Lung Cancer in Never Smokers: A Review

Should Never-Smokers at Increased Risk for Lung Cancer Be Screened?

INTRODUCTION

Lung cancer in never-smokers ranks among the 10 most common causes of death due to cancer worldwide and in the United States. However, it is unknown whether never-smokers at elevated risk for developing lung cancer may benefit from lung cancer screening.

METHODS

The MIcrosimulation SCreening ANalysis (MISCAN)-Lung microsimulation model was used to assess the effects of lung cancer screening for simulated cohorts of never-smokers at different levels of relative risk (RR) for lung cancer compared with never-smokers at average risk. The benefits and harms of screening were estimated for each cohort and compared with those of a cohort of ever-smokers eligible for lung cancer screening according to the United States Preventive Services Task Force (USPSTF) criteria.

RESULTS

The relative lung cancer mortality reduction in never-smokers was higher than the USPSTF eligible cohort (37% compared with 32%). However, the number of life-years gained per lung cancer death averted was lower (10.4 compared with 11.9) and the proportion of overdiagnosed cancers was higher (9.6% compared with 8.4%) for never-smokers compared with the USPSTF eligible cohort, as never-smokers are diagnosed at a later age. The estimated number of screens per lung cancer death averted ranged from 6162 for never-smokers at average risk to 151 for never-smokers with an RR of 35 compared with 353 for the USPSTF eligible cohort.

CONCLUSIONS

Never-smokers with RRs of 15 to 35 have similar to better trade-offs between benefits and harms compared with ever-smokers recommended for lung cancer screening by the USPSTF guidelines. For most never-smokers, lung cancer screening is not beneficial.

Lung Cancer in Never Smokers

Lung cancer is predominantly associated with cigarette smoking; however, a substantial minority of patients with the disease have never smoked. In the US it is estimated there are 17,000-26,000 annual deaths from lung cancer in never smokers, which as a separate entity would be the seventh leading cause of cancer mortality. Controversy surrounds the question of whether or not the incidence of lung cancer in never-smokers is increasing, with more data to support this observation in Asia. There are several factors associated with an increased risk of developing lung cancer in never smokers including second hand smoke, indoor air pollution, occupational exposures, and genetic susceptibility among others. Adenocarcinoma is the most common histology of lung cancer in never smokers and in comparison to lung cancer in smokers appears less complex with a higher likelihood to have targetable driver mutations.

Carcinoma of the lung in the absence of asbestosis: The value of lung fiber burden analysis

Asbestos is universally recognized as a carcinogen for the lower respiratory tract. However, asbestos is a contributory factor in a small fraction of lung cancers, the vast majority of which are related to cigarette smoking. The challenge for the pathologist is to determine when a lung cancer may be attributed to past asbestos exposure. The finding of asbestosis either clinically or pathologically is a useful marker for such a determination. However, in the absence of asbestosis, it has been suggested that a fiber burden as determined by analytical electron microscopy within the range of asbestosis is sufficient for determination of a causal contribution. We report here an example of a case of lung cancer in which fiber burden studies showed an asbestos concentration within the range of asbestosis as determined by scanning electron microscopy (SEM).

Gene mutation discovery research of non-smoking lung cancer patients due to indoor radon exposure

Although the incidence and mortality for most cancers such as lung and colon are decreasing in several countries, they are increasing in several developed countries because of an unhealthy western lifestyles including smoking, physical inactivity and consumption of calorie-dense food. The incidences for lung and colon cancers in a few of these countries have already exceeded those in the United States and other western countries. Among them, lung cancer is the main cause of cancer death in worldwide. The cumulative survival rate at five years differs between 13 and 21 % in several countries. Although the most important risk factors are smoking for lung cancer, however, the increased incidence of lung cancer in never smokers(LCINS) is necessary to improve knowledge concerning other risk factors. Environmental factors and genetic susceptibility are also thought to contribute to lung cancer risk. Patients with lung adenocarcinoma who have never smoking frequently contain mutation within tyrosine kinase domain of the epidermal growth factor receptor(EGFR) gene. Also, K-ras mutations are more common in individuals with a history of smoking use and are related with resistance to EFGR-tyrosine kinase inhibitors. Recently, radon(Rn), natural and noble gas, has been recognized as second common reason of lung cancer. In this review, we aim to know whether residential radon is associated with an increased risk for developing lung cancer and regulated by several genetic polymorphisms.

In vitro evaluation of antitumoral efficacy of catalase in combination with traditional chemotherapeutic drugs against human lung adenocarcinoma cells

Lung cancer is the most lethal cancer-related disease worldwide. Since survival rates remain poor, there is an urgent need for more effective therapies that could increase the overall survival of lung cancer patients. Lung tumors exhibit increased levels of oxidative markers with altered levels of antioxidant defenses, and previous studies demonstrated that the overexpression of the antioxidant enzyme catalase (CAT) might control tumor proliferation and aggressiveness. Herein, we evaluated the effect of CAT treatment on the sensitivity of A549 human lung adenocarcinoma cells toward various anticancer treatments, aiming to establish the best drug combination for further therapeutic management of this disease. Exponentially growing A549 cells were treated with CAT alone or in combination with chemotherapeutic drugs (cisplatin, 5-fluorouracil, paclitaxel, daunorubicin, and hydroxyurea). CalcuSyn(®) software was used to assess CAT/drug interactions (synergism or antagonism). Growth inhibition, NFκB activation status, and redox parameters were also evaluated in CAT-treated A549 cells. CAT treatment caused a cytostatic effect, decreased NFκB activation, and modulated the redox parameters evaluated. CAT treatment exhibited a synergistic effect among most of the anticancer drugs tested, which is significantly correlated with an increased H2O2 production. Moreover, CAT combination caused an antagonism in paclitaxel anticancer effect. These data suggest that combining CAT (or CAT analogs) with traditional chemotherapeutic drugs, especially cisplatin, is a promising therapeutic strategy for the treatment of lung cancer.

Lung Cancer Survival Among Chinese Americans, 2000 to 2010

PURPOSE

Despite being the leading cause of cancer death, no prior studies have characterized survival patterns among Chinese Americans diagnosed with lung cancer. This study was conducted to identify factors associated with survival after lung cancer in a contemporary cohort of Chinese patients with lung cancer.

METHODS

The study design is a prospective descriptive analysis of population-based California Cancer Registry data. Multivariable Cox proportional hazards models were used to estimate hazard ratios (HRs) for overall mortality. Participants were Chinese American residents diagnosed with first primary invasive lung cancer from 2000 to 2010 (2,216 men and 1,616 women).

RESULTS

Among Chinese men, decreased mortality was associated with care at a National Cancer Institute cancer center (HR, 0.85; 95% CI, 0.73 to 0.99) and adenocarcinoma versus small-cell carcinoma (HR, 0.78; 95% CI, 0.65 to 0.92). Women had better survival compared with men (HR, 0.82; 95% CI, 0.75 to 0.89), with mortality associated with never married versus currently married status (HR, 1.36; 95% CI, 1.11 to 1.66), lower versus higher neighborhood socioeconomic status (HR, 1.38; 95% CI, 1.10 to 1.72 comparing lowest to highest quintile), care at a cancer center (HR, 0.80; 95% CI, 0.67 to 0.96), and squamous cell relative to small-cell carcinoma (HR, 1.60; 95% CI, 1.04 to 2.48).

CONCLUSION

Focusing on factors associated with marital status, community socioeconomic status, and characteristics unique to National Cancer Institute-designated cancer centers may help to identify potential strategies for improving the length of survival for Chinese Americans.

A functional polymorphism in CSF1R gene is a novel susceptibility marker for lung cancer among never-smoking females

INTRODUCTION

It has been estimated that the proportion of never-smokers among females with lung cancer is 53% worldwide and 75% in Korea. We conducted a two-stage study to identify genetic factors responsible for lung cancer susceptibility in female never-smokers.

MATERIALS AND METHODS

In a discovery set, 1969 potentially functional single nucleotide polymorphisms (SNPs) of 1151 genes, which were related to cancer development and progression, were evaluated using the Affymetrix custom-made GeneChip in 181 female never-smokers with lung cancer and 179 controls. A replication study was performed on an independent cohort of 596 cases and 1194 healthy controls.

