads to occurrence of skin cancer. Normally DNA contains instructions for all the biological and chemical process in the body, when DNA is damaged changes happen in these instructions. As a result new cell growth can grow out of control, become malignant or form a mass of cells.
What causes Skin Cancer?
The UV radiation from the sun is considered a main cause of skin cancer as it plays a major role in the damage of the DNA. This radiation is also found in commercially tanning beds and tanning lamps. UV radiation can be distinguished into three wavelength bands -
- Ultraviolet A (UVA)
- Ultraviolet B (UVB)
- Ultraviolet C (UVC)
The atmospheric ozone completely absorbs UVC; however UVA and UVB rays reach the earth. It was once believed that only UVB is responsible for skin cancer, but scientists now believe that UVA also contributes to skin cancer. UVB light not only activates the process of oncogenes (when this gene is activated, it can turn normal cell to malignant one) but also causes other harmful changes in the skin cell DNA.
UVB rays also causes sunburn and is mainly responsible for squamous cell and basal cell carcinomas. UVA on the other hand causes deep penetration (more deep than UVB) and increases the risk of skin cancer, especially melanoma by weakening the skin’s immune system. Tanning beds are especially dangerous as they deliver high doses of UVA.
Other skin cancer causes besides UV light include heredity, exposure to toxic chemicals and certain treatments like radiation. |
