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Open in new tab Download slide OBJECTIVES Limited data exist on the characteristics of atypical epidermal growth factor receptor (EGFR) mutations in early-stage lung cancer. Our goal was to elucidate the associations with outcomes and recurrence patterns in resected stage I lung adenocarcinoma harbouring atypical EGFR mutations. METHODS Eligible patients between 2014 and 2019 were retrospectively identified and grouped into exon20 insertion mutations and major atypical mutations, which included G719X, L861Q and S768I. Disease-free survival (DFS) was evaluated in the entire cohort and stratified by radiologic characteristics. Recurrence patterns were investigated and compared between groups. A competing risk model was used to estimate the cumulative incidence of recurrence. RESULTS A total of 710 patients were finally included. Among them, 289 (40.7%) patients had exon 20 insertion mutations and 421 (59.3%) patients had major atypical mutations. There was no significant difference regarding DFS (P  = 0.142) between groups in the entire cohort. The interaction between mutation subtype and the presence of ground-glass opacities was significant (hazard ratio 2.00, 95% confidence interval 1.59–2.51, P  < 0.001), indicating DFS between exon 20 insertion mutations and major atypical mutations may be different among subsolid and solid tumours. Survival analysis consistently revealed no significant difference in subsolid tumours (P  = 0.680), but favourable DFS of exon 20 insertion mutations in solid tumours (P  = 0.037). Furthermore, patients with exon 20 insertion mutations had a lower risk of developing bone metastases did those with radiologic solid tumours (Gray's test, P  = 0.012). CONCLUSIONS Exon 20 insertion mutations were correlated with favourable DFS and lower incidence of bone metastases in radiologic solid lung adenocarcinomas harbouring atypical EGFR mutations. [ABSTRACT FROM AUTHOR]

Open in new tab Download slide Open in new tab Download slide OBJECTIVES To investigate the impact of lung window (LW) and mediastinal window (MW) settings on the clinical T classifications and prognostic prediction of patients with subsolid nodules. METHODS Seven hundred and nineteen surgically resected subsolid nodules were reviewed, grouping into pure ground-glass nodules (n  = 179) or part-solid nodules (n  = 540) using LW. Interobserver agreement on nodule classifications was assessed via kappa-value, and predictive performance of the solid portion measurement in LW and MW for pathological invasiveness and malignancy were compared using receiver-operating characteristic analysis. Cox regression was used to identify prognostic factors. Prognostic significance of T classifications based on LW (c[l]T) and MW (c[m]T) was evaluated by Kaplan–Meier method after propensity score matching. The performance of c(m)T for discrimination survival was estimated via the concordance index (C-index), net reclassification improvement and integrated-discrimination improvement. RESULTS By adopting MW, 124 part-solid nodules were reclassified as pure ground-glass nodules, and interobserver agreement improved to 0.917 (95% confidence interval 0.888–0.946). The solid portion size under MW more strongly predicted pathological invasiveness (P  =   0.030), but did not better predict pathological malignancy. For remaining 416 part-solid nodules, c(l)T and c(m)T were both independent risk factors. c(m)T led to T classifications shifts in 321 nodules (14 upstaged and 307 downstaged) with no significant prognostic difference existing between the shifted c(m)T and matching c(l)T group after propensity score matching. The corrected C-index was improved to 0.695 (0.620–1.000) when adopting c(m)T with no significant difference in net reclassification improvement (P  =   0.098) and integrated-discrimination improvement (P  =   0.13) analysis. CONCLUSIONS As there is no significant benefit provided by MW in evaluating clinical T classification and prognosis, the current usage of LW is appropriate for assessing subsolid nodules. [ABSTRACT FROM AUTHOR]