Factors that may increase your risk of skin cancer include:
- Fair skin. Anyone, regardless of skin color, can get skin cancer. However, having less pigment (melanin) in your skin provides less protection from damaging UV radiation. If you have blond or red hair and light-colored eyes, and you freckle or sunburn easily, you’re much more likely to develop skin cancer that is a person with darker skin.
- A history of sunburns. Having had one or more blistering sunburns as a child or teenager increases your risk of developing skin cancer as an adult. Sunburns in adulthood also are a risk factor.
- Excessive sun exposure. Anyone who spends considerable time in the sun may develop skin cancer, especially if the skin isn’t protected by sunscreen or clothing. Tanning, including exposure to tanning lamps and beds, also puts you at risk. A tan is your skin’s injury response to excessive UV radiation.
- Sunny or high-altitude climates. People who live in sunny, warm climates are exposed to more sunlight than are people who live in colder climates. Living at higher elevations, where the sunlight is strongest, also exposes you to more radiation.
- Moles. People who have many moles or abnormal moles called dysplastic nevi are at increased risk of skin cancer. These abnormal moles — which look irregular and are generally larger than normal moles — are more likely than others to become cancerous. If you have a history of abnormal moles, watch them regularly for changes.
- Precancerous skin lesions. Having skin lesions known as actinic keratoses can increase your risk of developing skin cancer. These precancerous skin growths typically appear as rough, scaly patches that range in color from brown to dark pink. They’re most common on the face, head, and hands of fair-skinned people whose skin has been sun damaged.
- A family history of skin cancer. If one of your parents or a sibling has had skin cancer, you may have an increased risk of the disease.
- A personal history of skin cancer. If you developed skin cancer once, you’re at risk of developing it again.
- A weakened immune system. People with weakened immune systems have a greater risk of developing skin cancer. This includes people living with HIV/AIDS and those taking immunosuppressant drugs after an organ transplant.
- Exposure to radiation. People who received radiation treatment for skin conditions such as eczema and acne may have an increased risk of skin cancer, particularly basal cell carcinoma.
- Exposure to certain substances. Exposure to certain substances, such as arsenic, may increase your risk of skin cancer.
The risk of basal and squamous cell skin cancers goes up as people get older. Older people have been exposed to the sun for a longer time. Still, these cancers are now being seen in younger people too, probably because they are spending more time in the sun without protecting their skin.
Men are 2 times as likely as women to have basal cell cancers and about 3 times as likely to have squamous cell cancers of the skin. This could be because they spend more time in the sun.
Having had a skin cancer
Anyone who has had one keratinocyte cancer has a much higher chance of having another one.
Certain long-term or severe skin problems
Scars from bad burns, areas of skin over bad bone infections, and skin damaged by certain skin diseases are more likely to develop skin cancer, but this risk is fairly small.
Some patients with psoriasis (a long-lasting inflammatory skin disease) are treated with psoralen and ultraviolet light treatments (PUVA). This can increase their risk of getting squamous cell skin cancer, and maybe other skin cancers, too.
Xeroderma pigmentosum: This very rare disease makes the skin less able to repair sun damage. This disease tends to run in families. People with this disease get many skin cancers, sometimes starting in childhood.
Basal cell nevus syndrome: This rare condition is present at birth. It causes some people to have many basal cell cancers. It often runs in families.
Weakened immune system
People with weak immune systems are more likely to develop non-melanoma skin cancer. For instance, people who have had an organ transplant often take medicines to weaken the immune system so that the body cannot reject the organ. These people are more likely to develop non-melanoma skin cancer. Skin cancers in people with weak immune systems tend to grow faster and are more likely to be fatal.
A small number of skin cancers seem to be linked to infection with human papillomavirus (HPV). This group of viruses can cause warts. The warts are different from the common type of warts that people get on their hands and feet. The HPV-related warts are often in the genital area and around the anus. They are linked to skin cancers in these areas.
Smoking is a risk factor for squamous cell skin cancer, but it is not a known risk for basal cell cancer.
Scientists have found that certain people are more likely than others to develop skin cancer after sun exposure. In these people, certain parts of the normal cells are more sensitive to being damaged by sunlight.
Xeroderma pigmentosum (XP)
This is a rare, inherited condition. People with XP are less able to repair damage caused by sunlight and are at greater risk of melanoma and other skin cancers.
Exposure to ionizing radiation can induce cutaneous malignancies in humans, usually basal cell carcinoma, squamous cell carcinoma, and spindle cell carcinoma. Radiation-induced cancers of the skin have been reported in patients receiving ionizing radiation as therapy. In the past, acne, facial hair, and tinea capitis were treated with x-ray therapy. Patients receiving these types of therapy later developed severe radiodermatitis in the form of skin atrophy, telangiectasia, hypopigmentation, or hyperpigmentation. Some of these patients developed large, invasive, deforming skin cancers. These inappropriate uses of x-ray therapy have been discontinued, but accidental exposure to x-rays and exposure for medical reasons continues to cause radiation dermatitis. Occupational exposure and the resultant radiodermatitis and skin cancers, such as squamous cell carcinoma on the fingers of dentists, is no longer seen. The use of fractionated doses of radiation has reduced the long-term side effects of radiation therapy. Rare cases of squamous cell carcinoma caused by radioactive gold jewelry have also been noted.
CHRONIC IRRITATION OR INFLAMMATION
Skin cancers can develop in areas of chronic inflammation or irritation. Squamous cell carcinoma has been noted to occur in many skin diseases with a chronic inflammatory or irritant course, such as long-standing granulomas, venereal granulomas, syphilis, lupus vulgaris, leprosy, SLE, chronic ulcers, osteomyelitis sinuses, old burn scars, hidradenitis suppuritiva, poikiloderma congenital, dystrophic epidermolysis bullosa, and porokeratosis of Mibelli. Squamous cell carcinoma of the oral cavity can be induced by chronic irritation secondary to chewing tobacco or betel nuts.
Many malignant neoplasms are caused by viruses in animals. In humans, such associations have rarely been documented. Human papillomavirus (HPV) has been identified in lesions of verrucous carcinoma, Bowenoid papulosis, epidermodysplasia verruciforms, and in situ epidermoid carcinoma. Many papillomavirus subtypes have been identified, and HPV types 5, 8, 14, 16, 17, and 33 are associated with various epidermal carcinomas and carcinoma of the cervix. BPV 6 and 11 have been associated with verrucous carcinoma of the genitals (Buschke-Lowenstein tumor), while HPV 16 has been associated with squamous cell carcinoma of the nail bed. HPV 5 and HPV 8 have been found in most cases of epidermo-plasia verruci formis that have progressed to squamous cell carcinoma. It is possible that other inducing factors are needed to produce the malignant tumor from some of these papillomaviruses. These papillomaviruses appear potentially oncogenic in humans. There are other viruses, such as human T-cell lymphotropic virus-I (HTLV-I) in leukemia-lymphoma and Epstein-Barr virus in Burkitt’s lymphoma and nasopharyngeal carcinoma, that may be associated with some of the human malignancies, but conclusive information is not available.
People with certain risk factors are more likely than others to develop skin cancer. Risk factors vary for different types of skin cancer, but some general risk factors are having—
- A lighter natural skin color.
- The family history of skin cancer.
- A personal history of skin cancer.
- Exposure to the sun through work and play.
- A history of sunburns, especially early in life.
- A history of indoor tanning.
- Skin that burns, freckles, reddens easily, or becomes painful in the sun.
- Blue or green eyes.
- Blond or red hair.
- Certain types and a large number of moles.