Cervical oesophageal cancer with a cervical nodal metastasis
A 55-year-old woman presents with progressive dysphagia and a 3 cm right cervical node at level IV. Endoscopy shows a squamous carcinoma of the cervical oesophagus at 18–22 cm from the incisors, with the upper border 2 cm below the cricopharyngeus. PET shows the primary and the level IV node, with no other uptake. She is planned for definitive chemoradiotherapy. The team must decide on the superior and inferior field borders, whether to treat the retropharyngeal and supraclavicular nodes, and how to spare the spinal cord and parotids.
1. Define the superior and inferior borders of the target volume and justify them anatomically.
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The cervical oesophagus begins at the cricopharyngeus, approximately at the level of C6, and runs to the thoracic inlet at T1. The superior border should be at the lower border of the cricoid cartilage (C6) with a 3 cm margin above the gross tumour, which places it around C4–C5 to cover the pharyngo-oesophageal junction and the retropharyngeal nodes. The inferior border should extend at least 5 cm below the gross tumour to cover submucosal spread, which for a tumour ending at 22 cm would place the border in the upper thoracic oesophagus at approximately T4.
Laterally, the volume should include the paratracheal and recurrent laryngeal nodal stations in the tracheo-oesophageal groove and the supraclavicular fossa on the right, because the level IV node indicates drainage along the cervical chain. The spinal cord lies posterior to the oesophagus and must be excluded from the high-dose volume by using an AP/PA or IMRT technique.
2. Explain the anatomical basis for the level IV nodal involvement and which nodal stations should be electively covered.
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The cervical oesophagus drains via lymphatics that run longitudinally in the submucosal plexus and then to the paratracheal, recurrent laryngeal and deep cervical nodes. The right level IV node lies in the supraclavicular fossa, which receives drainage from the cervical oesophagus via the thoracic duct on the left and the right lymphatic duct on the right. Because the tumour is at 18–22 cm, it is above the carina and drains predominantly to cervical rather than mediastinal nodes.
Elective coverage should include bilateral level IV and supraclavicular nodes, the retropharyngeal nodes, and the upper paratracheal nodes (level 2R/2L) down to the carina. The retropharyngeal nodes lie medial to the carotid sheath and are at risk for upper cervical oesophageal tumours, so the superior border should reach the skull base if the tumour extends above C6.
3. What dose constraints would you apply to the spinal cord and parotids, and what trade-off might be required?
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The spinal cord is immediately posterior to the oesophagus, so the cord Dmax should be kept below 45–50 Gy; with a 60–66 Gy prescription this requires a steep dose gradient, typically using IMRT or VMAT with a posterior beam arrangement. The parotids lie lateral to the masseter and are at risk if the superior border reaches C4–C5, so the mean dose should be kept below 26 Gy to preserve salivary function.
The trade-off is that sparing the parotids may push dose posteriorly toward the cord, so the plan must prioritise cord tolerance. If the cord constraint cannot be met, consider a sequential plan with a cord block after 45 Gy, accepting a small risk of marginal recurrence. Document the compromise and consider proton therapy if available.