Objective: Accurate pretreatment staging in non-small cell lung cancer remains tantamount in formulating an appropriate treatment plan. The maximum standardized uptake value obtained with integrated fluorodeoxyglucose-positron emission tomography/computed tomography has been proposed to be a predictor of malignancy in mediastinal lymph nodes. A recent study has also suggested that accuracy of integrated fluorodeoxyglucose-positron emission tomography/computed tomography might be improved by increasing the maximum standardized uptake value used for calling a lymph node positive from 2.5 to 5.3. We tested the hypotheses that the maximum standardized uptake value is a predictor of individual lymph node metastasis in non-small cell lung cancer and that pathologic staging with mediastinoscopy might not be necessary in patients with a maximum standardized uptake value of less than 5.3 in their mediastinal lymph nodes.
Methods: This is a retrospective review of 765 lymph nodes sampled from 110 patients in a single institution with biopsy-proved non-small cell lung cancer. All patients underwent integrated fluorodeoxyglucose-positron emission tomography/computed tomography before biopsy or resection of their mediastinal lymph nodes. Surgical staging was the reference standard. All N2 lymph nodes were individually assessed according to station. Data were analyzed by using the Pearson chi(2) test.
Results: Twenty-one (19%) of 110 patients had N2 disease, and a total of 765 N2 lymph nodes were pathologically examined. The mean and median maximum standardized uptake values for N2 nodes with metastatic disease were 9.2 (95% confidence interval, 7.0-11.4) and 7.2 (range, 2.2-25.8), respectively. For benign N2 nodes, the mean and median maximum standardized uptake values were 1.5 (95% confidence interval, 1.4-1.6) and 1.0 (range, 1.0-9.6), respectively (P < .05). When integrated fluorodeoxyglucose-positron emission tomographic/computed tomographic scans were reinterpreted by using a maximum standardized uptake value of 5.3 as a cutoff for malignancy, sensitivity decreased from 93% to 81% (P = .15), specificity increased from 86% to 98% (P < .01), positive predictive value increased from 22% to 64% (P < .01), negative predictive value was unchanged at 99%, and overall accuracy of integrated positron emission tomography/computed tomography increased from 87% to 97% (P < .01).
Conclusions: The maximum standardized uptake value is a predictor of individual lymph node metastasis in non-small cell lung cancer. Accuracy of integrated positron emission tomography/computed tomography is significantly improved by using a maximum standardized uptake value of 5.3 to assign malignancy, thereby dramatically decreasing the number of false-positive results. More importantly, these results suggest that some patients with non-small cell lung cancer with a maximum standardized uptake value less than 5.3 in their N2 lymph nodes might be able to forego mediastinoscopy and proceed directly to thoracotomy. This represents a significant change in the current management of standardized uptake value-positive mediastinal lymph nodes in non-small cell lung cancer.