RESULTS

Sixteen SNPs with p < 0.05 for genotype distribution in the discovery set were enrolled in the replication study. Among 16 SNPs, three SNPs (colony-stimulating factor 1 receptor [CSF1R] rs10079250A>G, tumor protein p63 [TP63] rs7631358G>A, and corepressor interacting with RBPJ 1 [CIR1] rs13009079T>C) were found to be significantly associated with lung cancer in the same direction as the discovery set. Homology-based model for CSF1R indicated that the rs10079250A>G leads to increased positive charge of CSF-binding region of CSF1R, thereby increasing the chance of binding between CSF and CSF1R. In addition, this SNP was found to increase the phosphorylation of a mitogen-activated protein kinase, JNK.

CONCLUSIONS

Our results suggest that the three SNPs, particularly CSF1R rs10079250, may contribute to lung cancer susceptibility in never-smoking females.

Human papillomavirus infection and risk of lung cancer in never-smokers and women: an 'adaptive' meta-analysis

OBJECTIVES:

The incidence of lung cancer in Koreans is increasing in women and in both men and women with a never-smoking history. Human papillomavirus (HPV) infection has been suggested as a modifiable risk factor of lung cancer in never-smokers and women (LCNSW). This systematic review (SR) aimed to evaluate an association between HPV infection and lung cancer risk in LCNSW.

METHODS:

Based on a prior SR and some expert reviews, we identified refereed, cited, or related articles using the PubMed and Scopus databases. All case-control studies that reported the odds ratio of HPV infection in LCNSW were selected. An estimate of the summary odds ratio (SOR) with 95% confidence intervals (CI) was calculated.

RESULTS:

A total of four case-control studies were included. The fixed-effect model was applied because of homogeneity (I-squared=0.0%). The SORs in women and in never-smokers were 5.32 (95% CI, 1.75 to 16.17) and 4.78 (2.25 to 10.15) respectively.

CONCLUSIONS:

These results showed a significant effect of HPV infection in LCNSW. It is evident that developing a preventive plan against LCNSW may be necessary.

Hormonal Replacement Therapy and the Risk of Lung Cancer in Women: An Adaptive Meta-analysis of Cohort Studies

Objectives:

Approximately 10% to 15% of lung cancer cases occur in never-smokers. Hormonal factors have been suggested to lead to an elevated risk of lung cancer in women. This systematic review (SR) aimed to investigate the association between hormonal replacement therapy (HRT) and the risk of lung cancer in women using cohort studies.

Methods:

We first obtained previous SR articles on this topic. Based on these studies we made a list of refereed, cited, and related articles using the PubMed and Scopus databases. All cohort studies that evaluated the relative risk of HRT exposure on lung cancer occurrence in women were selected. Estimate of summary effect size (sES) with 95% confidence intervals (CIs) were calculated.

Results:

A total of 14 cohort studies were finally selected. A random effect model was applied due to heterogeneity (I-squared, 64.3%). The sES of the 14 articles evaluating the impact of HRT exposure on lung cancer occurrence in women indicated no statistically significant increase in lung cancer risk (sES, 0.99; 95% CI, 0.90 to 1.09).

Conclusions:

These results showed that HRT history had no effect on the risk of lung cancer in women, even though the sES of case-control studies described in previous SR articles indicated that HRT had a protective effect against lung cancer. It is necessary to conduct a pooled analysis of cohort studies.

Tobacco habituated and non-habituated subjects exhibit different mutational spectrums in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common non-skin cancer in the world. Tobacco chewing is implicated with most of the cases of HNSCC but this type of cancer is increasing in non-tobacco chewers as well. This study was instigated to provide comprehensive variant and gene-level data in HNSCC subjects of the Indian population and fill the gap in the literature on comparative assessment of gene mutations in cancer subjects with a habit of tobacco and those without any habit using targeted amplicon sequencing. We performed targeted Amplicon sequencing of 409 tumor suppressor genes and oncogenes, frequently mutated across many cancer types, including head and neck. DNA from primary tumor tissues and matched blood was analyzed for HNSCC patients with a habit of tobacco and those without any habit. PDE4DIP, SYNE1, and NOTCH1 emerged as the highly mutated genes in HNSCC. A total of 39 candidate causal variants in 22 unique cancer driver genes were identified in non-habitual (WoH) and habitual (WH) subjects. Comparison of genes from both the subjects, showed seven unique cancer driver genes (KIT, ATM, RNF213, GATA2, DST, RET, CYP2C19) in WoH, while WH showed five (IL7R, PKHD1, MLL3, PTPRD, MAPK8) and 10 genes (SETD2, ATR, CDKN2A, NCOA4, TP53, SYNE1, KAT6B, THBS1, PTPRT, and FGFR3) were common to both subjects. In addition to this NOTCH1, NOTCH2, and NOTCH4 gene were found to be mutated only in habitual subjects. These findings strongly support a causal role for tobacco, acting via PI3K and MAPK pathway inhibition and stimulation of various genes leading to oncogenic transformations in case of tobacco chewers. In case of non-tobacco chewers it appears that mutations in the pathway affecting the squamous epithelial lineage and DNA repair genes lead to HNSCC. Somatic mutation in CYP2C19 gene in the non-habitual subjects suggests that this gene may have a tobacco independent role in development and progression of HNSCC. In addition to sharing high mutation rate, NOTCH gene family was found to be mutated only in habitual sample. Further, presence of mutated genes not earlier reported to be involved in HNSCC, suggest that the Indian sub-continent may have different sets of genes, as compared to other parts of the world, involved in the development and progression of HNSCC.

MicroRNA-33b inhibits lung adenocarcinoma cell growth, invasion, and epithelial-mesenchymal transition by suppressing Wnt/β-catenin/ZEB1 signaling

Altered expression of microRNA (miRNA) is associated with lung carcinogenesis and metastasis. Our previous study of lung cancer miRNAs using the gene chip assay demonstrated altered miR-33b expression in lung adenocarcinoma. The present study further investigated miR-33b expression, function, and gene regulation in lung cancer cells in vitro and in nude mouse xenografts. Our data showed that the level of miR-33b expression was dramatically decreased in lung adenocarcinoma cell lines and tissues and that the reduced miR-33b expression was associated with tumor lymph node metastasis. Furthermore, restoration of miR-33b expression inhibited lung adenocarcinoma cell proliferation, migration, and invasion and tumor cell epithelial-mesenchymal transition (EMT) in vitro. Luciferase assay revealed that miR-33b bound to ZEB1 3'-UTR region and inhibited ZEB1 expression, while expression of ZEB1 mRNA and miR-33b was inversely associated with lung adenocarcinoma cell lines and tissues. Subsequently, we found that miR-33b suppressed the activity of WNT/β-catenin signaling in lung adenocarcinoma cells and in turn suppressed tumor cell growth and EMT in vitro and in vivo nude mouse xenografts. In conclusion, the present study provided novel insight into the molecular mechanism of lung adenocarcinoma progression. MicroRNA-33b should be further investigated as a potential therapeutic target in human lung adenocarcinoma.

Genomic alterations in lung adenocarcinoma

Treatment for non-small-cell lung cancer is evolving from the use of cytotoxic chemotherapy to personalised treatment based on molecular alterations. This past decade has witnessed substantial progress in the treatment of patients with EGFR mutations and ALK rearrangements, and it is now possible to study complex genomic alterations in cancer using next-generation sequencing. Sequencing data from large-scale consortia, such as The Cancer Genome Atlas, as well as several independent groups, have helped identify novel drivers and potentially targetable alterations in lung adenocarcinomas. These data clearly suggest that lung adenocarcinoma is associated with distinct genomic alterations compared with other lung cancer subtypes, and highlight the widespread molecular heterogeneity that underlies the disease. In this Review, we discuss some of the key findings from genomic studies of lung adenocarcinoma.

Genetic Polymorphism, Telomere Biology and Non-Small Lung Cancer Risk

Recent genome-wide association studies (GWAS) have identified a number of chromosomal regions associated with the risk of lung cancer. Of these regions, single-nucleotide polymorphisms (SNPs), especially rs2736100 located in the telomerase reverse transcriptase (TERT) gene show unique and significant association with non-small cell lung cancer (NSCLC) in a few subpopulations including women, nonsmokers, East Asians and those with adenocarcinoma. Recent studies have also linked rs2736100 with a longer telomere length and lung cancer risk. In this review, we seek to summarize the relationship between these factors and to further link the underlying telomere biology to lung cancer etiology. We conclude that genetic alleles combined with environmental (e.g., less-smoking) and physiological factors (gender and age) that confer longer telomere length are strong risk factors for NSCLC. This linkage may be particularly relevant in lung adenocarcinoma driven by epidermal growth factor receptor (EGFR) mutations, as these mutations have also been strongly linked to female gender, less-smoking history, adenocarcinoma histology and East Asian ethnicity. By establishing this connection, a strong argument is made for further investigating of the involvement of these entities during the tumorigenesis of NSCLC.

