Clinical Significance of Positron Emission Tomography in Subcentimeter Non-Small Cell Lung Cancer

摘要

Background This study evaluated the clinical significance of maximum standardized uptake value (SUVmax) on positron emission tomography (PET) in patients with subcentimeter non-small cell lung cancer (NSCLC).;Methods Between 2008 and 2014, 189 patients were investigated preoperatively by PET for c-N0 subcentimeter NSCLC, and SUVmax was reviewed. Pathologic invasiveness (PI) was defined as having at least one of the following factors: lymphatic invasion, vascular invasion, pleural invasion, or nodal metastasis. Survival rates were calculated by Kaplan-Meier estimation methods using the log-rank test.;Results Mean SUVmax was 1.7 ± 1.8 (range, 0.6 to 13.0), and the median was 1.0. PI was found in 28 (15%) patients with subcentimeter NSCLC. Multivariate analysis revealed that SUVmax was an independent significant clinical predictor of PI (p?= 0.0251) and a prognostic factor of overall survival (OS) (p?= 0.0485). A receiver operating characteristics curve elucidated the predictive cutoff value of PI as SUVmax?= 2.0. The high-SUVmax group (SUVmax >2.0; n?= 42) had significantly more radiologically pure-solid lesions (91% vs 14%; p < 0.0001) and postoperative nodal involvement (12% vs 0%; p?1 to ≤2 cm), and T1c (>2 to ≤3cm) [8, 9]. However, even c-N0 subcentimeter NSCLCs are not always in the early stage, and these tumors sometimes have nodal metastases and potential spread to locoregional or distant lesions after surgical resection [3, 5]. This finding indicates that “tumor size less than 1 cm” does not always indicate early-stage disease or absence of tumor spread. Additionally, the malignant behavior of these tumors is considered to be fully related to consolidation status on thin-section CT scans even for subcentimeter NSCLCs [3, 5].Fluorine 18 (18F)–fluorodeoxyglucose PET (FDG-PET) is widely used as an accurate noninvasive imaging test for identifying pulmonary malignant lesions. In general, the appropriate roles of FDG-PET in the evaluation of subcentimeter NCSLC remain unclear, mainly because of the high frequency of false-negative results caused by limitations in the resolution of the PET scanner, especially for small adenocarcinomas with a predominant lepidic component [10, 11, 12]. Conversely, we previously reported that FDG-PET was potentially effective to predict nodal involvement of subcentimeter NSCLC, which was strongly correlated with the consolidation status based on the findings of thin-section CT. Hence, FDG-PET could be a promising method as a quantitative assessment to predict the potential