Is [18F] fluoro-d-glucose PET combined with computed tomography useful for staging of T1 lung cancer with pure solid morphology? How much and how far?

Purpose To evaluate the usefulness of [18F] fluoro- d -glucose PET combined with computed tomography ([ 18 F]FDG PET/CT) in staging T1 lung tumors with pure solid morphology on CT, focusing on the different histology subtypes, accuracy, detection rate of metastases, and its impact on changes in TNM staging. Patients and methods Retrospectively, 238 patients with lung cancer and T1 nodules with pure solid morphology on CT scan, staged with [ 18 F]FDG PET/CT and chest contrast-enhanced CT (ceCT) were included. Primary tumor (T) sizes were assessed on chest ceCT and PET/CT. Maximum standardized uptake values (SUVmax) of the primary lung tumor were obtained from PET. Prevalence of lymph node and distant metastases was assessed for the three substages of T1 lung cancer (T1a, T1b, and T1c). Results Sixty-two (26%) patients with solid T1 lung cancer had lymph node metastases (T1a: 22%, T1b: 16%, T1c: 38%), and 29 (12%) showed distant metastases (T1a: 11%, T1b: 11%, T1c: 14%) in PET/CT imaging. [ 18 F]FDG PET/CT detected distant metastases in 12 patients with negative chest ceCT. [ 18 F]FDG PET/CT upstaged 26 patients (11%) and downstaged 13 patients (6%) compared with ceCT. Primary tumor histological subtypes and SUVmax values significantly correlated with the risk of lymph node and distant metastases ( P < 0.001). However, the sensitivity for mediastinal nodal detection (N+) was poor with both CT (35%) and [ 18 F]FDG PET/CT (47.5%). Conclusion [ 18 F]FDG PET/CT is useful for staging of pure solid T1 lung cancer with a detection rate of 26% for lymph node metastases and 12% for distant metastases. [ 18 F]FDG PET/CT is more accurate and has a higher positive predictive value than chest ceCT and leads to a change in the TNM stage in 17% of patients. Due to the limited sensitivity of FDG PET/CT in detecting lymph node metastases, lymphadenectomy cannot be omitted even in small pure solid T1 lung cancer.