In an adult with a right‑sided lower‑lip squamous cell carcinoma >2 cm (T2) and depth of invasion >5 mm, what neck dissection is recommended?

Neck Dissection for Right-Sided Lower Lip SCC >2 cm with Depth >5 mm

For a right-sided lower lip squamous cell carcinoma T2 (>2 cm) with depth of invasion >5 mm and clinically negative neck (N0), perform an ipsilateral (right-sided) selective supra-omohyoid neck dissection (levels I-III) at the time of primary tumor excision. 1, 2

Rationale for Elective Neck Dissection

• Depth >5 mm is a critical threshold: All carcinomas deeper than 6 mm metastasized in one series, and depth >2 mm significantly correlates with regional metastases 3
• Occult metastasis rate is substantial: The incidence of occult cervical metastases in clinically node-negative lower lip SCC exceeds 30% in many series, with depth of invasion being the best predictor 1
• T2 tumors (>2 cm) warrant elective treatment: Guidelines recommend elective treatment of uninvolved lymph node areas for larger T2 tumors to reduce cervical relapse risk 1

Surgical Approach: Selective Supra-Omohyoid Neck Dissection

• Perform ipsilateral (right-sided only) selective neck dissection levels I-III for this lateral lower lip tumor 1, 2
• Preserve the sternocleidomastoid muscle, internal jugular vein, and spinal accessory nerve during the selective dissection 1
• Lateral tumors allow ipsilateral-only treatment without compromising cervical control 1

Intraoperative Decision Algorithm

If Frozen Section Shows Positive Nodes:

• Convert to modified radical neck dissection (comprehensive dissection preserving non-lymphatic structures) 1
• Plan for postoperative radiotherapy if multiple nodes are involved, extracapsular spread is present, or margins are narrow (<5 mm) 1

If All Nodes Are Negative:

• No further neck treatment required 1
• Surveillance only with regular follow-up for at least 5 years 4

Timing: Simultaneous vs. Delayed

• Perform neck dissection simultaneously with primary tumor excision: Patients receiving simultaneous treatment achieve significantly better survival (100% in prophylactic cases, 83.3% in therapeutic cases) compared to delayed nodal management (24.7% with extracapsular spread) 5
• Delayed neck dissection after primary surgery carries worse prognosis, particularly if metastases develop with extracapsular extension 5

Critical Pitfalls to Avoid

• Do NOT omit elective neck dissection based solely on clinical examination: One study showed delayed neck metastasis developed in patients who had isolated lip resection without neck exploration, resulting in death despite salvage chemoradiotherapy 2
• Do NOT perform bilateral neck dissection for lateral tumors: Ipsilateral dissection is sufficient for right-sided lesions 1
• Do NOT delay neck treatment: Prophylactic neck dissection at the time of primary surgery provides superior outcomes compared to therapeutic dissection after metastases become clinically apparent 2, 5

Alternative: Sentinel Lymph Node Biopsy

• Sentinel node biopsy may be considered as a staging tool in clinically node-negative oral SCC, though this approach requires specialized lymphoscintigraphy and intraoperative gamma probe localization 1
• This technique is less established for lip SCC compared to melanoma or breast cancer, and selective neck dissection remains the gold standard 1

Postoperative Management

• Add radiotherapy if: surgical margins are narrow (<5 mm) or involved, multiple nodes are positive, or extracapsular rupture is present 1
• Surveillance for 5 years: 95% of recurrences and metastases occur within this timeframe 4