Nonmelanoma skin cancer is usually caused by overexposure to the sun and its ultraviolet (UV) rays. Overexposure to UV rays can result from:

• Having severe sunburn and blistering, especially during childhood.
• Spending a lot of time in the sun over many years.
• Using tanning beds or sunlamps, which are artificial sources of UV rays.

Other possible causes of skin cancer include repeated exposure to X-rays, certain chemicals (such as arsenic, coal tar, creosote), and radioactive substances (such as radium). Skin cancer may also be caused by ionizing radiation treatments for skin conditions such as eczema, psoriasis, or acne.^{1, 2}