Predictive molecular markers in non-small cell lung cancer

Single-cell sequencing reveals lung cell fate evolution initiated by smoking to explore gene predictions of correlative diseases

Continuous smoking leads to adaptive regulation and physiological changes in lung tissue and cells, and is an inductive factor for many diseases, making smokers face the risk of malignant and nonmalignant diseases. The impact of research in this area is getting more and more in-depth, but the stimulant effect, mechanism of action and response mechanism of the main cells in the lungs caused by smoke components have not yet been fully elucidated, and the early diagnosis and identification of various diseases induced by smoke toxins have not yet formed a systematic relationship method. In this study, single-cell transcriptome data were generated from three lung samples of smokers and nonsmokers through scRNA-seq technology, revealing the influence of smoking on lung tissue and cells and the changes in immune response. The results show that: through UMAP cell clustering, 16 intermediate cell states of 23 cell clusters of the four main cell types in the lung are revealed, the differences of the main cell groups between smokers and nonsmokers are explained, and the human lung cells are clarified. Components and their marker genes, screen for new marker genes that can be used in the evolution of intermediate-state cells, and at the same time, the analysis of lung cell subgroups reveals the changes in the intermediate state of cells under smoke stimulation, forming a subtype intermediate state cell map. Pseudo-time ordering analysis, to determine the pattern of dynamic processes experienced by cells, differential expression analysis of different branch cells, to clarify the expression rules of cells at different positions, to clarify the evolution process of the intermediate state of cells, and to clarify the response of lung tissue and cells to smoke components mechanism. The development of this study provides new diagnosis and treatment ideas for early disease detection, identification, disease prevention and treatment of patients with smoking-related diseases, and lays a theoretical foundation based on cell and molecular regulation.

The XRCC1 and TP53 gene polymorphisms are associated with advanced-stage disease and early distant metastasis at diagnosis in non-small cell lung cancer

Background

Studies on single nucleotide polymorphisms (SNPs) in non-small cell lung cancer (NSCLC) suggest that DNA repair capacity may have prognostic implications for disease recurrence and survival. However, there is no study investigating the relationship between SNPs and the risk of metastasis at the time of initial diagnosis in patients with NSCLC.

Objective

This study aimed to investigate the potential predictive value of SNPs in detecting the risk of metastasis at the time of initial diagnosis and poor prognosis in patients with NSCLC.

Material and Methods

In this prospective cohort study, we evaluated 275 patients with NSCLC. Analysis of SNPs from peripheral blood cells was performed by a polymerase chain reaction. Excision repair cross-complementing group 1 (ERCC1)- Asn118Asn, excision repair cross-complementing group 2 (ERCC2)-Lys751Gln, X-ray repair cross-complementing group 1 (XRCC1)-Arg399Gln, and tumor protein 53 (TP53)-Arg72Pro polymorphisms were evaluated in conjunction with the development of metastasis.

Results

The ERCC1 normal genotype, ERCC2 heterozygote genotype, XRCC1 normal genotype, and TP53 normal genotype were associated with a higher stage and more advanced-stage disease at the time of initial diagnosis (P = 0.027, 0.005, <0.001, and 0.006, respectively). Also, XRCC1 normal genotype and TP53 normal genotype were associated with the risk of metastasis at the time of initial diagnosis (P = <0.001 and 0.002, respectively). Moreover, the XRCC1 normal genotype was associated with the risk of brain metastasis at the time of initial diagnosis (P = 0.031).

Conclusions

We showed that SNPs are related to a higher stage and more advanced-stage disease at the time of initial diagnosis in patients with NSCLC, and XRCC1 and TP53 gene polymorphisms are associated with the risk of metastasis. These results may contribute to the identification of high-risk groups and may help to earlier diagnosis and treatment in patients with NSCLC.

Association of Base Excision Repair Gene Polymorphisms with the Response to Chemotherapy in Advanced Non-Small Cell Lung Cancer

Background:

Base excision repair (BER) plays an important role in the maintenance of genome integrity and anticancer drug resistance. This study aimed to explore the role of BER gene polymorphisms in response to chemotherapy for advanced non-small cell lung cancer (NSCLC) patients treated with platinum-based chemotherapy.

