Risk factors

Factors that may increase your risk of Merkel cell carcinoma include:

• Excessive exposure to natural or artificial sunlight. Being exposed to ultraviolet light, such as the light that comes from the sun or from tanning beds, increases your risk of Merkel cell carcinoma. The majority of Merkel cell carcinomas appear on skin surfaces frequently exposed to sun.
• A weakened immune system. People with weakened immune systems — including those with HIV infection, those taking drugs that suppress the immune response or those with chronic leukemias — are more likely to develop Merkel cell carcinoma.
• History of other skin cancers. Merkel cell carcinoma is associated with the development of other skin cancers, such as basal cell or squamous cell carcinoma.
• Older age. Your risk of Merkel cell carcinoma increases as you age. This cancer is most common in people older than age 50, though it can occur at any age.
• Light skin color. Merkel cell carcinoma usually arises in people who have light-colored skin. Whites are much more likely to be affected by this skin cancer than are blacks.