Since 'radical lobectomy' was reported by Cahan in 1960, the standard surgical care for lung cancer has been lobectomy, in which units of the lobe are excised with their specific regional hilar and mediastinal lymphatics. However, pulmonary function-preserving limited resection for lung cancer has gradually become more prevalent in the late 20th century. In 1995, Ginsberg et al. conducted a randomized controlled trial in which limited resection (segmentectomy and wide-wedge resection) and lobectomy for stage I lung cancer were compared and reported that limited resection should not be applied to healthy patients with clinical stage IA lung cancer. The detection of small-sized and early-stage lung cancers has improved with advancement in diagnostic technology. Ground-glass opacity of lung nodules, as recognized on thin-slice computed tomography, has also been widely recognized as being correlated with less-invasive pathological findings of alveolar epithelial cell replacement of cancer cells. The Lung Cancer Surgical Study Group of the Japan Clinical Oncology Group conducted a cohort study of early peripheral lung cancer and investigated the validity thin-slice computed tomography criteria to diagnose non-invasive lung adenocarcinoma for the preoperative prediction of pathological non-invasive cancer. Following this observational study, the on-going JCOG0802/WJOG4607L, JCOG0804/WJOG4507L and JCOG1211 trials were initiated to confirm the validity of limited resection for stage I lung cancer patients stratified according to preoperative thin-slice computed tomography findings; these trials will clarify whether limited resection for lung cancer is not function-preserving but also only curative surgery.