Carcinoma of the Larynx: Mode of Spread, T1N1M0 Glottic Management & Transoral Laser Microsurgery

PART 1: MODE OF SPREAD OF CARCINOMA LARYNX

A. Local (Direct) Spread

• Anteriorly: to the anterior commissure, then through the anterior commissure tendon (ACT) into the thyroid cartilage or supraglottis
• Posteriorly: to the arytenoid and cricoarytenoid joint (causing cord fixation)
• Superiorly: into the ventricle and supraglottis (transglottic spread)
• Inferiorly: into the subglottis (>5 mm subglottic extension has prognostic importance)
• The ACT is actually a barrier to deep invasion; spread across the anterior commissure does not automatically mean deep invasion unless tumor goes above (into PES) or below it (into cricothyroid membrane)

B. Lymphatic Spread

• Supraglottic: 12-40% across all T stages
• Glottic: 18% occult rate overall

C. Distant (Hematogenous) Spread

• Most common site: lungs
• Less common: liver, skeletal system (ribs, vertebrae, skull)
• Mediastinal nodes (lymphatic): classified as distant metastases
• Incidence by site:
  • Glottic SCC: 3.1-8.8%
  • Supraglottic SCC: 3.7-15%
  • Subglottic SCC: ~14.3%
• Risk factors for distant metastases: T4 primary, N2/N3 nodal disease, extracapsular spread, locoregional recurrence

PART 2: T1N1M0 GLOTTIC CARCINOMA - MANAGEMENT IN DETAIL

Understanding the Staging First

• T1: Tumor limited to one (T1a) or both (T1b) vocal cords, with normal cord mobility
• N1: Single ipsilateral lymph node, ≤3 cm
• M0: No distant metastases
• Stage: This is Stage III disease

Treatment Approach

• Options include surgery (TLM/laser cordectomy, open partial laryngectomy) OR radiotherapy
• T1 tumors alone achieve 5-year local control of 81-90% with RT and excellent rates with TLM
• The presence of N1 disease, however, changes the overall treatment plan

1. Surgery (Selective Neck Dissection): Levels II-IV on the ipsilateral side. For N1 disease, a selective neck dissection is the standard surgical approach. If performing surgery on the primary (TLM), it can be done as a combined approach.
2. Radiotherapy to the Neck: RT (with or without concurrent chemotherapy if high-risk pathologic features like extracapsular spread or close margins are found) can treat both the primary and the ipsilateral neck simultaneously.

• If surgery is used for the primary + neck dissection: adjuvant RT to the neck is given if pathologic features are adverse (positive margins, extracapsular spread, multiple nodes)
• If RT is the chosen modality: concurrent chemoradiation (CRT) is the standard for Stage III disease, treating both primary and neck
• CRT achieves better functional, oncologic, and survival outcomes than RT alone in stage III disease

1. Multidisciplinary team discussion
2. Option A - TLM for primary + ipsilateral selective neck dissection (Levels II-IV) → adjuvant RT/CRT if pathological adverse features
3. Option B - Primary CRT (concurrent cisplatin-based chemotherapy + RT to primary and ipsilateral neck)
4. Option B is commonly chosen because it avoids open surgery and addresses both primary and the neck simultaneously
5. If N1 node shows extracapsular extension after any approach → adjuvant CRT is indicated

PART 3: TRANSORAL LASER MICROSURGERY (TLM) - IN DETAIL

What is TLM?

Core Principles

1. No external incision - all work done through the open mouth
2. The laser beam is manipulated using a micromanipulator attached to the operating microscope
3. The CO2 laser (10,600 nm wavelength) is the workhorse of TLM - it cuts through tissue with precision and simultaneous hemostasis
4. Tumors may be divided and removed piecemeal (in sections), which does NOT compromise oncologic outcomes - the key is achieving clear resection margins
5. Frozen-section analysis of margins guides the depth of resection intraoperatively

Equipment Required

• Rigid direct laryngoscope (suspension laryngoscopy setup)
• Operating microscope (provides magnification 6x-25x)
• CO2 laser with a micromanipulator (for vocal cord and glottic work)
• KTP laser (532 nm) or thulium laser - used for angiolytic (vascular-targeted) work, especially in the office/awake setting
• Suction and irrigation
• Microlaryngoscopy instruments (fine forceps, scissors)