Methods:

During the period from November 2009 to January 2016, a total of 152 patients diagnosed with NSCLC Stage IIIB and IV in the First Hospital of Jilin University were admitted into this study. The XRCC1 G28152A, MUTYH G972C, HOGG1 C1245G, and PARP1 T2444C polymorphisms of all the patients were detected by mass spectrometry. The logistic regression was used for statictical analysis. All tests were bilateral test, and a P < 0.05 was considered statistically significant.

Results:

The logistic regression model showed that the response rate of chemotherapy of the PARP1 T2444C polymorphisms, CC genotype (odds ratio [OR]: 5.216, 95% confidence interval [CI]: 1.568–17.352, P = 0.007), TC genotype (OR: 2.692, 95% CI: 1.007–7.198, P = 0.048), as well as the genotype of TC together with CC (OR: 3.178, 95% CI: 1.229–8.219, P = 0.017) were significantly higher than those of TT wild type. There was no relationship between the MUTYH G972C, XRCC1 G28152A, and HOGG1 C1245G gene polymorphisms and chemosensitivity.

Conclusions:

The PARP1 2444 mutation allele C might be associated with the decreased sensitivity to platinum-based chemotherapy in advanced NSCLC. These findings may be helpful in designing individualized cancer treatment.

Association of EGFR mutations with low BRCA1 gene expression in non-small cell lung cancer

Clinical studies suggest that the mRNA expression level of excision repair cross complementing group 1 gene (ERCC1) is associated with epidermal growth factor receptor (EGFR) mutation and breast cancer susceptibility 1 gene (BRCA1) mRNA expression in non-small cell lung cancer (NSCLC). In this study, the correlation between EGFR mutation status and ERCC1 and BRCA1 gene expression in Chinese NSCLC patients was examined. Real-time polymerase chain reaction (PCR) and direct sequencing were used to detect mRNA expression levels and EGFR mutation status, respectively in microdissected formalin-fixed paraffin-embedded non-small cell lung cancer tissues. EGFR mutations were detected in 27/103 patients (26.2%) and were found to be gender-related (P=0.001). The BRCA1 mRNA expression level was associated with histology, while there was no association with ERCC1. For the EGFR mutant-type, a high BRCA1 gene expression was detected in 2 cases (20.0%) and a low expression in 8 cases (80.0%), while for EGFR wild-type, a high BRCA1 gene expression was detected in 20 cases (43.5%) and a low expression in 26 cases (56.5%). There was no difference in the one-year survival period, according to results obtained for either the ERCC1 or BRCA1 mRNA expression levels. EGFR mutations in NSCLC samples are more likely to express low ERCC1 and BRCA1 mRNA levels. In these latter samples, a statistically significant difference was observed. However, to examine their correlation and clinical outcomes, additional studies are required.

The Role of Nuclear Factor Kappa B in the Pathogenesis of Pulmonary Diseases: Implications for Therapy

The nuclear factor kappa B (NF-kappaB) transcription factor plays a key role in the induction of pro-inflammatory gene expression, leading to the synthesis of cytokines, adhesion molecules, chemokines, growth factors and enzymes. Results of studies in in vitro and in vivo models of inflammation and malignancy have also suggested central roles for NF-kappaB in programmed cell death, or apoptosis. NF-kappaB plays a central role in a variety of acute and chronic inflammatory diseases. In the common lung diseases associated with a significant inflammatory component such as severe sepsis, acute lung injury, acute respiratory distress syndrome, cystic fibrosis and asthma, the pathogenic roles of NF-kappaB have been extensively investigated. In COPD, activation of NF-kappaB has been implicated in disease pathogenesis but its exact role is less clearly demonstrable in this heterogeneous patient population. However, the principal risk factor for COPD, cigarette smoking, is strongly associated with NF-kappaB activation. Activation of NF-kappaB has been demonstrated in mineral dust diseases and probably plays a role in the pathogenesis of these chronic illnesses. NF-kB also plays a variety of roles in lung cancer including resistance to chemotherapy, inhibition of tumorigenesis and inducing expression of antiapoptotic genes. The complex NF-kappaB pathway offers a variety of potential molecular targets for chemotherapeutic intervention. A variety of agents aimed at modulating NF-kappaB activity are in various stages of investigation.

