Link between UV and skin cancer

On this page:

1. Sun exposure

2. Outdoor work

3. Solariums

4. Impact of climate change

5. References

The major cause of melanoma and keratinocyte cancers (KC) is exposure to UV radiation^[1]. The International Agency for Research on Cancer (IARC) has classified solar and UV radiation as carcinogenic to humans ^[2].

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Sun exposure

Excessive UV radiation damages DNA in skin cells producing genetic mutations that can lead to skin cancer. Sunlight is the main source of UV radiation and solariums are a source of artificial UV radiation. Solar radiation causes cutaneous malignant melanoma, squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) of the skin^[2].

Different patterns of sun exposure are associated with different types of skin cancer. Melanomas can arise in different ways, depending on a person’s genes. Some melanomas develop after chronic sun exposure, mostly on sun exposed areas of the body, whereas other melanomas can develop after modest amounts of sun exposure on less exposed areas of the body in people with genetic susceptibility to melanoma ^[3].

Sun exposure during childhood and adolescence has been shown to greatly impact an individual’s lifetime risk of developing skin cancer. Sun exposure in childhood has also been associated with melanoma ^[4]. Intense sun exposure in the first 10 years of life has been shown to nearly double the lifetime risk of melanoma ^[5]. In relation to KC, childhood and adolescent (intermittent and non-occupational) sun exposure increases the risk of BCC, while cumulative sun exposure, including occupational exposure, increases SCC risk^[6]. In Australia, both BCC and SCC rates are around three times higher in latitudes closer to the equator^[7][8], where UV radiation is higher.

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Outdoor work

People who work outdoors are exposed to five to ten times more UV than indoor workers ^[9]. It is estimated that around 200 melanomas and 34,000 KCs per year are due to occupational exposure in Australia ^[10]. Systematic reviews conclude that outdoor work constitutes an independent and robust risk factor for the development of cutaneous SCC and BCC^[11][12].

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Solariums

In 2009, IARC added UV emitting tanning beds to its highest cancer risk category, labelling them as "carcinogenic to humans" after deeming them to be more dangerous than previously suggested^[13][2]. By January 2016, all state and territories (except Northern Territory where no commercial solariums operate) introduced a complete ban of commercial solariums.

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Impact of climate change

The ozone layer acts as a barrier to UV radiation; its depletion over the 20th century has resulted in higher radiation levels reaching the earth’s surface. International measures to protect the ozone layer are showing signs of impact, but improvements have not yet returned ozone to pre-1970s levels^[14][15].

The CSIRO and the Bureau of Meteorology have projected that mean temperatures within Australia will rise by 0.6 to 1.5°C by 2030 compared with the climate of 1980 to 1999.^[16] Warmer temperatures may result in Australians increasing their sun exposure and wearing less covering clothing, thereby increasing their risk of skin cancer.^[17] However, very high temperatures may in contrast prompt behaviours to avoid sun exposure,^[17] and therefore "there is considerable uncertainty in modelling future human behaviour in response to climate change"^[14].

