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Mediastinoscopy May Not Be Necessary in Non-Small Cell Lung Cancer Patients With Mediastinal Lymph Nodes Having a Maximum Standard Uptake Value of Less Than 5.3
B. E. Lee1, C. Foster2, E. Abella3, T. Lown1, D. Lau1, D. Follette*1. 1UC Davis Cancer Center, Sacramento, CA, 2UC Davis Medical Center, Sacramento, CA, 3Northern California PET Imaging Center, Sacramento, CA,
BACKGROUND:
Accurate pre-treatment staging in non-small cell lung cancer (NSCLC) remains tantamount in formulating an appropriate treatment plan. The maximum standard uptake value (max-SUV) obtained with integrated fluorodeoxyglucose-positron emission-computed tomography (FDG-PET-CT) has been proposed to be a predictor of malignancy in mediastinal lymph nodes. A recent study has also suggested that accuracy of integrated FDG-PET-CT may be improved by increasing the max-SUV used for calling a lymph node positive from 2.5 to 5.3. We tested the hypotheses that the max-SUV is a predictor of individual lymph node metastasis in NSCLC and that pathologic staging with mediastinoscopy may not be necessary in patients with a max-SUV < 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 proven NSCLC. All patients underwent integrated FDG-PET-CT prior to 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 was analyzed using the Pearson chi-squared test.
RESULTS:
Twenty-one patients (21/110, 19%) had N2 disease and a total of 765 N2 lymph nodes were pathologically examined. The mean and median max-SUVs 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 max-SUVs were 1.5 (95% confidence interval, 1.4-1.6) and 1.0 (range, 1.0-9.6), respectively (p <0.05). When integrated FDG-PET-CT scans were re-interpreted using a max-SUV of 5.3 as a cutoff for malignancy, sensitivity decreased from 93% to 81% (p =0.15), specificity increased from 86% to 98% (p < 0.01), positive predictive value increased from 22% to 64% (p < 0.01), negative predictive value was unchanged at 99% and overall accuracy of integrated FDG-PET-CT increased from 87% to 97% (p <0.01).
CONCLUSIONS:
The max-SUV is a predictor of individual lymph node metastasis in NSCLC. Accuracy of integrated FDG-PET-CT is significantly improved by using a max-SUV of 5.3 to assign malignancy as the result of dramatically decreasing the number of false-positive results. More importantly, these results indicate that NSCLC patients with a max-SUV less than 5.3 in their N2 lymph nodes may be able to forego mediastinoscopy and proceed directly to thoracotomy. This represents a significant change in the current management of SUV positive mediastinal lymph nodes in NSCLC.
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