Melanoma and the Importance of Sunlight
Melanoma and the Importance of Sunlight
Joy Stepinski
June 1, 2025
With summer fast approaching, people are inclined to spend time outside in the brilliant sunshine. Throughout many decades, caution has been heeded to avoid too much sun and apply sunblock for skin protection. Although a plethora of health literature gives warnings about the sun and its cause for melanoma, many research findings show evidence of the sun’s benefit for the skin.
The Centers for Disease Control and Prevention (CDC) website states that skin cancer is the most common form of cancer in the United States [1]. Malignant melanoma is a specific type of skin cancer that affects melanocytes [2], the special cells in the skin that make melanin. Originating from the Greek word melanos (meaning dark), melanin produces the pigment that gives hair, skin, and eyes color.
Considered to be the body’s own natural sunscreen, melanin protects against ultraviolet radiation [3]. The skin produces melanin when exposed to the sun. When the outer layer of skin, or epidermis, comes into contact with sunlight, the tan coloration of the skin increases the amount of melanin.
Malignant melanoma is considered the deadliest form of skin cancer. Derived from the melanocytes, this type of cancer can also develop in other areas of the body. Melanocyte cells are not just found in the skin. Melanocytes are developed from the neural crest, which is a structure that appears during embryonic development when the fetus starts to grow. During embryonic development, melanocytes also migrate to mucosal cells, including in the mouth and gastrointestinal tract; the eye; and the protective layer of the brain and spinal cord (meninges) [2].
The CDC educates the public by stating that “most cancers are caused by too much exposure to ultraviolet (UV) light” [4]. Recommended sun safety measures are staying in the shade, wearing long-sleeve clothing and a hat, and applying sunscreen of at least SPF 15 or higher. Yet if the body produces melanin, a protective biomolecule, with sun contact, are these guiding principles valid?
One author [5] pointed out a very curious timeline about the rise in cutaneous malignant melanoma (CMM), which is melanoma originating from the skin. The incidence of CMM has increased among fair skin toned people for decades at a rate of 4 – 5%. According to the author, to stop this trend, one must scrutinize the cause. The CMM rate has been increasing since 1935, before many sun alternative devices and products entered the market. For instance, fluorescent lights appeared in the 1940s, sunscreen absorbing UVB rays in the 1950s, tanning devices in the 1970s, and sunscreen absorbing UVA and UVB in the 1980s.
When looking at potential causes before 1935, the author highlights that in the early 20th century, society drastically reduced time spent outdoors. “People went against evolution by going indoors during the day to work, which drastically decreased their daily amount of cutaneous vitamin D3 and exposed them to only UVA radiation passing through glass windows” (p. 4).
How do windows contribute to ill health? Glass windows filter out UVB and allow UVA light to enter. UVB radiation is essential to the body, responsible for the synthesis of melanin and vitamin D3. Vitamin D is known as the “sunshine vitamin” responsible for healthy bone, immune, heart, and brain function. When people spend too much time inside, they are only exposed to UVA light. UVA radiation has the opposite effect by damaging DNA in melanocytes and degrading vitamin D. Spending time inside in buildings and cars away from UVB light likely contributes to malignant melanoma for this very reason.
Studies show that sun exposure is protective for people who work outdoors. Outdoor workers are exposed to approximately three to ten times the amount of sunlight than indoor workers and have a much lower rate of CMM [5]. A meta-analysis discussed that a lower risk of melanoma is associated with heavy occupational sun exposure and a higher risk is found in people with only intermittent amounts of sunlight [6].
While suntanning is advantageous, sunburns are not recommended. Sunburns occur with too much sun exposure when the skin is not accustomed to it, resulting in an inflammatory process of the skin and damage to DNA in melanocytes. As a result, sunburns have a direct association with melanoma. While this may send a message to avoid the sun, sunburn is actually an indicator of intermittent sun exposure.
Sunscreen has been encouraged for decades as a sun safety measure to protect against melanoma with its UV filters. Yet despite widespread availability and use, the melanoma incidence continues to increase. According to one study, using sunscreens as a protective effect against melanoma has not even been proven [7]. Although sunscreens often prevent sunburn, their use should be prudent as they should not negate the importance of sun exposure. Furthermore, studies show that sunscreens with UV filters contain many chemicals that can adversely affect the endocrine system and produce general toxicity.
In a separate Swedish study of 29,518 participants, researchers investigated the effects of sun avoidance. Of the 2,545 deaths among the subjects, all-cause mortality was inversely related to sun exposure habits. People who avoided the sun had a twofold higher risk of death [8] from cancer, heart disease, and cerebrovascular disease. The author of the study reported that “skin cancers that occurred in those exposing themselves to the sun had a better prognosis” [9].
UVB light is important not only for melanocytes, but also vitamin D3 production. At the beginning of the warm season, people should build up their sun exposure with a goal of tanning, but not burning. For unpigmented skin, 20 to 30 minutes of sun produces 10,000 to 25,000 IU of vitamin D [10]. People with darker pigmentation require approximately five times longer in sunlight to achieve the same amount of vitamin D.
Sunlight is essential for survival. As summer approaches, get outside for that daily dose of sunshine! Light rays are needed by the body to protect it from a variety of conditions, including melanoma.
References:
1. U.S. Centers for Disease Control and Prevention. (2024). Melanoma of the skin statistics. https://www.cdc.gov/skin-cancer/statistics/index.html
2. Heistein, J. B., Acharya, U, Mukkamalla, S. K. R. Malignant Melanoma. (2024). In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK470409/
3. Solano, F. (2014). Melanins: Skin pigments and much more—types, structural models, biological functions, and formation routes. New Journal of Science, 2014(1), 498276.
4. U.S. Centers for Disease Control and Prevention. (2024). Sun safety facts. https://www.cdc.gov/skin-cancer/sun-safety/index.html
5. Godar, D. E. (2011). Worldwide increasing incidences of cutaneous malignant melanoma. Journal of skin cancer, 2011(1), 858425. https://doi.org/10.1155/2011/858425
6. Elwood, J. M., & Jopson, J. (1997). Melanoma and sun exposure: an overview of published studies. International journal of cancer, 73(2), 198-203.
7. Krause, M., Klit, A., Blomberg Jensen, M., Søeborg, T., Frederiksen, H., Schlumpf, M., ... & Drzewiecki, K. T. (2012). Sunscreens: are they beneficial for health? An overview of endocrine disrupting properties of UV‐filters. International journal of andrology, 35(3), 424-436. https://doi.org/10.1111/j.1365-2605.2012.01280.x
8. Lindqvist, P. G., Epstein, E., Landin‐Olsson, M., Ingvar, C., Nielsen, K., Stenbeck, M., & Olsson, H. (2014). Avoidance of sun exposure is a risk factor for all‐cause mortality: Results from the Melanoma in Southern Sweden cohort. Journal of Internal Medicine, 276(1), 77-86.
9. Frelick, M. (2016). Avoiding sun as dangerous as smoking. Medscape Medical News. https://www.medscape.com/viewarticle/860805
10. Straughan, J. L. (2010). Sunshine and the cardiovascular benefits-a dose of sunshine!: your life and your heart. Cardiovascular Journal of Africa, 21(3), 168-170.