Assessing the Generalizability of the National Lung Screening Trial: Comparison of Patients with Stage 1 Disease

RATIONALE

The findings of the NLST (National Lung Screening Trial) are the basis for screening high-risk individuals according to age and smoking history. Although screening is covered for eligible Medicare beneficiaries, the generalizability of the NLST in the elderly population has been questioned.

OBJECTIVES

Compare outcomes of patients diagnosed with stage 1 non-small cell lung cancer in the NLST to a nationally representative cohort of elderly patients Methods: Analysis of Surveillance, Epidemiology, and End Results (SEER)-Medicare and NLST datasets for patients with stage 1 disease aged 65 to 74 years.

MEASUREMENTS AND MAIN RESULTS

Lung cancer-specific mortality, all-cause mortality, and 30-, 60-, and 90-day treatment mortality were measured. When compared with the NLST group undergoing surgery for stage 1 non-small cell lung cancer, those in the SEER-Medicare NLST eligible cohort had no difference in adjusted odds ratios for 30-, 60-, and 90-day surgical mortality (P values = 0.97, 0.65, and 0.46, respectively). Although the 5-year cancer-specific survival did not differ between cohorts (hazard ratio [HR], 0.84 NLST vs. SEER-Medicare NLST eligible; P = 0.21), the adjusted HR estimate for all-cause mortality was better in the NLST cohort (HR, 0.71; P < 0.01). For patients who did not receive surgery for early-stage disease (presumably for curative intent), the outcomes were far worse (13.1, 18.9, 23.9%, for 30-, 60-, and 90-day treatment mortality, respectively).

CONCLUSIONS

Elderly patients with minimal comorbid conditions meeting the inclusion criteria of the NLST who underwent surgery had excellent postoperative outcomes and similar lung cancer-specific 5-year survivorship. In those with significant comorbidities or those not undergoing surgery, competing causes of death may diminish the benefit, and there is no evidence to recommend screening in this group.

Racial and Ethnic Disparities in Early-Stage Lung Cancer Survival

BACKGROUND

Black patients with lung cancer diagnosed at early stages-for which surgical resection offers a potential cure-experience worse overall survival than do their white counterparts. We undertook a population-based study to estimate the racial and ethnic disparity in death from competing causes and assessed its contribution to the gap in overall survival among patients with early-stage lung cancer.

METHODS

We collected survival time data for 105,121 Hispanic, non-Hispanic Asian, non-Hispanic black, and non-Hispanic white patients with early-stage (IA, IB, IIA, and IIB) lung cancer diagnosed between 2004 and 2013 from the Surveillance, Epidemiology, and End-Results registries. We modeled survival time using competing risk regression and included as covariates sex, age at diagnosis, race/ethnicity, stage at diagnosis, histologic type, type of surgical resection, and radiation sequence.

RESULTS

Adjusting for demographic, clinical, and treatment characteristics, non-Hispanic blacks experienced worse overall survival compared with non-Hispanic whites (adjusted hazard ratio [aHR], 1.05; 95% CI, 1.02-1.08), whereas Hispanics and non-Hispanic Asians experienced better overall survival (aHR, 0.93; 95% CI, 0.89-0.98; and aHR, 0.82; 95% CI, 0.79-0.86, respectively). Worse survival from competing causes of death, such as cardiovascular disease and other cancers-rather than from lung cancer itself-led to the disparity in overall survival among non-Hispanic blacks (adjusted relative risk, 1.07; 95% CI, 1.02-1.12).

CONCLUSIONS

Narrowing racial and ethnic disparities in survival among patients with early-stage lung cancer will rely on more than just equalizing access to surgical resection and will need to include better management and treatment of smoking-related comorbidities and diseases.

Comparing Pulmonary Nodule Location During Electromagnetic Bronchoscopy With Predicted Location on the Basis of Two Virtual Airway Maps at Different Phases of Respiration

BACKGROUND

Electromagnetic navigational bronchoscopy (ENB) is guided bronchoscopy to pulmonary nodules (PN) that relies on a preprocedural chest CT to create a three-dimensional (3D) virtual airway map. The CT is traditionally done at a full inspiratory breath hold (INSP), but the procedure is performed while the patient tidal breaths, when lung volumes are closer to functional residual capacity. Movement of a PN from INSP to expiration (EXP) has been shown to average 17.6 mm. Therefore, the hypothesis of this study is that preprocedural virtual maps built off a CT closer to physiological lung volumes during bronchoscopy may better represent the actual 3D location of a PN.

METHODS

Consecutive patients with a PN needing a histological diagnosis were enrolled. A preprocedure INSP and EXP CT scan were obtained to create two virtual maps. During the airway inspection, the system tracked the sensor probe to collect 3D points that were reconstructed into the lumen registration map. This map is thought to best represent the patient's airways during bronchoscopy. Predicted PN location on an EXP and INSP map was compared with lumen registration.

RESULTS

Twenty consecutive PN underwent ENB. The predicted PN location, compared with lumen registration, was significantly closer on EXP vs INSP (4.5 mm ± 3.3 mm vs 14.8 mm ± 9.7 mm; p < 0.0001).

