Cutaneous squamous cell carcinoma (SCC) is one of the most common types of non-melanoma skin cancer and arises from keratin-producing cells within the epidermis. Unlike superficial lesions confined to the upper skin layers, SCC is an invasive malignancy with the potential to penetrate deeper tissues and, in more advanced cases, metastasize to regional lymph nodes or distant sites. Although many cases are highly treatable when detected promptly, a subset of SCC behaves aggressively and can become life-threatening.
SCC occurs more frequently in older males, although it also affects females and younger individuals. A previous history of SCC, basal cell carcinoma, or melanoma substantially increases risk. Other contributing factors include actinic keratoses, chronic sun exposure, photoaging, and repeated sunburns, particularly in people with fair skin, blue or green eyes, and blond or red hair. The disease may also develop in darker skin types, although less commonly. Additional risks include prior skin injuries, chronic inflammation, certain genetic conditions such as xeroderma pigmentosum, exposure to ionizing radiation or arsenic, the use of immunosuppressive medications, and long-term immune suppression from disease or organ transplantation. Cigarette smoking and infections with certain types of human papillomavirus further contribute to its development.
More than ninety percent of SCCs arise from DNA mutations induced by ultraviolet radiation. Other mechanisms include immune suppression, aging, tobacco exposure, and oncogenic viral infections. These genetic alterations typically affect tumour-suppressor pathways and allow keratinocytes to proliferate uncontrollably.
Clinically, SCC often presents as an enlarging, scaly, or crusted lump that may develop from pre-existing lesions such as actinic keratoses. Lesions commonly arise on sun-exposed areas, including the face, scalp, ears, neck, forearms, and hands, but may occur anywhere on the body. They can become tender, ulcerated, or bleeding, and vary widely in size and appearance. Several clinical variants exist, including keratoacanthoma, which grows rapidly and may regress; verrucous carcinoma, which presents as a warty, slow-growing tumour; cutaneous horns characterized by prominent keratin projections; Marjolin’s ulcer arising in chronic wounds; and multiple eruptive SCC-like lesions associated with certain genetic or immunologic syndromes.
Staging of SCC is essential for determining prognosis and guiding treatment. The American Joint Committee on Cancer (AJCC) system evaluates tumour size, invasion depth, and involvement of nearby structures or lymph nodes. Smaller lesions lacking high-risk features are classified as early-stage disease, whereas tumours that invade deeper tissues such as the maxilla, mandible, or skull base are categorized as advanced. Tumours with high-risk features, such as large diameter, poor differentiation, perineural invasion, immunosuppression, or location on high-risk anatomical sites, carry a greater likelihood of recurrence and metastasis.
Diagnosis is usually made clinically and confirmed through skin biopsy or surgical excision. In high-risk cases or when symptoms imply possible spread, additional investigations such as ultrasound, CT, MRI, or targeted lymph node biopsies may be required. Histopathologic assessment determines the SCC subtype, depth of invasion, and margin status, each of which plays a role in treatment planning.
Surgical excision with an appropriate margin of normal tissue remains the primary and most effective treatment for cutaneous SCC. Less invasive methods such as shave excision, curettage and electrocautery, or cryotherapy may be suitable for small, low-risk lesions. Mohs micrographic surgery is considered the gold standard for large tumours on the face, recurrent SCCs, or lesions in areas where tissue preservation is critical. Radiotherapy may be used when surgery is not possible or as an adjunct treatment for high-risk disease. In advanced, recurrent, or metastatic SCC, systemic therapies—including agents such as cemiplimab or targeted epidermal growth factor receptor inhibitors—are increasingly incorporated into multidisciplinary management.
Preventive strategies are essential for individuals at high risk. Effective measures include avoiding midday sun, wearing protective clothing, using broad-spectrum SPF 50+ sunscreen, and abstaining from indoor tanning. Oral nicotinamide and systemic retinoids such as acitretin or isotretinoin may be recommended for those prone to frequent SCC development. Early detection is critical, as small and thin lesions have an excellent cure rate, while thicker or deeply invasive tumours carry a higher risk of recurrence or disease-related mortality. Many high-risk patients develop additional SCCs within five years of the initial diagnosis and remain at increased risk for other skin cancers. Regular dermatologic surveillance and monthly self-examinations are strongly encouraged.
Centre for Medical and Surgical Dermatology, in Pickering led by board-certified Dermatologist Dr. Breslavets, provides comprehensive diagnosis, treatment, and long-term management of cutaneous SCC. Care plans are fully individualized according to tumour type, size, location, histologic features, and patient-specific factors. CMSDerm offers expert biopsy techniques, advanced surgical excision, multidisciplinary coordination when required, and ongoing dermatologic surveillance to reduce recurrence risk and ensure early detection of new lesions. The clinic’s dermato-oncology and surgical dermatology services encompass the entire continuum of SCC care, providing patients with thorough, evidence-based, and long-term skin cancer management.
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