Skin cancer — the abnormal growth of skin cells — most often develops on skin exposed to the sun. But this common form of cancer can also occur on areas of your skin not ordinarily exposed to sunlight.
There are three major types of skin cancer — basal cell carcinoma, squamous cell carcinoma and melanoma.
You can reduce your risk of skin cancer by limiting or avoiding exposure to ultraviolet (UV) radiation. Checking your skin for suspicious changes can help detect skin cancer at its earliest stages. Early detection of skin cancer gives you the greatest chance for successful skin cancer treatment.
What are the symptoms of skin cancer?
Skin cancer develops primarily on areas of sun-exposed skin, including the scalp, face, lips, ears, neck, chest, arms and hands, and on the legs in women. But it can also form on areas that rarely see the light of day — your palms, beneath your fingernails or toenails, and your genital area.
Skin cancer affects people of all skin tones, including those with darker complexions. When melanoma occurs in people with dark skin tones, it's more likely to occur in areas not normally exposed to the sun, such as the palms of the hands and soles of the feet.
There are three main types of skin cancer. While a number of other forms of skin cancer do exist, they are exceedingly rare.
Basal cell carcinoma signs and symptoms
Basal cell carcinoma usually occurs in sun-exposed areas of your body, such as your neck or face.
Basal cell carcinoma may appear as:
- A pearly or waxy bump
- A flat, flesh-colored or brown scar-like lesion
Squamous cell carcinoma signs and symptoms
Most often, squamous cell carcinoma occurs on sun-exposed areas of your body, such as your face, ears and hands. People with darker skin are more likely to develop squamous cell carcinoma on areas that aren't often exposed to the sun.
Squamous cell carcinoma may appear as:
- A firm, red nodule
- A flat lesion with a scaly, crusted surface
Melanoma signs and symptoms
Melanoma can develop anywhere on your body, in otherwise normal skin or in an existing mole that becomes cancerous. Melanoma most often appears on the face or the trunk of affected men. In women, this type of cancer most often develops on the lower legs. In both men and women, melanoma can occur on skin that hasn't been exposed to the sun.
Melanoma can affect people of any skin tone. In people with darker skin tones, melanoma tends to occur on the palms or soles, or under the fingernails or toenails.
Melanoma signs include:
- A large brownish spot with darker speckles
- A mole that changes in color, size or feel or that bleeds
- A small lesion with an irregular border and portions that appear red, white, blue or blue-black
- Dark lesions on your palms, soles, fingertips or toes, or on mucous membranes lining your mouth, nose, vagina or anus
What are the causes of skin cancer?
Skin cancer occurs when errors (mutations) occur in the DNA of skin cells. The mutations cause the cells to grow out of control and form a mass of cancer cells.
Much of the damage to DNA in skin cells results from ultraviolet (UV) radiation found in sunlight and in the lights used in tanning beds. But sun exposure doesn't explain skin cancers that develop on skin not ordinarily exposed to sunlight. This indicates that other factors may contribute to your risk of skin cancer, such as being exposed to toxic substances or having a condition that weakens your immune system.
What are the risk factors?
Factors that may increase your risk of skin cancer include:
- Fair skin
- A history of sunburns
- Excessive sun exposure
- Sunny or high-altitude climates
- Precancerous skin lesions
- A family history of skin cancer
- A personal history of skin cancer
- A weakened immune system
- Exposure to radiation
- Exposure to certain substances