Non-melanoma skin cancers, also referred to as 'keratinocyte cancers', are the most common class of skin cancers.[5]Sánchez G, Nova J, Rodriguez-Hernandez AE, et al. Sun protection for preventing basal cell and squamous cell skin cancers. Cochrane Database Syst Rev. 2016 Jul 25;(7):CD011161.
http://www.ncbi.nlm.nih.gov/pubmed/27455163?tool=bestpractice.com
Worldwide, there were an estimated 1.2 million new cases of non-melanoma skin cancer (excluding basal cell carcinoma), with an estimated 70,000 deaths in 2022.[6]Sung H, Ferlay J, Siegel RL, et al. Global cancer statistics 2020: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin. 2021 May;71(3):209-49.
https://acsjournals.onlinelibrary.wiley.com/doi/10.3322/caac.21660
http://www.ncbi.nlm.nih.gov/pubmed/33538338?tool=bestpractice.com
Squamous cell carcinoma (SCC) is the second most common non-melanoma skin cancer worldwide (after basal cell carcinoma). SCCs are most frequently observed in photoexposed skin, often in people >40 years of age. Men have a higher incidence than women, and those with Fitzpatrick skin type I and II (white) are at increased risk.[7]Gogia R, Binstock M, Hirose R, et al. Fitzpatrick skin phototype is an independent predictor of squamous cell carcinoma risk after solid organ transplantation. J Am Acad Dermatol. 2013 Apr;68(4):585-91.
http://www.ncbi.nlm.nih.gov/pubmed/23107311?tool=bestpractice.com
[8]Larese Filon F, Buric M, Fluehler C. UV exposure, preventive habits, risk perception, and occupation in NMSC patients: a case-control study in Trieste (NE Italy). Photodermatol Photoimmunol Photomed. 2019 Jan;35(1):24-30.
http://www.ncbi.nlm.nih.gov/pubmed/30058127?tool=bestpractice.com
[9]Laughter MR, Maymone MBC, Karimkhani C, et al. The burden of skin and subcutaneous diseases in the United States from 1990 to 2017. JAMA Dermatol. 2020 Aug 1;156(8):874-81.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7287935
http://www.ncbi.nlm.nih.gov/pubmed/32520352?tool=bestpractice.com
SCC incidence is highest near the equator and doubles with each 8° to 10° decrement in geographic latitude.[10]Johnson TM, Rowe DE, Nelson BR, et al. Squamous cell carcinoma of the skin (excluding lip and oral mucosa). J Am Acad Dermatol. 1992 Mar;26(3 Pt 2):467-84.
http://www.ncbi.nlm.nih.gov/pubmed/1564155?tool=bestpractice.com
However, in the UK, incidence rates of non-melanoma skin cancer have increased by 166% between 1990s and 2017.[11]Ibrahim N, Ali SR, Dobbs TD, et al. The incidence of non-melanoma skin cancer in the UK and the Republic of Ireland: a systematic review. Eur J Dermatol. 2023 Jun 1;33(3):218-29.
http://www.ncbi.nlm.nih.gov/pubmed/37594326?tool=bestpractice.com
Of note, SCC is the most common skin cancer in patients with Fitzpatrick skin type V and VI (brown and black) skin types and in organ transplant recipients taking immunosuppressive drugs (especially those with white skin and a history of significant sun exposure).[12]Massey PR, Schmults CD, Li SJ, et al. Consensus-based recommendations on the prevention of squamous cell carcinoma in solid organ transplant recipients: a Delphi consensus statement. JAMA Dermatol. 2021 Sep 1 [Epub ahead of print].
http://www.ncbi.nlm.nih.gov/pubmed/34468690?tool=bestpractice.com
[13]Zakhem GA, Pulavarty AN, Lester JC, et al. Skin cancer in people of color: a systematic review. Am J Clin Dermatol. 2022 Mar;23(2):137-51.
http://www.ncbi.nlm.nih.gov/pubmed/34902111?tool=bestpractice.com
[14]Hogue L, Harvey VM. Basal cell carcinoma, squamous cell carcinoma, and cutaneous melanoma in skin of color patients. Dermatol Clin. 2019 Oct;37(4):519-26.
https://www.sciencedirect.com/sdfe/pdf/download/eid/1-s2.0-S0733863519300518/first-page-pdf
http://www.ncbi.nlm.nih.gov/pubmed/31466591?tool=bestpractice.com
[15]Jin F, Vajdic CM, Poynten IM, et al. Cancer risk in people living with HIV and solid organ transplant recipients: a systematic review and meta-analysis. Lancet Oncol. 2024 Jul;25(7):933-44.
http://www.ncbi.nlm.nih.gov/pubmed/38936380?tool=bestpractice.com
NIH: skin cancer treatment PDQ - health professional version
Opens in new window
Tropical Australia has the highest incidence of all types of skin cancer, with incidence of SCC of around 1/100 for the population of white people.[16]Buettner PG, Raasch BA. Incidence rates of skin cancer in Townsville, Australia. Int J Cancer. 1998 Nov 23;78(5):587-93.
https://onlinelibrary.wiley.com/doi/pdf/10.1002/%28SICI%291097-0215%2819981123%2978%3A5%3C587%3A%3AAID-IJC10%3E3.0.CO%3B2-E
http://www.ncbi.nlm.nih.gov/pubmed/9808527?tool=bestpractice.com
In England, a study of first primary SCC between 2013 and 2015 showed a rate of 77.3 per 100,000 person-years for male patients and 34.1 per 100,000 person-years for female patients.[17]Venables ZC, Autier P, Nijsten T, et al. Nationwide incidence of metastatic cutaneous squamous cell carcinoma in England. JAMA Dermatol. 2019 Mar 1;155(3):298-306.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6521686
http://www.ncbi.nlm.nih.gov/pubmed/30484823?tool=bestpractice.com
In a US study, the lifetime risk of SCC was estimated to be 9% to 14% in men, and 4% to 9% in women.[18]Miller DL, Weinstock MA. Nonmelanoma skin cancer in the United States: incidence. J Am Acad Dermatol. 1994 May;30(5 pt 1):774-8.
https://www.doi.org/10.1016/s0190-9622(08)81509-5
http://www.ncbi.nlm.nih.gov/pubmed/8176018?tool=bestpractice.com
The approximate annual incidence is >100,000 in the US.[19]Rogers HW, Weinstock MA, Feldman SR, et al. Incidence estimate of nonmelanoma skin cancer (keratinocyte carcinomas) in the US population, 2012. JAMA Dermatol. 2015 Oct;151(10):1081-6.
https://jamanetwork.com/journals/jamadermatology/fullarticle/2281227
http://www.ncbi.nlm.nih.gov/pubmed/25928283?tool=bestpractice.com
Data from a US population-based cohort indicates that the overall incidence of SCC increased by 263% between 1976-1984 and 2000-2010.[20]Muzic JG, Schmitt AR, Wright AC, et al. Incidence and trends of basal cell carcinoma and cutaneous squamous cell carcinoma: a population-based study in Olmsted County, Minnesota, 2000 to 2010. Mayo Clin Proc. 2017 Jun;92(6):890-8.
http://www.ncbi.nlm.nih.gov/pubmed/28522111?tool=bestpractice.com