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Background: Adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) are both small tumors with good prognosis after surgical resection, and most of them present as ground glass opacities (GGOs) on computed tomography (CT) screening. However, the differences in clinicopathologic features and genetic alterations between AIS and MIA are poorly elaborated, and few studies have evaluated the prognosis of MIA with different invasive components. Meanwhile, the histological features of lung lesions presenting as unchanged pure GGOs are barely understood., Methods: Clinicopathologic features and genetic alterations of AIS (n = 59) and MIA (n = 62) presenting as GGOs were analyzed. Long-term preoperative observation (ranging from 2 to 1967 days) and postoperative follow-up (ranging from 0 to 92 months) was conducted., Results: The tumor size and consolidation/tumor ratio were significantly larger in the MIA cohort than those in the AIS cohort both on CT and microscopy images. Immunohistochemically, the expression of p53, Ki67, and cyclin D1 was higher in MIA than in AIS. The EGFR mutation rate was significantly higher in MIA, while other genetic alterations showed no differences. Six MIA cases showed recurrence or metachronous adenocarcinoma and all the cases with a predominant micropapillary invasive pattern demonstrated this feature., Conclusions: The current CT measurements may be helpful in distinguishing AIS from MIA, but show limited utility in predicting the histology of unchanged pure GGOs. The invasive pattern may have an influence on the postoperative process of MIA; therefore, further studies are needed to evaluate the current diagnostic criteria and treatment strategy for MIA.

Background: Yes-associated protein (YAP) has been reported to be associated with the prognosis of various cancers and also to affect epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) activity in ovarian cancer cell lines. However, few studies have evaluated YAP protein expression in lung cancer, and the results have lacked consistency., Methods: YAP expression was evaluated in a total of 205 curatively resected lung adenocarcinomas and 36 cases of EGFR-mutated TKI-treated patients. Correlations between the expression of YAP and clinicopathologic features, response to EGFR-TKI treatment, and prognostic significance were analyzed., Results: High cytoplasmic YAP expression was positively correlated with the clinicopathologic parameters that have been associated with favorable prognosis. Multivariate analysis revealed that high cytoplasmic YAP expression was an independent prognostic factor in lung adenocarcinomas (progression-free survival: hazard ratio [HR] 0.659; 95 % confidence interval [CI] 0.431-1.010; p = 0.050; overall survival: HR, 0.474; 95 % CI 0.263-0.854; p = 0.013) and EGFR-TKI-treated patients with EGFR mutation (progression-free survival: HR, 0.346; 95 % CI 0.146-0.818; p = 0.016; overall survival: HR, 0.291; 95 % CI 0.125-0.676; p = 0.004)., Conclusions: High cytoplasmic YAP expression predicted a good clinical outcome for patients with lung adenocarcinoma and in EGFR-TKI-treated patients. Therefore, YAP may play a role in EGFR-TKI-treated lung cancer, and YAP targeting may enhance therapeutic effects in combination with other cancer drugs.

Background: MET gene copy number gain (CNG) and protein overexpression have been reported in lung cancer, but the clinical implications in early stage adenocarcinoma remain unclear., Methods: We investigated MET gene copy number and protein expression in 141 cases of surgically resected stage I pulmonary adenocarcinoma. MET gene CNG was determined by silver in situ hybridization, and MET protein expression was assessed by immunohistochemistry. The correlation between MET gene CNG/protein expression and clinicopathologic parameters and prognostic significance was analyzed., Results: MET gene CNG was found in 24.1% (34 of 141) of the cases and was associated with larger tumor size, pleural invasion, and lymphatic vessel invasion. MET gene CNG was inversely correlated with the presence of lepidic subtype (r = -0.17, p = 0.045) and was not associated with EGFR, KRAS mutation, or ALK gene rearrangement. In addition, MET gene CNG was significantly associated with shorter disease-free survival (DFS) (49 vs. 75 months; p < 0.001) and shorter overall survival (OS) (65 vs. 78 months; p = 0.01). Multivariate analysis confirmed that MET gene CNG was significantly associated with poorer DFS [p < 0.001; hazard ratio (HR) 5.5; 95% confidence interval (CI) 2.2-13.9] but was not significantly associated with OS. MET overexpression was observed in 71.3% of cases (97 of 136), but it was not correlated with gene CNG., Conclusions: MET gene CNG is an independent poor prognostic factor in patients with stage I lung adenocarcinoma. It is associated with aggressive pathologic features and is inversely correlated with the presence of lepidic subtype.

Background: Epidermal growth factor receptor (EGFR) mutation alone may be insufficient to predict clinical outcomes in the response to EGFR-tyrosine kinase inhibitor (TKI) therapy. The secondary mutation T790 M and MET amplification are mechanisms of acquired resistance to EGFR-TKI in approximately 50 % of patients, but the remaining mechanisms are unknown., Methods: Eight metastatic lesions and specimens from 41 non-small cell lung carcinoma (NSCLC) patients harbouring activating EGFR mutations who underwent surgical resection and EGFR-TKI therapy were available. Immunohistochemistry was used to evaluate E-cadherin, β-catenin, and PTEN. Chromogenic in situ hybridisation and silver-enhanced in situ hybridisation were used to evaluate EGFR and MET amplification., Results: Patients with E-cadherin/β-catenin alteration showed a poor objective response rate (ORR) (p = 0.005) and shorter overall survival (p = 0.059). Additionally, β-catenin alteration was associated with a poor ORR (p = 0.012). Of the metastatic tumours, three cases (37.5 %) showed the acquisition of altered E-cadherin/β-catenin and PTEN loss and two cases (25 %) demonstrated MET/EGFR amplification., Conclusions: Altered E-cadherin/β-catenin expression in NSCLC harbouring EGFR mutations was associated with a poor response to EGFR-TKI. During metastatic progression, changes in E-cadherin/β-catenin were found. These results may suggest that E-cadherin/β-catenin alteration is related to poor TKI response and resistance.