1. Epidemiology

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Introduction

Keratinocyte cancer (KC), formerly known as non-melanoma skin cancer, comprises basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC).

In Australia, KCs accounted for an estimated 939,000 treatments in 2015,[1] although they cause only about 560 deaths annually.[2] Keratinocyte cancers accounted for 8% of all health spending on cancer (excluding cancer screening) in Australia in 2008–2009,[2] and Medical Benefits Schedule reimbursements for KC diagnosis, treatment and pathology cost an estimated $703 million in 2015.[1] Thus, these mostly non-fatal cancers represent a large public health problem with disproportionately high costs.

Moreover, the predilection of KCs for the head and neck means that their treatment is often clinically complex, with cosmetic ramifications for affected patients. Keratinocyte cancers are traditionally treated by surgical excision (see: Surgical treatment). A 2002 national survey found that over 70% of BCCs and the majority of cSCCs, regardless of body site, were excised.[3] The main non-surgical treatments are cryotherapy for upper and lower limb lesions, electrodessication and curettage (see: Cryotherapy and electrodessication and curettage), and topical agents like imiquimod (see: Topical treatments and photodynamic therapy).

The environmental cause of most BCCs and cSCCs is exposure to solar radiation.[4] This inference is supported by evidence from numerous epidemiological studies showing that KCs rarely develop in dark-skinned populations, who are far less sun-sensitive than white populations, and that white populations living in regions with high levels of ambient solar ultraviolet (UV) radiation have especially high KC rates.[3][5][6] Compared with people born in Australia, immigrants from high-latitude UK show lower incidence rates,[3] and their age of arrival in Australia is inversely proportional to their KC risk.[5] Strong positive associations between childhood sun exposure and BCC suggest that UV radiation received early in life increases BCC risk in adulthood.[6]

Less than 1% of skin cancers in Australia are attributable to other factors.[7] These include immunosuppression, exposure to ionising radiation, exposure to arsenic, human papillomavirus (HPV) infection, and cigarette smoking.

Skin cancers can be prevented by sun protection.[8] While KC eradication among Australians is not feasible, there is emerging evidence for the success of skin cancer awareness and prevention campaigns that commenced in the early 1980s with the aim of reducing the rates of both KC and melanoma, particularly among vulnerable and high-risk groups like children and outdoor workers (see: Prevention of keratinocyte cancer (UV protection strategies, chemoprevention and vitamin D).[9] Since the introduction of these campaigns, sun protection behaviour has improved among Australians.[10] Stabilisation of incidence rates of KC in Australians younger than 60 years was first seen around 2002,[11] and decreasing incidence has recently been reported among young adults.[12]

Primary prevention is known to be cost effective in reducing the large health expenditure on skin cancer,[13] but ongoing substantial investment in sun protection campaigns[8] is needed to maintain the trend of decreasing incidence in KC into the future and across all age groups (see also: Economics of keratinocyte cancer).

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References

  1. 1.0 1.1 Fransen M, Karahalios A, Sharma N, English DR, Giles GG, Sinclair RD. Non-melanoma skin cancer in Australia. Med J Aust 2012 Nov 19;197(10):565-8 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/23163687.
  2. 2.0 2.1 Australian Institute of Health and Welfare. Skin cancer in Australia. Canberra, ACT: AIHW, Department of Health; 2016 Jul 13 [cited 2018 Oct 8]. Report No.: CAN 96. Available from: https://www.aihw.gov.au/reports/cancer/skin-cancer-in-australia/contents/table-of-contents.
  3. 3.0 3.1 3.2 Non-melanoma Skin Cancer Working Group. The 2002 national non-melanoma skin cancer survey. Carlton, VIC: National Cancer Control Initiative; 2003 Nov [cited 2018 Oct 8]. Sponsored by Cancer Council. Available from: https://canceraustralia.gov.au/publications-and-resources/cancer-australia-publications/national-cancer-control-initiative-1997-2002-report.
  4. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans.. Radiation. IARC Monogr Eval Carcinog Risks Hum 2012;100(Pt D):7-303 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/23189752.
  5. 5.0 5.1 English DR, Armstrong BK, Kricker A, Winter MG, Heenan PJ, Randell PL. Demographic characteristics, pigmentary and cutaneous risk factors for squamous cell carcinoma of the skin: a case-control study. Int J Cancer 1998 May 29;76(5):628-34 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/9610717.
  6. 6.0 6.1 Corona R, Dogliotti E, D'Errico M, Sera F, Iavarone I, Baliva G, et al. Risk factors for basal cell carcinoma in a Mediterranean population: role of recreational sun exposure early in life. Arch Dermatol 2001 Sep;137(9):1162-8 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/11559211.
  7. Olsen CM, Wilson LF, Green AC, Bain CJ, Fritschi L, Neale RE, et al. Cancers in Australia attributable to exposure to solar ultraviolet radiation and prevented by regular sunscreen use. Aust N Z J Public Health 2015 Oct;39(5):471-6 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/26437734.
  8. 8.0 8.1 Weinstock MA. The struggle for primary prevention of skin cancer. Am J Prev Med 2008 Feb;34(2):171-2 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/18201649.
  9. Iannacone MR, Green AC. Towards skin cancer prevention and early detection: evolution of skin cancer awareness campaigns in Australia. Melanoma Manag 2014 Aug;1(1):75-84 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/30190812.
  10. Hill D, Marks R. Health promotion programs for melanoma prevention: screw or spring? Arch Dermatol 2008 Apr;144(4):538-40 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/18427051.
  11. Staples MP, Elwood M, Burton RC, Williams JL, Marks R, Giles GG. Non-melanoma skin cancer in Australia: the 2002 national survey and trends since 1985. Med J Aust 2006 Jan 2;184(1):6-10 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/16398622.
  12. Olsen CM, Williams PF, Whiteman DC. Turning the tide? Changes in treatment rates for keratinocyte cancers in Australia 2000 through 2011. J Am Acad Dermatol 2014 Jul;71(1):21-6.e1 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/24685358.
  13. Gordon LG, Rowell D. Health system costs of skin cancer and cost-effectiveness of skin cancer prevention and screening: a systematic review. Eur J Cancer Prev 2015 Mar;24(2):141-9 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/25089375.

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