Squamous cell carcinoma of the skin: Emerging need for novel biomarkers

Table 1 Risk factors for the development of squamous cell carcinoma of the skin

Exposure to ultraviolet (UV) radiation (UVA, UVB)

Therapy with methoxalen and UVA

Fair skin type

Ionizing radiation

Genodermatosis (albinism, xeroderma pigmentosum, epidermolysis bullosa)

Chronic inflammation of skin (lupus erythematosus, epidermolysis bullosa)

Chronically injured skin with ulcers (burn scars, leg ulcers, epidermolysis bullosa)

Human papilloma virus infection

Exposure to chemical carcinogens

Immunosuppression

Immunosuppressive medications

Organ transplantation

Osteomyelitis

Sinus tracts

Precursor lesions (actinic and arsenical keratoses)

In situ squamous cell carcinoma (Bowen’s disease and Erythro plasia Queyrat)

Tobacco smoking

Leukemia and lymphoma

Originated from Madan et al[2], with permission.

Table 2 Risk factors for recurrence and metastasis of cutaneous squamous cell carcinoma

Variable	Approximate relative risk1
	Recurrence	Metastasis
Rapid tumor growth	-	-
Tumor size > 2 cm	2	2
Tumor location (lip/ear)	2	3
Immunosuppression	-	2
Previous radiotherapy	-	-
Previously treated cSCC	3	4
RDEB -associated cSCC	-	-
Tumor depth > 4 mm	2	5
Poor differentiation	2	3
Acantholytic features	-	-
Spindle-cell features	-	-
Perineural invasion	5	5

Originated from Alam et al[1], with permission.

¹A relative risk of 1 is defined as the likelihood of recurrence or metastasis of a small primary cutaneous squamous cell carcinoma (cSCC). Dashes indicate an association with increased risk, but of which there are insufficient data to estimate the relative risk. RDEB: Recessive dystrophic epidermolysis bullosa.