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Squamous cell carcinoma in situ, also called Bowen’s Disease, is a cancer of the squamous cells that has not yet become invasive. Squamous cell carcinoma (SCC) is one of the most common skin cancers, second only to basal cell carcinoma, and can affect any part of the body, especially those most exposed to sunlight, toxins, or human papillomavirus (HPV). Because it is not yet invasive, squamous cell carcinoma in situ is very treatable and can often be completely removed.
A carcinoma is any cancer of the epithelial cells. Epithelial cells line the organs, including skin, make up some glands, and are one of the main cell types in the body. Squamous cells are a type of epithelial cell present in the inside of the mouth, skin, anal canal, vagina, tongue, urinary bladder, prostate, cervix, esophagus, lungs, and blood vessels.
Though SCC can appear in any of these places, it’s more likely to appear in places that have been chronically exposed to sunlight, especially for light skinned people; radiation; chemical toxins such as arsenic; and tobacc;, as well in places where there have been multiple injuries and scar tissue. The sexually transmitted infection HPV can also cause squamous cell carcinoma, normally on the genitals and on the cervix. Other risk factors less likely to affect the location of the cancer include advancing age, being male, genetics, and compromised immune system, especially from immunosuppressant medications taken after organ transplants.
In situ literally means “in place,” which, in the case of cancer, means it hasn’t moved or begun to invade the deeper structures of the skin. This makes SCC in situ far more treatable than invasive SCC. When visible, squamous cell carcinoma in situ often looks like an irregular, red, scaly patch that won’t go away. If it’s caught before it becomes invasive, the carcinoma may be removed, thus eliminating the risk of it spreading and causing serious complications. When untreated, the SCC may become invasive, forming a tumor and, in rare cases, metastasizing to other organs with potentially deadly consequences.
Squamous cell carcinoma in situ often remains in situ for a long time, but can cause serious disfigurements and other complications if left untreated. The treatment plan for most carcinomas involve cutting the cancer out, often through excision, electrodessication, or laser therapy. For a small squamous cell carcinoma in situ, a patient might receive a topical anti-cancer cream or cryosurgery, in which the carcinoma is frozen off with liquid nitrogen. A carcinoma over 2cm (0.78 in) has a high risk of invading deeper into the skin, and should be cut out, or even treated with radiation therapy.