Incidence trends of lung cancer by immigration status among Chinese Americans

BACKGROUND

Lung cancer is the leading cause of cancer-related death among Chinese Americans. A detailed examination of incidence trends by immigration status and histology may inform the etiology of lung cancer in this growing population.

METHODS

California Cancer Registry data were enhanced with data on patient nativity. Lung cancer incidence rates for Chinese males and females were computed for the years 1990-2010, and rates by immigration status and histology were computed for 1990-2004. Trends were assessed with annual percentage change (APC) statistics (two-sided P values) based on linear regression.

RESULTS

A total of 8,167 lung cancers were diagnosed among California Chinese from 1990 to 2010. Overall incidence increased nonstatistically among U.S.-born males (APC, 2.1; 95% CI, -4.9 to 9.7), but decreased significantly among foreign-born (APC, -1.7; 95% CI, -2.9 to -0.6). Statistically significant decreasing trends were observed for non-small cell lung cancer (NSCLC), specifically the squamous cell and large cell carcinoma subtypes among foreign-born males. Among females, incidence decreased nonsignificantly among U.S.-born (APC, -2.8; 95% CI, -9.1 to 4.0) but was stable among foreign-born (APC, -0.4; 95% CI, -1.7 to 1.0). A statistically significant decreasing trend was observed for squamous cell among foreign-born females.

CONCLUSIONS

These data provide critical evidence base to inform screening, research, and public health priorities in this growing population.

IMPACT

Given the low smoking prevalence among Chinese Americans, especially females, and few known lung cancer risk factors in U.S. never-smoker populations, additional research of etiologic genetic or biologic factors may elucidate knowledge regarding lung cancer diagnosed in never smokers.

Cancer research in Asian American, Native Hawaiian, and Pacific Islander populations: accelerating cancer knowledge by acknowledging and leveraging heterogeneity

The Asian American, Native Hawaiian, and Pacific Islander population is large, growing, and extremely heterogeneous. Not only do they bear unique burdens of incidence and outcomes for certain cancer types, they exhibit substantial variability in cancer incidence and survival patterns across the ethnic groups. By acknowledging and leveraging this heterogeneity through investing in cancer research within these populations, we have a unique opportunity to accelerate the availability of useful and impactful cancer knowledge. See all the articles in this CEBP Focus section, "Cancer in Asian and Pacific Islander Populations."

Genetic association between AGPHD1 variant and lung cancer risk

The knowledge of molecular mechanism that underlies the genetic predisposition to lung cancer is yet limited. Results from previous studies addressing the association of AGPHD1 variant rs8034191 with lung carcinogenesis remain inconclusive. Herein, we combined these data and re-examined the association. We performed a meta-analysis of Asian studies identified through various ways. Using the data collected from each eligible study, we combined the effect estimates (ORs and its 95 % CIs) with the fixed effects model (Mantel-Haenszel method). Statistical analyses were done using STATA software. Data from nine studies (29,290 subjects) carried out in Asian populations were analyzed in this work. There was no overall association between variant rs8034191 and lung cancer risk under the allele frequency model (OR = 1.03, 95 % CI = 0.93-1.13, P heterogeneity = 0.522). We observed the same associations under other genetic models and in the subgroup analyses by ethnicity and smoking status. Our results indicate that variant rs8034191 in the AGPHD1 gene may not modify the genetic risk of lung cancer in Asian populations.

Prognostic role of p53 and Ki-67 immunohistochemical expression in patients with surgically resected lung adenocarcinoma: a retrospective study

OBJECTIVE

p53 mutations and the Ki-67 protein are frequently observed in various types of human cancer; the abnormal expression of p53 and Ki-67 in the tumor is associated with poor survival of lung cancer patients. We aimed to assess the prognostic role of immunohistochemical (IHC) expression of p53 and Ki-67 in lung adenocarcinoma tissue.

METHODS

Tumor samples from 136 patients who had undergone surgical resection for lung adenocarcinoma were retrospectively evaluated for p53 and Ki-67 expression by immunohistochemistry. Associations of clinical and pathologic variables with p53 and Ki-67 were determined using the χ(2) test. After excluding two patients (follow-up loss), 134 cases were evaluated for associations between p53, Ki-67, clinical and pathologic variables, and survival by using the Cox proportional hazards regression model and Kaplan-Meier method.

RESULTS

In the 136 patients, p53 was positive in 71.0% (93/131), and Ki-67 showed high in 49.2% (61/124). Unlike p53, Ki-67 was associated with male sex, smoking, and poor tumor differentiation (P=0.004, P=0.001 and P=0.006). Of these, poor tumor differentiation strongly was correlated with high level of Ki-67 expression (P=0.008). Neither p53 nor Ki-67 was associated with increased risk of death (P=0.318, P=0.053); however, age ≥60 years and lymph node involvement were significant predictors of death (P=0.039 and P=0.042). The log-rank test revealed a significant association between Ki-67 and lower survival in all patients (χ(2)=5637; P=0.018); however, the risk was limited to stage III cases (χ(2)=5.939; P=0.015). Unlike p53, patients with high level of Ki-67 expression showed lower 3-year actuarial survival than those without (log-rank test, χ(2)=4.936; P=0.026).

CONCLUSIONS

IHC expression of Ki-67 in lung adenocarcinoma tissue shows stronger association with poor tumor differentiation, and negatively affects patients' survival in advanced-stage lung cancer; however, the role of p53 on patient outcome needs further study.

Coffee consumption and incidence of lung cancer in the NIH-AARP Diet and Health Study

BACKGROUND

Coffee drinkers had a higher risk of lung cancer in some previous studies, but as heavy coffee drinkers tend to also be cigarette smokers, such findings could be confounded. Therefore, we examined this association in the nearly half a million participants of the US NIH-AARP Diet and Health Study.

METHODS

Typical coffee intake and smoking history were queried at baseline. During 4 155 256 person-years of follow-up, more than 9000 incident lung cancer cases occurred. We used Cox proportional hazards regression to estimate hazard ratios (HRs)and 95% confidence intervals for coffee intake and subsequent incidence of lung cancer. We also comprehensively adjusted for tobacco smoking and examined associations by detailed strata of tobacco use.

RESULTS

Coffee drinkers were far more likely to smoke than non-drinkers. Although coffee drinking was associated with lung cancer in age- and sex- adjusted models (HR for ≥ 6 cups/day compared with none: 4.56, 4.08-5.10), this association was substantially attenuated after adjusting for smoking (HR: 1.27, 1.14-1.42). Similar findings were observed for each different histological type of lung cancer, and for participants drinking predominantly caffeinated or decaffeinated coffee. Little evidence for an association was observed in our stratified analyses, either within never smokers or in most categories of tobacco use.

CONCLUSIONS

Coffee drinking was positively associated with lung cancer in our study, although the association was substantially attenuated after adjustment for tobacco smoking. As our adjustment for lifetime tobacco use was imperfect, it is likely that the remaining association is due to residual confounding by smoking, although other explanations are possible.

