The primary risk factor for developing melanoma is UV radiation exposure, particularly from sunlight and tanning beds. UV radiation causes direct DNA damage in skin cells, leading to mutations that trigger malignant transformation. This risk is especially high in individuals with fair skin, history of sunburns, or intense intermittent sun exposure. Unlike chronic irritation, obesity, or smoking, UV radiation directly affects melanocytes where melanoma arises. Reducing UV exposure is crucial for prevention and early detection strategies.

Reference: Fitzpatrick's Dermatology in General Medicine, 9th Edition.