P. Crosbie

The role of the tumor-microenvironment in lung cancer-metastasis and its relationship to potential therapeutic targets.

Non-small cell lung cancer (NSCLC) accounts for >80% of lung cancer cases and currently has an overall five-year survival rate of only 15%. Patients presenting with advanced stage NSCLC die within 18-months of diagnosis. Metastatic spread accounts for >70% of these deaths. Thus elucidation of the mechanistic basis of NSCLC-metastasis has potential to impact on patient quality of life and survival. Research on NSCLC metastasis has recently expanded to include non-cancer cell components of tumors-the stromal cellular compartment and extra-cellular matrix components comprising the tumor-microenvironment. Metastasis (from initial primary tumor growth through angiogenesis, intravasation, survival in the bloodstream, extravasation and metastatic growth) is an inefficient process and few released cancer cells complete the entire process. Micro-environmental interactions assist each of these steps and discovery of the mechanisms by which tumor cells co-operate with the micro-environment are uncovering key molecules providing either biomarkers or potential drug targets. The major sites of NSCLC metastasis are brain, bone, adrenal gland and the liver. The mechanistic basis of this tissue-tropism is beginning to be elucidated offering the potential to target stromal components of these tissues thus targeting therapy to the tissues affected. This review covers the principal steps involved in tumor metastasis. The role of cell-cell interactions, ECM remodeling and autocrine/paracrine signaling interactions between tumor cells and the surrounding stroma is discussed. The mechanistic basis of lung cancer metastasis to specific organs is also described. The signaling mechanisms outlined have potential to act as future drug targets minimizing lung cancer metastatic spread and morbidity.

Tracking genomic cancer evolution for precision medicine: the lung TRACERx study.

TRACERx, a prospective study of patients with primary non-small cell lung cancer, aims to map the genomic landscape of lung cancer by tracking clonal heterogeneity and tumour evolution from diagnosis to relapse.

Molecular histology of lung cancer: From targets to treatments

Lung cancer is the leading cause of cancer-related death worldwide with a 5-year survival rate of less than 15%, despite significant advances in both diagnostic and therapeutic approaches. Combined genomic and transcriptomic sequencing studies have identified numerous genetic driver mutations that are responsible for the development of lung cancer. In addition, molecular profiling studies identify gene products and their mutations which predict tumour responses to targeted therapies such as protein tyrosine kinase inhibitors and also can offer explanation for drug resistance mechanisms. The profiling of circulating micro-RNAs has also provided an ability to discriminate patients in terms of prognosis/diagnosis and high-throughput DNA sequencing strategies are beginning to elucidate cell signalling pathway mutations associated with oncogenesis, including potential stem cell associated pathways, offering the promise that future therapies may target this sub-population, preventing disease relapse post treatment and improving patient survival. This review provides an assessment of molecular profiling within lung cancer concerning molecular mechanisms, treatment options and disease-progression. Current areas of development within lung cancer profiling are discussed (i.e. profiling of circulating tumour cells) and future challenges for lung cancer treatment addressed such as detection of micro-metastases and cancer stem cells.

EBUS-TBNA in Elderly Patients with Lung Cancer: Safety and Performance Outcomes

Background: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) enables minimally invasive lymph node sampling during bronchoscopy under conscious sedation. The primary purpose of this study was to investigate the safety profile of EBUS-TBNA in an elderly population. The secondary aim was to assess the efficacy of EBUS-TBNA for nodal staging and pathological diagnosis in elderly patients with primary lung cancer. Methods: This was a prospective cohort study of patients undergoing EBUS-TBNA, between March 2010 and August 2012, at a single U.K. hospital site. Procedure and outcome data including 6-month follow-up were collected prospectively. Patients were divided into less than 70 (<70yrs) or 70 and older (≥70yrs) age categories for analysis. Results: Four hundred and fifty-one patients underwent EBUS-TBNA during the study period. Mean age of the patients was 66.9 ± 11.9 years, 43.9% (n=198) of them were aged ≥70yrs. Older patients (≥70yrs) had a worse performance status (p=0.0001) and required significantly lower levels of sedation (p<0.000001) but had similar overall complication rates (<70yrs 8.7% versus ≥70yrs 5.1%; p=0.13) and tolerated the procedure better than younger patients (p=0.036). Sensitivity (92.9% versus 86.4%; p=0.12) was equivalent, but negative predictive value (91.8% versus 73.9%; p=0.001) and diagnostic accuracy (96.0% versus 90.2%; p=0.02) of nodal sampling in patients with confirmed or suspected lung cancer (n=273) was higher in the ≥70yrs cohort (n=131, 48.0%). However, the prevalence of nodal malignancy was significantly different between the two groups as was the proportion of patients subject to surgical lymph node sampling after negative EBUS-TBNA. EBUS-TBNA samples produced low non–small-cell lung cancer–not otherwise specified rates (6.9%) and high levels of successful epidermal growth factor receptor mutation analysis (97.5%) irrespective of age category. Conclusion: EBUS is a safe and well-tolerated procedure in elderly patients, which facilitates accurate pathological diagnosis and minimally invasive staging in patients with lung cancer.