The 3p21.3 tumor suppressor NPRL2 plays an important role in cisplatin-induced resistance in human non-small-cell lung cancer cells

NPRL2 is one of the novel candidate tumor suppressor genes identified in the human chromosome 3p21.3 region. The NPRL2 has shown potent tumor suppression activity in vitro and in vivo and has been suggested to be involved in DNA mismatch repair, cell cycle checkpoint signaling, and regulation of the apoptotic pathway. In this study, we analyzed the endogenous expression of the NPRL2 protein and the cellular response to cisplatin in 40 non-small-cell lung cancer cell lines and found that expression of NPRL2 was significantly and reciprocally correlated to cisplatin sensitivity, with a Spearman correlation coefficient of -0.677 (P < 0.00001). Exogenously introduced expression of NPRL2 by N-[1-(2,3-dioleoyloxyl)propyl]-NNN-trimethylammoniummethyl sulfate:cholesterol nanoparticle-mediated gene transfer significantly resensitized the response to cisplatin, yielding a 40% greater inhibition of tumor cell viability and resulting in a 2- to 3-fold increase in induction of apoptosis by activation of multiple caspases in NPRL2-transfected cells compared with untransfected cells at an equal dose of cisplatin. Furthermore, a systemic treatment with a combination of NPRL2 nanoparticles and cisplatin in a human H322 lung cancer orthotopic mouse model significantly enhanced the therapeutic efficacy of cisplatin and overcame cisplatin-induced resistance (P < 0.005). These findings implicate the potential of NPRL2 as a biomarker for predicting cisplatin response in lung cancer patients and as a molecular therapeutic agent for enhancing response and resensitizing nonresponders to cisplatin treatment.

Cyclin D1 (CCND1) A870G gene polymorphism modulates smoking-induced lung cancer risk and response to platinum-based chemotherapy in non-small cell lung cancer (NSCLC) patients

PURPOSE

The cyclin D1 (CCND1) A870G gene polymorphism is linked to the outcome in patients with resectable non-small cell lung cancer (NSCLC). Here, we investigated the impact of this polymorphism on smoking-induced cancer risk and clinical outcome in patients with NSCLC stages I-IV.

METHODS

CCND1 A870G genotype was determined by polymerase chain reaction (PCR) and restriction fragment length polymorphism analysis (RFLP) of DNA extracted from blood. The study included 244 NSCLC patients and 187 healthy control subjects.

RESULTS

Patient characteristics were: 70% male, 77% smokers, 43% adenocarcinoma, and 27% squamous cell carcinoma. Eighty-one percent of the patients had stages III-IV disease. Median age at diagnosis was 60 years and median survival was 13 months. Genotype frequencies of patients and controls both conformed to the Hardy Weinberg equilibrium. The GG genotype significantly correlated with a history of heavy smoking (>or=40 py, P=0.02), and patients with this genotype had a significantly higher cigarette consumption than patients with AA/AG genotypes (P=0.007). The GG genotype also significantly correlated with tumor response or stabilization after a platinum-based first-line chemotherapy (P=0.04). Survival analysis revealed no significant differences among the genotypes.

CONCLUSION

Evidence was obtained that the CCND1 A870G gene polymorphism modulates smoking-induced lung cancer risk. Further studies are required to explore the underlying molecular mechanisms and to test the value of this gene polymorphism as a predictor for platinum-sensitivity in NSCLC patients.

