What are the guidelines for radiotherapy contouring in an adult patient, possibly with a history of smoking, diagnosed with cervical esophageal squamous cell carcinoma (ESCC) undergoing intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT)?

Radiotherapy Contouring for Cervical Esophageal Squamous Cell Carcinoma

For cervical esophageal squamous cell carcinoma treated with IMRT or VMAT, use CT-based simulation with the gross tumor volume (GTV) including the primary tumor and involved regional lymph nodes, with a clinical target volume (CTV) extending 5 cm cephalad and caudal to the tumor plus 1.5-2 cm radial margin, and deliver elective nodal irradiation to bilateral neck levels III, IV, VI and upper mediastinal nodes to 40-45 Gy, followed by a boost to the GTV to at least 60-66 Gy. 1, 2, 3

Target Volume Definition

Gross Tumor Volume (GTV)

• The GTV should include the primary tumor and all involved regional lymph nodes as identified on CT simulation, endoscopy reports, barium swallow, and PET/CT scans when available. 1
• Review all imaging modalities with the multidisciplinary team before simulation to inform treatment volume determination. 1
• For cervical esophageal cancer specifically, 86.7% of local failures occur within the GTV, emphasizing the critical importance of adequate GTV coverage and dose. 2

Clinical Target Volume (CTV)

• The CTV should extend 5 cm cephalad and caudal from the GTV, with a 1.5-2 cm radial margin to account for microscopic disease spread. 1
• Account for respiratory motion uncertainties when defining the planning target volume (PTV). 1

Elective Nodal Irradiation (ENI)

• Elective nodal irradiation to bilateral neck levels III, IV, and VI plus upper mediastinal lymph nodes is strongly recommended, as patients receiving ENI demonstrate superior nodal regional control compared to involved-field irradiation alone. 2, 4
• The supraclavicular region accounts for 62.5% of regional failures, making it a critical area for elective coverage. 2
• The biologically equivalent dose of approximately 40-45 Gy should be delivered electively to clinically negative regions at risk for microscopic spread. 1, 4

Radiation Dose Prescription

Definitive Dose to GTV

• Deliver a minimum of 60 Gy to the GTV, with doses ≥66 Gy achieving local control rates of 94.7% in cervical esophageal cancer. 2, 3
• The American Radium Society recommends 60-70 Gy for definitive concurrent chemoradiotherapy in cervical esophageal squamous cell carcinoma. 3
• A dose-response relationship exists for cervical esophageal cancer, with EQD2 (equivalent dose in 2 Gy fractions) to GTV being an independent predictor of locoregional failure-free survival. 2
• Standard fractionation of 2 Gy per fraction is recommended, delivered once daily. 1, 5

Elective Nodal Dose

• Deliver 40-45 Gy to elective nodal regions at risk for microscopic disease. 1, 4

Simulation and Treatment Planning

Technical Requirements

• CT-based simulation with 3D treatment planning is mandatory. 1
• IMRT or VMAT is appropriate for cervical esophageal cancer to reduce dose to critical normal structures including the larynx, spinal cord, thyroid, and major vessels. 1, 2, 3
• Use immobilization devices for reproducibility of daily setup. 1
• IV and/or oral contrast during CT simulation may aid in target localization when clinically appropriate. 1

Critical Structure Constraints

• Spinal cord: maximum dose <45 Gy 1
• Heart: limit one-third of heart to <50 Gy, with particular attention to minimizing left ventricle doses 1
• Lungs: limit volume receiving ≥20 Gy to ≤20% of total lung volume, and volume receiving ≥10 Gy to ≤40% of total lung volume 1
• Liver: limit 60% of liver to <30 Gy 1
• Kidneys: at least two-thirds of one kidney should receive <20 Gy 1

Important Clinical Considerations

Concurrent Chemotherapy

• Platinum-based doublet concurrent chemotherapy regimens (cisplatin/5-FU or carboplatin/paclitaxel) should be administered with radiotherapy for locally advanced cervical esophageal squamous cell carcinoma. 3, 5
• The American Radium Society recommends definitive concurrent chemoradiotherapy as the standard larynx-preserving approach for locally advanced disease. 3

Treatment Duration

• Complete the entire radiotherapy course within 8 weeks to avoid compromising locoregional control and survival. 1
• Avoid treatment interruptions or dose reductions for manageable acute toxicities through aggressive supportive care rather than treatment breaks. 1

Prognostic Factors

• N stage, hoarseness, and recurrent laryngeal nerve lymph node involvement are independent predictors of poorer overall survival. 2
• N stage and radiation dose to GTV are independent predictors of locoregional failure-free survival. 2
• Unresectable status and M1LYM disease are associated with significantly worse locoregional control and overall survival. 4

Common Pitfalls and Toxicity Management

Acute Toxicity

• Grade 3 radiation esophagitis occurs in approximately 55% of patients, requiring proactive management with antiemetics, antacids, and nutritional support. 5
• Monitor patients weekly during treatment with vital signs, weight, and blood counts. 1
• Consider feeding jejunostomy or nasogastric tubes when estimated caloric intake falls below 1500 kcal/day. 1

Late Toxicity

• Hypothyroidism develops in 31.6% of patients at 5 years and 62.5% at 10 years, requiring long-term thyroid function monitoring. 4
• Cardiovascular disease occurs in 17.5% at 5 years and 21.3% at 10 years, necessitating cardiovascular surveillance in long-term survivors. 4
• Patients achieving disease control typically do not require permanent gastrostomy tubes or tracheostomy, preserving laryngopharyngeal function. 4

Geographic Miss Prevention

• Since 83% of initial progression occurs locoregionally in cervical esophageal cancer, meticulous target delineation with adequate margins and elective nodal coverage is essential to prevent geographic misses. 4, 5
• Correlate all available imaging (CT, PET/CT, endoscopy, barium swallow) with clinical findings before finalizing treatment volumes. 1