Skin Cancer Causes
Ultraviolet (UV) light exposure, most commonly from sunlight, is overwhelmingly the most frequent cause of skin cancer.
Other important causes of skin cancer include the following:
- Use of tanning booths
- Immunosuppression, or impairment of the immune system, which protects the body from germs or substances that cause an allergic reaction
- Exposure to unusually high levels of radiation, such as from X-rays
- Contact with certain chemicals, such as arsenic (miners, sheep shearers, and farmers) and hydrocarbons in tar, oils, and soot (which may cause squamous cell carcinoma)
The following people are at the greatest risk of skin cancer:
- People with fair skin, especially types that freckle, sunburn easily, or become painful in the sun
- People with light (blond or red) hair and blue or green eyes
- Those with certain genetic disorders that deplete skin pigment , such as albinism and xeroderma pigmentosum (a disease in which DNA repair mechanisms, especially in response to ultraviolet light, is impaired)
- People who have already been treated for skin cancer
- People with numerous moles, unusual moles, or large moles that were present at birth
- People with close family members who have developed skin cancer
- People who had at least one severe sunburn early in life
- People with burns unrelated to sunburn
- People with indoor occupations and outdoor recreational habits
Basal cell carcinomas and squamous cell carcinomas are more common in older people. Melanomas are more common in younger people, especially in people ages 25 to 29.
Skin Cancer Symptoms
Skin cancer symptoms depend on the type of skin cancer that has developed.
A basal cell carcinoma (BCC) usually looks like a raised, smooth, pearly bump on the sun-exposed skin of the head, neck, or shoulders. Others signs include:
- Small blood vessels may be visible within the tumor.
- A central depression with crusting and bleeding (ulceration) frequently develops.
- A BCC often appears as a sore that does not heal.
A squamous cell carcinoma (SCC) is commonly a well-defined, red, scaling, thickened bump on sun-exposed skin. It may ulcerate and bleed, and left untreated, may develop into a large mass.
The majority of malignant or cancerous melanomas are brown-to-black pigmented lesions. Other signs of a cancerous melanoma include:
- A change in size, shape, color, or elevation of a mole
- The appearance of a new mole during adulthood, or new pain, itching, ulceration, or bleeding of an existing mole
The following easy-to-remember guideline, "ABCDE," is useful for identifying malignant melanoma:
- Asymmetry -- One side of the lesion does not look like the other.
- Border irregularity -- Margins may be notched or irregular.
- Color -- Melanomas are often a mixture of black, tan, brown, blue, red, or white.
- Diameter -- Cancerous lesions are usually larger than 6 mm across (about the size of a pencil eraser).
- Evolution -- has a mole changed over time?