Skin cancer involves the abnormal growth of skin cells. Identifying factors that increase susceptibility helps understand who is more prone to its development.
Genetics and Skin Characteristics
Biological factors influence skin cancer risk. People with fair skin, light-colored hair, and light-colored eyes face an increased risk. This susceptibility stems from lower melanin levels, which provide natural protection against ultraviolet (UV) radiation.
A family history of melanoma or other skin cancers also elevates personal risk due to shared genetic predispositions. For instance, inherited mutations in genes like CDKN2A are associated with a higher likelihood of developing melanoma, with a lifetime risk potentially reaching 60-90% in affected families. The presence of numerous moles (over 50-100), or large or atypical moles (dysplastic nevi), further contributes to risk. Atypical moles, while benign, are markers for increased melanoma risk; having ten or more can increase risk by as much as 12 times. Rare genetic syndromes, such as Xeroderma Pigmentosum (XP), drastically increase skin cancer susceptibility. Individuals with XP have impaired DNA repair mechanisms, making them extremely sensitive to UV light and leading to a significantly elevated risk of developing skin cancers, often at a young age.
Sun Exposure and Geographic Influence
UV radiation exposure is a major contributor to skin cancer risk. Prolonged, cumulative exposure to sunlight over a lifetime increases the risk, particularly for non-melanoma skin cancers like basal cell and squamous cell carcinomas. This chronic exposure damages skin cells over time, leading to cancerous changes.
A history of severe, blistering sunburns, especially during childhood or adolescence, significantly elevates the risk of melanoma. Just one blistering sunburn in childhood or adolescence can more than double an individual’s chances of developing melanoma later in life. The intense, intermittent UV exposure from such burns is particularly damaging.
The use of artificial UV radiation from tanning beds also presents a strong link to increased skin cancer risk, including melanoma and squamous cell carcinoma. Individuals who used tanning beds for the first time before age 35 face a 75% increased risk of melanoma, and even a single tanning bed session can increase melanoma risk by 20%. Geographic location plays a role, as living in areas with a high UV index, such as those closer to the equator or at higher altitudes, naturally increases exposure. Professions or hobbies involving extensive time outdoors, like construction work, farming, or gardening, also elevate risk due to chronic sun exposure. Outdoor workers, for example, have a significantly higher risk of squamous cell carcinoma (odds ratio 1.77) and basal cell carcinoma (odds ratio 1.43).
Health Conditions and Medical History
Medical conditions and history can heighten skin cancer risk. A weakened immune system, due to conditions like HIV/AIDS, organ transplantation, or immunosuppressant medications, diminishes the body’s ability to detect and eliminate cancerous cells. This particularly increases the risk for squamous cell carcinoma.
Individuals previously diagnosed with any type of skin cancer face a substantially increased risk of developing another. About 60% of people who have had one skin cancer will be diagnosed with a second within ten years.
Actinic keratoses, which are rough, scaly patches from sun damage, are considered precancerous lesions. Their presence indicates significant sun exposure and signals an increased risk for squamous cell carcinoma. Patients with actinic keratosis have over five times the increased risk of developing skin cancer, with the risk for squamous cell carcinoma being more than seven times higher.
Certain medical treatments, such as radiation therapy for other cancers, can increase the risk of skin cancer in the treated area years later. Studies indicate that patients who received radiation therapy may have a 26% higher probability of being diagnosed with skin cancer, including melanoma and hemangiosarcoma.