PET-CT for Oesophageal and — Stomach Cancer

In oesophageal cancer, PET-CT is used to detect disease that has spread beyond the primary tumour — to lymph nodes in the chest, abdomen, or neck, and to organs such as the liver, lungs, or bones. It is part of standard staging according to NCCN and ESMO guidelines. It does not accurately show how deeply the tumour has grown into the oesophageal wall; endoscopic ultrasound does that. The two scans together give your team a picture that neither provides alone.

A clear PET-CT is encouraging, but its meaning depends on your tumour type. In oesophageal cancer and intestinal-type gastric cancer — where tumours reliably absorb the PET tracer — a clear result is meaningful. In signet ring cell or mucinous gastric cancers, which often produce little uptake, a clear PET does not confirm the cancer is contained. Ask your oncologist whether your tumour type is reliably FDG-avid, and what other staging information they are using alongside the scan result.

PET-CT and EUS answer different questions and neither replaces the other. PET-CT looks for disease that has spread to distant lymph nodes and organs. EUS assesses how deeply the primary tumour has grown into the oesophageal or stomach wall — the T-stage — and evaluates nearby lymph nodes at close range. T-stage is one of the main factors that determines whether you go directly to surgery or need chemotherapy or radiotherapy first. A PET-CT alone does not provide that information reliably.

Signet ring cell carcinoma is a subtype of stomach cancer named for the appearance of its cells under a microscope. It tends to spread diffusely along the stomach wall rather than forming a distinct mass, and its cells absorb relatively little of the radioactive tracer PET relies on. The scan can appear completely normal even when disease is present and extensive. If your biopsy shows signet ring histology, ask your team directly whether PET is expected to be informative in your case, or whether other staging tools will take priority.

No. Peritoneal metastases are not reliably detected by PET-CT or by CT alone. They typically appear as thin deposits or small nodules along the abdominal lining rather than bulky masses, and they produce insufficient tracer uptake for PET to register. ESMO guidelines recommend diagnostic laparoscopy for locally advanced gastric cancer specifically because imaging misses peritoneal spread in a substantial proportion of patients. If your staging plan does not include laparoscopy, it is reasonable to ask your surgeon whether one is indicated for your case.

CION coordinates PET-CT scans with partner imaging centres rather than running its own scanners. Your care team will arrange the referral and ensure the images are reviewed as part of your overall staging assessment. On the day, you will typically be asked to fast for several hours beforehand and will receive a radioactive tracer injection. You then wait quietly for around an hour while the tracer distributes, before the scan itself. The full appointment usually takes two to three hours in total, though your team will give you specific instructions.