What is the preferred treatment for verrucous squamous carcinoma of the lip?

Treatment of Verrucous Squamous Cell Carcinoma of the Lip

Surgical excision with full-thickness resection is the definitive treatment for verrucous squamous cell carcinoma of the lip, requiring 5-10 mm surgical margins with histologic confirmation of clear margins. 1, 2, 3

Primary Treatment Approach

Surgical Excision (First-Line Treatment)

Full-thickness excision is mandatory for all lip squamous cell carcinomas, including the verrucous subtype. 4, 3 The surgical approach should include:

• Initial surgical margins of 8-10 mm around the clinically visible tumor for most lip carcinomas 3
• Minimum 5 mm margins may be adequate for well-defined, lower-risk lesions, with 66% of cases achieving clear margins at this distance 2
• Full-thickness excision extending through the entire lip structure (skin, muscle, and mucosa) 3
• Frozen section analysis at the time of surgery to confirm negative margins, with additional excision if margins are positive 2

The lip is a high-risk anatomic location that warrants wider margins than typical cutaneous SCC. 1 For lip lesions specifically, margins of 6 mm or more with histologic examination are recommended to maintain 95% confidence of complete excision. 1

Critical Margin Considerations

Accounting for tissue shrinkage is essential when planning surgical margins. Excised lip tissue shrinks by 41-47.5% from the time of excision to histopathologic evaluation, with most shrinkage occurring immediately upon excision. 5 This means:

• A planned 5 mm clinical margin may measure only 2.6-2.9 mm histologically
• Surgeons should plan wider initial margins to compensate for this predictable shrinkage 5

Incomplete or inadequate excision (margins ≤2 mm) significantly increases local recurrence risk. 6 In one series, 27% of excised lip lesions had close or positive margins, and these cases showed significantly higher recurrence rates (P = 0.05). 6

Alternative Treatment Modalities

Radiotherapy

Radiotherapy is an acceptable alternative when surgery is not feasible or for optimal cosmetic/functional outcomes in select cases. 1 Specific indications include:

• Patients where surgical morbidity would be unacceptably high 1
• Lesions where radiotherapy may provide superior functional or aesthetic results 1
• Equivalent 10-year local control rates (92.5%) compared to surgery when appropriately selected 7

However, radiotherapy alone for lip lesions should be approached with caution as some data suggest 2-year recurrence-free survival may be lower with radiotherapy (82%) compared to surgery (though this difference may reflect case selection). 6

Adjuvant Radiotherapy for Inadequate Excision

When re-excision is not feasible after incomplete excision, adjuvant radiotherapy should be strongly considered to improve local control. 6 This is particularly important given that:

• Close or positive margins significantly predict recurrence 6
• Adjuvant radiotherapy can salvage cases with inadequate initial excision 6

Non-Recommended Modalities

Curettage and electrodesiccation, cryosurgery, and topical therapies are NOT appropriate for lip SCC. 1 These modalities:

• Curettage and cautery: Only appropriate for small (<1 cm) well-differentiated primary SCC in non-terminal hair-bearing locations (lip is excluded) 1
• Cryosurgery: Not appropriate for high-risk anatomic sites like the lip 1
• Topical therapies (imiquimod, 5-FU) and photodynamic therapy: Not recommended for invasive SCC 1

Neck Management

Neck dissection should be performed for clinically palpable lymph nodes. 4, 3 The lip drains primarily to submandibular lymph nodes, with potential drainage to submental, intraparotid, or internal jugular nodes, including possible contralateral drainage. 3

Elective prophylactic lymph node dissection for lip SCC >6 mm depth has weak evidence (Strength of Recommendation C) and is not routinely practiced. 1

Reconstruction Considerations

• Free vascularized soft tissue flaps (radial forearm, anterolateral thigh) are preferred when continuity is maintained 4
• Bony flaps (fibula) are required if mandibular continuity is disrupted 4

Follow-Up Protocol

Patients require surveillance for 5 years, as 95% of local recurrences and metastases occur within this timeframe. 1 Follow-up should include:

• Regular clinical examination for recurrent disease 1
• Patient education on self-examination 1
• Annual screening for new keratinocyte cancers and melanoma 1
• High incidence of metachronous lip lesions (up to 25% may develop second lip lesions) 7

Key Pitfalls to Avoid

• Underestimating required margins: The lip is a high-risk site requiring wider margins than typical cutaneous SCC 1
• Ignoring tissue shrinkage: Plan surgical margins accounting for 41-47.5% shrinkage 5
• Accepting close margins: Margins ≤2 mm significantly increase recurrence risk and warrant re-excision or adjuvant radiotherapy 6
• Using inappropriate modalities: Avoid curettage, cryotherapy, or topical treatments for lip SCC 1