Improvement of non-small-cell lung cancer staging by means of positron emission tomography

Background: Exact staging of ipsi- and contralateral mediastinal lymph-node metastases (N 1/2 vs. N3) is essential for the therapeutic strategy in non -small-cell lung cancer (NSCLC). CT and mediastinoscopy are the standards o f reference for N staging. However, even with these combined measures the e xtent of invasion of mediastinal lymph nodes can remain vague. (18)FDG Posi tron Emission Tomography ((18)FDG-PET) has recently been shown to detect in vaded nodes with high accuracy. The purpose of this study was to evaluate ( 18)FDG-PET as an aid in N staging. Methods: 27 patients with suspected NSCL C were clinically staged by means of CT, bronchoscopy, mediastinoscopy, and bone scintigraphy, Additionally,(18)FDG-PET was performed preoperatively f or analysis of topography of invaded lymph nodes. CT and (18)FDG-PET were e valuated in a blinded fashion. Surgical therapy was performed with radical lymphadenectomy, CT N staging as well as PET N staging results were compare d with the pathological diagnoses (pTN). Specificity, sensitivity, and accu racy of CT and PET in N staging were calculated. Results: 14 squamous-cell carcinomas, 10 adenocarcinomas, and 3 non-malignant tumors were found. In 8 patients no invasion was found (NO), in 13 patients an ipsilateral invasio n (N1/2), and in 3 patients a contralateral invasion (N3). In the correct d etection of N1/2 the sensitivity of CT and of PET was 0.77, the specificity of CT and of PEI was 0.79. The accuracy of CT was 0.74 and of PET 0.78, By combining CT and PET accuracy was 0.85. Conclusions: Adequate preoperative LN staging is possible with both CT and (18)FDG-PET. The accuracy, however , can be improved by a combination of CT and (18)FDG-PET.