ESOPHAGEAL CARCINOMA-TARGET VOLUME DELINEATION

General Principles

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  • The standard of care in radiotherapy for esophageal cancer uses CT-based planning with IMRT or 3D-CRT employing multiple beam angles and allowing dose conformality.
  • Accurate delineation of target volumes, normal structures, and OARs as well as evaluation of DVHs is essential.
  • The esophagus begins at the lower border of the cricoid cartilage and descends through the mediastinum into the abdomen; therefore, understanding anatomic relations (neck, mediastinum, lungs, heart, spinal cord, etc.) is essential.
  • Simulation: patients are typically positioned with arms above the head to maximize beam arrangements. For distal or GE junction tumors, respiratory motion assessment (4DCT, gating, breath-hold) should be incorporated.
  • Nil per os for 2–3 hours prior to simulation is recommended for distal or GE junction tumors to reduce gastric/bowel gas. IV contrast helps improve nodal delineation.
  • Using the 40 cm standard distance from incisors: cervical esophagus ≈15–20 cm, upper thoracic ≈18–25 cm, mid/distal thoracic ≈25–30/32 cm, abdominal esophagus ≈30–40 cm.
  • Subdivision by anatomy is recommended: cervical, thoracic, and GE junction malignancies.
  • Tumors involving multiple esophageal segments should be contoured following guidelines for all involved subsites.
  • Regardless of tumor location, lungs should be contoured for DVH analysis.
  • GTV should be delineated on CT and PET; endoscopy and endoscopic ultrasound help define invasion depth and peri-esophageal lymph nodes. Bronchoscopy recommended when tumor is above carina to rule out tracheoesophageal fistula.
  • ITV defined as envelope of internal motion of GTV on 4DCT, expanded to CTV then to PTV.
  • Standard ITV→CTV expansion: 1 cm radially for peri-esophageal lymph nodes; 3–4 cm superior-inferior along mucosa to cover submucosal spread and skip lesions.
  • CTV expansion can be reduced to 0.5 cm where overlapping heart/uninvolved liver when motion management is adequate.
  • Large stomach/abdominal involvement in GE junction tumors may require ≥4 cm gastric margin, especially for pre-op doses <4500 cGy.
  • Uninvolved vertebral bodies and kidneys excluded from CTV; uninvolved gastric mucosa requires only 2 cm margin.
  • For involved lymph nodes: GTV→CTV margin 0.5–1 cm. CTV→PTV margin 0.5 cm.
  • Regional lymph nodes included based on tumor location: cervical/upper thoracic—bilateral supraclavicular basins; mid/lower thoracic—mediastinal nodes (levels 2, 4, 7); GE junction—para-aortic and gastrohepatic ligament nodes.
  • Siewert classification defines type I (1–5 cm above junction), type II (1 cm above to 2 cm below), type III (2–5 cm below junction). Staging now classifies all with epicenter ≤2 cm into gastric cardia as esophageal.

Suggested Target Volumes

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Esophagus SubdivisionDefinitionITV → CTV MarginCTV → PTV MarginElective Nodal CoverageDose
Cervical Incisors to approximately 15–20 cm 3 cm superior and inferior (oriented along mucosa), 1 cm radially 0.5 cm Periesophageal, supraclavicular, ± anterior mediastinal 50.4 Gy in 1.8 Gy/fraction; consider boost to 60–70 Gy for SCC
Upper thoracic From 18–20 cm to approximately 25 cm 3 cm superior and inferior (oriented along mucosa), 1 cm radially 0.5 cm Periesophageal, supraclavicular, ± anterior mediastinal 50.4 Gy in 1.8 Gy/fraction
Lower thoracic From 25 cm to approximately 37 cm 3 cm superior and inferior (oriented along mucosa), 1 cm radially 0.5 cm Periesophageal 50.4 Gy in 1.8 Gy/fraction (definitive); 41.4–50.4 Gy in 1.8 Gy/fraction (pre-operative)
Abdominal / GE junction From approximately 37 to 42 cm 3 cm superior (along esophageal mucosa) and 1–2 cm inferior (along gastric mucosa) for 50.4 Gy dose; ≥4 cm gastric margin appropriate for pre-operative doses ≤4500 cGy 0.5 cm Periesophageal, gastrohepatic ligament (paracardiac and left gastric stations), celiac axis, ± splenic hilum 50.4 Gy in 1.8 Gy/fraction (definitive); 41.4–50.4 Gy in 1.8 Gy/fraction (pre-operative)