Additional value of FDG-PET to contrast enhanced-computed tomography (CT) for the diagnosis of mediastinal lymph node metastasis in non-small cell lung cancer. A Japanese multicenter clinical study

This study was a controlled multicenter clinical study to verify the diagnostic effects of additional fluorodeoxyglucose-positron emission tomography (FDG-PET) to contrast-enhanced CT for mediastinal lymph node metastasis in patients with operable non-small cell lung cancer (NSCLC). NSCLC patients with enlarged mediastinal lymph nodes (short diameter, 7-20 mm), confirmed using contrast-enhanced CT, were examined using FDG-PET to detect metastases prior to surgery. The primary endpoint was the accuracy for concomitantly used CT and FDG-PET showing the additional effects of FDG, compared with CT alone. The secondary endpoints were the clinical impact of FDG-PET on therapeutic decisions and adverse reaction from FDG administration. The images were interpreted by investigators at each institution. Moreover, blinded readings were performed by an image interpretation committee independent of the institutions. The gold standard was the pathological diagnosis determined by surgery or biopsy after PET, and patients in whom a pathological diagnosis was not obtained were excluded from the analysis. Among 99 subjects, the results for 81 subjects eligible for analysis showed that the accuracy improved from 69.1% (56/81) for CT alone to 75.3% (61/81) for CT + PET (p=0.404). These findings contributed to treatment decisions in 63.0% (51/81) of the cases, mainly with regard to the selection of the operative procedure. The results of the image interpretation committee showed that the accuracy improved from 64.2% (52/81) (95% confidence interval (CI) 52.8-74.6) for CT to 75.3% (61/81) (95% CI 64.5-84.2) for CT + PET. The accuracy for 106 mediastinal lymph nodes improved significantly from 62.3% (66/106) (95% CI 52.3-71.5) for CT to 79.2% (84/106) (95% CI 70.3-86.5) for CT + PET (p<0.05). We found that no serious adverse drug reactions appeared in any of the 99 patients who received FDG, except for transient mild outliers in the laboratory data for two patients. The addition of FDG-PET to contrast-enhanced CT imaging for the staging of NSCLC improved the diagnostic accuracy for mediastinal lymph node metastasis. FDG-PET improved the precision of the staging of NSCLC and contributed to the surgical decisions. (author)