Visualisation of metastatic oesophageal and gastric cancer and prediction of clinical response to palliative chemotherapy using ¹⁸FDG PET

Aim: This study assessed the value of ¹⁸F-deoxyglucose positron emission tomography (FDG-PET) for visualisation and early metabolic response assessment in metastatic gastro-oesophageal cancer. Patients, methods: Twenty-six patients who were treated for metastatic disease (20 adenocarcinomas, 6 squamous cell cancers) underwent FDG-PET before and two weeks after the onset of palliative chemotherapy with either oxaliplatin + 5-FU/LV or with docetaxel + capecitabine. PET results were validated according to clinical response based on RECIST criteria. Results: Twenty-four tumours (92%) could be visualised by FDG-PET and were also assessable by a second PET scan at 2 weeks. The 2 tumours that were not detectable by PET were both gastric cancers belonging to the non-intestinal subtype according to Lauren. Median time to progression and overall survival were not significantly different for metabolic responders and non-responders (6.3 vs 5.3 months and 14.1 vs 12.5 months, respectively). Conclusion: In this heterogeneous study population, FDG-PET had a limited accuracy in predicting clinical response. However, the metabolic response prediction was particularly good in the subgroup of patients with oesophageal squamous cell cancer. Therefore, FDG-PET and assessment of cancer therapy clearly merits further investigation in circumscribed patient populations with metastatic disease.