Comprehensive Analysis of the Incidence and Survival Patterns of Lung Cancer by Histologies, Including Rare Subtypes, in the Era of Molecular Medicine and Targeted Therapy: A Nation-Wide Cancer Registry-Based Study From Taiwan

Lung cancer is the third most common cancer in the world and has the highest cancer mortality rate. A worldwide increasing trend of lung adenocarcinoma has been noted. In addition, the identification of epidermal growth factor receptor (EGFR) mutations and the introduction of EGFR inhibitors to successfully treat EGFR mutated non-small cell lung cancers are breakthroughs for lung cancer treatment. The current study evaluated the incidence and survival of lung cancer using data collected by the Taiwan Cancer Registry between 1996 and 2008. The results showed that the most common histologic subtype of lung cancer was adenocarcinoma, followed by squamous cell carcinoma, small cell carcinoma, large cell carcinoma, neuroendocrine tumors, lymphoma, and sarcoma. Overall, the incidence of lung cancer in Taiwan increased significantly from 1996 to 2008. An increased incidence was observed for adenocarcinoma, particularly for women, with an annual percentage change of 5.9, whereas the incidence of squamous cell carcinoma decreased. Among the subtypes of lung cancer, the most rapid increase occurred in neuroendocrine tumors with an annual percentage change of 15.5. From 1996-1999 to 2005-2008, the 1-year survival of adenocarcinoma increased by 10% for men, whereas the 1-, 3-, and 5-year survivals of adenocarcinoma for women increased by 18%, 11%, and 5%, respectively. Overall, the incidence of lung cancer has been increasing in Taiwan, although the trends were variable by subtype. The introduction of targeted therapies was associated with a significantly improved survival for lung adenocarcinoma in Taiwan; however, more studies are needed to explain the rising incidence of lung adenocarcinoma. In addition, it is important to investigate the molecular pathogenesis of the various subtypes of lung cancer to develop novel therapeutic agents.

Integrated analysis of DNA methylation and microRNA regulation of the lung adenocarcinoma transcriptome

Lung adenocarcinoma, as a common type of non-small cell lung cancer (40%), poses a significant threat to public health worldwide. The present study aimed to determine the transcriptional regulatory mechanisms in lung adenocarcinoma. Illumina sequence data GSE 37764 including expression profiling, methylation profiling and non-coding RNA profiling of 6 never-smoker Korean female patients with non-small cell lung adenocarcinoma were obtained from the Gene Expression Omnibus (GEO) database. Differentially methylated genes, differentially expressed genes (DEGs) and differentially expressed microRNAs (miRNAs) between normal and tumor tissues of the same patients were screened with tools in R. Functional enrichment analysis of a variety of differential genes was performed. DEG-specific methylation and transcription factors (TFs) were analyzed with ENCODE ChIP-seq. The integrated regulatory network of DEGs, TFs and miRNAs was constructed. Several overlapping DEGs, such as v-ets avian erythroblastosis virus E26 oncogene homolog (ERG) were screened. DEGs were centrally modified by histones of tri-methylation of lysine 27 on histone H3 (H3K27me3) and di-acetylation of lysine 12 or 20 on histone H2 (H2BK12/20AC). Upstream TFs of DEGs were enriched in different ChIP-seq clusters, such as glucocorticoid receptors (GRs). Two miRNAs (miR-126-3p and miR-30c-2-3p) and three TFs including homeobox A5 (HOXA5), Meis homeobox 1 (MEIS1) and T-box 5 (TBX5), played important roles in the integrated regulatory network conjointly. These DEGs, and DEG-related histone modifications, TFs and miRNAs may be important in the pathogenesis of lung adenocarcinoma. The present results may indicate directions for the next step in the study of the further elucidation and targeted prevention of lung adenocarcinoma.

Non-small-cell lung cancer

Lung cancer is one of the most frequently diagnosed cancers and is the leading cause of cancer-related death worldwide. Non-small-cell lung cancer (NSCLC), a heterogeneous class of tumours, represents approximately 85% of all new lung cancer diagnoses. Tobacco smoking remains the main risk factor for developing this disease, but radon exposure and air pollution also have a role. Most patients are diagnosed with advanced-stage disease owing to inadequate screening programmes and late onset of clinical symptoms; consequently, patients have a very poor prognosis. Several diagnostic approaches can be used for NSCLC, including X-ray, CT and PET imaging, and histological examination of tumour biopsies. Accurate staging of the cancer is required to determine the optimal management strategy, which includes surgery, radiochemotherapy, immunotherapy and targeted approaches with anti-angiogenic monoclonal antibodies or tyrosine kinase inhibitors if tumours harbour oncogene mutations. Several of these driver mutations have been identified (for example, in epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK)), and therapy continues to advance to tackle acquired resistance problems. Also, palliative care has a central role in patient management and greatly improves quality of life. For an illustrated summary of this Primer, visit: http://go.nature.com/rWYFgg.

Common Oncogene Mutations and Novel SND1-BRAF Transcript Fusion in Lung Adenocarcinoma from Never Smokers

Lung adenocarcinomas from never smokers account for approximately 15 to 20% of all lung cancers and these tumors often carry genetic alterations that are responsive to targeted therapy. Here we examined mutation status in 10 oncogenes among 89 lung adenocarcinomas from never smokers. We also screened for oncogene fusion transcripts in 20 of the 89 tumors by RNA-Seq. In total, 62 tumors had mutations in at least one of the 10 oncogenes, including EGFR (49 cases, 55%), K-ras (5 cases, 6%), BRAF (4 cases, 5%), PIK3CA (3 cases, 3%), and ERBB2 (4 cases, 5%). In addition to ALK fusions identified by IHC/FISH in four cases, two previously known fusions involving EZR- ROS1 and KIF5B-RET were identified by RNA-Seq as well as a third novel fusion transcript that was formed between exons 1–9 of SND1 and exons 2 to 3′ end of BRAF. This in-frame fusion was observed in 3/89 tested tumors and 2/64 additional never smoker lung adenocarcinoma samples. Ectopic expression of SND1-BRAF in H1299 cells increased phosphorylation levels of MEK/ERK, cell proliferation, and spheroid formation compared to parental mock-transfected control. Jointly, our results suggest a potential role of the novel BRAF fusion in lung cancer development and therapy.

Profile of ceritinib in the treatment of ALK+ metastatic non-small-cell lung cancer

Lung cancer has become one of the leading causes of death in both men and women in the United States, with approximately 230,000 new cases and 160,000 deaths each year. Approximately 80% of lung cancer patients are diagnosed with non-small-cell lung cancer (NSCLC), a subset of epithelial lung cancers that are generally insensitive to chemotherapy. An estimated 3%–7% of NSCLC patients harbor tumors containing anaplastic lymphoma kinase (ALK) gene rearrangement as an oncogenic driver. Subsequent development of the first-generation tyrosine kinase inhibitor crizotinib demonstrated substantial initial ALK+-tumor regression, yet ultimately displayed resistance in treated patients. The recently approved tyrosine kinase inhibitor ceritinib has been shown to be an effective antitumor agent against crizotinib-naïve and -resistant ALK+-NSCLC patients. In this review, we will provide an overview of biology and management of ALK+-NSCLC with a special focus on clinical development of ceritinib.

Oxidative DNA damage is involved in cigarette smoke-induced lung injury in rats

OBJECTIVE

Reactive oxygen species (ROS) induced by exogenous toxicants are suggested to be involved in carcinogenesis by oxidative modification of DNA. 8-Hydroxyl-2-deoxyguanosine (8-OHdG) has been considered as a reliable biomarker for oxidative DNA damage both in vivo and in vitro studies. But the effect of smoking on oxidative damage has not yet been fully elucidated.

METHODS

Wistar rats were exposed to cigarette smoke at concentrations of 20 and 60 % for 30 min, twice/day for 45 weeks. Then the histopathology of lung tissues, levels of ROS, 8-OHdG, and total antioxidant (T-AOC), expression of DNA repair enzymes, e.g. 8-oxyguaine DNA glycosylase (OGG1), and MutThomolog 1 (Oxidized Purine Nucleoside Triphosphatase, MTH1) were determined in urine, peripheral blood lymphocytes, and lung tissue.

RESULTS

The results showed that long-term cigarette smoke exposure can cause obvious damages of lung tissue in rats. In addition, a significant and cigarette smoke concentration-dependent increase in ROS and 8-OHdG were observed compared with the non-exposed control rats. In contrast, the expression of OGG1 and MTH1, and T-AOC levels were obviously decreased after long-term exposure to cigarette smoke.

CONCLUSION

These findings indicate that long-term exposure to cigarette smoker increases ROS levels, decreases total antioxidant capacity, and interferes DNA repair capacity that eventually induces oxidative DNA damage, which appears to play an important role in cigarette smoke-induced lung injury in rats, and determination of 8-OHdG levels might be a useful method for monitoring oxidative damage in cigarette smokers.

