Age

Basal cell,
Squamous cell

Most skin cancers appear after age 50. The actual damage may have taken place years earlier.

Complexion

Basal cell,
Squamous cell,
Melanoma

If you have light colored eyes and fair skin that burns or freckles easily (usually people with red or blond hair), you are at greater risk.

Where you live

If you live in an area with a higher level of UV radiation from the sun (such as closer to the equator) you are at increased risk.

Cumulative sun exposure

If you have had long-term, cumulative exposure to the UV rays of the sun, without good protection, you are at greater risk.

Exposure to artificial sources of UV radiation

Exposure to artificial sources of UV radiation, such as sunlamps and tanning booths, can cause skin damage that can lead to melanoma.

Dysplastic nevi

About one out of every ten people has at least one unusual mole that looks different from an ordinary mole. The medical term for these moles is dysplastic nevi. They are more likely than ordinary moles to become cancerous. The risk is greatest if you have a large number of dysplastic nevi. The risk is especially high if you have a family history of both dysplastic nevi and melanoma.

Many ordinary moles

If you have more than 50 ordinary moles, you are at increased risk of melanoma.

Personal history of melanoma or nonmelanoma skin cancers

If you have been treated for melanoma, you have a high risk of a second melanoma. Some people develop more than two melanomas. People who had one or more of the common skin cancers (basal cell carcinoma or squamous cell carcinoma) are at increased risk of melanoma.

Family history of melanoma

Having two or more close relatives who have had melanoma is a risk factor. About 10 percent of all patients with melanoma have a family member with this disease.

Weakened immune system

If your immune system is weakened by certain cancers, by drugs given following organ transplantation, or by HIV, you are at increased risk.