Sunlight, especially ultraviolet (UV) radiation, does far more than cause a simple sunburn. Beneath the surface, it alters fundamental cellular processes, driving damage that accumulates over time. This hidden effect not only accelerates skin aging, but also plays a key role in the development of cancer.

The skin, as the body’s first barrier, is constantly exposed to this type of environmental stress. Over time, this cumulative exposure leads to what is known as photoaging, a process that accelerates the natural deterioration of the skin. Unlike chronological aging, this type of damage is directly related to external factors, mainly repeated solar radiation over the years.

But the impact is not limited to what is visible. At the cellular level, UV radiation can directly damage DNA or generate reactive oxygen species (ROS), highly reactive molecules that trigger oxidative stress. This environment promotes mutations, alters cellular function, and creates ideal conditions for the development of skin tumors.

This is where the connection to cancer becomes especially relevant. The cumulative damage to DNA and the increase in oxidative stress are not isolated events, but processes that, over time, can allow cells to lose control of their growth. This facilitates the appearance of precancerous lesions and, eventually, skin cancer. In other words, repeated exposure to radiation not only ages the skin but also alters its behavior at the cellular level, creating an environment favorable for tumor development.

Within this process, not all radiation acts in the same way. UVB radiation is mainly responsible for sunburn, as it causes direct damage to DNA. On the other hand, UVA radiation penetrates deeper into the skin and generates indirect damage through the production of free radicals. Both contribute to premature aging and increase the risk of skin cancer.

In recent years, it has also become clear that visible light plays an important role. Although it was ignored for a long time, it is now known to induce pigmentation, inflammation, and worsen conditions such as melasma, especially in individuals with darker skin tones.

This set of effects has led to a rethinking of how we understand sun protection. It is no longer just about avoiding sunburn, but about protecting the skin from a broader spectrum of radiation that impacts multiple biological levels. In this context, photoprotection becomes a comprehensive health strategy, not just an aesthetic one.

However, one of the most important points is that sun damage does not occur uniformly in all individuals. There are different ways in which the skin responds to prolonged exposure, leading to distinct patterns of aging. Some individuals develop thinner and more fragile skin, with a higher predisposition to precancerous lesions, while others show thicker and more pigmented skin as a result of defense mechanisms activated in response to damage.

This suggests that the body not only receives damage but also attempts to adapt. However, these defense mechanisms are not always sufficient to prevent long-term consequences. In fact, certain responses may be associated with a higher risk of developing specific types of skin cancer.

Another critical aspect is exposure during childhood. A significant proportion of cumulative sun damage occurs in the early years of life. It is even estimated that before the age of 20, a person has already received up to half of their lifetime UV exposure.

This has important implications, as sunburns during childhood are strongly associated with an increased risk of melanoma in adulthood. Despite this, studies show that sun protection measures are not consistently applied in children, highlighting a significant gap between knowledge and practice.

In this context, education becomes a key tool. Programs aimed at promoting sun protection habits from an early age have proven effective in changing behaviors and reducing long-term risks. However, there is still considerable room for improvement in the adoption of these strategies.

Regarding available tools, sunscreens remain one of the main defense strategies. However, their development has evolved significantly. New products aim to provide broader protection, covering not only UVB and UVA radiation but also part of the visible light spectrum.

Some of these advances include filters capable of protecting against blue light, as well as the incorporation of antioxidants that help neutralize free radicals generated by radiation. This represents an important shift toward more comprehensive protection based on the actual mechanisms of cellular damage.

Despite these advances, controversies have also emerged. Concerns have been raised about the safety of certain sunscreen ingredients, as well as their potential impact on hormonal health or the environment. Although evidence in humans is still limited, these concerns have driven the development of safer and more effective formulations.

 

Figure 1. Different types of light affect the skin through distinct mechanisms. UVB causes direct DNA damage, UVA promotes deeper oxidative stress and aging, and visible light contributes to pigmentation and inflammation. Together, these effects accumulate over time, highlighting the importance of daily photoprotection to reduce long-term damage and skin cancer risk.

 

Another common topic is the relationship between sunscreen use and vitamin D. There is concern that excessive protection could reduce its synthesis. However, evidence indicates that regular sunscreen use does not significantly compromise vitamin D levels in most individuals.

Finally, it is important to consider that some medical treatments, especially in oncology, can increase the skin’s sensitivity to light. This means that patients undergoing certain treatments may experience more intense reactions even with mild sun exposure, making photoprotection even more important.

Overall, all of this redefines the role of photoprotection. It is no longer just a basic aesthetic or preventive recommendation, but a complex strategy that acts at multiple levels of the body. From protecting DNA to modulating oxidative stress, protecting the skin from the sun is, in reality, protecting long-term health.

 

Main reference:

Pellacani, G., Lim, H. W., Stockfleth, E., Sibaud, V., Brugués, A. O., & Saint Aroman, M. (2024). Photoprotection: Current developments and controversies. Journal of the European Academy of Dermatology and Venereology : JEADV, 38 Suppl 5, 12–20. https://doi.org/10.1111/jdv.19677 

 

Other references:

Burnett, M. E., Hu, J. Y., & Wang, S. Q. (2012). Sunscreens: obtaining adequate photoprotection. Dermatologic therapy, 25(3), 244–251. https://doi.org/10.1111/j.1529-8019.2012.01503.x 

Lautenschlager, S., Wulf, H. C., & Pittelkow, M. R. (2007). Photoprotection. Lancet (London, England), 370(9586), 528–537. https://doi.org/10.1016/S0140-6736(07)60638-2 

Gasparro, F.P., Mitchnick, M. and Nash, J.F. (1998), A Review of Sunscreen Safety and Efficacy. Photochemistry and Photobiology, 68: 243-256. https://doi.org/10.1111/j.1751-1097.1998.tb09677.x