Overview of Squamous Cell Carcinoma

Squamous cell carcinoma (SCC) is the second most common type of skin cancer. It involves the malignant transformation and proliferation of squamous (flat, scaly) cells, which are the most abundant type of cell in the epidermis.

Cutaneous squamous cell carcinoma is usually localized, but it can metastasize. When confined to the skin, it is easily treated and cured. In most cases, cutaneous SCC develops in patients with known factors, such as excessive exposure to the sun.

Patients with fair skin and a history of sun exposure (e.g., sunburn) are at increases risk for SCC, as well as other forms of skin cancer. These people lack pigmentation, which protects the skin from damaging ultraviolet rays.

Squamous Cell Carcinoma Causes

The greatest risk for SCC occurs in light-skinned individuals with excessive sun exposure. The cumulative damage, particularly after repeated sunburns, causes abnormal changes (mutations) in cellular DNA. DNA contains the genetic blueprint and once the genetic blueprint is altered, all subsequent cellular division duplicates the defect. The defective cells multiply rapidly and cause a tumor to form.

Ultraviolet rays are not the only predisposing factors for developing SCC. Additional factors can be significant, depending on the individual. These include excessive exposure to radiation or x-rays, exposure to arsenic (a chemical found in some well water), and excessive exposure to tars, soot, and some industrial oils. In addition, SCC is more likely to develop in chronic ulcers and in burn scars and other scar tissue. Scar SCC usually develops years after the original injury. Individuals who are chronically immunosuppressed, such as by medication or disease, are predisposed to the development of skin cancer as well.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 14 Aug 1999

Last Modified: 24 Aug 2015