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SCOPE 2 is a randomised Phase II/III trial studying radiotherapy dose escalation and positron emission tomography (PET) response in patients with oesophageal cancer treated with definitive chemoradiation. Patients with upper third oesophageal tumours >15cm ab oral with supraclavicular fossa (SCF) nodal involvement (N+ by TNM criteria) are eligible for participation, providing total contiguous disease length is <10cm. The current radiotherapy guidance does not specifically cover the scenario of involved SCF nodes. There are no widely available delineation protocols for this group of patients. Therefore, we developed a new protocol to provide guidance for clinicians and to ensure consistency of nodal outlining within the trial.

A literature search was performed to review existing evidence for elective nodal irradiation (ELNI) and upper third oesophagus nodal anatomy. Existing nodal outlining atlases were reviewed, adapted and incorporated into existing SCOPE 2 radiotherapy guidance to produce the new protocol.

There is no clinical evidence to recommend ELNI of the SCF in node negative patients, so this guidance only applies to patients with positive nodes in the SCF. The lymphatics of the proximal third oesophagus drain into bilateral deep cervical nodes that are contained within the SCF (2). Therefore, we have recommended that patients with positive SCF nodes receive irradiation of whole ipsilateral SCF and contralateral SCF. There is no randomisation to the dose escalation arm of GTVn in SCOPE 2 so CTVscf is treated to 5000cGy in 25#.

Table 1: Anatomical Boundaries of the Supraclavicular Fossa. Boundaries adapted from RTOG Breast Cancer Contouring Atlas and RTOG Head and Neck Atlases.

Image 1: A 5mm minimum margin is included around involved node. SCF volume is labelled CTVscf. 

Image 2: Coronal view of bilateral SCF volume

Summary of volumes:

GTVn = whole involved node, >30mm from GTVp
CTVn = Involved node + 5mm in all directions
CTVscf = CTVn + whole bilateral SCF
PTVscf = CTVscf + 5mm margin in all directions (6mm sup-inf if using 3mm slices)
PTV_5000 = PTVscf + standard dose PTV

This new delineation protocol provides a standardised approach that can be adopted by the wider radiotherapy community. Using this protocol within the context of a randomised trial allows for assessment of loco-regional control rates, survival data and monitors for unexpected toxicity. Trial clinical outcome data will inform further versions of the delineation protocol.