What is the primary treatment for squamous cell carcinoma?

Primary Treatment for Squamous Cell Carcinoma

Surgical excision is the treatment of choice for the majority of cutaneous squamous cell carcinomas (SCCs), as it allows for complete removal of the tumor and histological assessment of margins. 1

Types of Surgical Approaches

Standard Excision

• For low-risk, well-defined tumors <2 cm in diameter:
  • Minimum 4-mm margin around the tumor border (95% clearance rate) 1, 2
  • Excision to mid-subcutaneous adipose tissue depth 1

For High-Risk Tumors

• Wider margins (6 mm or more) are required for:
  • Tumors >2 cm in diameter
  • Broders' grade 2,3, or 4 (moderate to poor differentiation)
  • Tumors extending into subcutaneous tissue
  • High-risk locations (ear, lip, scalp, eyelids, nose) 1, 2

Mohs Micrographic Surgery

• Recommended for high-risk SCCs 1
• Particularly valuable when:
  • Tumor margins are ill-defined
  • Preservation of normal tissue is critical for functional/cosmetic outcomes
  • Tumors are in cosmetically sensitive areas 1

Alternative Treatment Options

Curettage and Electrodesiccation

• May be considered for small (<1 cm), well-differentiated, primary SCCs in non-hair-bearing sites 1
• Contraindications:
  • Hair-bearing sites (risk of missing tumor extending down follicular structures)
  • If subcutaneous layer is reached during procedure (switch to excision)
  • High-risk or recurrent tumors 1

Radiation Therapy

• Option for patients who are not surgical candidates 1
• May be preferred for certain anatomic locations (lip, nasal vestibule, ear) where it provides better cosmetic/functional outcomes 1
• Also used as adjuvant therapy for high-risk features (perineural invasion, positive margins) 1

Cryosurgery

• May be considered for low-risk SCCs when more effective therapies are contraindicated 1
• Prior biopsy necessary to establish diagnosis histologically 1
• Not appropriate for recurrent disease 1

Management of Advanced Disease

Regional Lymph Node Metastases

• Surgical resection with or without adjuvant radiation therapy 1
• For inoperable disease: combination chemoradiation therapy 1

Metastatic Disease

• EGFR inhibitors (cetuximab) for recurrent/metastatic head and neck SCC 1, 3
• Pembrolizumab for PD-L1 positive recurrent/metastatic head and neck SCC 1, 4
• Multidisciplinary consultation recommended 1

Important Considerations

Deep Margin Assessment

• Pay special attention to deep margins - 94% of incomplete excisions involve the deep margin 5
• Ensure excision extends to appropriate depth (mid-subcutaneous tissue) 1

Follow-up

• 95% of local recurrences and metastases occur within 5 years
• High-risk SCC patients should be observed for recurrent disease for at least 5 years 1
• Patient education on self-examination is essential 1

Common Pitfalls

1. Inadequate deep margin assessment (more common than radial margin failure) 5
2. Underestimating subclinical extension in high-risk tumors
3. Failure to identify high-risk features requiring wider margins
4. Inappropriate use of non-surgical modalities for high-risk tumors

Remember that the goal of treatment is complete removal or destruction of the primary tumor and any metastases, with histological confirmation of margin clearance whenever possible 1.