UV Rays and Skin Cancer
Skin cancer is the most common type of cancer in fair-skinned populations in many parts of the world. The incidence, morbidity, and mortality rates of skin cancer is increasing, and therefore, pose a significant public health concern. Skin cancers are mainly divided into melanoma, and nonmelanoma skin cancers, the latter including basal and squamous cell carcinomas. Melanoma is responsible for most of the cancer related mortalities, and nonmelanomas typically have more benign courses with locally aggressive features.
Sunlight is a continuous spectrum of electromagnetic radiation that is divided into three major spectrums of wavelength: ultraviolet, visible, and infrared. Ultraviolet range is the most significant spectrum of sunlight that causes photoaging and skin cancer. Ultraviolet radiation damages the skin by direct cellular damage and alterations in immunologic function. It produces DNA damage, gene mutations, immunosuppression, oxidative stress, and inflammatory responses, all of which have an important role in photoaging of the skin and skin cancer. Ultraviolet radiation causes mutation in the p53 tumor suppressor genes which are involved in DNA repair, the result is ‘dysregulation of apoptosis, expansion of mutated keratinocytes and initiation of skin cancer’. UVA radiation has an important role in the carcinogenesis of stem cells of the kin. UVB radiation induces DNA damage, which causes inflammatory responses and tumorigenesis.
Different skin types are found to have different prevalence's of skin cancer. The low incidence of cutaneous malignancies in darker skinned groups is primarily a result of photoprotection provided by increased epidermal melanin, which provides an inherent sun protection factor of up to 13.4 in darker skinned individuals. Epidermal melanin in blacks' filters twice as much UVB radiation as does than in Caucasians.
Lifestyle changes during the past five decades, with an increase in exposure to sunlight because of outdoor activities and worsening sunbathing habits often result in skin cancers. Among caucasions, intense early sunburns and blistering sunburns are closely associated with the development of melanoma. As a result of chronic UV exposure, skin aging, wrinkles, uneven skin pigmentation, loss of skin elasticity, and disturbance of skin barrier functions result. The development of melanomas is often associated with painful sunburns. It was found that more than one severe sunburn in childhood is associated with a two-fold increase in melanoma risk. A history of sunlight exposure, particularly sunburns, during childhood is the most important behavioral risk factor for the development of non-melanoma and melanoma skin cancer. The epidemiology implicating UV exposure as a cause of melanoma is further supported by biological evidence that damage caused by ultraviolet radiation, particularly damage to DNA, plays a central role in the development of melanoma. The relative risk of skin cancer is three times as high among people born in areas that receive high amounts of ultraviolet radiation from the sun than those who move to those areas in adulthood. Likewise, outdoor workers have a higher risk than indoor workers.
Ultraviolet immunosuppression is considered an important event in skin carcinogenesis. UV exposure adversely affects the skin's immune system by diminishing antigen-presenting cell function, inducing immunosuppressive cytokine production, and modulating contact and delayed type hypersensitivity reactions. The role of UV-induced immunosuppression and its relevance to the mechanism of skin cancer has not been fully elucidated. One study showed that renal transplant recipients, who are taking immunosuppressive therapies, have increased immunosuppression and decreased immunosurveillance; therefore, they are more susceptible to cancers, especially skin cancers.
Narayanan, D. L., Saladi, R. N., & Fox, J. L. (2010). Ultraviolet radiation and skin cancer. International journal of dermatology, 49(9), 978–986. https://doi.org/10.1111/j.1365-4632.2010.04474.x
Holick, M.F. (2020). Sunlight, UV Radiation, Vitamin D, and Skin Cancer: How Much Sunlight Do We Need?. In: Reichrath, J. (eds) Sunlight, Vitamin D and Skin Cancer. Advances in Experimental Medicine and Biology, vol 1268. Springer, Cham. https://doi.org/10.1007/978-3-030-46227-7_2
The skin, also known as the integumentary system, is one of the largest organs in the human body. The skin mainly functions as a protective barrier against external factors. It also regulates body temperature through moisture control and reduces the harmful effects of UV radiation through metabolization. Skin cancer is a very common form of cancer that affects many patients throughout the world. One of the more serious forms of this type of cancer is called melanoma. Melanoma occurs when melanocytes become malignant and usually results from keratinized epithelial cells. Some of the common risk factors that may contribute to skin cancer include race, genetics, and sun exposure. Skin cancer is usually diagnosed by biopsy and histology examinations. Basal cell carcinoma and squamous cell carcinoma are often seen in patients who have skin cancer. Treatment options are available for both; however, it is very important that the cancer is detected early.
