The causes of skin cancer: a comprehensive review

Skin cancer is the most common type of cancer in fair-skinned populations around the world. The incidence and mortality rates of skin cancers are dramatically increasing and thus pose a threat to public health. Understanding the etiology and pathogenesis of skin cancer remains a goal for healthcare systems. A clearer understanding of causative factors is an essential step in the prevention of skin cancer. This article comprehensively reviews the causative agents which play a role in the development of skin cancer. Ultraviolet radiation (UV) from sun exposure is the most important cause of skin cancer. Sunburns and excessive exposures cause cumulative damage which induces immunosuppression and skin cancers. Ozone depletion, the level of UV light, elevation, latitude, altitude and weather conditions influence the emission of UV radiation reaching the earth's surface. Organ transplant recipients and AIDS patients have an increased incidence of skin cancers. Some treatment modalities, including radiation therapy, phototherapy and psoralen and long-wave ultraviolet radiation (PUVA) can also predispose to skin cancers. Viral infections such as the human papilloma virus can cause squamous cell carcinomas. Individuals with familial genetic syndromes are susceptible to specific types of skin cancers. Ionizing radiation, environmental pollutants, chemical carcinogens and work-related exposures have been associated with skin cancers. Exposure to artificial UV radiation (tanning beds and lamps), aging, skin color, diet and smoking are attributable risks. Skin cancers have been found in dermatoses and various types of keratoses, chronically injured or nonhealing wounds, and scars. This article provides a comprehensive and thorough overview of skin cancer, with an emphasis on understanding its epidemiology, incidence, etiology and related risk factors.