Patient Positioning and Setup

• Patient supine, neck extended (shoulder roll)
• General anesthesia with a small-diameter laser-safe endotracheal tube (prevents laser ignition)
• Direct laryngoscope placed transorally and suspended from a chest support
• Operating microscope brought into position over the laryngoscope
• CO2 laser micromanipulator coupled to the microscope

Cordectomy Classification (European Laryngological Society - ELS)

Surgical Technique - Step by Step

1. Exposure: Suspension laryngoscope placed to obtain the best possible view of the tumor - adequate exposure is essential
2. Assessment: The tumor extent is defined under microscopy; NBI (narrow band imaging) or stroboscopy may have been used preoperatively
3. Marking: The lines of resection are planned to achieve a 1-2 mm margin beyond visible tumor
4. Laser settings: CO2 laser set to super-pulse or ultra-pulse mode; power 2-8 W depending on tissue depth
5. Division: If the tumor is large, it is divided into sections (piecemeal resection) to facilitate removal and improve visualization of the deep margin
6. Margin assessment: Biopsy of deep and peripheral margins sent for frozen section; further resection if positive
7. Hemostasis: The CO2 laser provides excellent hemostasis for small vessels; larger bleeders managed with bipolar cautery
8. No wound closure: The raw surface is left to heal by secondary intention - re-epithelialization occurs within 4-6 weeks

TLM for Specific T Stages

• TLM cordectomy (Type II-IV) achieves 5-year local control of ~90-95%
• Laryngeal preservation rate >99%
• Voice quality is generally good, especially for Type II-III cordectomy
• Local recurrence can often be salvaged with repeat TLM or RT

• Type Vb or Type VI cordectomy
• Anterior commissure involvement is technically challenging; 5-year local control ~84-90%
• In 263 patients (Steiner series): T1a local control 90% (without AC) vs 84% (with AC); laryngeal preservation 99% vs 93%

• Type V extended cordectomy or wider resection
• Local control 64-87%; laryngeal preservation 75-87%

• TLM is feasible for T3 without cord fixation, without massive PES invasion, without cartilage invasion, and with favorable exposure
• Canis series (391 patients): 5-year OS 59%, disease-specific survival 84%, laryngeal preservation 83%

Advantages of TLM

1. No external incision, no neck dissection needed for the primary
2. Shorter hospital stay (often same-day or 24-hour discharge)
3. Preserves laryngeal function (voice, swallow, airway)
4. Can be repeated if recurrence occurs
5. Does not preclude future RT for recurrence or second primaries
6. Faster recovery and return to normal activities
7. Lower cost compared to radiotherapy
8. Piecemeal resection is safe - multiple studies confirm equivalent oncological outcomes

Disadvantages / Limitations

1. Requires expertise and a learning curve; not available at all centers
2. Poor visualization/exposure is an absolute contraindication - if the tumor cannot be adequately seen, TLM should not be attempted
3. Anterior commissure tumors are technically demanding
4. Voice outcomes may be inferior to RT for deeply invasive tumors (Type IV-V cordectomy)
5. Cartilage invasion is a relative contraindication (usually requires external surgery or total laryngectomy)
6. Significant subglottic extension (>1 cm) makes TLM difficult

TLM vs Radiotherapy for Early Glottic Cancer

Awake/Unsedated Laser Laryngeal Surgery (AULS) - Office-Based TLM

• KTP laser (Aura XP): 300-micron fiber, small, portable
• The laser energy is absorbed by the abnormal microcirculation within the lesion, leading to lesion ablation while sparing normal surrounding microstructure
• Only ~15 minutes of working anaesthesia time available with topical lidocaine
• Avoids general anaesthesia, hospital admission, and repeat formal operating procedures
• Particularly effective for recurrent respiratory papillomatosis and laryngeal dysplasia

• Cummings Otolaryngology Head and Neck Surgery, Chapter 105 (Squamous Cell Carcinoma of the Larynx) and Chapter 107 (Transoral Laser Microsurgery)
• Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Chapter 79 (Awake Laser Laryngeal Surgery)