The best way to prevent the occurrence of skin cancer is to limit sun exposure. UV radiation or sun exposure highly contributes to this form of cancer. It is very important to use “broad spectrum” sunscreen throughout both the winter and summer months. Broad spectrum sunscreen protects against many different types of ultraviolet rays. According to the Skin Cancer Foundation, “Regular daily use of SPF 15 sunscreen can reduce your risk of developing squamous cell carcinoma (SCC) by about 40 percent and lower your melanoma risk by 50 percent.” Additional recommendations state that it is necessary to use sunscreen every day, 30 minutes prior to going outside in all areas of exposed skin.
Based on the most recent guidelines, the first line treatment for skin cancer is complete removal of the primary tumor. Additionally, it is also very important to prevent further metastasis with additional radiation therapy in some patient populations. Treatment is highly dependent on the stage of the tumors and may require surgery/followup visits.
Ahmed, Bilal et al. “Malignant Melanoma: Skin Cancer-Diagnosis, Prevention, and Treatment.” Critical reviews in eukaryotic gene expression vol. 30,4 (2020): 291-297. doi:10.1615/CritRevEukaryotGeneExpr.2020028454
Kornek, Thomas, and Matthias Augustin. “Skin cancer prevention.” Journal der Deutschen Dermatologischen Gesellschaft = Journal of the German Society of Dermatology : JDDG vol. 11,4 (2013): 283-96; quiz 297-8. doi:10.1111/ddg.12066
Matsumura, Yasuhiro, and Honnavara N Ananthaswamy. “Toxic effects of ultraviolet radiation on the skin.” Toxicology and applied pharmacology vol. 195,3 (2004): 298-308. doi:10.1016/j.taap.2003.08.019
Skin cancer is one of the most common types of cancer. Basal cell carcinoma is the most common type of skin cancer affecting the basement membrane and deeper layers of the skin and very rarely metastasizes. Squamous cell carcinoma is the second most common type of skin cancer that affects the outermost layer of the skin in areas most likely exposed to the sun such as the hands and face. Melanoma is a lot less common than the other types but is more likely to invade nearby tissue and spread to other parts of the body. The majority of deaths associated with skin cancer are caused by melanoma.
Risk factors associated with the development of skin cancer include long-term exposure to UV radiation, family history of skin cancer, having light fair skin, male gender, and non-genetic factors such as chronic sun exposure, increased age and immunosuppressive therapy. There are several ways to get exposed to UV rays: sun exposure, tanning beds, sun/tanning lamps, mercury vapor lighting from stadiums and school gymnasiums, several types of lasers such as those used for eye surgery and halogen lamps, fluorescent and incandescent lights found in floor lamps, and light bulbs. The three types of UV rays are UVA, UVB, and UVC. UVA has the longest wavelength enabling it to penetrate the skin's dermis. UVB has a shorter wavelength so it’s only able to penetrate the skin's epidermis. With the shortest wavelength, UVC is unable to penetrate the skin. Additionally, there is a multitude of prescription and non-prescription medications shown to increase the skin’s sensitivity to UV radiation. These include antihistamines, NSAIDs, estrogen and progestin contraceptives, anti-acne medications, sulfonylureas, and sulfonamides.
