What is the recommended treatment approach for a patient with cancer of the supraglottic larynx using definitive radiotherapy?

Definitive Radiotherapy for Supraglottic Laryngeal Cancer

For supraglottic laryngeal cancer, definitive radiotherapy is an effective organ-preservation approach that achieves local control rates of 80-100% for early-stage disease (T1-T2) and 56-68% for advanced disease (T3-T4), with elective neck treatment mandatory even in clinically N0 patients. 1

Treatment Selection by Stage

Early-Stage Disease (T1-T2N0)

• Definitive radiotherapy alone is the preferred treatment for early supraglottic cancer, achieving 5-year local control rates of 86-100% for T1 and 59-83% for T2 lesions. 2, 3, 4
• Radiation therapy offers equivalent survival to conservation surgery but with superior functional outcomes and lower complication rates (4% vs. higher surgical morbidity). 3, 5
• Surgical salvage remains highly effective for radiation failures in early-stage disease, with ultimate local control rates reaching 89% for Stage II disease when salvage is included. 2

Advanced Disease (T3-T4a)

• Concurrent chemoradiation with high-dose cisplatin is the Category 1 recommendation for larynx preservation in resectable T3-T4a supraglottic cancer, offering significantly higher larynx preservation rates than radiation alone. 1, 6
• Local control rates for T3 disease with definitive radiotherapy range from 63-81%, and 35-56% for T4 disease. 2, 5, 4
• Concurrent chemoradiation provides superior larynx preservation compared to radiation alone or induction chemotherapy followed by radiation, though without overall survival benefit and at the cost of higher acute toxicity. 1

Mandatory Neck Management

All patients with supraglottic lesions require elective treatment of the neck, even if clinically N0, due to occult metastasis rates approaching 30-60%. 1

Radiation Field Design

• The bilateral neck must be included in the radiation field for all supraglottic cancers, regardless of nodal status. 1
• High-dose radiation (near maximum tolerable doses) using shrinking field technique is recommended, without routine prophylactic whole neck irradiation beyond the primary treatment fields. 4

Post-Treatment Neck Assessment (N+ Disease)

• Patients with clinically involved nodes (N+) who achieve complete clinical, radiologic, and metabolic response on PET-CT at ≥12 weeks post-treatment do not require elective neck dissection. 1
• The negative predictive value of post-treatment PET-CT is 95%, making observation appropriate for complete responders. 1
• Patients with equivocal FDG uptake on post-treatment imaging should undergo neck dissection. 1

Radiation Dose and Technique

• Moderate to high-dose radiotherapy (typically 66-70 Gy) delivered with curative intent is standard. 2, 5, 4
• Tumor volume on pretreatment CT scan and vocal cord mobility significantly influence local control probability. 3
• Nodes <3 cm are controlled in 88% of cases, while nodes ≥3 cm achieve only 45% control with radiation alone. 4

Critical Prognostic Factors

Favorable Features

• T1-T2 primary tumors with preserved vocal cord mobility achieve 83-100% local control. 3, 4
• N0 or N1 disease (88% cure rate for N0 vs. 43% for N2-N3). 4
• Tumor volume <6 cm³ on CT imaging. 3

Unfavorable Features

• T4 disease combined with N3 nodes represents the worst prognostic category and should receive multidisciplinary treatment including surgery rather than radiation alone. 4
• Base of tongue involvement significantly worsens prognosis. 4
• Multiple positive nodes predispose to locoregional recurrence. 2

Functional Outcomes and Complications

• 84% of patients with locoregional control after definitive radiotherapy retain laryngeal function, compared to permanent voice changes with surgical approaches. 5
• Severe late radiation toxicity occurs in approximately 20% of patients with controlled disease, requiring tracheostomy in 7% of cases. 4
• Acute toxicity during treatment is common but manageable. 2

Common Pitfalls to Avoid

• Never omit elective neck treatment in supraglottic cancer, even for clinically N0 disease—failure to treat the neck results in 30% recurrence rates. 1
• Do not perform planned neck dissection after complete response on PET-CT at ≥12 weeks; observation is equally effective and more cost-effective. 1
• Avoid radiation alone for T4N3 disease—this combination requires upfront surgery or concurrent chemoradiation. 4
• Do not delay post-treatment PET-CT before 12 weeks, as earlier imaging has reduced accuracy. 1
• Limited surgery after high-dose radiation carries significant morbidity—salvage should be definitive (total laryngectomy) when needed. 4