PET/CT in Oesophageal Cancer

1. Anatomy and lymph node drainage

• Extent: the oesophagus runs from the upper oesophageal sphincter through the neck, chest and diaphragm to the oesophagogastric junction (OGJ).
• Describe the primary: record its epicentre, distance from the incisors, longitudinal extent and relation to the OGJ. These guide staging and radiotherapy planning.
• Junction rule: a tumour centred within 2 cm of the OGJ and extending into the oesophagus uses the oesophageal staging scheme; a more distal tumour uses the gastric scheme. [3]
• Longitudinal lymphatics: involved nodes may lie well above or below the primary.
• Regional nodes: the AJCC eighth-edition map extends from the upper oesophageal sphincter to the coeliac artery. Coeliac nodes are regional, even for a distal primary.
• Distant disease: non-regional nodes and organ deposits are M1. Inspect liver, lung, bone and adrenal glands. [3]

2. Epidemiology and risk factors

• Squamous cell carcinoma (SCC): the dominant histology worldwide; especially prominent in eastern Asia and parts of Africa. Tobacco and alcohol are important risk factors.
• Adenocarcinoma: relatively more common in some high-income countries; associated with reflux, Barrett’s oesophagus and obesity.
• Why histology matters: treatment pathways and FDG uptake patterns can differ. [4] [5]

3. Classification and the FDG signal

• Tracer biology: FDG is a glucose analogue taken up by tumour and inflammatory cells; PET localises metabolism, not histology.
• Positive finding: focal uptake is more convincing with a matching lesion on diagnostic CT or endoscopy.
• Negative finding: tiny lesions can be missed because of limited spatial resolution. [2] [6]

4. Diagnosis and initial work-up

1. Endoscopy and biopsy: establish histology and locate the lesion.
2. Contrast-enhanced CT: map the primary, adjacent structures and visible metastases.
3. FDG PET/CT: in a patient still eligible for radical treatment, search for additional disease that could change treatment intent or radiation fields.
4. Selective EUS: resolve a local question, such as sampling a node outside the planned field. Endoscopic resection is more informative about depth in suspected early mucosal disease. [1] [2]

• NICE: offer FDG PET/CT after endoscopy and whole-body CT for oesophageal or OGJ tumours suitable for radical treatment, except T1a.
• ESMO: perform PET in candidates for oesophagectomy to seek occult metastases.
• EUS: use when its result guides management, not solely to distinguish T2 from T3.
• Laparoscopy: in locally advanced OGJ adenocarcinoma extending into the cardia, it can answer a peritoneal question PET may miss. [1] [2]

5. Staging: what PET can and cannot assign

Table 1. Simplified AJCC eighth-edition categories; clinical and pathological stage groupings are separate and are not inferred from PET uptake alone. [3]

• PET strength: revealing disease outside the expected regional field.
• Nodal limits: a node beside an avid primary can merge with it; an involved small node can be PET-negative. Coeliac nodes remain regional N disease.
• Unexpected M1 focus: compare diagnostic CT, add targeted MRI or ultrasound when useful, and biopsy if feasible before abandoning radical treatment. [2] [3] [7]

6. PET tracers

• Established tracer: ¹⁸F-FDG for staging, selected response assessment and suspected recurrence.
• Strength and limit: it highlights metabolically active SCC and adenocarcinoma but is not cancer-specific and can miss microscopic disease.
• Other tracers: research tools in oesophageal carcinoma, without an established role in the NICE/ESMO staging pathway. They do not replace indicated contrast CT, EUS or tissue sampling. [1] [2] [6]

7. Indications for FDG PET/CT

Table 2. Indications and limits, based chiefly on NICE, ESMO and the cited trials. [1] [2] [8] [9] [10]

8. Diagnostic performance and treatment response

• Distant metastases: an older staging meta-analysis reported pooled sensitivity of 71% for FDG PET versus 52% for CT. These pre-modern-scanner estimates are not a patient-specific prediction. [7]
• Regional nodes: EUS was more sensitive than PET in that analysis. PET adds a whole-body search; anatomical or endoscopic tests still answer wall and nearby-node questions. [7]
• Early response in a trial: CALGB 80803 studied oesophageal/OGJ adenocarcinoma. A fall in SUVmax of less than 35% after induction chemotherapy triggered a chemotherapy switch during chemoradiotherapy. Pathological complete response in the two switched groups was 18% and 20%. [8]
• Clinical meaning: that phase II result supports a studied response-adapted strategy, not a universal instruction to switch treatment. Serial scans require comparable scanner, reconstruction, uptake interval and glucose conditions. [6] [8]
• After chemoradiotherapy: radiation oesophagitis can remain FDG avid, while small residual cancer can be PET-negative.
• Complete-response question: preSANO used PET/CT for interval metastases and combined endoscopy, deep biopsies, EUS and suspicious-node sampling for local response. SANO studied surveillance only after a multimodal clinical complete response. A negative PET alone cannot justify omitting surgery or declaring pathological complete response. [9] [10]

9. Patient preparation and scan timing

• Standard preparation: follow the local validated FDG protocol, including fasting, a blood-glucose check and a documented uptake interval.
• For serial scans: record treatment dates; use the same scanner and acquisition method when possible.
• Before interpretation: ask about recent biopsy, dilatation, stent, surgery, radiation and systemic therapy. A low-dose non-contrast PET/CT component does not replace diagnostic contrast CT. [6]
• After chemoradiotherapy: early diffuse uptake along the treated segment is less specific than a new focal mass with a CT correlate. No single SUV threshold reliably separates inflammation from tumour; use endoscopic and clinical assessment when local treatment would change. [9]

10. What to look at when reporting

• Primary: histology, location, length, relationship to the OGJ, CT wall finding and baseline FDG avidity.
• Regional nodes: describe stations and side; recognise that the coeliac basin is regional in the oesophageal map.
• Distant sites: report each non-regional node or organ lesion separately, with its CT correlate and degree of certainty.
• Treatment context: state scan dates, recent procedures, radiation field, chemotherapy and comparability with baseline imaging.
• Clinical conclusion: identify the finding that could change intent and specify targeted imaging or biopsy when confirmation is needed. Avoid assigning T depth or complete pathological response from PET alone. [3] [6]

11. Pitfalls

Table 3. FDG is sensitive to inflammation and limited by lesion size. A focal PET abnormality needs anatomical context. [6] [9] [11]

12. What the guidelines say

Table 4. These are separate oesophageal/OGJ recommendations; the gastric-cancer PET pathway is more selective. [1] [2]

Test yourself

Two quick questions. Choose an answer to see the explanation.

Further reading: Oesophageal cancer and GIST (extended article).

Spotted an error or something out of date? Report an error