What studies demonstrate ultraviolet (UV) radiation from sunlight as a causative factor in the development of carcinomas (cancer)?

From the Guidelines

Ultraviolet (UV) radiation from sunlight is a well-established causative factor for skin cancer, including melanoma, squamous cell carcinoma, and basal cell carcinoma, as demonstrated by high-quality studies such as the ESMO clinical practice guidelines for diagnosis, treatment, and follow-up of cutaneous melanoma 1. The evidence suggests that increased UV light exposure, particularly in genetically predisposed populations, is responsible for the ongoing increase in incidence and mortality of skin cancer over recent decades. Key findings from the studies include:

• UV irradiation is a major carcinogen involved in melanoma genesis, and prevention of UV exposure, including regular use of sunscreen, has been shown to diminish the incidence of primary cutaneous melanomas in an Australian population 1.
• The incidence of malignant melanoma varies from 3–5/100 000/year in Mediterranean countries to 12–25 in Nordic countries and is still rising, with increased UV light exposure being a contributing factor 1.
• Behavioral counseling to prevent skin cancer, including techniques to reduce UV radiation exposure, has been shown to be effective in reducing the risk of skin cancer, particularly in young persons aged 10 to 24 years 1. Some of the key mechanisms by which UV radiation contributes to skin cancer include:
• Direct damage to DNA, leading to mutations in tumor suppressor genes and oncogenes
• Suppression of skin immunity, reducing the body's ability to identify and eliminate cancerous cells
• Increased risk of skin cancer with cumulative sun exposure, particularly for squamous cell carcinoma, and intense, intermittent exposure and sunburns for melanoma.

From the Research

Studies on Sunlight as a Causative Factor of Cancer

• The study 2 published in Anticancer research in 2022, highlights the carcinogenic effects of sun exposure, which increase the risk for skin cancer, especially for fair-skinned individuals.
• Another study 3 published in British medical bulletin in 2022, found that workplace exposure to solar ultraviolet (UV) causes malignant melanoma and non-melanoma skin cancer.
• A study 4 published in Current opinion in pediatrics in 1998, notes that melanoma risk is linked to sun sensitivity and childhood exposures, and sunscreen use has been promoted for prevention of skin cancer.
• The study 5 published in International journal of environmental research and public health in 2020, suggests that insufficient sun exposure may be responsible for an increased incidence of various diseases, including breast cancer, colorectal cancer, and hypertension.

Key Findings

• The studies 2, 3 suggest that sun exposure is a causative factor of skin cancer, particularly for fair-skinned individuals and those exposed to solar UV radiation at work.
• The study 4 emphasizes the importance of sun protection, including sun avoidance, protective clothing, and eyewear, in addition to sunscreens, to prevent skin cancer.
• The study 5 highlights the need for balanced sun exposure to minimize the risks of skin cancer while also preventing other diseases associated with insufficient sun exposure.
• A more recent study 6 published in Journal of oncology pharmacy practice in 2025, reviews the effectiveness of sunscreen in preventing skin cancer and notes that sunscreen reduces the incidence of melanoma and non-melanoma skin cancers, although the effect is contingent upon the type of sunscreen and adherence to recommended guidelines.