What are the guidelines for adjuvant radiotherapy (RT) contouring in carcinoma of the epiglottis after laser excision?

Adjuvant Radiotherapy Contouring for Epiglottic Carcinoma Post-Laser Excision

For epiglottic carcinoma treated with laser excision, adjuvant radiotherapy should target the tumor bed and involved/dissected lymph node regions at 2 Gy per fraction to 56-60 Gy in the absence of positive margins or extracapsular extension, or 60-66 Gy if microscopically positive margins or extracapsular nodal extension are present. 1

Risk-Stratified Dose and Volume Guidelines

High-Risk Features (Positive Margins or Extracapsular Extension)

• Deliver 60-66 Gy at 2 Gy/fraction once daily to regions with microscopically positive surgical margins and extracapsular nodal extension 1
• Without concurrent chemotherapy, target 66 Gy specifically, though evidence is limited for this recommendation 1
• Critical timing consideration: Complete radiotherapy within 85 days of surgery, as time to completion may be more important than dose itself 1

Standard-Risk Features (Negative Margins, No Extracapsular Extension)

• Deliver 56-60 Gy at 2 Gy/fraction once daily to the tumor bed and involved, dissected lymph node regions 1
• This applies when perineural invasion, lymphovascular invasion, or close margins (1-3 mm) are present without frank positive margins 1

Target Volume Contouring Principles

Primary Tumor Bed Coverage

• Include the entire resection bed with appropriate margin accounting for anatomical constraints 2
• For epiglottic tumors, recognize that margins >5 mm are anatomically not feasible on ventral and dorsal surfaces due to laryngeal anatomy 3
• Consider preepiglottic space involvement, particularly for infrahyoid epiglottic lesions which have higher recurrence rates 4

Nodal Coverage Strategy

• Ipsilateral neck dissection levels should be included in the radiation field for well-lateralized lesions 5
• For supraglottic/epiglottic primaries with 89% epiglottic involvement, bilateral neck coverage is typically warranted unless tumor is strictly lateralized 6
• Treat dissected nodal regions to the same dose as the primary tumor bed based on risk stratification 1

Fractionation Considerations

Standard Fractionation (Preferred)

• 2 Gy per fraction, once daily, 5 days per week is the standard approach for adjuvant therapy 1
• Total treatment time should be minimized, ideally completing within 6-7 weeks from start of radiotherapy 1

When Altered Fractionation May Be Considered

• Generally not recommended in the adjuvant setting for epiglottic carcinoma 1
• Altered fractionation is reserved for definitive radiotherapy in specific scenarios (T3 N0-1 disease without concurrent chemotherapy) 1

Critical Pathologic Features Requiring Attention

Indications for Concurrent Chemotherapy

• Positive margins (tumor on ink) mandate concurrent platinum-based chemotherapy with radiotherapy 1
• >1 mm extracapsular extension or ≥5 positive nodes require concurrent chemoradiation 1
• Standard regimen: Cisplatin 100 mg/m² every 21 days during radiotherapy 2

Intermediate-Risk Features (Radiation Alone May Suffice)

• Close margins (1-3 mm), perineural invasion, or lymphovascular invasion 1
• 2-4 positive nodes and/or ≤1 mm extracapsular extension 1
• Single positive node >3 cm requires multidisciplinary discussion as evidence is uncertain 1

Common Pitfalls and Caveats

Anatomical Constraints Specific to Epiglottis

• Do not expect 5 mm margins on all surfaces—this is anatomically impossible for epiglottic resections 3
• Infrahyoid epiglottic tumors have worse outcomes than suprahyoid lesions due to preepiglottic space and thyroid cartilage involvement 4
• Consider xeroradiography or modern cross-sectional imaging to assess anterior extension into preepiglottic space 4

Timing Imperatives

• Surgery to completion of RT should be <85 days as this may be the most critical prognostic factor 1
• Delays beyond this threshold significantly compromise outcomes 1

Volume Design Considerations

• Radiation volumes are not standardized and must be individualized based on surgical findings, pathology, and anatomical subsites at risk 2
• For supraglottic primaries including epiglottis, bilateral neck coverage is typically required unless strictly lateralized 6
• Elective nodal regions at intermediate/low risk require 44-63 Gy depending on estimated tumor burden 1

Long-Term Surveillance

• Monitor TSH every 6-12 months as hypothyroidism occurs in 20-25% of patients receiving neck irradiation 5