What is the management approach for a floor of mouth cancer with midline crossing, extension to the posterior tongue border, and metastasis to submental, level 2, and level 3 lymph nodes?

Management of Floor of Mouth Cancer with Midline Crossing and Metastatic Lymph Nodes

The optimal management for a floor of mouth cancer crossing the midline with extension to posterior tongue border and metastasis to submental, level 2, and level 3 lymph nodes requires surgical resection with bilateral neck dissection followed by adjuvant chemoradiotherapy.

Initial Assessment and Staging

• Imaging studies: Contrast-enhanced CT or MRI of the primary tumor and neck is mandatory 1

  • The puffed-cheek technique during CT can better delineate oral cavity tumors 1
  • PET-CT is recommended for this advanced disease to assess for distant metastasis 1

• Biopsy: Mandatory for pathological confirmation 1

  • Should include assessment of depth of invasion, perineural and lymphovascular infiltration

Surgical Management

Primary Tumor Resection

• Wide surgical excision of the primary tumor with adequate margins (≥1 cm) 1
• Bilateral approach is necessary since the tumor crosses the midline 2
• Posterior extension to tongue border requires careful assessment for base of tongue involvement 2
• Reconstructive options after resection:
  • Microvascular free tissue transfer is preferred for large defects 1
  • Pectoralis major myocutaneous flap is a reliable alternative 3

Neck Dissection

• Bilateral neck dissection is mandatory due to:

  • Tumor crossing the midline 2
  • Presence of metastatic nodes on both sides 2

• Type of neck dissection:

  • Comprehensive neck dissection for the side with clinically positive nodes (levels I-V) 2
  • At minimum, selective neck dissection (levels I-IV) for the contralateral side 2
  • Special attention to submental nodes (level IA) which are already involved 4, 5

• Special consideration: Include sublingual lymph nodes in the dissection, as these can harbor metastasis in floor of mouth cancers and are not typically included in standard neck dissections 4, 5

Adjuvant Therapy

Indications for Adjuvant Treatment

• Chemoradiotherapy is strongly indicated due to:
  • Advanced primary tumor crossing midline with posterior extension 2
  • Multiple positive lymph nodes at multiple levels 2, 1

Radiation Therapy Protocol

• Dose: 66 Gy with concurrent cisplatin 1
• Target volumes:
  • Primary site plus 2-3 cm margins or anatomic zone 2
  • Bilateral neck fields 2
• Timing: Should begin within 6-7 weeks after surgery 1

Follow-up and Surveillance

• Close monitoring for at least 5 years due to high risk of recurrence 6
• Regular clinical examinations with focus on:
  • Primary site (most common site of recurrence - 41%) 6
  • Regional lymph nodes 6
  • Distant metastasis (occurs in up to 30% of patients) 6
• Imaging studies as clinically indicated 1
• Functional assessment of speech, swallowing, and nutrition 1
• Thyroid function monitoring every 6-12 months if neck was irradiated 1

Prognostic Considerations

• Poor prognostic factors in this case:

  • Midline crossing tumor
  • Posterior extension
  • Multiple positive lymph nodes
  • Involvement of multiple neck levels

• Expected 5-year disease-specific survival for advanced floor of mouth cancer treated with composite resection and radiation therapy is approximately 55% 6

Pitfalls and Caveats

• Inadequate surgical margins significantly decrease survival 6
• Failure to address sublingual lymph nodes may lead to recurrence even with formal neck dissection 4, 5
• Delayed initiation of adjuvant therapy (beyond 6-7 weeks) may compromise outcomes 1
• Underestimation of contralateral neck involvement in midline-crossing tumors can lead to regional recurrence 2