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).