CONCLUSIONS

Predicted 3D nodule location using an EXP scan for ENB is significantly closer to actual nodule location when compared with an INSP scan, but whether this leads to increased yields needs to be determined.

Physician Assessment of Pretest Probability of Malignancy and Adherence With Guidelines for Pulmonary Nodule Evaluation

BACKGROUND

The annual incidence of pulmonary nodules is estimated at 1.57 million. Guidelines recommend using an initial assessment of nodule probability of malignancy (pCA). A previous study found that despite this recommendation, physicians did not follow guidelines.

METHODS

Physician assessments (N = 337) and two previously validated risk model assessments of pretest probability of cancer were evaluated for performance in 337 patients with pulmonary nodules based on final diagnosis and compared. Physician-assessed pCA was categorized into low, intermediate, and high risk, and the next test ordered was evaluated.

RESULTS

The prevalence of malignancy was 47% (n = 158) at 1 year. Physician-assessed pCA performed better than nodule prediction calculators (area under the curve, 0.85 vs 0.75; P < .001 and .78; P = .0001). Physicians did not follow indicated guidelines when selecting the next test in 61% of cases (n = 205). Despite recommendations for serial CT imaging in those with low pCA, 52% (n = 13) were managed more aggressively with PET imaging or biopsy; 12% (n = 3) underwent biopsy procedures for benign disease. Alternatively, in the high-risk category, the majority (n = 103 [75%]) were managed more conservatively. Stratified by diagnosis, 92% (n = 22) with benign disease underwent more conservative management with CT imaging (20%), PET scanning (15%), or biopsy (8%), although three had surgery (8%).

CONCLUSIONS

Physician assessment as a means for predicting malignancy in pulmonary nodules is more accurate than previously validated nodule prediction calculators. Despite the accuracy of clinical intuition, physicians did not follow guideline-based recommendations when selecting the next diagnostic test. To provide optimal patient care, focus in the areas of guideline refinement, implementation, and dissemination is needed.

Assessing the Correlation Between Physical Activity and Quality of Life in Advanced Lung Cancer

BACKGROUND AND OBJECTIVE

Increasing physical activity (PA) is safe and beneficial in lung cancer (LC) patients. Advanced-stage LC patients are under-studied and have worse symptoms and quality of life (QoL). We evaluated the feasibility of monitoring step count in advanced LC as well as potential correlations between PA and QoL.

METHODS

This is a prospective, observational study of 39 consecutive patients with advanced-stage LC. Daily step count over 1 week (via Fitbit Zip), QoL, dyspnea, and depression scores were collected. Spearman rank testing was used to assess correlations. Correlation coefficients (ρ) >0.3 or <-0.3 (more and less correlated, respectively) were considered potentially clinically significant.

RESULTS

Most (83%) of the patients were interested in participating, and 67% of those enrolled were adherent with the device. Of those using the device (n = 30), the average daily step count was 4877 (range = 504-12 118) steps/d. Higher average daily step count correlated with higher QoL (ρ = 0.46), physical (ρ = 0.61), role (ρ = 0.48), and emotional functioning (ρ = 0.40) scores as well as lower depression (ρ = -0.40), dyspnea (ρ = -0.54), and pain (ρ = -0.37) scores.

CONCLUSION

Remote PA monitoring (Fitbit Zip) is feasible in advanced-stage LC patients. Interest in participating in this PA study was high with comparable adherence to other PA studies. In those utilizing the device, higher step count correlates with higher QoL as well as lower dyspnea, pain, and depression scores. PA monitoring with wearable devices in advanced-stage LC deserves further study.

Palliative Care in Lung Cancer: A Review

Lung cancer patients are at high risk of suffering due to severe and refractory symptoms, concomitant respiratory comorbidity, frequent disease progression, and treatment that can worsen and compromise quality of life. Palliative care (PC) has shown multiple benefits to cancer patients such as better quality of life, higher patient and family satisfaction, improved disease understanding, less symptom burden, fewer depressive symptoms, less aggressive end of life care, and even improved survival with early implementation. For these reasons, multiple societies have recognized PC as an essential component of lung cancer care, and early PC is recommended for patients with metastatic disease or refractory symptoms. Unfortunately, utilization of PC is both low and often near the end of life, increasing risk for suffering. Misconceptions about PC often underlie delayed referral to PC. This review summarizes the literature for utilization of PC in lung cancer and focuses on patient benefits, misconceptions, barriers, and implementation.

The Association between Smoking Abstinence and Mortality in the National Lung Screening Trial

RATIONALE

Smoking is the largest contributor to lung cancer risk, and those who continue to smoke after diagnosis have a worse survival. Screening for lung cancer with low-dose computed tomography (LDCT) reduces mortality in high-risk individuals. Smoking cessation is an essential component of a high-quality screening program.

OBJECTIVES

To quantify the effects of smoking history and abstinence on mortality in high-risk individuals who participated in the NLST (National Lung Screening Trial).

