Targeted next-generation sequencing for analyzing the genetic alterations in atypical adenomatous hyperplasia and adenocarcinoma in situ

Advancements in the diagnosis and treatment of sub‑centimeter lung cancer in the era of precision medicine (Review)

Lung cancer is the malignancy with the highest global mortality rate and imposes a substantial burden on society. The increasing popularity of lung cancer screening has led to increasing number of patients being diagnosed with pulmonary nodules due to their potential for malignancy, causing considerable distress in the affected population. However, the diagnosis and treatment of sub-centimeter grade pulmonary nodules remain controversial. The evolution of genetic detection technology and the development of targeted drugs have positioned the diagnosis and treatment of lung cancer in the precision medicine era, leading to a marked improvement in the survival rate of patients with lung cancer. It has been established that lung cancer driver genes serve a key role in the development and progression of sub-centimeter lung cancer. The present review aimed to consolidate the findings on genes associated with sub-centimeter lung cancer, with the intent of serving as a reference for future studies and the personalized management of sub-centimeter lung cancer through genetic testing.

Endobronchial spread of adenocarcinoma is a distinct pattern of invasion and associated with inferior clinical outcomes in lung adenocarcinoma

AIM

The spread of lung adenocarcinoma cells into the bronchi and bronchioles is not well documented. We termed this histological finding "endobronchial spreading of adenocarcinoma" (EBSA) and investigated its prevalence and clinical significance.

METHODS AND RESULTS

We reviewed 320 resected specimens from patients diagnosed with invasive adenocarcinoma, and EBSA was observed in 144 patients (45%). EBSA was significantly associated with advanced pathological stage, higher histological grade, larger tumour invasion, lymphovascular infiltration, and spread through air spaces. Patients with EBSA had significantly shorter relapse-free survival (RFS) and cancer-specific survival (CSS) in univariate analysis (P < 0.001). In a subgroup analysis of patient with small-sized (invasion size ≤30 mm) adenocarcinoma in the localized stage, EBSA was an independent inferior prognostic indicator in multivariate analysis. In a subgroup analysis of patients with small-sized Grade 1 nonmucinous adenocarcinoma (n = 61), EBSA was observed in 11 patients, and the presence of EBSA was associated with significantly shorter RFS and CSS (P = 0.026 and P = 0.001, respectively).

CONCLUSION

Our results demonstrated that EBSA is a significant risk factor for disease recurrence and cancer-related deaths. EBSA can be regarded as a distinctive pattern of invasion and its recognition can be beneficial in the diagnosis of lung adenocarcinoma.

Selection of potential targets for stratifying congenital pulmonary airway malformation patients with molecular imaging: is MUC1 the one?

Currently there is a global lack of consensus about the best treatment for asymptomatic congenital pulmonary airway malformation (CPAM) patients. The somatic KRAS mutations commonly found in adult lung cancer combined with mucinous proliferations are sometimes found in CPAM. For this risk of developing malignancy, 70% of paediatric surgeons perform a resection for asymptomatic CPAM. In order to stratify these patients into high- and low-risk groups for developing malignancy, a minimally invasive diagnostic method is needed, for example targeted molecular imaging. A prerequisite for this technique is a cell membrane bound target. The aim of this study was to review the literature to identify potential targets for molecular imaging in CPAM patients and perform a first step to validate these findings.A systematic search was conducted to identify possible targets in CPAM and adenocarcinoma in situ (AIS) patients. The most interesting targets were evaluated with immunofluorescent staining in adjacent lung tissue, KRAS+ CPAM tissue and KRAS- CPAM tissue.In 185 included studies, 143 possible targets were described, of which 20 targets were upregulated and membrane-bound. Six of them were also upregulated in lung AIS tissue (CEACAM5, E-cadherin, EGFR, ERBB2, ITGA2 and MUC1) and as such of possible interest. Validating studies showed that MUC1 is a potential interesting target.This study provides an extensive overview of all known potential targets in CPAM that might identify those patients at risk for malignancy and conducted the first step towards validation, identifying MUC1 as the most promising target.