Identification of stage-specific biomarkers in lung adenocarcinoma based on RNA-seq data

Tumorigenesis is a multistep process that attributes to the sequential accumulation of abnormal expression in key oncogenes or tumor suppressors. We aimed to identify stage-specific biomarkers to distinguish lung adenocarcinoma (LAC) stages in cancer progression. RNA-sequencing data of LAC and matched adjacent non-cancer tissues were downloaded from the Cancer Genome Atlas, including 29 pairs of samples from LAC at stage I, 14 from LAC at stage II, 13 from LAC at stage III, and 1 from LAC at stage IV. Differentially expressed genes (DEGs) were analyzed for each case at different stages of LAC. DEGs were further annotated based on transcription factor data information, tumor-associated gene database, and protein-protein interaction database. Functional annotation was performed for genes in PPI network by DAVID online tool. Our analysis identified 11 high-frequency DEGs in the stage I, 29 in the stage II, and 90 in the stage III of LAC. Among them, eight genes were significantly correlated with LAC stages and identified as biomarkers in LAC progression. ANGPTL5, C7orf16, EDN3, LOC150622, HOXA11AS, IL1F5, and USH1G significantly distinguished stage III from stages I and II. GJB6 was significantly enriched in the gap junction trafficking pathway, while C7orf16 and EDN3 were enriched in Wnt signaling pathway, cell cycle, and G protein-coupled receptor (GPCR) signaling. Up-regulated GJB6 especially in LAC stage II and down-regulated C7orf16 and EDN3 specifically in stage III were identified as biomarkers for distinguishing cancer stage in tumor progression through dysregulating gap junction, Wnt signaling, and GPCR signaling pathways.

Lung cancer molecular epidemiology in China: recent trends

Lung cancer is both the most common diagnosed cancer and the leading cause of cancer related deaths in China. During the past three decades, the incidence and mortality of lung cancer in China are increasing rapidly. According to data from National Central Cancer Registry (NCCR) in 2010, the crude incidence of lung cancer in China was 46.08 per 100,000 population (61.86 per 100,000 men and 29.54 per 100,000 women), with an estimated over 600,000 new diagnosed lung cancer patients (416,333 males and 189,613 females). Meanwhile, the crude mortality of lung cancer in China was 37.00 per 100,000 population (50.04 per 100,000 men and 23.33 per 100,000 women). Consistent with the change in developed countries, adenocarcinoma has become the most predominant histological subtype of lung cancer in China. For the majority advanced non-small-cell lung cancer (NSCLC) patients, especially patients with adenocarcinoma, targeted therapy became increasing important in the treatment. Chinese researcher have done a lot work in terms of lung cancer molecular epidemiology, therefore, in this review, we further summarized the epidemiology of driver genes in NSCLC, hoping to help clinicians to better screen certain driver genes in China for treatment decisions.

Interactions between household air pollution and GWAS-identified lung cancer susceptibility markers in the Female Lung Cancer Consortium in Asia (FLCCA)

We previously carried out a multi-stage genome-wide association study (GWAS) on lung cancer among never smokers in the Female Lung Cancer Consortium in Asia (FLCCA) (6,609 cases, 7,457 controls) that identified novel susceptibility loci at 10q25.2, 6q22.2, and 6p21.32, and confirmed two previously identified loci at 5p15.33 and 3q28. Household air pollution (HAP) attributed to solid fuel burning for heating and cooking, is the leading cause of the overall disease burden in Southeast Asia, and is known to contain lung carcinogens. To evaluate the gene-HAP interactions associated with lung cancer in loci independent of smoking, we analyzed data from studies participating in FLCCA with fuel use information available (n = 3; 1,731 cases; 1,349 controls). Coal use was associated with a 30% increased risk of lung cancer (OR 1.3, 95% CI 1.0-1.6). Among the five a priori SNPs identified by our GWAS, two showed a significant interaction with coal use (HLA Class II rs2395185, p = 0.02; TP63 rs4488809 (rs4600802), p = 0.04). The risk of lung cancer associated with coal exposure varied with the respective alleles for these two SNPs. Our observations provide evidence that genetic variation in HLA Class II and TP63 may modify the association between HAP and lung cancer risk. The roles played in the cell cycle and inflammation pathways by the proteins encoded by these two genes provide biological plausibility for these interactions; however, additional replication studies are needed in other non-smoking populations.

High expression of transcriptional factor HoxB9 predicts poor prognosis in patients with lung adenocarcinoma

AIMS

HoxB9, as a Hox family member, is known to play important roles in embryonic development. Recent studies showed that HoxB9 is engaged in cancer progression. However, the role of Hoxb9 in lung adenocarcinoma is unknown. The purpose of this study is to investigate the expression and prognostic value of HoxB9 in patients with lung adenocarcinoma.

METHODS AND RESULTS

The localization and expression of HoxB9 in lung adenocarcinoma were examined by immunohistochemistry. The correlation between HoxB9 expression levels with patient survival was assessed by Kaplan-Meier analysis. The epithelial-mesenchymal transition (EMT) markers and migratory ability were evaluated in HoxB9 up- and down-regulated H1299 lung adenocarcinoma cells. HoxB9 was found to be localized predominantly in the cell nuclei and expressed in 21.3% of lung adenocarcinomas. A significant increase in HoxB9 intensity in the high stage of lung adenocarcinoma was observed (P < 0.01). Increased expression of HoxB9 was related to T classification, more lymph node metastasis and a shorter patient overall survival (P < 0.05). However, the expression level of HoxB9 was not correlated with age and gender. Functionally, HoxB9 up-regulated EMT-related molecules and promoted cell migration in H1299 cells.

CONCLUSION

High expression of HoxB9 is a prognostic marker for lung adenocarcinoma patients.

CHRNA3 genetic polymorphism and the risk of lung cancer in the Chinese Han smoking population

Lung cancer is the leading cause of cancer-related deaths worldwide that result from the combined effected of smoking exposure and genetic susceptibility. CHRNA3, a nicotinic acetylcholine receptor gene, was associated with lung cancer risk. The aim of this study was to identify whether CHRNA3 polymorphisms increase lung cancer risk directly or indirectly through smoking behavior in the Chinese Han individuals. We conducted a case-control study including 228 individuals with lung cancer and 301 healthy individuals. Seventeen known SNPs within CHRNA3 were selected for genotyping. Odds ratios (OR) and 95 % confidence interval (CI) were calculated by unconditional logistic regression with adjustment for gender and age. Two SNPs (rs8042059 and rs7177514) showed a 1.54-fold (p = 0.036; 95 % CI = 1.03-2.32) and 1.52-fold (p = 0.043; 95 % CI = 1.01-2.27) increased risk for lung cancer in smokers, respectively. Rs8042059 also showed a significant association for variant genotypes (CA/AA) compared with the wild-type genotype (CC), with an OR = 1.84 (p = 0.042; 95 % CI, 1.02-3.33) in the dominant model. In addition, the haplotype analysis found that the haplotypes "TCAC" and "CTGT," composed of rs938682, rs12914385, rs11637630, and rs2869546, were associated with a 1.79-fold and 501-fold increased lung cancer risk, respectively. However, the polymorphisms of all SNPs were not significantly different between controls and cases among general or nonsmokers population. Rs8042059 and rs7177514 may increase lung cancer risk indirectly through smoking behavior in the Chinese Han population.

Lung cancer incidence decreases with elevation: evidence for oxygen as an inhaled carcinogen

The level of atmospheric oxygen, a driver of free radical damage and tumorigenesis, decreases sharply with rising elevation. To understand whether ambient oxygen plays a role in human carcinogenesis, we characterized age-adjusted cancer incidence (compiled by the National Cancer Institute from 2005 to 2009) across counties of the elevation-varying Western United States and compared trends displayed by respiratory cancer (lung) and non-respiratory cancers (breast, colorectal, and prostate). To adjust for important demographic and cancer-risk factors, 8-12 covariates were considered for each cancer. We produced regression models that captured known risks. Models demonstrated that elevation is strongly, negatively associated with lung cancer incidence (p < 10(-16)), but not with the incidence of non-respiratory cancers. For every 1,000 m rise in elevation, lung cancer incidence decreased by 7.23 99% CI [5.18-9.29] cases per 100,000 individuals, equivalent to 12.7% of the mean incidence, 56.8. As a predictor of lung cancer incidence, elevation was second only to smoking prevalence in terms of significance and effect size. Furthermore, no evidence of ecological fallacy or of confounding arising from evaluated factors was detected: the lung cancer association was robust to varying regression models, county stratification, and population subgrouping; additionally seven environmental correlates of elevation, such as exposure to sunlight and fine particulate matter, could not capture the association. Overall, our findings suggest the presence of an inhaled carcinogen inherently and inversely tied to elevation, offering epidemiological support for oxygen-driven tumorigenesis. Finally, highlighting the need to consider elevation in studies of lung cancer, we demonstrated that previously reported inverse lung cancer associations with radon and UVB became insignificant after accounting for elevation.