Adding pharmacogenomics to the development of new marine-derived anticancer agents

Nature has always been a highly productive tool in the development of anticancer therapies. Renewed interest in the potential of this tool has recently been sparked by the realization that the marine ecosystem can be used for the discovery and development of new compounds with clinical potential in advanced resistant tumors. These compounds can be incorporated into combination approaches in a chronic therapy scenario. Our marine anticancer program is using the sea to develop new agents with activity in resistant solid tumors and to identify new cellular targets for therapeutic intervention. This review describes the integration of different pharmacogenomic tools in the development of Yondelis™, Aplidin^® and Kahalalide F, three marine-derived compounds currently in Phase II or III development. Our results are reinforcing the targeted selectivity of these agents and opening the gates for customized therapies in cancer patients in the near future.

Prognostic factors in non-small cell lung cancer surgery

AIMS

Complete surgical resection of primary tumours remains the treatment with the greatest likelihood for survival in early-stage non-small cell lung cancer (NSCLC). Although TNM stage is the most important prognostic parameter in NSCLC, additional parameters are required to explain the large variability in postoperative outcome. The present review aims at providing an overview of the currently known prognostic markers for postoperative outcome.

METHODS

We performed an electronic literature search on the MEDLINE database to identify relevant studies describing the risk factors in NSCLC surgery. The references reported in all the identified studies were used for completion of the literature search.

RESULTS

Poor pulmonary function, cardiovascular disease, male gender, advanced age, TNM stage, non-squamous cell histology, pneumonectomy, low hospital volume and little experience of the surgeon were identified as risk factors for postoperative outcome. However, with the exception of TNM stage and extent of resection, the literature demonstrates conflicting results on the prognostic power of most factors. The role of molecular biological factors, neoadjuvant treatment and adjuvant treatment is not well investigated yet.

CONCLUSIONS

The advantage of knowing about the existence of comorbidity and prognostic risk factors may provide the clinician with the ability to identify poor prognostic patients and establish the most appropriate treatment strategy. The assessment of prognostic factors remains an area of active investigation and a promising field of research in optimising therapy of NSCLC patients.

Association between polymorphisms of ERCC1 and XPD and survival in non-small-cell lung cancer patients treated with cisplatin combination chemotherapy

ERCC1 (excision repair cross-complementation group 1) and XPD (ERCC2, excision repair cross-complementation group 2) as genes have been known to be belonged to the nucleotide excision repair pathway and therefore related to DNA repair. Polymorphisms in these genes have been rarely evaluated in terms of predicting cancer patient survival. We investigated whether these polymorphisms have an effect on response to chemotherapy and survival in 109 patients with non-small-cell lung cancer treated with cisplatin combination chemotherapy. Polymorphisms of ERCC1 Asn118Asn (C --> T), XPD Lys751Gln (A --> C) and Asp312Asn (G --> A) were evaluated using a SNaPshot kit. As for chemotherapy response, treatment response did not show statistically significant differences between the wild genotypes and the variant genotypes for the ERCC1 and XPD gene. The median survival time of all patients was 376 days (95% CI, 291-488). As for survival rate according to the polymorphism of codon 118 in ERCC1, median survival time in patients showing C/C genotype was 486 days (95% CI, 333-x), which was significantly different from the 281 days (95% CI, 214-376) of patients with the variant genotype (T/T or C/T) (P = 0.0058). Using the Cox-proportional hazards model, the polymorphism of codon 118 in ERCC1, response to chemotherapy, weight loss and performance status effected overall survival significantly (P = 0.0001, 0.0001, 0.0028 and 0.0184, respectively). However, polymorphisms of codons 751 and 312 in the XPD gene did not affect patient survival (P = 0.4711 and 0.4542, respectively). Therefore, we suggest that the C/C genotype in codon 118 of ERCC1 is a surrogate marker for predicting better survival in non-small-cell lung cancer patients treated with cisplatin combination chemotherapy.

