What is the recommended treatment for a 1‑cm squamous cell carcinoma in situ located at the base of the tongue?

Treatment Recommendation for 1-cm Squamous Cell Carcinoma In Situ at Base of Tongue

For a 1-cm squamous cell carcinoma in situ at the base of the tongue, single-modality treatment with either transoral surgical excision or definitive radiotherapy (IMRT/VMAT) is the recommended approach, with surgery preferred if technically feasible to preserve organ function and avoid radiation-related toxicity.

Treatment Algorithm

Primary Treatment Selection

The EHNS-ESMO-ESTRO guidelines explicitly state that early disease should be treated with single-modality treatment whenever possible 1. For a 1-cm carcinoma in situ at the base of tongue, this qualifies as early-stage disease requiring definitive local therapy.

Two equivalent options exist:

1. Conservative surgical excision (transoral approach, potentially with CO2 laser)

   • Provides tissue for complete pathologic assessment
   • Allows confirmation of complete excision with negative margins
   • Avoids radiation-related long-term toxicity
   • Preferred for small, accessible lesions

2. Definitive radiotherapy using IMRT or VMAT

   • Must use IMRT or VMAT technique (not conventional RT) 1
   • Appropriate when surgical access is challenging
   • Preserves tissue architecture

Key Decision Factors

The choice between surgery and radiotherapy should be based on:

• Surgical accessibility of the base of tongue lesion
• Expected functional outcomes (swallowing, speech)
• Patient fitness for anesthesia
• Facility expertise with transoral surgery

The guidelines emphasize that conservative surgery and RT may often provide similar locoregional control for early disease 1, so the decision hinges on minimizing treatment-related morbidity.

Critical Management Points

What NOT to Do

• Do not use chemoradiotherapy - This is carcinoma in situ (not invasive cancer), and the guidelines reserve concurrent chemoradiation for locally advanced disease 1
• Do not perform neck dissection - No nodal disease is expected with carcinoma in situ
• Do not use watchful waiting - While recent data suggests watchful waiting may be acceptable for cutaneous SCCIS with resolved biopsy sites 2, this does not apply to mucosal head and neck sites where progression risk and functional consequences differ significantly

Multidisciplinary Discussion Required

Treatment must be discussed in a multidisciplinary team (MDT) including surgeons, radiation oncologists, and supportive care specialists 1. This is particularly important for base of tongue lesions given the functional implications.

Treatment at High-Volume Centers

The guidelines recommend that patients should be treated at high-volume facilities 1, which is especially relevant for base of tongue surgery requiring specialized transoral techniques.

Evidence Considerations

Guideline Strength

The 2020 EHNS-ESMO-ESTRO guidelines provide Level I-IV evidence with Grade A recommendations for early-stage head and neck squamous cell carcinoma 1. These are the most recent and authoritative guidelines for this anatomic site.

Cutaneous vs. Mucosal SCCIS

The research evidence provided includes multiple studies on cutaneous squamous cell carcinoma in situ 3, 4, 5, 6, 2, which is fundamentally different from mucosal disease at the base of tongue. Cutaneous SCCIS has:

• Lower progression risk to invasive cancer
• Different treatment options (topical therapies, cryotherapy)
• Different natural history

These cutaneous studies should NOT guide treatment decisions for base of tongue lesions, which require definitive surgical or radiation therapy as outlined in the head and neck cancer guidelines.

Laryngeal SCCIS Data

One recent study examined laryngeal carcinoma in situ and found that primary surgery was associated with better overall survival (86% at 5 years) compared to radiotherapy (81%) or surveillance (73%) 7. While the larynx differs anatomically from the base of tongue, this supports the guideline recommendation for definitive treatment over observation.

Common Pitfalls to Avoid

1. Undertreating based on "in situ" designation - Mucosal SCCIS at the base of tongue requires definitive treatment, not topical therapy or observation
2. Using conventional radiotherapy - If RT is chosen, IMRT/VMAT is mandatory to minimize toxicity 1
3. Delaying treatment - Early single-modality treatment prevents progression to invasive disease requiring more aggressive multimodality therapy
4. Treating outside specialized centers - Base of tongue surgery requires expertise in transoral techniques