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 ([(18)F]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 (0-10 mm; 11-20 mm; and 21-30 mm); 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 10 mm, in 20 out of 120 patients (17%) with nodule size 11-20 mm, and in nine out of 37 tumors (28%) 21-30 mm 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 10 mm 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 <1 cm or showing glucose uptake <2 suggests lymphadenectomy could be avoided. A randomized trial should be performed to validate our data.