LYMPH-NODE STAGING IN NON-SMALL-CELL LUNG-CANCER WITH FDG-PET SCAN - A PROSPECTIVE-STUDY ON 690 LYMPH-NODE STATIONS FROM 68 PATIENTS

Purpose: To compare the accuracy of computed tomography-(CT) scan and the radiolabeled glucose analog F-18-fluoro-2-deoxy-D-glvcose (FDG) po sitron emission tomography (PET) visually correlated with CT (PET + CT ) in the locoregional lymph node (LN) staging of non-small-cell lung c ancer (NSCLC). Patients and Methods: Sixty-eight patients with potenti ally operable NSCLC underwent thoracic CT, PET, and invasive surgical staging (155), Imaging studies were read prospectively and blinded to the surgical and pathologic data. A five-point visual scale was used f or the interpretation of LNs on PET. Afterwards, with knowledge of the pathology, the relationship between standardized uptake values (SUVs) and the presence of metastasis in LNs was explored in a receiver oper ating characteristic (ROC) analysis, and the likelihood ratios (LRs) f or SUVs of LNs were determined. Results: ISS was available for 690 LN stations. CT correctly identified the nodal stage in 40 of 68 patients (59%), with understaging in 12 patients and overstaging in 16 patient s. PET + CT was accurate in 59 patients (87%), with understaging in fi ve patients and overstaging in four patients. In the detection of loca lly advanced disease (N2/N3), the sensitivity, specificity, and accura cy of CT were 75%, 63%, and 68%, respectively. for PET + CT, this was 93%, 95%, and 94% (P = .0004). In the ROC curve, the best SUV threshol d to distinguish benign from malignant LNs was 4.40. The analysis with this SUV threshold was not superior to the use of a five-point visual scale. The LR of a SUV less than 3.5 in an LN was 0.152; for a SUV be tween 3.5 and 4.5, it was 3.157; and for a SUV greater than 4.5, it wa s 253.096. Conclusion: PET + CT is significantly more accurate than CT alone in LN staging of NSCLC, A five-point visual scale is as accurat e as the use of an SUV threshold for LNs in the distinction between be nign and malignant nodes. The very high negative predictive value of m ediastinal PET could reduce the need for mediastinal ISS in NSCLC subs tantially.