Squamous-cell skin cancer, also known as cutaneous squamous-cell carcinoma (cSCC), is one of the main types of skin cancer along with basal cell cancer and melanoma. It usually presents as a hard lump with a scaly top but can also form an ulcer. Onset is often over months. Squamous-cell skin cancer is more likely to spread to distant areas than basal cell cancer. When confined to the outermost layer of the skin, a precancerous or in situ form of cSCC is known as Bowen's disease.
The greatest risk factor is high total exposure to ultraviolet radiation from the sun. Other risks include prior scars, chronic wounds, actinic keratosis, lighter skin, Bowen's disease, arsenic exposure, radiation therapy, tobacco smoking, poor immune system function, previous basal cell carcinoma, and HPV infection. Risk from UV radiation is related to total exposure, rather than early exposure. Tanning beds are becoming another common source of ultraviolet radiation. Risk is also elevated in certain genetic skin disorders, such as xeroderma pigmentosum and certain forms of epidermolysis bullosa. It begins from squamous cells found within the skin. Diagnosis is often based on skin examination and confirmed by tissue biopsy.
New in vivo and in vitro studies have proven that the upregulation of FGFR2, a subset of the fibroblast growth factor receptor (FGFR) immunoglobin family, has a critical role to play in the progression of cSCC cells. Mutation in the TPL2 gene causes overexpression of FGFR2, which activates mTORC1 and AKT pathways in both primary and metastatic cSCC cell lines. Only by using FGFR pan-inhibitor, AZD4547, could cell migration and cell proliferation on cSCC be attenuated Additionally, research has identified common driver mutations in cSCC, with alterations in the NOTCH and p53 pathways occurring at high frequency and mutations in the Hippo and Ras/MAPK/PI3K occurring at lower frequency
Decreasing exposure to ultraviolet radiation and the use of sunscreen appear to be effective methods of preventing squamous-cell skin cancer. Treatment is typically by surgical removal. This can be by simple excision if the cancer is small otherwise Mohs surgery is generally recommended. Other options may include application of cold and radiation therapy. In the cases in which distant spread has occurred chemotherapy or biologic therapy may be used.
As of 2015, about 2.2 million people have cSCC at any given time. It makes up about 20% of all skin cancer cases. About 12% of males and 7% of females in the United States developed cSCC at some point in time. While prognosis is usually good, if distant spread occurs five-year survival is ~34%. In 2015 it resulted in about 51,900 deaths globally. The usual age at diagnosis is around 66. Following the successful treatment of one case of cSCC people are at high risk of developing further cases.