Merkel cell carcinoma (MCC), a rare and aggressive skin cancer, is primarily caused by two main factors:
- Ultraviolet (UV) radiation exposure: Chronic exposure to UV light from the sun or artificial sources like tanning beds damages the DNA in skin cells, causing mutations in genes that normally suppress tumors and repair DNA. This damage leads to uncontrolled cell growth and the development of MCC. UV exposure also suppresses the immune system, reducing its ability to repair damage and fight cancer cells
- Merkel cell polyomavirus (MCPyV) infection: This common virus lives on the skin without causing symptoms in most people. However, in about 80% of MCC cases, the virus integrates its DNA into skin cells, disrupting normal cell function and contributing to cancer development. The exact mechanism by which MCPyV causes MCC is still not fully understood, and other factors like UV exposure and immune suppression also influence tumor growth
Additional risk factors that increase the likelihood of MCC include:
- Older age (most cases occur in people over 50 or 65 years)
- Fair skin that burns easily (less melanin protection)
- Weakened immune system due to diseases (e.g., HIV, leukemia) or immunosuppressive medications
- History of other skin cancers such as basal cell carcinoma or squamous cell carcinoma
In summary, Merkel cell carcinoma arises mainly from DNA damage caused by UV radiation and/or infection with Merkel cell polyomavirus, often compounded by immune system impairment and other risk factors
