[Potential value of FDG PET-CT in predicting occult lymph node metastasis in clinical stage IA lung adenocarcinoma].

Objective To investigate the predictive value of 18F-FDG PET-CT scan for occult lymph node metastasis in patients with stage ⅠA lung adenocarcinoma. Methods The image and pathological data of 272 patients with stage ⅠA lung adenocarcinoma from October 2006 to September 2015 were retrospectively analyzed. All patients underwent preoperative 18F-FDG PET-CT scan followed by lobectomy and systematic lymph node dissection. The correlation between occult lymph node metastasis and the maximum standardized uptake value (SUVmax) of primary tumor as well as other clinicopathological factors was analyzed to screen the risk factors of occult lymph node metastasis in stage ⅠA lung adenocarcinoma. Results Occult lymph node metastasis was detected in 50 patients (18.4%), with 24 (8.8%) patients of pN1 involvement and 26 (9.6%) of pN2 involvement. Among the 272 patients enrolled, 39 had pure ground glass nodule, 59 had part-solid nodule and 174 had solid nodule. All patients with pure ground glass nodule or nodule≤1 cm were pN0. For the 233 patients with part-solid and solid nodule, no lymph node metastasis was found in T1a stage (tumor length ≤1 cm). Primary tumor SUVmax (Z=-5.663, P 2.405 (P<0.001), central location (P=0.030) and higher histological grade (P=0.024) were independent predictors of occult lymph node metastasis. Conclusions For clinical stage ⅠA adenocarcinoma, primary tumor SUVmax > 2.405, central location and higher histological grade were independent risk factors for occult lymph node metastasis. Systematic lymph node dissection may be avoided in lung adenocarcinoma with pure ground glass density, tumor length ≤1 cm or SUVmax ≤ 2.405, due to the very low probability of nodal involvement. Key words: Carcinoma, non-small cell lung; Adenocarcinoma; Tomography, positron-emission; Lymph node