Commentary: Ground-Glass Opacity-An Unexpected Silver Lining

Central MessageThe presence of ground-glass opacity around a solid tumor predicts a favorable prognosis. In future TNM staging systems, tumors with ground glass opacity should be placed in a distinct category.See Article page 1469. The presence of ground-glass opacity around a solid tumor predicts a favorable prognosis. In future TNM staging systems, tumors with ground glass opacity should be placed in a distinct category. See Article page 1469. In the accompanying article by Hattori and colleagues,1Hattori A. Suzuki K. Takamochi K. Wakabayashi M. Aokage K. Saji H. et al.Prognostic impact of a ground-glass opacity component in clinical stage IA non–small cell lung cancer.J Thorac Cardiovasc Surg. 2021; 161: 1469-1480Abstract Full Text Full Text PDF PubMed Scopus (18) Google Scholar the authors further investigate the outcomes of patients registered in JCOG0201. This was a multi-institutional prospective study on the definition of radiologic early lung cancer—cancer without nodal metastasis or vascular or lymphatic invasion.2Suzuki K. Koike T. Asakawa T. Kusumoto M. Asamura H. Nagai K. et al.Japan Lung Cancer Surgical Study Group (JCOG LCSSG)A prospective radiological study of thin-section computed tomography to predict pathological noninvasiveness in peripheral clinical IA lung cancer (Japan Clinical Oncology Group 0201).J Thorac Oncol. 2011; 6: 751-756Abstract Full Text Full Text PDF PubMed Scopus (331) Google Scholar Patients enrolled in this landmark trial had the preoperative radiology findings correlated with the pathologic specimen. Lung carcinoma ≤2.0 cm in size and with a consolidation ≤25% of the maximum tumor diameter was considered to be radiologic early lung cancer. Since the publication JCOG0201 in 2011, the 8th edition of the TNM staging system has incorporated the extent of solid component in a partially solid lesion to the TNM schema but not necessarily the features of the ground-glass pathologic correlate. Other investigators have noted the prognostic significance of ground glass on long-term outcomes. Hattori and colleagues3Hattori A. Matsunaga T. Takamochi K. Oh S. Suzuki K. Prognostic impact of a ground glass opacity component in the clinical T classification of non-small cell lung cancer.J Thorac Cardiovasc Surg. 2017; 154: 2102-2110.e1Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar,4Hattori A. Hirayama S. Matsunaga T. Hayashi T. Takamochi K. Oh S. et al.Distinct clinicopathologic characteristics and prognosis based on the presence of ground glass opacity component in clinical stage IA lung adenocarcinoma.J Thorac Oncol. 2019; 14: 265-275Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar have previously demonstrated that the mere presence of ground-glass opacity (GGO) as part of an otherwise solid lesion had a favorable prognosis. In fact, the presence of GGO negated the predictive value of maximum tumor size or solid component on long-term survival.3Hattori A. Matsunaga T. Takamochi K. Oh S. Suzuki K. Prognostic impact of a ground glass opacity component in the clinical T classification of non-small cell lung cancer.J Thorac Cardiovasc Surg. 2017; 154: 2102-2110.e1Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar This effect was also seen in patients with multiple synchronous tumors.5Hattori A. Matsunaga T. Takamochi K. Oh S. Suzuki K. Radiological classification of multiple lung cancers and the prognostic impact based on the presence of a ground glass opacity component on thin-section computed tomography.Lung Cancer. 2017; 113: 7-13Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar The presence of GGO indicates less risk of invasive tumor6Aokage K. Miyoshi T. Ishii G. Kusumoto M. Nomura S. Katsumata S. et al.Influence of ground glass opacity and the corresponding pathological findings on survival in patients with clinical stage I non-small cell lung cancer.J Thorac Oncol. 2018; 13: 533-542Abstract Full Text Full Text PDF PubMed Scopus (45) Google Scholar and rendered the prognostic impact of visceral pleural invasion moot.4Hattori A. Hirayama S. Matsunaga T. Hayashi T. Takamochi K. Oh S. et al.Distinct clinicopathologic characteristics and prognosis based on the presence of ground glass opacity component in clinical stage IA lung adenocarcinoma.J Thorac Oncol. 2019; 14: 265-275Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar,7Fu F. Zhang Y. Wen Z. Zheng D. Gao Z. Han H. et al.Distinct prognostic factors in patients with stage I non-small cell lung cancer with radiologic part-solid or solid lesions.J Thorac Oncol. 2019; 14: 2133-2142Abstract Full Text Full Text PDF PubMed Scopus (46) Google Scholar Patients with pure GGO have almost zero risk of nodal involvement.8Ding N. Mao Y. Gao S. Xue Q. Wang D. Zhao J. et al.Predictors of lymph node metastasis and possible selective lymph node dissection in clinical stage IA non-small cell lung cancer.J Thorac Dis. 2018; 10: 4061-4068Crossref PubMed Scopus (20) Google Scholar Radiologic lesions without any GGO component exhibit a more malignant behavior. The ability to predict the biologic behavior of a tumor based on computed tomography findings has profound implications for choosing treatment. The patients with GGO may be the most likely to benefit from sublobar resection, or looking at it another way, not have to endure overtreatment with more extensive lung resection. This biologically distinct behavior of 2 nodules with solid components but distinguished by the mere presence or absence of GGO has broad implications for the extent of surgical therapy. While AJCC 8th edition characterizes the T stage according to the extent of solid component in a partially solid lesion, the result of JCOG0201 and other large series suggest that in future schemas, the mere presence or absence of GGO should determine stage, as pure ground-glass lesions and those with partial solid components behave in a distinct manner separate from purely solid lesions, with far less malignant potential. In the accompanying manuscript,1Hattori A. Suzuki K. Takamochi K. Wakabayashi M. Aokage K. Saji H. et al.Prognostic impact of a ground-glass opacity component in clinical stage IA non–small cell lung cancer.J Thorac Cardiovasc Surg. 2021; 161: 1469-1480Abstract Full Text Full Text PDF PubMed Scopus (18) Google Scholar the 5-year overall survival was significantly different between the “with GGO” and the “pure Solid” groups (95.1% vs 81.1%). Most interesting was the survival of more than 90% in patients with GGO, regardless of the solid component size. However, for patients without GGO component, survival diminished drastically with increasing size of tumor (c-T1a: 87.5%, c-T1b: 85.9%, c-T1c: 73.7%). The presence of GGO component to a lung cancer may be the silver lining for patient survival. Prognostic impact of a ground-glass opacity component in clinical stage IA non–small cell lung cancerThe Journal of Thoracic and Cardiovascular SurgeryVol. 161Issue 4PreviewWe performed a validation study to confirm the prognostic importance of the presence of a ground-glass opacity component based on data of the Japan Clinical Oncology Group study, JCOG0201, which was a prospective observational study to predict the pathological noninvasiveness of clinical stage IA lung cancer in Japan. Full-Text PDF