Association between lung cancer risk and single nucleotide polymorphisms in the first intron and codon 178 of the DNA repair gene, O6-alkylguanine–DNA alkyltransferase

The association between lung cancer risk and 2 polymorphisms, rs12268840 and rs2308327 (codon K178R), in the DNA repair protein, O6‐alkylguanine–DNA alkyltransferase, which are associated with interindividual differences in activity, have been investigated in 3 hospital‐based case–control studies. Genotyping was carried out on 617 subjects of whom 255 had lung cancer. In 2 of the 3 series, there was a significant inverse association between the 178R allele and case status (p < 0.05). In a meta‐analysis, the odds ratio (95% CI) associated with the 178R allele relative to the 178K allele was 0.64 (0.45–0.92, p = 0.01) and 0.51 (0.24–1.11, p = 0.09) in fixed effects and random effects models, respectively. In a pooled analysis, after adjustment for sex, age, pack years and series, the OR (95% CI) for a heterozygote was 0.67 (0.45–1.01) and for a 178R homozygote was 0.10 (0.01–0.94); the trend for a decreased risk with the number of R alleles was significant (p = 0.008). This trend was particularly pronounced in heavy smokers (trend test p = 0.003), but not significant in light smokers (p = 0.73). There was no evidence of an association between rs12268840 and lung cancer risk. These results suggest that the R allele may protect against lung cancer, specifically in heavy smokers, an effect that may result from this polymorphism affecting the function of the MGMT protein and/or levels in MGMT activity.

Prognostic and predictive biomarkers in early stage NSCLC: CTCs and serum/plasma markers

Resection of early stage non-small cell lung cancer (NSCLC) offers patients the best hope of cure, however recurrence rates post-resection remain high suggesting the presence of micro-metastatic disease at the time of surgery undetected by standard staging methods. A critical step in the metastatic cascade is the entry of tumor cells into the circulation enabling their distribution to and seeding of distant organs. This review explores the evidence for predictive and prognostic circulating biomarkers in the early stage NSCLC population. We summarize studies that have explored a variety of targets including circulating proteins, nucleic acids and more recently circulating tumor cells (CTCs) as potentially clinically relevant biomarkers in the early stage setting. Circulating biomarkers may add clinically relevant information about the biological behavior of tumors over and above that provided by pathological staging. Improvement in the stratification of patients according to the likelihood of metastatic relapse after radical treatments such as surgical resection could allow more effective targeting of systemic therapies such as adjuvant chemotherapy.

Circulating Tumor Cells Detected in the Tumor-Draining Pulmonary Vein Are Associated with Disease Recurrence after Surgical Resection of NSCLC

&NA; Tumor recurrence after surgical resection of NSCLC obstructs long‐term disease‐free survival in approximately 50% of cases. Our data suggest that combining circulating tumor cell enumeration (as single cells or clusters) in tumor‐draining pulmonary vein and peripheral blood (assessed by CellSearch) at the time of NSCLC surgery better identifies those patients at higher risk for lung cancer recurrence than does peripheral circulating tumor cell number alone.

Can Computed Tomography Characteristics Predict Outcomes in Patients Undergoing Radial Endobronchial Ultrasound-Guided Biopsy of Peripheral Lung Lesions?

Introduction: Percutaneous computed tomography (CT)-guided lung biopsy is a standard minimally invasive technique for sampling peripheral lung lesions. Radial endobronchial ultrasound (EBUS) offers an alternative approach but it has yet to be defined which patients are most suited to this procedure. The primary aim of this study was to investigate whether CT characteristics could predict the success of radial EBUS-guided sampling. Methods: The University Hospital South Manchester provides a radial EBUS service, under conscious sedation without fluoroscopy, double-hinged curettes, or guide sheaths, to a large cancer Network in the United Kingdom. This retrospective analysis of a prospectively maintained database included all patients undergoing radial EBUS from January 2011 to June 2013. Lesion size, structure, location, and presence of a bronchus sign on thoracic CT were analyzed against predefined outcomes using multivariate analysis. Results: One-hundred and seventeen patients underwent radial EBUS in the study period (mean age 69.5, mean lesion size 36.6 mm). The presence of a bronchus sign on CT was the only independent predictor of all predefined outcomes: (1) lesion identification with radial EBUS, (2) positioning of probe within the center of the lesion, and (3) accurate pathological diagnosis; odds ratio (OR) 31.1 (7.8–123.9, p < 0.0001), OR 44.8 (5.6–354.9, p < 0.0001) and OR 46.6 (11.1–195.3, p < 0.0001) respectively. The sensitivity and diagnostic accuracy for those patients with a bronchus sign on CT was 87.3% and 86.7% compared with 12.5% and 11.1% for those lacking the bronchus sign. Discussion: The patients most likely to benefit from radial EBUS, without the use of adjuncts, are those with a bronchus sign on CT.

