Squamous cells are a type of epithelial cell that line and surround tissues throughout the body. Normal squamous cells have a flat, pancake-like shape, and this flattened morphology facilitates functions like gas or nutrient transfer through the cells. Squamous cell carcinoma develops when normal squamous cells begin to proliferate out of control, forming cancerous tumors with the ability to invade surrounding healthy tissue. The cancer can be caused by a number of internal or environmental factors.
Exposure to UV Rays
A common cause of some forms of squamous cell carcinoma is exposure to UV rays. The skin is made up of several layers of squamous cells, ranging from live, proliferating cells in the basal layers of skin, to dead skin cells found at the surface. Via exposure to the sun's rays, UVA and UBV radiation enter into the layers of cells, causing DNA damage in proliferating squamous skin cells. Over time, this damage leads to an accumulation of genetic mutations, and eventually allows the squamous cells to proliferate uncontrollably, possibly forming a cancerous tumor. Medline Plus recommends protecting the skin from ultraviolet rays and radiation damage by wearing sunscreen with a rating of at least SPF 15, and avoiding direct sun exposure between the hours of 10 AM and 4 PM.
Albinism
In some cases, inherited genetic disorders can cause squamous cell carcinomas. Oculocutaneous albinism, a genetic condition that affects pigmentation within the eye and skin, can significantly increase the risk of developing squamous cell caricnomas of the skin, according to the Merck Manuals. Under normal condition, cells in the skin, called melanocytes, produce a dark pigment called melanin. This pigment acts as sun protection, and the level of melanin in the skin is a measure of an individual's susceptibility to sun damage. Patients with oculocutaneous albinism are deficient in melanin, leaving their skin without natural sun protection. As a result, individuals with this disease can be severely affected by UV rays, and therefore have a greater chance of develping squamous cell carcinoma of the skin due to sun exposure. The Merck Manuals recomment that patients with oculocutaneous albinism avoid sun exposure and wear UV protection on their skin, as well a sunglasses to protect their eyes from sun damage.
Cigarette Smoke
Many squamous cell caricnomas occur in the lungs, with squamous cell carcinoma accounting for between 25 and 30 percent of lung cancers, according to the University of Maryland Medical Center. Squamous cells help form the air sacs of the lungs, and the flattened shape of the cells allows for the transfer of oxygen from inhaled air into blood vessels surrounding the lungs. Squamous cell carcinoma of the lungs is commonly caused by exposure to cigarette smoke. Nicotine smoke contains a number of carcinogens, and the accumulation of these chemicals in the lungs can lead to genetic mutations in the squamous cells in the air sacs. The risk of developing squamous cell carcinoma of the lung increases with the number of cigarettes smoked and the level of exposure to second-hand smoke over time.