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References

1. Armstrong B. How sun exposure causes skin cancer: An epidemiological perspective. In: Hill D, Elwood JM, English DR. Prevention of Skin Cancer. Dordrecht, Netherlands: Kluwer Academic Publishers; 2004. p. 89-116.
2. International Agency for Cancer Research. Radiation. Volume 100D. A Review of Human Carcinogens:. Lyon France: World Health Organization; 2012 Available from: http://monographs.iarc.fr/ENG/Monographs/vol100D/mono100D.pdf.
3. Whiteman DC, Pavan WJ, Bastian BC. The melanomas: a synthesis of epidemiological, clinical, histopathological, genetic, and biological aspects, supporting distinct subtypes, causal pathways, and cells of origin. Pigment Cell Melanoma Res 2011 Oct;24(5):879-97 Available from: http://www.ncbi.nlm.nih.gov/pubmed/21707960.
4. Whiteman DC, Whiteman CA, Green AC. Childhood sun exposure as a risk factor for melanoma: a systematic review of epidemiologic studies. Cancer Causes Control 2001 Jan;12(1):69-82 Available from: http://www.ncbi.nlm.nih.gov/pubmed/11227927.
5. Veierød MB, Adami HO, Lund E, Armstrong BK, Weiderpass E. Sun and solarium exposure and melanoma risk: effects of age, pigmentary characteristics, and nevi. Cancer Epidemiol Biomarkers Prev 2010 Jan;19(1):111-20 Available from: http://www.ncbi.nlm.nih.gov/pubmed/20056629.
6. Kricker A, Weber M, Sitas F, Banks E, Rahman B, Goumas C, et al. Early Life UV and Risk of Basal and Squamous Cell Carcinoma in New South Wales, Australia. Photochem Photobiol 2017 Nov;93(6):1483-1491 Available from: http://www.ncbi.nlm.nih.gov/pubmed/28710897.
7. National Cancer Control Initiative. A report by the National Cancer Control Initiative Non-melanoma Skin Cancer Working Group for the state and territory cancer councils. Carlton: NCCI; 2003 Nov Available from: http://canceraustralia.gov.au/sites/default/files/publications/nmscreport1_504af01fd661f.pdf.
8. Staples M, Marks R, Giles G. Trends in the incidence of non-melanocytic skin cancer (NMSC) treated in Australia 1985-1995: are primary prevention programs starting to have an effect? Int J Cancer 1998 Oct 5;78(2):144-8 Available from: http://www.ncbi.nlm.nih.gov/pubmed/9754642.
9. Australian Radiation Protection and Nuclear Safety Agency. Resource guide for UV protective products. Yallambie: Commonwealth of Australia; 2003 [cited 2020 Sep 10].
10. Fritschi L, Driscoll T. Cancer due to occupation in Australia. Aust N Z J Public Health 2006 Jun;30(3):213-9 Available from: http://www.ncbi.nlm.nih.gov/pubmed/16800196.
11. Bauer A, Diepgen TL, Schmitt J. Is occupational solar ultraviolet irradiation a relevant risk factor for basal cell carcinoma? A systematic review and meta-analysis of the epidemiological literature. Br J Dermatol 2011 Sep;165(3):612-25 Available from: http://www.ncbi.nlm.nih.gov/pubmed/21605109.
12. Schmitt J, Seidler A, Diepgen TL, Bauer A. Occupational ultraviolet light exposure increases the risk for the development of cutaneous squamous cell carcinoma: a systematic review and meta-analysis. Br J Dermatol 2011 Feb;164(2):291-307 Available from: http://www.ncbi.nlm.nih.gov/pubmed/21054335.
13. WHO International Agency for Research on Cancer Monograph Working Group, El Ghissassi F, Baan R, Straif K, Grosse Y, Secretan B, et al. A review of human carcinogens--part D: radiation. Lancet Oncol 2009 Aug;10(8):751-2 Available from: http://www.ncbi.nlm.nih.gov/pubmed/19655431.
14. Andrady AL, Aucamp PJ, Bais AF, Ballaré CL, Bjorn LO, Bornman JF, et al. Environmental effects of ozone depletion: 2006 assessment: interactions of ozone depletion and climate change. Executive summary. Photochem Photobiol Sci 2007 Mar;6(3):212-7 Available from: http://www.ncbi.nlm.nih.gov/pubmed/17344958.
15. Li F, Stolarski RS, Newman PA. Stratospheric ozone in the post-CFC era. Atmos. Chem. Phys 2009;9, 2207-13 Available from: http://www.atmos-chem-phys.net/9/2207/2009/acp-9-2207-2009.html.
16. CSIRO, Bureau of Meterology. State of the climate 2014. Canberra: Commonwealth of Australia; 2014 [cited 2020 Sep 10] Available from: http://www.bom.gov.au/state-of-the-climate/documents/state-of-the-climate-2014_low-res.pdf.
17. Makin J. Implications of climate change for skin cancer prevention in Australia. Health Promot J Austr 2011 Dec;22 Spec No:S39-41 Available from: http://www.ncbi.nlm.nih.gov/pubmed/22518918.