Is ¹⁸F-FDG-PET/CT useful in staging of locally advanced signet-ring cell esophageal adenocarcinoma?

Objective: Signet-ring cell esophageal carcinoma (SRCEC) is a subtype of adenocarcinoma in which >10 %–50 % of cells have intracellular mucin. There is limited information regarding PET/CT in staging SRCEC. The purpose of this study is to evaluate the usefulness of PET/CT in staging patients with locally advanced SRCEC. Methods: 91 patients with biopsy-proven SRCEC and pretreatment FDG-PET/CT were included. SUVmax of the primary tumor, and size and SUVmax of regional lymph nodes were evaluated. In patients who had presurgical FDG-PET/CT after neoadjuvant therapy, response of the primary tumor and nodal metastases were assessed. Results: Primary tumor was avid in 80/91 (88 %) (SUVmax range 3.8–28). Stage of 11 tumors without FDG uptake was T1N0–1 (n = 3), T2N0 (n = 1) and T3N0–2 (n = 7). 68 (75 %) patients had non-FDG avid nodes. Biopsy in 32/68 patients with non-FDG avid nodes was positive in 12 (38 %). 23 had FDG avid nodes, 14 were biopsied and 3 were positive for metastases. After chemoradiation, 73 (86 %) had persistent FDG uptake in the primary tumor (SUVmax range 3.5–17.9) and 68 (93 %) had residual viable malignancy. 8/11 patients with resolution of FDG uptake in the primary tumor had persistent malignancy. Regarding nodal metastases, 41/84 (49 %) had residual nodal disease in surgical specimens and only 4 (10 %) had nodes that were FDG avid. Conclusion: PET/CT is useful in detecting the primary tumor in patients with SRCEC during the initial staging and after neoadjuvant therapy. The utility of PE/CT in detecting locoregional nodal disease prior to and after chemoradiation is limited.