What is considered the most lethal primary skin cancer?

• A. Basal cell carcinoma
• B. Squamous cell carcinoma
• C. Malignant melanoma
• D. Merkel cell carcinoma

Answer: (C)

Malignant melanoma is the most lethal primary skin cancer because of its high tendency to spread to regional lymph nodes and distant organs. The prognosis hinges on how deep the tumor grows (thickness) and whether it has ulceration; even relatively small lesions can metastasize, making melanoma the leading cause of skin cancer–related deaths. Basal cell carcinoma, while the most common, almost never metastasizes and is highly curable with local treatment. Squamous cell carcinoma can metastasize and is more dangerous than basal cell carcinoma, but its overall mortality is still lower than that of melanoma. Merkel cell carcinoma is very aggressive and deadly per case, but it is rare, so its impact on overall skin cancer mortality is less than melanoma. Thus, melanoma is considered the most lethal.