Molecular oncology — perspectives in lung cancer

Despite novel therapies in lung cancer treatment the 5-year survival rate still remains poor. Furthermore, screening concepts for early diagnosis, based on conventional sputum cytology and chest radiography, have so far not demonstrated an impact on decreasing lung-cancer mortality. More specific molecular markers allow new insights in the process of lung carcinogenesis. Furthermore they raise the hope that they provide new tools for early diagnosis and screening of high-risk individuals, determination of prognosis, and identification of innovative treatments. In this review, these perspectives of molecular targets in lung cancer will be discussed and summarised. Angiogenesis-stimulating factors (VEGF, FGF, MMP, etc.), parameters concerning tumour cell proliferation and apoptosis (EGFR, p53, K-ras, rb, bcl-2, etc.) are well known. Several of these genetic factors have already been investigated, but no single parameter has yet gained a sufficient selectivity regarding prognostic significance or therapeutic efficacy. New aspects in the complex tumour-stroma interaction and the interactive, cross-talking signal transduction pathways and recently developed functional genomic approaches, such as DNA microarrays and proteomics might lead to further progress in biological staging models and treatment concepts.

Molecular approaches to lung cancer evaluation

The stagnation of therapeutic results in lung cancer over the last decade(s) is a matter of great concern, also due to the constantly increasing incidence of the disease. Among the reasons for this failing therapeutic progress is the lack of understanding of the molecular mechanisms underlying the disease. Presently molecular biology techniques contribute to the deciphering of these mechanisms. This review article gives an overview of the actual situation. The genetic changes leading to malignancy are successively considered at the DNA, RNA and protein levels. Alterations at the DNA level represent the bulk of the available data, being related to p53 mutations, alterations in the beta-tubulin gene, microsatellite alterations, methods for identifying individual and isolated aberrant cells, identification of epigenetic mechanisms such as methylation of the promoter region of tumor suppressor genes; alterations in pre-neoplastic lesions are also evoked. In all cases, the techniques are described and results presented. RNA based methods are critically considered, and the yeast functional assay described. Protein based methods are also considered. The use of cDNA microarrays opens new perspectives and brings the simultaneous identification of numerous DNA alterations at a grip, with hopefully significant improvements in treatment results and increased efficiency for early detection and prevention.

Molecular markers and targeted therapy with novel agents: prospects in the treatment of non-small cell lung cancer

Detection of genomic differences predictive of drug response or resistance in individual patients may allow therapy to be customized to the characteristics of particular tumors. Preliminary findings are that non-small cell lung cancer patients overexpressing ERCC1 mRNA have lower response to cisplatin chemotherapy, while those overexpressing ribonucleotide reductase mRNA have limited benefit from gemcitabine. In addition, overexpression of beta-tubulin III and stathmin can influence the sensitivity to microtubule interacting drugs, like vinorelbine and paclitaxel. The introduction of biological agents which target highly specific intracellular pathways offers the promise of enhancing the efficacy of cytotoxic chemotherapy. Among many promising biological agents is the monoclonal antibody C225, which blocks the EGFR receptor. The addition of C225 appears to induce responses in a proportion of colon cancer patients refractory to 5-FU or irinotecan, supporting pre-clinical evidence of synergistic activity. It also appears from xenograft data that C225 enhances the sensitivity of tumors to radiation and docetaxel or the combination.

Pharmacogenomic strategies for developing customized chemotherapy in non-small cell lung cancer

In this review, we deal with six groups of cytotoxic drugs commonly used in the treatment of non-small cell lung cancer (NSCLC). Although there are many reviews of thymidylate synthase (TS) and antifolate inhibitors, in this article, we have tried to highlight aspects that are more important for medical oncologists to consider when treating NSCLC patients. There is compelling evidence that TS gene transcripts and TS polymorphisms could be used to decide which patients can best benefit from adjuvant chemotherapy approaches, especially in colorectal cancer, and not less importantly, to tailor chemotherapy in metastatic NSCLC when using drugs akin to fluorouracil, such as pemetrexed. Secondly, cisplatin is central to chemotherapy combinations and evidence indicates that DNA repair capacity influences response to cisplatin-based regimens. ERCC1 gene transcript stands out as a predictive marker of cisplatin sensitivity. Thirdly, preliminary studies indicate that upregulation of beta-tubulin III correlates with response to paclitaxel and vinorelbine. Fourthly, overexpression of ribonucleotide reductase can influence response to gemcitabine. Fifthly, we describe mechanisms of resistance to topoisomerase I inhibitors, although this subject has not yet been completely elucidated. Finally, to understand the mechanisms of resistance to EGF-R inhibitors, which have been shown to be useful in many different types of cancer, the Src-STAT signaling pathways are described here in detail. Hopefully, the assessment of Src and of STAT-3 can be implemented as predictive markers.

