Lymph node involvement in T1 non-small-cell lung cancer : could glucose uptake and maximal diameter be predictive criteria?

Objective: The introduction of modern staging systems such as computed tomography (CT) and positron emission tomography/CT (PET/CT) with fluorodeoxyglucose ([18F]FDG) has increased the detection of small peripheral lung cancers at an early stage. We analyzed the behavior of pathological T1 non-small-cell lung cancer (NSCLC) to identify criteria predictive of nodal involvement, and the role of cancer size in lymph node metastases. Methods: We retrospectively analyzed 219 patients with pathological T1 NSCLC. All patients were staged by high-resolution CT and PET as stage I, and underwent anatomical resection and radical lymphadenectomy. Our data were collected based on pathological nodule size (0-10mm; 11-20mm; and 21-30mm); morphological features of lung nodule and FDG uptake of the tumor measured by standardized uptake value (SUV). Results: A total of 190 patients (87%) were pN0, 14 (6%) pN1, and 15 (7%) pN2. No nodal involvement was observed in any of the 62 patients with nodule size less than 10mm, in 20 out of 120 patients (17%) with nodule size 11-20mm, and in nine out of 37 tumors (28%) 21-30mm in size (p=0.0007). All 55 patients with nodule SUV<2.0 and all 26 non-solid lesions were pN0 (respectively, p=0.0001 and p=0.03). All nodal metastases occurred among the group of 132 patients with size larger than 10mm and SUV higher than 2.0 with a 22% rate of nodal involvement of (29 patients) (p<0.0001). Conclusions: The low probability of lymph node involvement in NSCLC <1cm or showing glucose uptake <2 suggests lymphadenectomy could be avoided. A randomized trial should be performed to validate our data.