Effective lung cancer control: An unaccomplished challenge in cancer research

Lung cancer has always been a burden to the society since its non-effective early detection and poor survival status. Different imaging modalities such as computed tomography scan have been practiced for lung cancer detection. This review focuses on the importance of sputum cytology for early lung cancer detection and biomarkers effective in sputum samples. Published articles were discussed in light of the potential of sputum cytology for lung cancer early detection and risk assessment across high-risk groups. Recent developments in sample processing techniques have documented a clear potential to improve or refine diagnosis beyond that achieved with conventional sputum cytology examination. The diagnostic potential of sputum cytology may be exploited better through the standardization and automation of sputum preparation and analysis for application in routine laboratory practices and clinical trials. The challenging aspects in sputum cytology as well as sputum-based molecular markers are to ensure appropriate standardization and validation of the processing techniques.

Gene Expression Profiles of Multiple Synchronous Lesions in Lung Adenocarcinoma

Many studies support a stepwise continuum of morphologic changes between atypical adenomatous hyperplasia (AAH) and lung adenocarcinoma (ADC). Here we characterized gene expression patterns and the association of differentially expressed genes and immune tumor microenvironment behaviors in AAH to ADC during ADC development. Tumor tissues from nine patients with ADC and synchronous multiple ground glass nodules/lesions (GGN/Ls) were analyzed using RNA sequencing. Using clustering, we identified genes differentially and sequentially expressed in AAH and ADC compared to normal tissues. Functional enrichment analysis using gene ontology terms was performed, and the fraction of immune cell types was estimated. We identified up-regulated genes (ACSL5 and SERINC2) with a stepwise change of expression from AAH to ADC and validated those expressions by quantitative PCR and immunohistochemistry. The immune cell profiles revealed increased B cell activities and decreased natural killer cell activities in AAH and ADC. A stepwise change of differential expression during ADC development revealed potential effects on immune function in synchronous precursors and in tumor lesions in patients with lung cancer.

Adenocarcinoma spectrum lesions of the lung: Detection, pathology and treatment strategies

Adenocarcinoma has become the most prevalent lung cancer sub-type and its frequency is increasing. The earliest stages in the development of lung adenocarcinomas are visible using modern computed tomography (CT) as ground glass nodules. These pre-invasive nodules can progress over time to become invasive lung adenocarcinomas. Lesions in this developmental pathway are termed 'adenocarcinoma spectrum' lesions. With the introduction of lung cancer screening programs there has been an increase in the detection of these lesions raising questions about natural history, surveillance and treatment. Here we review how the radiological appearance of an adenocarcinoma spectrum lesion relates to its underlying pathology and explore the natural history and factors driving lesion progression. We examine the molecular changes that occur at each stage of adenocarcinoma spectrum lesion development, including the effects of the driver mutations, EGFR and KRAS, that are key to invasive adenocarcinoma pathology. A better understanding of the development of pre-invasive disease will create treatment targets. Our understanding of how tumours interact with the immune system has led to the development of new therapeutic strategies. We review the role of the immune system in the development of adenocarcinoma spectrum lesions. With a clear preinvasive phase there is an opportunity to treat early adenocarcinoma spectrum lesions before an invasive lung cancer develops. We review current management including surveillance, surgical resection and oncological therapy as well as exploring potential future treatment avenues.

Tumor Differentiation and EGFR Mutation Associated with Disease-Free Survival in Stage IA Lung Adenocarcinoma Patients with Curative Surgery

Background

Nearly 30% of stage IA non-small-cell lung cancer patients eventually die of recurrence or metastasis. This study aimed to predict stage IA lung adenocarcinoma (LADC) patients who underwent radical resection with a high risk of recurrence or metastasis.

Methods

Information on clinicopathological, genetic and therapeutic features and recurrence status was collected in this retrospective and two-center study. A nomogram based on multivariate analysis was established to predict disease-free survival. Further stratification was performed to identify populations with a high risk of relapse.

Results

A total of 1584 patients with pathological stage IA LADC who underwent radical surgery between 2011 and 2015 were enrolled from two medical institutions in this study. The nomogram including tumor differentiation and EGFR mutation had a higher C-index of 0.880 (95% CI 0.833–0.926) compared to 0.598 (95% CI 0.486–0.711) for the AJCC 8th TNM staging system. Furthermore, the C-index for the validation cohort was 0.798 (95% CI 0.738–0.857). In addition, the 3-year cumulative nonrecurrence rate in the high-risk group stratified by this model was 21.8% compared to 98.1% in the low-risk group.

Conclusion

This study proposed a new nomogram including tumor differentiation and EGFR mutation to predict recurrence or metastatic probability in stage IA LADC patients who underwent radical surgery. This nomogram could identify patients in the high-risk group and help guide adjuvant treatment in the future.

