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ObjectivesThere have been few studies that have fully elucidated the relationship between genomic mutations in pulmonary adenocarcinomas and occult lymph node (LN) metastases (pN1-2) despite a preoperative clinical N0 stage (cN0). It is well known that anaplastic lymphoma kinase (ALK) rearrangements are more likely to occur in younger patients with high grade tumors. The aim of this study was to investigate the genomic status, examine the clinicopathologic features, and evaluate whether ALK mutations are associated with occult LN metastases.Materials and methodsWe retrospectively evaluated 459 Japanese patients who underwent pulmonary resection of cN0 adenocarcinomas between January 2012 and December 2015. The clinicopathologic characteristics, including age, sex, smoking index, tumor maximum diameter and consolidation/tumor ratio on computed tomography (CT), maximum standardized uptake value on positron emission tomography (PET) and gene mutations (epidermal growth factor receptor [EGFR], ALK, and kirsten ras genes (KRAS), were evaluated.ResultsALK and EGFR and KRAS mutations were all mutually exclusive. Among 324 patients found to have mutations, ALK was involved in 19 (5.9%), EGFR in 266 (82.1%), and KRAS in 39 (12.0%). The incidence of occult LN metastases did not differ significantly between those with or without mutations (p=0.27). On univariate and multivariate analyses, tumors with ALK were more likely to have occult LN metastases (p=0.03). In cN0 tumors with ALK, pN1 was diagnosed in 26.3% and pN2 in 10.5%, whereas pN1 or pN2 stage was found in <10.0% in those with EGFR or KRAS mutations or with no mutations at all. No significant difference was found in the 2-year disease-free survival among those with gene mutations (p=0.08).ConclusionThis study highlights the frequency of PET- and CT-negative occult LN metastases in resected adenocarcinomas with ALK rearrangement. Our multivariate analysis showed that ALK rearrangements were associated with a significantly higher incidence of occult LN metastasis compared with ALK-negative adenocarcinomas.

Background The aim of this study was to evaluate regional postoperative preserved pulmonary function (PPPF) and three‐dimensional (3D) volumetric changes according to the number of resected subsegments and investigate the factors that most affected pre‐/post PPPF. Methods Patients who underwent thoracoscopic lobectomy (n = 73), and segmentectomy (n = 87) were eligible for inclusion in the study. They were classified according to the number of resected subsegments which ranged from 1 to 10. The percentage of pre‐/postoperative forced expiratory volume in 1 s (FEV1) was used for comparison. Furthermore, lung volumetric changes were calculated using 3D computed tomography (CT) volumetry. Results The percentage of pre‐/postoperative EFV1 between 4 and 5–7 and between 5–7 and 10 were significant (p = 0.03 and p < 0.01, respectively), but not between 1–2 to 4 (p = 0.99). The difference between volumetric changes in the left lower lobe of patients with a number of resected subsegments was significant (p < 0.01). On univariate and multivariate analyses, chronic inflammation was significant for decrease in recovery percentages. When the PPPF was compared among resected subsegments, it gradually decreased with an increase in the number of patients without a postoperative procrastination of inflammation (p < 0.01). Conclusions Segmentectomy is feasible and useful for PPPF. Even a relatively large‐volume resection procedure where 5–7 subsegments are resected can preserve pulmonary function. Chronic inflammation was statistically identified as a risk factor for postoperative preserved pulmonary function. Key points

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