289 * PREDICTORS OF NON-CANCEROUS LESION IN LUNG TUMOUR SHOWING GROUND-GLASS OPACITY ON THIN-SECTION COMPUTED TOMOGRAPHY BASED ON A MULTI-INSTITUTIONAL PROSPECTIVE STUDY

Abstract

Objectives: Peripheral small lung tumours (LTs) showing ground-glass opacity (GGO) tend to be treated without preoperative histological diagnosis due to difficulty in obtaining tissue samples. Exclusion of non-cancerous lesions (NCLs) is essential when considering non-surgical treatment such as stereotactic radiotherapy. Here, we sought for preoperative predictors of NCLs in peripheral LTs. Methods: Between May 2009 and April 2011, 333 patients were prospectively enrolled from 51 institutions to the JCOG0804/WJOG4507L trial which investigated the efficacy of lesser pulmonary resection. The key eligibility criteria were: 1) peripherally located definitive or suspected LC with maximum diameter ≤2 cm, and 2) radiological non-invasive tumour with consolidation/tumour ratio (CTR) of <0.25 based on thin-section CT (Suzuki J Thorac Oncol 2011;6:751–6). Among all resected LTs, the incidences of NCL and pre-cancerous lesions were examined. Also, the logistic regression analysis was conducted to investigate a predictor of NCL using the maximum tumour dimension (≤1cm/>1 cm) and CTR (0/>0) as an explanatory variable. Results: Among 333 patients, 345 LTs were included in the analysis. There were 314 (91.0%) LC, 17 (4.9%) pre-cancerous lesions, and 14 (4.1%) NCL. The maximum tumour dimension ≤1 cm was detected to be a significant predictor of NCL with multivariate analysis. There were 10 (8.6%) NCLs in 116 LT ≤1 cm, while 4 (1.7%) NCLs in 229 LTs >1 cm. Conclusion: NCLs were found only in 4.1% of peripheral LTs with GGO. However, when tumour diameter was 1 cm or smaller, approximately 10% were NCLs, necessitating histological diagnosis when non-surgical treatment is considered.