Rationale for Lung Adenocarcinoma Prevention and Drug Development Based on Molecular Biology During Carcinogenesis

Lung adenocarcinoma (LUAD) is the most common and aggressive subtype of lung cancer with the greatest heterogeneity and aggression. Inspite of recent years’ achievements in understanding the pathogenesis of this disease, as well as the development of new therapeutic approaches, our knowledge on crucial early molecular events during its development is still rudimentary. Recent classification and grading of LUAD has postulated that LUAD does not arise spontaneously, but through a stepwise process from lung adenomatous premalignancy atypical adenomatous hyperplasia to adenocarcinoma in situ, minimally invasive adenocarcinoma, and eventually frankly invasive predominant adenocarcinoma. In this review, we discuss the molecular processes that drive the evolutionary process that results in the formation of LUAD. We also describe how to handle lung premalignancy in clinical settings based on the most recent advances in genomic biology and our own understanding of lung cancer prevention.

Clinicopathologic Features and Genetic Alterations in Adenocarcinoma In Situ and Minimally Invasive Adenocarcinoma of the Lung: Long-Term Follow-Up Study of 121 Asian Patients

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.

The incidence of lymph node metastasis in patients with different oncogenic driver mutations among T1 non-small-cell lung cancer

OBJECTIVE

To investigate the incidence and distribution of lymph node metastasis in patients with different gene mutations among pathological T1 non-small-cell lung cancers (NSCLC).

METHODS

NSCLC cases resected in our institution between 2016 and 2018 were included. Driver mutation testing was performed in all resected tumor tissues. These patients were grouped by the type of gene mutations. On the basis of protein that mutant-genes encoded involved in the molecular pathway, the genotypes were further classified into four distinct groups: upstream receptor mutant protein (EGFR, HER2 and MET); downstream regulator mutant protein (KRAS and BRAF); fusion mutant protein (ROS1, ALK and RET) and the wild type group. The incidence of lymph node metastasis was compared among different groups.

RESULTS

Of the 1052 patients enrolled, the frequency of positive mutations was 68.0%. The incidence of lymph node metastasis were as follows: wild type (19.3%), ROS1 (72.8%), BRAF (55.5%), ALK (44.7%), HER2 (40%), RET (23.1%), KRAS (15.3%), EGFR (15.3%) and MET mutation (0%) (P < 0.001). The incidence of lymph node metastasis was significantly higher in fusion mutant protein group (45.1%) compared with others (wild type 19.3%, downstream regulator mutant protein 19.1%, upstream receptor mutant protein 15.3%, all P < 0.001). Patients with fusion genes also showed higher proportion of vascular invasion and positive lymph node ratio of greater than 0.33 compared to others.

CONCLUSION

Different genotypes of NSCLC have different propensity to develop lymph node metastasis. Cases of fusion gene mutations had a higher risk and burden of lymph node metastasis than other genotypes, which may indicate that more intensive treatment or surveillance strategies should be applied for these patients.

Clinicopathological Characteristics and Mutations Driving Development of Early Lung Adenocarcinoma: Tumor Initiation and Progression

Lung cancer is the leading cause of cancer-related deaths worldwide, with lung adenocarcinoma representing the most common lung cancer subtype. Among all lung adenocarcinomas, the most prevalent subset develops via tumorigenesis and progression from atypical adenomatous hyperplasia (AAH) to adenocarcinoma in situ (AIS), to minimally invasive adenocarcinoma (MIA), to overt invasive adenocarcinoma with a lepidic pattern. This stepwise development is supported by the clinicopathological and molecular characteristics of these tumors. In the 2015 World Health Organization classification, AAH and AIS are both defined as preinvasive lesions, whereas MIA is identified as an early invasive adenocarcinoma that is not expected to recur if removed completely. Recent studies have examined the molecular features of lung adenocarcinoma tumorigenesis and progression. EGFR-mutated adenocarcinoma frequently develops via the multistep progression. Oncogene-induced senescence appears to decrease the frequency of the multistep progression in KRAS- or BRAF-mutated adenocarcinoma, whose tumor evolution may be associated with epigenetic alterations and kinase-inactive mutations. This review summarizes the current knowledge of tumorigenesis and tumor progression in early lung adenocarcinoma, with special focus on its clinicopathological characteristics and their associations with driver mutations (EGFR, KRAS, and BRAF) as well as on its molecular pathogenesis and progression.