What is the leading cause of skin cancer?

The leading cause of skin cancer is indeed the exposure to direct sunlight. Ultraviolet (UV) radiation from the sun is a major risk factor, as it can cause DNA damage in skin cells, leading to mutations that may develop into cancer over time. The skin is particularly sensitive to UV rays, and repeated or intense exposure can increase the likelihood of developing skin tumors, such as melanoma, basal cell carcinoma, and squamous cell carcinoma.

While genetic factors, chemical exposures, and smoking can contribute to the risk of various cancers, they are not as strongly associated with skin cancer as UV radiation from sunlight. Genetic predisposition may play a role in an individual's susceptibility, and certain chemicals might contribute to skin damage or irritation, but these factors are secondary when compared to the direct impact of sunlight exposure.