Squamous-Cell Carcinoma

Squamous-cell carcinoma (SCC), also known as epidermoid carcinoma, is a group of cancers originating from squamous epithelial cells.

These cells form the surface layer of the skin, line hollow organs, and are present in the respiratory and digestive tracts. Despite sharing a common name, SCCs can manifest differently depending on the affected body site.

By Body Location

Head and Neck Cancer

Approximately 90% of head and neck cancers, which include malignancies of the mouth, nasal cavity, nasopharynx, throat, and associated structures, are due to SCC.

Skin

Cutaneous squamous-cell carcinoma is the second most common skin cancer, with over 1 million cases annually in the United States.

Thyroid

Primary squamous-cell carcinoma of the thyroid is aggressive and carries a poor prognosis.

Oesophagus

Esophageal SCC (ESCC) typically occurs nearer the mouth, while adenocarcinomas (EAC) occur closer to the stomach. Common symptoms include dysphagia and painful swallowing. Surgery, chemotherapy, and radiotherapy are treatment options depending on the disease stage.

Lung

In the lung, SCC usually presents as a centrally located large-cell cancer, often linked to smoking. It can cause hypercalcaemia through ectopic production of parathyroid hormone-related protein.

Penis

Human papillomavirus (HPV), particularly HPV 16 and 18, is implicated in penile SCC. Carcinomas in situ include Bowen's disease, Erythroplasia of Queyrat, and Bowenoid papulosis.

Vagina and Cervix

Vaginal SCC typically spreads slowly but can metastasize to the lungs and liver. It is the most common type of vaginal cancer.

Other Locations

SCC can also affect the prostate, ovary, bladder, and eye, with specific characteristics and prognoses varying by location.

Diagnosis

Diagnosis typically involves a biopsy for histopathology. TP63 staining is a key histological marker for SCC, essential for identifying squamous cells.

Classification

SCCs are thought to originate from repeated, uncontrolled division of cancer stem cells of epithelial lineage. They can be classified by their tissue of origin or histopathologic subtypes according to the International Classification of Diseases for Oncology (ICD-O) system. Subtypes include papillary, verrucous, large-cell keratinizing and nonkeratinizing, spindle-cell, and adenoid/pseudoglandular SCC.

Prevention

Diet has been found to influence skin cancer risk, including SCC. High-fat dairy consumption, tobacco smoking, and high alcohol intake increase SCC risk. Conversely, green leafy vegetables, raw fruits, and vegetables may offer protective benefits.

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Self-assessment MCQs (single best answer)

What percentage of head and neck cancers are due to squamous-cell carcinoma (SCC)?

Which virus is particularly implicated in penile squamous-cell carcinoma (SCC)?

Which histological marker is key for identifying squamous-cell carcinoma (SCC)?

What is the second most common skin cancer in the United States?

Which of the following dietary habits may increase the risk of squamous-cell carcinoma (SCC)?

Where does esophageal squamous-cell carcinoma (ESCC) typically occur?

Which subtype of squamous-cell carcinoma (SCC) is most commonly associated with the lung and often linked to smoking?

What is a common symptom of esophageal squamous-cell carcinoma (ESCC)?

Which of the following is NOT a potential location for squamous-cell carcinoma (SCC)?

What type of biopsy result would indicate a highly differentiated squamous-cell carcinoma of the mouth?