Management of advanced non-small cell lung cancer: current trends

Carcinoma of the lung continues to be the leading cause of cancer-related deaths for Americans. Major efforts have been made in the treatment of advanced non-small cell lung cancer; chemotherapy and investigations in the last decade have yielded a number of new agents and combinations. Despite progress with newer agents for the treatment of non-small cell lung cancer, only 14% of patients with the disease are alive 5 years after the initial diagnosis. Toward improving the outcome of patients with advanced non-small cell lung cancer, a few trends can be identified. These include further work on combination chemotherapy, the introduction of novel biologic agents into treatment, and predicting which patients will respond to chemotherapy. These trends are discussed in this review.

Characteristics of long-term survivors of untreated lung cancer

Non-small cell lung cancer (NSCLC) is a malignant tumor with poor prognosis. Although the prognostic variables determining short-term survival have been well described, relatively little attention has been paid to factors associated with long-term survival. In search of these factors we studied the expression of several molecular markers in NSCLC. Only tumor samples of patients with squamous cell carcinomas and stage III tumors with a postoperative survival of at least 5 years and those of patients who died within 2 years after resection were selected for this study. The expression of several parameters including oncogene and suppressor gene products, proliferative, apoptotic, angiogenic and resistance-related factors were investigated and the differences in these two extreme populations were determined by the Wilcoxon rank sum test. Factors involved in proliferation (ras, fos, erbB-1, jun, cyclin A) were downregulated whereas factors involved in apoptosis (p53, bcl-2, CD95) were upregulated in the long survival group. Direct measurement of parameters of proliferation (cell cycle analysis by flow cytometry, PCNA index) revealed a lower proliferative activity in tumors of the long survivors compared to short survivors. In conclusion, tumors of the long survival group are characterized by a downregulation of factors involved in proliferation and an upregulation of factors involved in apoptosis. These tumors may grow more slowly and this may influence long-term survival of patients with NSCLC.

The Value of Platinum Compounds in Non—Small-Cell Lung Cancer

The value of platinum compounds has come into question with the advent of newer chemotherapy agents in the management of patients with advanced non-small-cell lung cancer. These newer agents, which include the taxanes, topoisomerase I inhibitors, gemcitabine, and vinorelbine, appear to have higher single-agent response rates and more favorable toxicity profiles when compared to the platinum compounds. However, the toxicity of the platinum compounds is now minimized with the advent of more effective antiemetics. In addition, phase III clinical trials have demonstrated that the strategy of cisplatin dose intensity and prolonged duration of therapy with platinum compounds does not improve overall survival; therefore, moderate doses of cisplatin and a shorter duration of therapy can be given to further decrease toxicity. Furthermore, while phase II trials utilizing nonplatinum-based combination chemotherapy appear to demonstrate superior response rates and survival in comparison to platinum-based doublets, results of phase III trials have demonstrated no improvement in survival. Platinum combination chemotherapy remains the standard approach for stage IV non-small-cell lung cancer. More substantial advances will likely be made with novel molecular targeted therapy, such as the epidermal growth factor receptor inhibitors, which demonstrate synergy with the platinum compounds.

Translational oncogenomics: toward rational therapeutic decision-making

The wealth of data in basic science and translational research may often represent a conundrum for clinical oncologists, who need to selectively consider this abundant information and translate it into therapeutic decisions. For the sake of simplicity, we have classified the multiplicity of genetic abnormalities in five repertoires that are rapidly assessable and useful for stratification in clinical trials: allelic imbalance, aberrant promoter methylation, gene mRNA overexpression, microtubule alterations, and polymorphisms. Allelic imbalance refers to chromosomal instability, which is a major feature of cancer, and innovative techniques used in colorectal cancer should also be implemented in lung cancer. Epigenetic changes (variations in transcription levels) have been extensively studied in non-small cell lung cancer. Methylation techniques have shown that these epigenetic changes commonly occur at the same frequency in numerous genes, both well-known ( FHIT, APC, p16 ) and recently discovered ( TMS1, RASSF1 ) in non-small cell lung cancer and in breast cancer. Innovative techniques like quantitative polymerase chain reaction can determine gene expression profiles, mainly overexpression of mRNAs, which may be related to resistance to specific cytotoxic drugs. In the near future, we hope these profiles can be used to individualize chemotherapy. Multiple microtubule alterations related to overexpression of different genes can also be used to predict response to taxanes and Vinca alkaloids. Finally, the assessment of polymorphisms could enable us to understand their functional consequences in chemotherapy response.

