From the Guidelines
For skin squamous cell carcinoma (SCC), the recommended surgical margins are 4-6 mm for low-risk tumors, as stated in the most recent guidelines from 2018 1. The margins for skin squamous cell carcinoma depend on the tumor's risk factors, with low-risk tumors requiring smaller margins and high-risk tumors requiring wider margins.
- Low-risk tumors (less than 2 cm in diameter, well-differentiated) typically require a 4-6 mm margin, as recommended by the guidelines of care for the management of cutaneous squamous cell carcinoma 1.
- High-risk tumors (larger than 2 cm, poorly differentiated, located on high-risk areas like ears, lips, or genitalia, or with perineural invasion) may require wider margins of 6-10 mm, as suggested by the multiprofessional guidelines for the management of the patient with primary cutaneous squamous cell carcinoma 1. The goal of surgical excision is to completely remove the tumor with clear margins to prevent recurrence while maintaining function and cosmesis.
- Deeper margins should extend to the subcutaneous fat or fascia depending on tumor depth, as recommended by the guidelines of care for the management of cutaneous squamous cell carcinoma 1.
- Post-excision pathological confirmation of clear margins is essential, and if margins are positive, re-excision or adjuvant therapy may be necessary, as stated in the guidelines of care for the management of cutaneous squamous cell carcinoma 1. Mohs micrographic surgery is often preferred for high-risk areas or recurrent tumors as it allows for complete margin assessment while preserving healthy tissue, as recommended by the guidelines of care for the management of cutaneous squamous cell carcinoma 1.
From the Research
Surgical Margins for Skin Squamous Cell Carcinoma
- The recommended lateral surgical excision margin (LEM) for low-risk squamous cell carcinomas (SCCs) is 4-6 mm, as stated in 2.
- For high-risk SCCs, Mohs surgery or resection with complete circumferential peripheral and deep margin assessment is recommended, according to 2.
- If the SCC is >20 mm in area with no other high-risk factors and can be repaired primarily, 10-mm clinical margins may be used, as mentioned in 2.
- A study published in 3 found that surgical excision remains the gold standard for the management of cutaneous squamous cell cancers, with national guidelines predicting 95% oncological clearance with a margin of 4 mm for low-risk and 6 mm for high-risk tumors.
- Another study published in 4 formulated guidelines for appropriate margins of excision of primary cutaneous squamous cell carcinoma based on a prospective study of subclinical microscopic tumor extension, recommending 4 mm margins for most squamous cell carcinomas, but at least a 6 mm margin for high-risk tumors.
- The variations in guideline recommendations for peripheral and deep surgical margins are noted in 5, highlighting the need for international collaboration and consensus to determine a more unified and evidence-based approach to surgical excision as a treatment for nonmelanoma skin cancer.
Factors Influencing Surgical Margins
- Tumor size, with larger tumors (>2 cm) requiring wider margins, as mentioned in 3 and 4.
- Histologic grade, with higher grade tumors requiring wider margins, as noted in 4.
- Invasion of the subcutaneous tissue, which increases the risk of subclinical tumor extension, as stated in 4.
- Location in high-risk areas, which also increases the risk of subclinical tumor extension, as mentioned in 4.