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SCC (Squamous Cell Carcinoma)

What is Squamous Cell Carcinoma (SCC)? Squamous Cell Carcinoma (SCC) refers to cancer caused by uncontrolled proliferation of the squamous epithelium, and therefore may be present on any surface of the skin or mucosal membrane lined by the same.

What causes squamous cell carcinoma?

The common factor giving rise to all types of SCC is inflammatory damage to the tissue that is usually chronic in nature, as it results in long-term damage to the DNA and can thus interfere with the pathways involved in cell regulation and turnover. Familial predisposing conditions that interfere with cell regulation may also be implicated in the development of SCC.

The inflammatory processes that may the etiologic agents include:

  • Old burn scars or ulceration, chemical burns, or those associated with UV radiation. 
  • Infections (HPV, HIV, and chronic osteomyelitis).
  • Autoimmune processes (psoriasis).
  • Environmental carcinogens (tobacco, ionizing radiation, coal, tar).

What types are the types of Squamous Cell Carcinoma?

Squamous cell carcinoma can be classified by the location of origin as they usually present differently and have different risk factors. Each of these cancers can then be further categorized based on histopathological morphology.

  • Cutaneous squamous cell carcinoma (cSCC) is usually found on the skin exposed to UV radiation. 
  • Squamous cell carcinomas in situ (SCCIS), also known as Bowen disease and intraepidermal carcinomas, are usually found in the area where they originate. SCCIS was usually found in areas exposed to ionizing radiation, especially in the 1920s. However, like cSCC, the most common risk factor today is exposure to UV radiation.
  • Squamous cell carcinoma of the lung is a type of non-small cell lung cancer (NSCLC) that is strongly associated with cigarette use. This is the reason it is most often found in areas of the lung with the highest exposure to the smoke, such as the center of the lung and within the main airways. 
  • Squamous cell carcinoma of the head and neck (SCCHN) are found in the mucosal surfaces of the head and neck. This can include the lips, any part of the oral cavity, and the pharynx. SCCHN is a heterogeneous group not only in terms of location, but also risk factors which can include exposure to tobacco (smoking and chewing), alcohol use, betel nut, HPV infection, and genetic predisposition, such as Fanconi anemia). Squamous cell carcinoma of the esophagus has historically been associated with smoking, alcohol use, and poor nutrition. However, more recently an increase in upper esophageal SCC has been found to be associated with HPV infections.
  • Verrucous Carcinoma is a rare form of SCC that is associated with a fungated or verrucous morphology. It may be found as a type of SCCHN and may be associated either with the use of tobacco and betel nut or infection with HPV. It may also be classified as a type of anogenital squamous cell carcinomas, which are most often caused by HPV infections and may be found in the vulva, glans penis, scrotum, or perianal region. 
  • Squamous cell carcinomas of unknown origin are rare, invasive type of SCC. They comprise 5% of the carcinomas of unknown primary site, which in turn account for 2% of all invasive cancers. The diagnosis and management of these cancers is dependent on the lymph nodes associated with the primary discovery, as they point to the most likely origin of the cancer.

Source: Types of Squamous Cell Carcinoma. (n.d.). Abramson Cancer Center | Penn Medicine. Retrieved July 15, 2022, from https://www.pennmedicine.org/cancer/types-of-cancer/squamous-cell-carcinoma/types-of-squamous-cell-carcinoma