Cytidine deaminase polymorphism predicts toxicity of gemcitabine-based chemotherapy

BACKGROUND

The aim of this study was to ascertain whether single nucleotide polymorphisms of cytidine deaminase (CDA), a key enzyme in the metabolism pathway of gemcitabine, could predict clinical outcomes of cancer patients with gemcitabine-based chemotherapy.

METHODS

We searched MEDLINE and EMBASE up to January 2013 to identify eligible studies. A rigorous quality assessment of eligible studies was conducted according to the Newcastle-Ottawa Quality Assessment Scale. For each included study, the overall survival (OS), overall response rate (ORR) and toxicities were extracted and pooled using random-effects model.

RESULTS

In total, data from 13 studies were included. CDA 208A>G and CDA 435C>T were not included in quantified synthesis due to limited data. CDA 79A>C polymorphism was not significantly associated with OS; however, patients carrying the variant CDA 79C allele were likely to have a poor survival, hazard ratio (HR)=1.03, 95% CI 0.957-1.27 (AC+CC vs. AA). CDA 79A>C polymorphism did not correlated with ORR, odds ratio (OR)=0.719, 95% CI 0.363-1.425 (AC+CC vs. AA). However, patients with the variant CDA 79C allele would experience more grade ≥ 3 leucopenia (OR=2.933, 95% CI 1.357-6.605) and tended to have more severe neutropenia (OR=1.313, 95% CI 0.157-10.981).

CONCLUSIONS

These results suggest that CDA 79A>C polymorphisms is a potential biomarker for toxicity of gemcitabine-based chemotherapy and a CDA testing before gemcitabine administration is preferred.

Expression of interleukin-12 by adipose-derived mesenchymal stem cells for treatment of lung adenocarcinoma

Background

Studies have revealed mesenchymal cells tend to directionally migrate toward tumor cells and inhibit tumor growth. However, there have been rare reports about adipose-derived mesenchymal stem cells (AMSCs), which achieved stable expression of interleukin (IL)-12 to inhibit lung adenocarcinoma cell migration and invasion. We aimed to achieve stable expression of IL-12 in AMSCs through transgenic technology and utilize the paracrine effect of IL-12 to inhibit lung adenocarcinoma cell migration and invasion.

Methods

Adipose-derived AMSCs were transduced with lentivirus encoding IL-12. IL-12/AMSCs and lung adenocarcinoma A549 cells were co-cultured using a cylinder column to assess cellular attraction, and expression of Ki67 was detected. Dual-chamber transwell experiments were used to assess migration and invasiveness of A549 cells exposed to conditioned media from IL-12/AMSCs.

Results

When A549 cells were co-cultured with lentivirus vectors (LV)-IL-12-green fluorescent protein (GFP)/AMSCs, the intercellular distance was great (346.44 ± 41.07 μm vs. 201.58 ± 27.96 μm vs. 191.45 ± 24.07 μm) (F = 25.414, P < 0.05); the Ki67-positive rate was low (59.13 ± 17.21% vs. 92.31 ± 6.11% vs. 94.25 ± 5.27%) (F = 21.426, P < 0.05). When the lower Transwell chamber contained culture medium from LV-IL-12-GFP/AMSCs, the percentage of the invasive A549 cells was low (31.55 ± 6.21% vs. 70.65 ± 10.46% vs. 68.65 ± 9.50%) (F = 27.494, P < 0.05). The percentages of colonized A549 cells that invaded the culture media of LV-IL-12-GFP/AMSCs were low (4.46 ± 1.21 vs. 10.11 ± 2.07 vs. 9.48 ± 1.4) (F = 23.219, P < 0.05).

Conclusions

AMSCs could target lung carcinoma and mediate stable expression of IL-12, to play a role in tumor treatment.

Multiple primary malignancies in patients with non-small cell lung cancer

OBJECTIVE

Information regarding multiple primary malignancies is important, as it has the potential to clarify etiological factors and may indicate the need to refine patient follow-up to include screening for associated malignancies. Upper aerodigestive tract cancer often develops in patients with smoking-related lung cancer; however, little is known about the frequencies or types of other primary malignancies in patients with non-small cell lung cancer (NSCLC) without a history of smoking.

METHODS

We retrospectively evaluated the records of patients examined and/or treated for NSCLC at the Institute of Biomedical Research and Innovation between January 2007 and June 2012. Patients In total, 938 patients, including 599 men (never-smoker/ever-smoker: 35/564) and 339 women (never-smoker/ever-smoker: 236/103), were analyzed.

RESULTS

Among the 209 patients (22.3%) with multiple primary malignancies, 151 had a history of smoking and 58 were never-smokers. The most common cancers were gastric (43 cases), colorectal (33 cases), and prostate (29 cases) cancer. Smoking-related cancer was more common in current smokers and ex-smokers for both men and women. Among women with NSCLC, never-smokers were more likely to have thyroid cancer than those with a history of smoking (5.1% vs. 0%, p=0.021).

CONCLUSION

In this study, several differences in malignancies were observed between never-smokers and patients with a history of smoking. Thyroid cancer and NSCLC co-existed in some women without a history of smoking, implicating predisposing factors other than tobacco smoke in the onset of these cancers.

sGC-cGMP signaling: target for anticancer therapy

The biologic endogenous production of cGMP was reported in the 1960s and followed by the demonstration of guanylyl cyclase activity and the isoforms of soluble and membrane-bound guanylyl cyclases. During the same period, cGMP specific phosphodiesterases also was discovered. Murad's lab established link between the endothelium derived relaxation factor (EDRF) and elevated cGMP concentration in the vascular system. October 12, 1998, the Nobel Assembly awarded the Nobel Prize in Medicine or Physiology to scientists Robert Furchgott, Louis Ignarro, and Ferid Murad for their discoveries concerning nitric oxide (NO) as a signaling molecule in the cardiovascular system. In contrast with the short research history of the enzymatic synthesis of NO, the introduction of nitrate-containing compounds for medicinal purposes marked its 150th anniversary in 1997. Glyceryl trinitrate (nitroglycerin; GTN) is the first compound of this category. Alfred Nobel (the founder of the Nobel Prize) himself had suffered from angina pectoris and was prescribed nitroglycerin for his chest pain while he refused to take due to the induction of headaches. Almost a century after its first chemical use, research in the nitric oxide and 3',5'-cyclic guanosine monophosphate (NO/cGMP) pathway has dramatically expanded and the role of NO/cGMP in physiology and pathology has been extensively studied. Soluble guanylyl cyclase (sGC) is the receptor for NO. The α1β1 heterodimer is the predominant isoform of sGC that is obligatory for catalytic activity. NO binds to the ferrous (Fe(2+)) heme at histidine 105 of the β1 subunit and leads to an increase in sGC activity and cGMP production of at least 200-fold. In this chapter, we reviewed the studies of sGC-cGMP signaling in cell proliferation; introduced our work of targeting sGC-cGMP signaling for cancer therapy; and explored the role of sGC-cGMP signaling in the chromatin-microenvironment.

Republished: lung cancer in never-smokers. Does smoking history matter in the era of molecular diagnostics and targeted therapy?

Lung cancer in never-smokers was recognised as a distinct clinical entity around the mid-2000s because these patients tended to be Asian women and diagnosed at a younger age with a preponderance of adenocarcinoma and better survival outcome despite a more advanced stage of presentation. It was soon discovered that lung cancer in never-smokers had a higher prevalence of activating EGFR mutations and we tend to classify lung cancer by smoking status for screening purpose. With the discoveries of many actionable driver mutations such as activating EGFR mutations and ALK rearrangement in adenocarcinoma of the lung we have switched to classifying non-small cell lung cancer into different individual molecular subgroups based on the presence of a dominant driver mutation. Although many actionable driver mutations are found in never-smokers with adenocarcinoma, this review will summarise that a substantial proportion of patients with these actionable driver mutations had a previous smoking history. Alternatively among the driver mutations that are associated with smoking history, a fair amount of these patients were never-smokers. Thus smoking status should not be used as a screen strategy for identifying driver mutations in clinical practice. Finally smoking history may have predictive and/or prognostic significance within individual molecular subgroups and identifying the difference according to smoking history may help optimise future targeted therapy.