Determinants of response and resistance to cytotoxics

There is an underlying feeling in the oncology community that chemotherapy has reached a therapeutic "glass ceiling" in non-small cell lung cancer, and that we will never attain the acceptable survival rates that are just beyond our reach. Multiple clinical trials have tested doublets, triplets, and sequential chemotherapy in what is often regarded as a futile attempt to break through this ceiling. Recent large randomized trials have not shown that any of these combinations is superior to any of the others. Nevertheless, the analysis of DNA and RNA from patients' serum can permit us to assess genes that may be specific targets of certain cytotoxic agents and others that may be markers of multidrug resistance. With this information, we will hopefully be able to create guidelines for individualized chemotherapy. With this in mind, the Spanish Lung Cancer Group has designed a trial to test the involvement of various genes in resistance to gemcitabine and cisplatin. With the gene corral that will emerge from this trial, we will create an up-front diagnostic test for selecting the most appropriate gemcitabine plus cisplatin regimen for the treatment of non-small cell lung cancer.

Drug resistance in non-small cell lung cancer

There is an underlying feeling in the oncology community that chemotherapy has reached a therapeutic glass ceiling in non-small cell lung cancer (NSCLC) and that we will never attain the acceptable survival rates that are just beyond our reach. Multiple clinical trials have tested doublets, triplets and sequential chemotherapy in what is often regarded as a futile attempt to break through this ceiling. Recent large randomized trials have not demonstrated that any of these combinations is superior to any of the others. Nevertheless, the analysis of DNA or RNA from patients can permit us to assess genes that may be specific targets of certain cytotoxic agents and others that may be markers of multidrug resistance. With this in mind, the Spanish Lung Cancer Group has designed a trial to test the involvement of various genes in resistance to gemcitabine and cisplatin.

The role of chemotherapy in early non-small-cell lung cancer management

Great advances have been made in chemotherapy in advanced and metastatic non-small-cell lung cancer (NSCLC), and a major milestone was reached with the administration of neoadjuvant chemotherapy in stage IIIA N2 disease. The systemic nature of lung cancer has been confirmed by many genetic analyses documenting micrometastases in negative lymph nodes and bone marrow, and mRNA gene overexpression as a surrogate of cancer cells has been identified in peripheral blood. Furthermore, serum or plasma cell-free tumor DNA has been observed even in tumors with a diameter of less than 2 cm. Pharmacogenetic screening can lead to tailored chemotherapy even in patients with early disease through the use of a genetic tool kit that will allow us to optimize the use of chemotherapy by using serial measurements of serum DNA that can help to detect residual disease and re-assess the chemosensitivity of sub-clinical micrometastatic disease. The ongoing (neo)adjuvant taxol/carboplatin hope (NATCH) trial is testing the value of three cycles of chemotherapy given pre- or post-operatively compared with surgery alone and will analyze genetic abnormalities in serum DNA at three different points during patient follow-up. Our major concern in this review is to analyze the pros and cons of chemotherapy in NSCLC. Although this review is not a formal meta-analysis, we have discussed the most relevant published studies in this field. We conclude that not only is there no evidence of detrimental effects of chemotherapy, in fact, there are many indications that chemotherapy induces response in up to 80% of patients and downgrades N2 disease in up to 50% of patients. This translates into significantly better survival when accompanied by complete resection. Since at least 50% of patients with stage IB disease develop distant metastases, it seems logical to explore the role of chemotherapy in early disease.