Nodal staging in lung cancer: a risk stratification model for lymph nodes classified as negative by EBUS-TBNA.

Background: Over the last 10 years, endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has become established as the first-line nodal staging procedure of choice for lung cancer patients. However, the pathway for patients following a negative EBUS-TBNA has not been clearly defined. The primary aim of this study was to develop and validate a risk stratification model to categorize lymph nodes deemed negative by EBUS-TBNA into “low-risk” and “high-risk” groups, where “risk” refers to the risk of false negative sampling. Methods: A retrospective analysis of a prospectively maintained database at a UK tertiary EBUS-TBNA centre was performed. Only patients with primary lung cancer and only negative lymph nodes by EBUS-TBNA were included in the analysis. A risk stratification model was built from a derivation set using independent predictors of malignancy and the validation set used to evaluate the constructed model. The study period was from March 2010 to August 2013. Results: Three hundred twenty-nine lymph nodes were included in the analysis (derivation set n = 196, validation set n = 133). Lymph node standardized uptake value, the standardized uptake value ratio between the lymph node and primary tumor, and heterogeneous echogenicity during sonographic assessment were the only independent predictors of malignancy. Using a simplified scoring system based on the natural logs of the odds ratios from the multivariable analysis on the derivation sample, lymph nodes can be stratified into low risk (score ⩽1) and high risk (score ≥2). One hundred forty-one of 142 and 94 of 96 lymph nodes classified as low risk in the derivation and validation set, respectively, were ultimately proven to be benign and 35 of 54 and 24 of 37 lymph nodes classified as high risk were proven malignant. The negative predictive value of the risk stratification model for the derivation set and validation set was 99.3% (95% confidence interval 96.1%–99.6%) and 97.9% (95% confidence interval 92%–99.6%), respectively. Conclusion: This risk stratification model may assist lung cancer multidisciplinary teams in deciding which patients need further staging procedures and which may proceed directly to treatment after a negative EBUS.

A study of patients with isolated mediastinal and hilar lymphadenopathy undergoing EBUS-TBNA

Background Isolated mediastinal and/or hilar lymphadenopathy (IMHL) may be caused by benign and malignant disorders or be ‘reactive’. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has a reported low negative predictive value (NPV) in IMHL, necessitating mediastinoscopy in selected patients. The aim of this study was to examine the NPV of EBUS-TBNA in an IMHL population and determine whether clinical variables differentiate between pathological and reactive IMHL. Methods Analysis of a prospectively maintained database of consecutive patients with IMHL referred to a single UK centre for EBUS-TBNA. Results 100 patients with IMHL had EBUS-TBNA during the study (March 2010–February 2013), mean age 58.6±15.7 years, 63% men, 70% white British and mean follow-up 16.8±8.6 months. Pathological cause of IMHL established in 52 patients (sarcoidosis n=20, tuberculosis n=18, carcinoma n=7, lymphoma n=6, benign cyst n=1), 43 from EBUS-TBNA. 48/57 negative EBUS-TBNA samples were true negatives reflecting reactive lymphadenopathy in 48%. The diagnostic accuracy of EBUS-TBNA was 91% and NPV was 84.2% (95% CI 72.6% to 91.5%). Multivariate analysis of clinical covariates showed age (odds ratio (OR) 1.07, 95% CI 1.01 to 1.13; p=0.033), the presence of a relevant comorbidity (OR 9.49, 95% CI 2.20 to 41.04; p=0.003) and maximum lymph node size (OR 0.70, 95% CI 0.59 to 0.83; p=0.00004) to differentiate between reactive and pathological IMHL. Stratification of the study population according to comorbidity and maximum lymph node size (<20 mm) identified a low-risk cohort (n=32) where the NPV of EBUS-TBNA was 93.8% (95% CI 79.9% to 98.3%). Conclusions Reactive lymphadenopathy accounts for a significant proportion of patients with IMHL. In carefully selected patients with IMHL and a negative EBUS-TBNA, surveillance rather than further invasive sampling may be an appropriate strategy.