Alterations of a spectrum of driver genes in female Chinese patients with advanced or metastatic squamous cell carcinoma of the lung

OBJECTIVES

Female patients with squamous cell carcinomas of the lung (SQCLC) in China differ from male patients in that most females are life-long never/light smokers. We hypothesized that the clinical characteristics and mutation profiles of a spectrum of driver genes in Chinese female patients with advanced SQCLC would also differ from those of male patients.

PATIENTS AND METHODS

We examined the pathological subtype of SQCLC retrospectively by immunohistochemistry (IHC) and screened 38 female and 40 male patients with IIIB/IV-stage SQCLC in China from 2009 to 2012. Mutation analyses of EGFR, PIK3CA, KRAS, and PTEN were performed using PCR-based DNA sequencing. FGFR1 amplification and ALK rearrangements were detected by fluorescent in situ hybridization (FISH). A Cox regression model was used to assess the association between clinical features and genomic mutation status.

RESULTS

There were significantly fewer female patients with a history of smoking than males (5.3% vs. 90%; P<0.001). A younger average age at diagnosis (54.5 vs. 61 years; P=0.032) and a higher percentage of peripheral-type disease (47.4% vs. 25.0%; P=0.040) were observed in females. No difference in ECOG score, tumor size, metastatic status, or overall survival between females and males was seen. PIK3CA mutations were significantly less common in female patients than males (0/38 vs. 6/40; P=0.026). However, no significant difference in the mutational frequencies of EGFR, KRAS, PTEN, ALK, or FGFR1 was observed between females and males.

CONCLUSIONS

Our data demonstrated that female patients with SQCLC are apparently a subtype, with a significantly lower percentage having a smoking history, a younger average age at diagnosis, a higher percentage of peripheral-type disease on radiological presentation, and a lower frequency of PIK3CA mutations. Given the similar survival outcomes between the genders, whether it is a distinct disease entity needs to be studied further in larger populations.

Prevalence and natural history of ALK positive non-small-cell lung cancer and the clinical impact of targeted therapy with ALK inhibitors

Improved understanding of molecular drivers of carcinogenesis has led to significant progress in the management of lung cancer. Patients with non-small-cell lung cancer (NSCLC) with anaplastic lymphoma kinase (ALK) gene rearrangements constitute about 4%-5% of all NSCLC patients. ALK+ NSCLC cells respond well to small molecule ALK inhibitors such as crizotinib; however, resistance invariably develops after several months of treatment. There are now several newer ALK inhibitors, with the next generation of agents targeting resistance mutations. In this review, we will discuss the prevalence and clinical characteristics of ALK+ lung cancer, current treatment options, and future directions in the management of this subset of NSCLC patients.

Current status of chemotherapy use and clinical outcome in octogenarians with advanced non-small cell lung cancer

BACKGROUND

Although about one-fourth of patients dying of lung cancer are aged 80 years or older in Korea, the current treatment status and outcome in octogenarians are largely unknown. We aimed to evaluate the proportion of octogenarians with advanced non-small cell lung cancer (NSCLC) who receive systemic chemotherapy and analyze the clinical outcome in these patients.

METHODS

The medical records of 281 octogenarians who were diagnosed with stage IIIB/IV or recurrent NSCLC were retrospectively reviewed.

RESULTS

In total, 127 out of 281 patients (45 %) received chemotherapy. Among the patients with ECOG PS 0-2, 119 patients (57 %) received chemotherapy. The first-line treatments were platinum doublets in 61 patients (48 %), single-agent chemotherapy in 34 (27 %), and epidermal growth factor receptor tyrosine kinase inhibitors in 32 (25 %). In patients with ECOG PS 0-2, patients who received chemotherapy lived longer compared with patients who only received best supportive care (16.1 vs. 4.0 months, P < 0.001). Among the 127 patients who received chemotherapy, patients who received EGFR TKIs showed longer survival than patients who only received cytotoxic agents (21.4 vs. 9.8 months, P < 0.001). In a multivariate analysis, ECOG PS 3-4 and smoking history were unfavorable prognostic factors, while recurrent disease and systemic chemotherapy were favorable prognostic factors.

CONCLUSION

Nearly half of octogenarians with advanced NSCLC received systemic chemotherapy. The patients showed prolonged survival compared with the best supportive care group. Further studies are warranted to provide an optimal tailored treatment for octogenarians.

Predictive value of thymidylate synthase for the prognosis and survival of lung adenocarcinoma patients

Chemotherapy represents an important treatment modality for lung adenocarcinoma. Thymidylate synthase (TS) is an essential enzyme in DNA synthesis, and its overexpression has been associated with reduced sensitivity to antifolate agents. The aim of the current study was to investigate the expression of TS and the effect on prognosis in lung adenocarcinoma patients. Adenocarcinoma and adjacent carcinoma tissues were resected from 100 patients with lung adenocarcinoma and the TS levels were detected by immunohistochemical analysis. The values for overall survival (OS) and disease-free survival (DFS) were determined using the Kaplan-Meier analysis. The results indicated that the TS protein was expressed predominantly in adenocarcinoma tissues, which exhibited higher TS expression compared with the adjacent tissues (P<0.001). The statistical analysis indicated that TS expression was associated with the clinical stage and history of smoking (P<0.05). The Kaplan-Meier analysis results indicated that the DFS and OS in patients with high TS expression levels were significantly shorter compared with those with low expression levels (P<0.05). In conclusion, the results from this study suggested that TS may serve as an independent predictive factor for survival rate, which may indicate the prognosis of lung adenocarcinoma patients.

Relationship between 18F-FDG accumulation and lactate dehydrogenase A expression in lung adenocarcinomas

(18)F-FDG PET has been widely used in the management of malignant tumors. Lactate dehydrogenase A (LDHA) plays an important role in the development, invasion, and metastasis of malignancies. However, the relationship between (18)F-FDG accumulation and LDHA expression has not been investigated.

METHODS

Retrospective analysis was conducted for 51 patients with lung adenocarcinomas who underwent (18)F-FDG PET. The relationship between maximum standardized uptake value and the expression of LDHA, glucose transporter 1 (GLUT1), and hexokinase 2 (HK2) were examined. RNA interference was used to analyze the role of LDHA in tumor metabolism and growth in A549 cells. The AKT, also known as protein kinase B, pathway was also investigated to evaluate the molecular mechanisms of the relationship between LDHA expression and (18)F-FDG uptake.

RESULTS

Maximum standardized uptake value was significantly higher in the LDHA high-expression group than the LDHA low-expression group (P = 0.018). GLUT1 expression in lung adenocarcinomas was positively correlated with (18)F-FDG accumulation and LDHA expression whereas HK2 expression was not. Knockdown of LDHA led to a significant decrease in GLUT1 expression, (18)F-FDG uptake, and cell proliferation. The activated form of AKT was also decreased after LDHA knockdown.

CONCLUSION

LDHA increases (18)F-FDG accumulation into non-small cell lung cancer, possibly by upregulation of GLUT1 expression but not HK2 expression. LDHA may modulate (18)F-FDG uptake in lung adenocarcinomas via the AKT-GLUT1 pathway. These results indicate that (18)F-FDG PET/CT may predict LDHA expression levels and response to anti-LDHA therapy in lung adenocarcinomas.

Identification of recurrent FGFR3-TACC3 fusion oncogenes from lung adenocarcinoma

PURPOSE

Targetable oncogenic alterations are detected more commonly in patients with non-small cell lung cancer (NSCLC) who never smoked cigarettes. For such patients, specific kinase inhibitors have emerged as effective clinical treatments. However, the currently known oncogenic alterations do not account for all never smokers who develop NSCLC. We sought to identify additional oncogenic alterations from patients with NSCLC to define additional treatment options.

EXPERIMENTAL DESIGN

We analyzed 576 lung adenocarcinomas from patients of Asian and Caucasian ethnicity. We identified a subset of cancers that did not harbor any known oncogenic alteration. We performed targeted next-generation sequencing (NGS) assay on 24 patients from this set with >75% tumor cell content.

