F-054TUMOUR STANDARDIZED UPTAKE VALUE ON POSITRON EMISSION TOMOGRAPHY IS A NOVEL PREDICTOR OF ADENOCARCINOMA IN SITU FOR C-STAGE IA LUNG CANCER PATIENTS WITH PART-SOLID NODULE ON THIN-SECTION COMPUTED TOMOGRAPHY SCAN

Abstract

Adenocarcinoma in situ (AIS), which was defined as having a pathologically non-invasive nature by the new IASLC/ATS/ERS classification, might be included in patients that showed part-solid nodule on thin-section CT. Between 2008 and 2011, 556 c-stage IA lung cancer patients underwent pulmonary resection. The findings obtained by preoperative thin-section CT were reviewed for all patients and categorized as pure ground-glass nodule (GGN), part-solid, or pure-solid based on the findings on thin-section CT, i.e. consolidation/tumour ratio (CTR). Part-solid nodule was defined as a tumour with 0 < CTR < 1.0, which indicated focal nodular opacity containing both solid and GGN components. All patients were evaluated by positron emission tomography (PET) and the maximum standardized uptake value (SUVmax) was recorded. Several clinicopathological features were investigated to identify predictors of AIS using multivariate analyses. 112 c-stage IA lung cancer patients showed a part-solid appearance on thin-section CT. Among them, AIS was found in 10 (23.8%) of 42 patients with 0 < CTR ≤ 0.5 in contrast to 3 (4.3%) of 70 patients with 0.5 < CTR < 1.0. According to multivariate analyses, SUVmax and CTR were significant predictors of AIS in patients with part-solid nodule (P = 0.0421, 0.0221). Mean SUVmax of the patients with AIS was 0.57 (0-1.6). Moreover, in the subgroup of part-solid nodule with SUVmax ≤ 1.0 and CTR ≤ 0.40, which were shown as cutoff values of predicting AIS based on the result of receiver operating characteristics curve, 6 (40%) of 15 patients with these criteria showed pathologic non-invasive nature even in the patients with part-solid nodule. Among clinical stage IA adenocarcinoma with part-solid nodule on thin-section CT scan, extremely low level of SUVmax could correspond to a radiologically pure GGO and pathologically AIS. Preoperative tumour SUVmax on PET could yield important information for predicting the non-invasiveness in patients with part-solid nodule. All authors have declared no conflicts of interest.