Selection of sublobar resection for c-stage IA non-small cell lung cancer based on a combination of structural imaging by CT and functional imaging by FDG PET.

PURPOSE The purpose of this study was to establish criteria for the indication of sublobar resection or lobectomy in cT1N0M0 non-small cell lung cancer (NSCLC), based on information from both computed tomography (CT) and fluorodeoxyglucose positron emission tomography (FDG PET). MATERIALS AND METHODS A total of 248 cT1N0M0 NSCLC tumors treated surgically were subjected to high-resolution or thin-slice CT (HR/TSCT) study, and 99 of these tumors were also subjected to FDG PET study. Four types of data were collected: (1) tumor size based on HR/TSCT (0-10 mm, 11-20 mm or 21-30 mm); (2) percentage of ground-glass opacity (GGO) region (GGO type or solid type); (3) pathological type (invasive cancer [INVC] or non-INVC [NINVC]); (4) FDG uptake in the tumor (grades 0, 1, and 2). RESULTS One of 42 tumors (2.4%) less than 1 cm in size, 29 of 132 tumors (22.0%) 1-2 cm in size, and 25 of 74 tumors (33.8%) 2-3 cm in size were judged to be INVC (p = 0.0002). GGO type tumors (2.3%) were less likely to be INVC than solid type tumors (32.9%) (p <0.0001). None of the 28 GGO tumors less than 1 cm in size was INVC; however, the possibility of INVC remained in solid type tumors less than 1 cm in size. In tumors whose diameter was more than 1 cm, INVC was possible regardless of their size or character (GGO or solid). One of 23 (4.3%), 4 of 33 (12.1%) and 14 of 43 tumors (32.6%) whose FDG uptake showed grades 0, 1, and 2, respectively, microscopically revealed INVC (p = 0.0028). All tumors whose FDG uptake was grade 0 and whose size was less than 1 cm were NINVC. On the other hand, tumors whose FDG uptake was grade 1 or 2 or whose size was more than 1 cm retained the possibility of INVC. All 5 tumors (5.0%) which were found to have lymph node metastasis showed grade 2 FDG uptake. CONCLUSION The criteria for operation for cT1N0M0 NSCLC based on HR/TSCT and FDG PET findings are the following: (1) a tumor less than 1 cm in size and either a GGO type or whose PET grade is 0 (wedge resection); (2) a tumor greater than 1 cm in size and whose PET grade is 0 or 1 (segmentectomy with lymph node dissection); or (3) a tumor whose PET grade is 2 (lobectomy with systemic lymph node dissection).