Squamous Cell Carcinoma
Understanding Skin Cancer
Cancer begins in cells, the building blocks that make up tissues. Tissues make up the skin and other organs of the body.
Normal cells grow and divide to form new cells as the body needs them. When normal cells grow old or get damaged, they usually die, and new cells take their place.
But sometimes this process goes wrong. New cells form when the body doesn't need them, and old or damaged cells don't die as they should. The buildup of extra cells often forms a mass of tissue called a growth or tumor.
Growths on the skin can be benign (not cancer) or malignant (cancer). Benign growths are not as harmful as malignant growths.
Benign growths (such as moles):
- Are rarely a threat to life
- Generally can be removed and usually don't grow back
- Don't invade the tissues around them
- Don't spread to other parts of the body
Malignant growths (such as melanoma, basal cell cancer, or squamous cell cancer):
- May be a threat to life
- Often can be removed but sometimes grow back
- May invade and damage nearby organs and tissues
- May spread to other parts of the body
Types of Skin Cancer
Skin cancers are named for the type of cells that become malignant (cancer). The three most common types are:
Melanoma begins in melanocytes (pigment cells). Most melanocytes are in the skin.
Melanoma can occur on any skin surface. In men, it's often found on the skin on the head, on the neck, or between the shoulders and the hips. In women, it's often found on the skin on the lower legs or between the shoulders and the hips.
Melanoma is rare in people with dark skin. When it does develop in people with dark skin, it's usually found under the fingernails, under the toenails, on the palms of the hands, or on the soles of the feet.
Basal cell skin cancer:
Basal cell skin cancer begins in the basal cell layer of the skin. It usually occurs in places that have been in the sun. For example, the face is the most common place to find basal cell skin cancer.
In people with fair skin, basal cell skin cancer is the most common type of skin cancer.
Squamous cell skin cancer:
Squamous cell skin cancer begins in squamous cells. In people with dark skin, squamous cell skin cancer is the most common type of skin cancer, and it's usually found in places that are not in the sun, such as the legs or feet.
However, in people with fair skin, squamous cell skin cancer usually occurs on parts of the skin that have been in the sun, such as the head, face, ears, and neck.
Unlike moles, skin cancer can invade the normal tissue nearby. Also, skin cancer can spread throughout the body. Melanoma is more likely than other skin cancers to spread to other parts of the body. Squamous cell skin cancer sometimes spreads to other parts of the body, but basal cell skin cancer rarely does.
When skin cancer cells do spread, they break away from the original growth and enter blood vessels or lymph vessels. The cancer cells may be found in nearby lymph nodes. The cancer cells can also spread to other tissues and attach there to form new tumors that may damage those tissues.
The spread of cancer is called metastasis.
When you're told that you have skin cancer, it's natural to wonder what may have caused the disease. The main risk factor for skin cancer is exposure to sunlight (UV radiation), but there are also other risk factors. A risk factor is something that may increase the chance of getting a disease.
People with certain risk factors are more likely than others to develop skin cancer. Some risk factors vary for the different types of skin cancer.
Studies have shown that the following are risk factors for the three most common types of skin cancer:
Sunlight is a source of UV radiation. It's the most important risk factor for any type of skin cancer. The sun's rays cause skin damage that can lead to cancer.
Severe, blistering sunburns:
People who have had at least one severe, blistering sunburn are at increased risk of skin cancer. Although people who burn easily are more likely to have had sunburns as a child, sunburns during adulthood also increase the risk of skin cancer.
Lifetime sun exposure:
The total amount of sun exposure over a lifetime is a risk factor for skin cancer.
Although a tan slightly lowers the risk of sunburn, even people who tan well without sunburning have a higher risk of skin cancer because of more lifetime sun exposure.
Sunlight can be reflected by sand, water, snow, ice, and pavement. The sun's rays can get through clouds, windshields, windows, and light clothing.
In the United States, skin cancer is more common where the sun is strong. For example, more people in Texas than Minnesota get skin cancer. Also, the sun is stronger at higher elevations, such as in the mountains.
Doctors encourage people to limit their exposure to sunlight.
Sunlamps and tanning booths:
Artificial sources of UV radiation, such as sunlamps and tanning booths, can cause skin damage and skin cancer. Health care providers strongly encourage people, especially young people, to avoid using sunlamps and tanning booths. The risk of skin cancer is greatly increased by using sunlamps and tanning booths before age 30.
People who have had melanoma have an increased risk of developing other melanomas. Also, people who have had basal cell or squamous cell skin cancer have an increased risk of developing another skin cancer of any type.
Melanoma sometimes runs in families. Having two or more close relatives (mother, father, sister, brother, or child) who have had this disease is a risk factor for developing melanoma. Other types of skin cancer also sometimes run in families. Rarely, members of a family will have an inherited disorder, such as xeroderma pigmentosum or nevoid basal cell carcinoma syndrome, that makes the skin more sensitive to the sun and increases the risk of skin cancer.
Skin that burns easily:
Having fair (pale) skin that burns in the sun easily, blue or gray eyes, red or blond hair, or many freckles increases the risk of skin cancer.
Certain medical conditions or medicines:
Medical conditions or medicines (such as some antibiotics, hormones, or antidepressants) that make your skin more sensitive to the sun increase the risk of skin cancer. Also, medical conditions or medicines that suppress the immune system increase the risk of skin cancer.
People with skin cancer are at risk of developing another skin cancer. Limit your time in the sun and stay away from sunlamps and tanning booths. Keep in mind that getting a tan may increase your risk of developing another skin cancer.
The best way to prevent skin cancer is to protect yourself from the sun:
- Avoid outdoor activities during the middle of the day. The sun's rays are the strongest between 10 a.m. and 4 p.m. When you must be outdoors, seek shade when you can.
- Protect yourself from the sun's rays reflected by sand, water, snow, ice, and pavement. The sun's rays can go through light clothing, windshields, windows, and clouds.
- Wear long sleeves and long pants. Tightly woven fabrics are best.
- Wear a hat with a wide brim all around that shades your face, neck, and ears. Keep in mind that baseball caps and some sun visors protect only parts of your skin.
- Wear sunglasses that absorb UV radiation to protect the skin around your eyes.
- Use sunscreen lotions with a sun protection factor (SPF) of at least 15. (Some doctors will suggest using a lotion with an SPF of at least 30.) Apply the product's recommended amount to uncovered skin 30 minutes before going outside, and apply again every two hours or after swimming or sweating.
Sunscreen lotions may help prevent some skin cancers. It's important to use a broad-spectrum sunscreen lotion that filters both UVB and UVA radiation. But you still need to avoid the sun during the middle of the day and wear clothing to protect your skin.