In order to protect patients, always advise them to avoid as much direct sun exposure as possible, especially during peak UV radiation hours between 10am and 3pm. Other activities to help protect the skin include: Smoking cessation; applying sunscreen with an SPF of 30 or greater; selecting cosmetic products, contact lenses and sunglasses that provide UV protection; and performing skin self-exams.
Bamler W: The possible health consequences of UV exposure. Dtsch Arztebl Int 2016; 113: 663–4. DOI: 10.3139/arztebl.201663
Uptodate. 2020. Types of Skin Cancer. [online] Available at: <https://www-uptodate-com.jerome.stjohns.edu/contents/overview-of-antiretroviral-agents-used-treathivsearch=antiretroviral%20therapy &source=search_result&selectedTitle=2~150type=default=2> [Accessed June 2, 2020].
Ultraviolet (UV) radiation is a type of electromagnetic radiation that can’t be seen by the human eye. It is released from the sun, as well as from man-made sources like tanning beds, sun lamps, welding torches, etc. UV rays can penetrate into the skin and cause harm by altering skin texture and DNA, which can lead to skin cancers. Basal cell and squamous cell cancers are the most common types of skin cancers. Melanoma is not as common but also the most dangerous type. In addition, UV exposure can also lead to other health issues, including sunburn, premature aging of the skin, eye problems, and weakened immune system.
There are 3 main types of UV rays: UVA, UVB, and UVC. UVA rays have a longer wavelength and are able to penetrate into the dermis. They are the main rays to cause skin cells to age. UVB, the main rays to cause sunburns, has a shorter wavelength and affects the epidermis or superficial outer layer of the skin. UVC rays react with the ozone in our atmosphere and do not reach our skin; they are not normally a risk factor for skin cancer.
The sun is the main source of UV radiation. Risk of skin cancer development is typically related to lifetime sun exposure, but other factors are involved that may make some people more susceptible. Some risk factors include family history, light skin, increased age, immunosuppressive therapy, etc. Medications can also increase the skin’s sensitivity to UV radiation, and extra precautions should be taken to limit sun exposure. Examples include antihistamines, oral contraceptives, NSAIDS, sulfonamide antibiotics, etc.
One benefit of UV exposure is increased vitamin D production. Vitamin D has many health benefits, and deficient individuals will need to bring their levels up. However, rather than increasing UV exposure which can be dangerous, it may be better for these individuals to get vitamin D from their diet or through vitamin supplements.
Ultraviolet (UV) Radiation. American Cancer Society. https://www.cancer.org/cancer/cancer-causes/radiation-exposure/uv-radiation.html. Accessed June 5, 2020.
Ultraviolet radiation is an electromagnetic radiation that comes from the sun and man-made sources like tanning beds and welding torches.There are also different types of UV rays, based on how much energy they have. Higher-energy UV rays are a form of ionizing radiation, which means they have enough energy to remove an electron from an atom or molecule. This radiation can damage the DNA and lead to patients having cancer. Although this is very high energy UV rays, they don't have enough energy to penetrate deeply into the body, therefore, it mainly affects the skin. There are UVA, UVB and UVC rays which are differentiated from the energy levels they have. UVB rays have higher energy than UVB, which can penetrate through the skin, risking patients getting skin cancer. There is an index which can be used to measure how severe the UV rays are reaching the earth’s surface that day. You can use an UV index, which ranges from a rating of 1 through 11. The higher the number, the greater intensity of the UV rays. There are different predicted ratings in areas with a different zip code. Different ways to protect yourself from the UV rays are by wearing sunglasses, using sunscreen (with a high SPF), to stay indoors when the sun is at its peak, which is usually between 11am to 4pm. Other measures you can take are wearing a hat when it's sunny outside, or staying in the shade, etc. These are all measures to help you protect yourself from the risk of getting skin cancer. The 2 most common types of skin cancer that people get are basal cells and squamous cells carcinomas. The rates of skin cancer has significantly increased in people with lighter skin tones, therefore they need to take more precaution to protect themselves.