RESULTS

EGFR mutations were the most common oncogenic alteration from both Asian (53%) and Caucasian (41.6%) patients. No known oncogenic alterations were present in 25.7% of Asian and 31% of Caucasian tumor specimens. We identified a FGFR3-TACC3 fusion event in one of 24 patients from this subset using targeted NGS. Two additional patients harboring FGFR3-TACC3 were identified by screening our entire cohort (overall prevalence, 0.5%). Expression of FGFR3-TACC3 led to IL3 independent growth in Ba/F3 cells. These cells were sensitive to pan-fibroblast growth factor receptor (pan-FGFR) inhibitors but not the epidermal growth factor (EGFR) inhibitor gefitinib.

CONCLUSIONS

FGFR3-TACC3 rearrangements occur in a subset of patients with lung adenocarcinoma. Such patients should be considered for clinical trials featuring FGFR inhibitors.

Significance of the progesterone receptor and epidermal growth factor receptor, but not the estrogen receptor, in chemically induced lung carcinogenesis in female A/J mice

In the present study, the expression levels of female hormone receptors, estrogen receptor (ER) and progesterone receptor (PR) and the epidermal growth factor receptor, (EGFR), as well as proliferating cell nuclear antigen (PCNA) were examined in lung tumors that were induced by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in female A/J mice. Each seven-week-old mouse was administered with 2 mg NNK via intraperitoneal injection and the mice were subsequently euthanized at week 52. Lung tumors, including adenomas, carcinomas in adenomas and adenocarcinomas, were obtained and analyzed by immunohistochemistry for the expression levels of the receptors, ER, PR and EGFR, and PCNA. The results were as follows: i) In mouse lung adenomas, a significant correlation was identified between the size of the tumor and PCNA expression, although not with the expression of the receptors (ER, PR and EGFR); ii) in the carcinoma components of the carcinomas in adenomas, the size of the tumor and PCNA expression were correlated, while EGFR expression demonstrated a significant correlation with PR expression; iii) in adenocarcinomas, the tumor size significantly correlated with PCNA, EGFR and PR expression; and iv) EGFR and PR expression was identified to be significantly correlated in adenocarcinomas, and to a certain extent in the carcinoma components of the carcinomas in adenomas, although not in the adenomas. Notably, ER expression was not associated with tumor growth or the other factors, particularly EGFR expression, and no significant differences were identified between the three types of lesion. These results indicate that PR, like EGFR, may be significant in lung carcinogenesis.

Telomere length in white blood cell DNA and lung cancer: a pooled analysis of three prospective cohorts

We investigated the relationship between telomere length and lung cancer in a pooled analysis from three prospective cohort studies: the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, conducted among men and women in the United States, and previously published data from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Trial conducted among male smokers in Finland, and the Shanghai Women's Health Study (SWHS), which is comprised primarily of never-smokers. The pooled population included 847 cases and 847 controls matched by study, age, and sex. Leukocyte telomere length was measured by a monochrome multiplex qPCR assay. We used conditional logistic regression models to calculate ORs and their 95% confidence intervals (CI) for the association between telomere length and lung cancer risk, adjusted for age and pack-years of smoking. Longer telomere length was associated with increased lung cancer risk in the pooled analysis [OR (95% CI) by quartile: 1.00; 1.24 (0.90-1.71); 1.27 (0.91-1.78); and 1.86 (1.33-2.62); P trend = 0.000022]. Findings were consistent across the three cohorts and strongest for subjects with very long telomere length, i.e., lung cancer risks for telomere length [OR (95% CI)] in the upper half of the fourth quartile were 2.41 (1.28-4.52), 2.16 (1.11-4.23), and 3.02(1.39-6.58) for the PLCO trial, the ATBC trial, and the SWHS, respectively. In addition, the association persisted among cases diagnosed more than 6 years after blood collection and was particularly evident for female adenocarcinoma cases. Telomere length in white blood cell DNA may be a biomarker of future increased risk of lung cancer in diverse populations.

Menopausal hormone therapy and lung cancer-specific mortality following diagnosis: the California Teachers Study

Previous results from research on menopausal hormone therapy (MHT) and lung cancer survival have been mixed and most have not studied women who used estrogen therapy (ET) exclusively. We examined the associations between MHT use reported at baseline and lung cancer-specific mortality in the prospective California Teachers Study cohort. Among 727 postmenopausal women diagnosed with lung cancer from 1995 through 2007, 441 women died before January 1, 2008. Hazard Ratios (HR) and 95% Confidence Intervals (CI) for lung-cancer-specific mortality were obtained by fitting multivariable Cox proportional hazards regression models using age in days as the timescale. Among women who used ET exclusively, decreases in lung cancer mortality were observed (HR, 0.69; 95% CI, 0.52–0.93). No association was observed for estrogen plus progestin therapy use. Among former users, shorter duration (<5 years) of exclusive ET use was associated with a decreased risk of lung cancer mortality (HR, 0.56; 95% CI, 0.35–0.89), whereas among recent users, longer duration (>15 years) was associated with a decreased risk (HR, 0.60; 95% CI, 0.38–0.95). Smoking status modified the associations with deceases in lung cancer mortality observed only among current smokers. Exclusive ET use was associated with decreased lung cancer mortality.

Genomic and transcriptional alterations in lung adenocarcinoma in relation to smoking history

PURPOSE

Cigarette smoking is the major pathogenic factor for lung cancer. The precise mechanisms of tobacco-related carcinogenesis and its effect on the genomic and transcriptional landscape in lung cancer are not fully understood.

EXPERIMENTAL DESIGN

A total of 1,398 (277 never-smokers and 1,121 smokers) genomic and 1,449 (370 never-smokers and 1,079 smokers) transcriptional profiles were assembled from public lung adenocarcinoma cohorts, including matched next-generation DNA-sequencing data (n = 423). Unsupervised and supervised methods were used to identify smoking-related copy-number alterations (CNAs), predictors of smoking status, and molecular subgroups.

RESULTS

Genomic meta-analyses showed that never-smokers and smokers harbored a similar frequency of total CNAs, although specific regions (5q, 8q, 16p, 19p, and 22q) displayed a 20% to 30% frequency difference between the two groups. Importantly, supervised classification analyses based on CNAs or gene expression could not accurately predict smoking status (balanced accuracies ∼60% to 80%). However, unsupervised multicohort transcriptional profiling stratified adenocarcinomas into distinct molecular subgroups with specific patterns of CNAs, oncogenic mutations, and mutation transversion frequencies that were independent of the smoking status. One subgroup included approximately 55% to 90% of never-smokers and approximately 20% to 40% of smokers (both current and former) with molecular and clinical features of a less aggressive and smoking-unrelated disease. Given the considerable intragroup heterogeneity in smoking-defined subgroups, especially among former smokers, our results emphasize the clinical importance of accurate molecular characterization of lung adenocarcinoma.

CONCLUSIONS

The landscape of smoking-related CNAs and transcriptional alterations in adenocarcinomas is complex, heterogeneous, and with moderate differences. Our results support a molecularly distinct less aggressive adenocarcinoma entity, arising in never-smokers and a subset of smokers.

Conserved recurrent gene mutations correlate with pathway deregulation and clinical outcomes of lung adenocarcinoma in never-smokers

BACKGROUND

Novel and targetable mutations are needed for improved understanding and treatment of lung cancer in never-smokers.

METHODS

Twenty-seven lung adenocarcinomas from never-smokers were sequenced by both exome and mRNA-seq with respective normal tissues. Somatic mutations were detected and compared with pathway deregulation, tumor phenotypes and clinical outcomes.

RESULTS

Although somatic mutations in DNA or mRNA ranged from hundreds to thousands in each tumor, the overlap mutations between the two were only a few to a couple of hundreds. The number of somatic mutations from either DNA or mRNA was not significantly associated with clinical variables; however, the number of overlap mutations was associated with cancer subtype. These overlap mutants were preferentially expressed in mRNA with consistently higher allele frequency in mRNA than in DNA. Ten genes (EGFR, TP53, KRAS, RPS6KB2, ATXN2, DHX9, PTPN13, SP1, SPTAN1 and MYOF) had recurrent mutations and these mutations were highly correlated with pathway deregulation and patient survival.

CONCLUSIONS

The recurrent mutations present in both DNA and RNA are likely the driver for tumor biology, pathway deregulation and clinical outcomes. The information may be used for patient stratification and therapeutic target development.