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　Many thoracic surgeons revealed that consolidation tumor ratio or solid component size on thin-section computed tomography has been considered more prognostic than maximum tumor size in non-small cell lung cancer (NCSLC). According to the results, the 8th TNM classification drastically changed the staging system, i.e., clinical T category was determined based on the invasive or solid component size excluding a ground-glass opacity (GGO). However, several debates are arising over the application of radiological solid size for the clinical T staging. Meanwhile, recent several institutional reports have noticed a significantly simple fact that the presence of a GGO denotes an influence on the favorable prognosis of NSCLC. More important, radiologic pure-solid lung cancers without a GGO exhibit more malignant behaviors with regard to both the clinical and pathological aspects, and show several histologic types that have a poorer prognosis than radiologic part-solid lung cancer. In contrast, favorable prognostic impact of the presence of a GGO component was demonstrated, which was irrespective of the solid component size in cases in which the tumor showed a GGO component. Recently, this concept has been gradually noticed on a nationwide level. 　Obvious distinctions regarding the several baseline characteristics between the tumor with/without GGO component is a fundamental biological feature of early-stage lung cancer, which would result in a big difference in prognosis, modes of recurrence, overall behavior, and appropriate operative strategies. As a future perspective, the presence or absence of a GGO should be considered as an important parameter in the next clinical T classification.52Juntendo Medical Journal2022. 68(1), 52-59Key words: lung cancer, ground-glass opacity, surgeryMini ReviewsLatest Clinical Evidence and Operative Strategy for Small-Sized Lung CancersIntroductionSince the Japan Clinical Oncology Group (JCOG) study prospectively validated the radiological defi-nition that enabled prediction of the pathological noninvasiveness of clinical stage IA lung cancer based on the findings of thin-section computed tomography (CT)1), many thoracic surgeons have revealed that consolidation tumor ratio (CTR) and solid component size were more prognostic than maximum tumor size for resected non–small cell lung cancer (NCSLC)2-6). This finding is extremely important in the history of general thoracic surgery. Subsequently, the 8th edition of the TNM staging Department of General Thoracic Surgery, Juntendo University School of Medicine, Tokyo, JapanCorresponding author: Aritoshi HattoriDepartment of General Thoracic Surgery, Juntendo University School of Medicine1-3, Hongo 3-chome, Bunkyo-ku, Tokyo, 113-8431, JapanTEL: +81-3-3813-3111　FAX: +81-3-5800-0281　E-mail: ahattori@juntendo.ac.jp〔Received　Oct. 7, 2021〕〔Accepted　Nov. 1, 2021〕J-STAGE Advance published date: Jan. 21, 2022Copyright © 2022 The Juntendo Medical Society. This is an open access article distributed under the terms of Creative Commons Attribution License (CC BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original source is properly credited. doi: 10.14789/jmj.JMJ21-0030-OTsystem drastically changed the staging system, with the clinical T category being determined according to solid component size and excluding ground-glass opacity (GGO)7). In contrast, new issues are emerging from the proposed changes concerning T parameters. Much of the confusion is caused by the absence of a consensus on how to make uniform the measurements of solid compo-nent size in many part-solid tumors in which solid component size is difficult or impossible to measure8, 9). In such circumstances, we have reported a new and simple fact that the presence of a GGO denotes a great influence on the favorable prognosis of NSCLC, and the radiological solid component size is Aritoshi HATTORI, Kenji SUZUKI