Second most common cancer in sun-exposed sites in older people
More aggressive than Basal Cell Carcinoma (BCC)
Can metastasize
Risk Factors
Sun Exposure
Industrial Carcinogens:
Tars, oils
Chronic Ulcers
Pre-existing Conditions:
Solar keratoses, Bowen’s disease (SCC in situ), cutaneous horn, keratoacanthoma, chronic inflammation (e.g., lupus vulgaris)
Scars:
Previous burns, trauma, or skin disorders
Oral Cavity:
Tobacco and betel nut chewing
Immunosuppression
Cigarette Smoking
Human Papillomavirus (HPV)
Types of SCC
Carcinoma in Situ:
Lesion has not invaded through the basement membrane
Sharply defined red, scaling plaques
Invasive SCC:
Typical presentation
Periungual SCC
Marjolin Ulcers:
Occur in pre-existing ulcers/scars
Perioral Ulcers:
At the vermillion border of the lip
Verrucous Carcinoma
Anogenital Carcinoma
Clinical Presentation
General Characteristics:
Enlarging scaly or crusted lumps
Often arise within pre-existing actinic keratosis or intraepidermal carcinoma
Grow over weeks to months
May ulcerate
Often tender or painful
Located on sun-exposed sites: face, lips, ears, hands, forearms, and lower legs
Size varies from a few millimeters to several centimeters in diameter
Distribution: sun-exposed areas, especially lower lip and ear
Prognostic Factors
Size: Greater than 2cm
Thickness: Increased thickness
Fixation: To underlying structures
Differentiation: Poor differentiation
Outline: Irregular outline
Ulceration: Presence of ulceration
Bleeding: Bleeding lesions
Fungation: Presence of fungating growth
Induration: Hardening or sclerosis
Location: Facial sites have increased recurrence rates
Recurrent Tumor: Higher risk of recurrence
Chronic Scar: SCC arising from chronic scars
Perineural Involvement: Altered sensation around the tumor indicating neural involvement
Metastasis: Spread to multiple lymph nodes
Surgical Margins and Incomplete Excision Rate
Goal: Achieve a histopathological involvement of margins in less than 5% of excisions. This is based on a standard benchmark for complete excision, ensuring minimal recurrence.
Histopathological Margin Assessment: Involves microscopic examination to confirm if tumour cells are present at the edge of the excised tissue. Presence of tumour cells at the margin suggests incomplete excision, increasing the risk of recurrence.
Recommended Surgical Margins Based on Risk Level
Squamous Cell Carcinoma (SCC):
Low-Risk Lesions: 4 mm margin.
High-Risk Lesions: 6 mm margin.
Basal Cell Carcinoma (BCC):
Low-Risk Tumours: 2–3 mm margin.
High-Risk Tumours: Greater than 5 mm margin.
Rationale: Surgical margins are tailored to balance complete tumour excision with preservation of normal tissue, particularly in cosmetically or functionally significant areas.
Considerations in Determining Surgical Margin
Tumour Characteristics:
Histologic subtype (e.g., infiltrating, sclerosing for BCC).
Size of the lesion (e.g., larger SCCs or BCCs generally require broader margins).
Location of Lesion:
Tumours on high-risk anatomical sites (e.g., head and neck) often require larger margins or referral for specialist care due to complexity in these areas.
Patient Factors:
Preference and concerns regarding cosmetic outcomes.
Functional implications depending on lesion location (e.g., near facial muscles, joints).
Referral to a Specialist (Dermatologist or Plastic Surgeon)
General Criteria for Referral:
Tumour on the head and neck, which often presents a higher risk due to anatomical complexity.
High-risk histologic subtypes, such as infiltrative or sclerosing BCC.
Tumours larger than 2 cm in diameter.
Recurrent or previously incompletely excised tumours.
Specialist Procedures:
Specialists may use advanced techniques like Mohs micrographic surgery, which allows for real-time microscopic examination of tumour margins to ensure complete excision while preserving surrounding tissue.
High-Risk SCC Features and Multidisciplinary Referral
High-Risk SCC Features:
Tumour diameter greater than 20 mm.
Tumour depth exceeding 4 mm.
Recurrent lesions.
High-risk anatomical locations (head and neck).
Evidence of perineural or lymphovascular invasion.
Poor differentiation of tumour cells.
Patient immunosuppression, which increases the likelihood of tumour recurrence or metastasis.
Multidisciplinary Team (MDT) Referral:
For high-risk SCC cases, refer to an MDT for comprehensive management, which may include surgery, adjuvant radiotherapy, and/or systemic therapy in advanced cases.
Alternative Treatment Modalities
Non-surgical Options:
Mohs Micrographic Surgery: Effective for high-risk or cosmetically sensitive areas.
Curettage and Cautery: Used for certain low-risk BCCs and SCCs.
Cryotherapy: Freezing method suitable for superficial BCCs and SCCs.
Topical Therapies:
Imiquimod or 5-fluorouracil cream can be considered for superficial lesions.
Photodynamic Therapy (PDT): Effective for superficial and low-risk lesions but with limited penetration depth.
Radiotherapy: Considered for patients who are unfit for surgery or when further locoregional control is necessary.
Referral to Medical Oncology: Necessary for cases of metastatic SCC, which may require systemic therapy.
Management of Incompletely Excised Lesions
Referral for Specialist Management:
Incompletely excised or recurrent lesions are typically referred to specialists.
Further Management Options:
Re-excision: To ensure clear margins.
Topical Treatments: For cases where surgery is not feasible or margins involved are minor.
Monitoring: In select cases based on the involved margin (lateral vs. deep) and patient factors.
Follow-up Care and Patient Education
Ongoing Surveillance:
Essential for all patients with a history of keratinocyte carcinoma to detect recurrence, metastasis, or new primary cancers.
Follow-up can be managed by either the general practitioner or a non-GP specialist, based on patient risk factors and tumour characteristics.
Patient Education:
Advise on sun protection, skin self-examinations, and awareness of signs of recurrence.
Reinforce the importance of routine follow-ups and preventive measures for long-term skin health.
Prognosis and Follow-up
Cure Rate:
Most SCCs are cured by treatment
Early Treatment:
Cure is most likely if treatment is undertaken when the lesion is small
Risk of Recurrence or Death:
Greater for tumors > 20mm in diameter and/or > 2mm in thickness at the time of surgical excision
High-Risk Patients:
About 50% develop a second SCC within 5 years of the first
Increased risk of other skin cancers, especially melanoma
Regular self-skin examinations and long-term annual skin checks by an experienced health professional are recommended
