Relevance of [18F]fluorodeoxyglucose positron emission tomography-positive lymph nodes after neoadjuvant chemotherapy for squamous cell oesophageal cancer

BACKGROUND: Several studies have examined the clinical significance of metabolic response in primary tumours by [(18) F]fluorodeoxyglucose positron emission tomography ((18) F-FDG-PET) in patients with oesophageal cancer who undergo neoadjuvant therapy. The relevance of the metabolic response in lymph nodes is unclear. METHODS: Consecutive patients with oesophageal cancer who underwent neoadjuvant chemotherapy followed by surgery were studied. (18) F-FDG-PET was performed before and 2-3 weeks after completion of neoadjuvant chemotherapy, assessing FDG uptake in primary tumours and lymph nodes considered to be metastatic. RESULTS: Before therapy, 156 (73·9 per cent) of 211 patients had PET-positive nodes, of whom 89 (57.1 per cent) had no evidence of metabolic activity in these lymph nodes following chemotherapy. There was a significant relationship between post-treatment lymph node status assessed by FDG-PET and numbers of pathologically confirmed metastatic lymph nodes. Patients with post-treatment PET-positive nodes had shorter survival than those without (5-year survival rate 25 versus 62·6 per cent; P < 0·001). There was no difference in survival between patients with PET-positive nodes before but not after therapy and patients who had PET-negative nodes throughout (5-year survival rate 59 versus 71 per cent respectively; P = 0·207). Multivariable analysis identified post-treatment nodal status assessed by FDG-PET and tumour depth as independent prognostic factors. CONCLUSION: Identification of PET-positive lymph nodes after completion of chemotherapy is a predictor of poor prognosis of patients with oesophageal cancer scheduled for surgery. FDG-PET lymph node status after neoadjuvant chemotherapy is more important than that before chemotherapy.