METHODS

This is a secondary analysis of a randomized controlled trial (NLST).

MEASUREMENTS AND MAIN RESULTS

Measurements included self-reported demographics, medical and smoking history, and lung cancer-specific and all-cause mortality. Cox regression was used to study the association of mortality with smoking status and pack-years. Kaplan-Meier survival curves were examined for differences in survival based on trial arm and smoking status. Current smokers had an increased lung cancer-specific (hazard ratio [HR], 2.14-2.29) and all-cause mortality (HR, 1.79-1.85) compared with former smokers irrespective of screening arm. Former smokers in the control arm abstinent for 7 years had a 20% mortality reduction comparable with the benefit reported with LDCT screening in the NLST. The maximum benefit was seen with the combination of smoking abstinence at 15 years and LDCT screening, which resulted in a 38% reduction in lung cancer-specific mortality (HR, 0.62; 95% confidence interval, 0.51-0.76).

CONCLUSIONS

Seven years of smoking abstinence reduced lung cancer-specific mortality at a magnitude comparable with LDCT screening. This reduction was greater when abstinence was combined with screening, highlighting the importance of smoking cessation efforts in screening programs.

Management of Pulmonary Nodules by Community Pulmonologists: A Multicenter Observational Study

BACKGROUND:

Pulmonary nodules (PNs) are a common reason for referral to pulmonologists. The majority of data for the evaluation and management of PNs is derived from studies performed in academic medical centers. Little is known about the prevalence and diagnosis of PNs, the use of diagnostic testing, or the management of PNs by community pulmonologists.

METHODS:

This multicenter observational record review evaluated 377 patients aged 40 to 89 years referred to 18 geographically diverse community pulmonary practices for intermediate PNs (8-20 mm). Study measures included the prevalence of malignancy, procedure/test use, and nodule pretest probability of malignancy as calculated by two previously validated models. The relationship between calculated pretest probability and management decisions was evaluated.

RESULTS:

The prevalence of malignancy was 25% (n = 94). Nearly one-half of the patients (46%, n = 175) had surveillance alone. Biopsy was performed on 125 patients (33.2%). A total of 77 patients (20.4%) underwent surgery, of whom 35% (n = 27) had benign disease. PET scan was used in 141 patients (37%). The false-positive rate for PET scan was 39% (95% CI, 27.1%-52.1%). Pretest probability of malignancy calculations showed that 9.5% (n = 36) were at a low risk, 79.6% (n = 300) were at a moderate risk, and 10.8% (n = 41) were at a high risk of malignancy. The rate of surgical resection was similar among the three groups (17%, 21%, 17%, respectively; P = .69).

CONCLUSIONS:

A substantial fraction of intermediate-sized nodules referred to pulmonologists ultimately prove to be lung cancer. Despite advances in imaging and nonsurgical biopsy techniques, invasive sampling of low-risk nodules and surgical resection of benign nodules remain common, suggesting a lack of adherence to guidelines for the management of PNs.

Clinical Utility of a Bronchial Genomic Classifier in Patients With Suspected Lung Cancer

BACKGROUND

Bronchoscopy is often the initial diagnostic procedure performed in patients with pulmonary lesions suggestive of lung cancer. A bronchial genomic classifier was previously validated to identify patients at low risk for lung cancer after an inconclusive bronchoscopy. In this study, we evaluated the potential of the classifier to reduce invasive procedure utilization in patients with suspected lung cancer.

METHODS

In two multicenter trials of patients undergoing bronchoscopy for suspected lung cancer, the classifier was measured in normal-appearing bronchial epithelial cells from a mainstem bronchus. Among patients with low and intermediate pretest probability of cancer (n = 222), subsequent invasive procedures after an inconclusive bronchoscopy were identified. Estimates of the ability of the classifier to reduce unnecessary procedures were calculated.

RESULTS

Of the 222 patients, 188 (85%) had an inconclusive bronchoscopy and follow-up procedure data available for analysis. Seventy-seven (41%) patients underwent an additional 99 invasive procedures, which included surgical lung biopsy in 40 (52%) patients. Benign and malignant diseases were ultimately diagnosed in 62 (81%) and 15 (19%) patients, respectively. Among those undergoing surgical biopsy, 20 (50%) were performed in patients with benign disease. If the classifier had been used to guide decision making, procedures could have been avoided in 50% (21 of 42) of patients undergoing further invasive testing. Further, among 35 patients with an inconclusive index bronchoscopy who were diagnosed with lung cancer, the sensitivity of the classifier was 89%, with 4 (11%) patients having a false-negative classifier result.

CONCLUSIONS

Invasive procedures after an inconclusive bronchoscopy occur frequently, and most are performed in patients ultimately diagnosed with benign disease. Using the genomic classifier as an adjunct to bronchoscopy may reduce the frequency and associated morbidity of these invasive procedures.

TRIAL REGISTRY

ClinicalTrials.gov; Nos. NCT01309087 and NCT00746759; URL: www.clinicaltrials.gov.

Technical Aspects of Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration: CHEST Guideline and Expert Panel Report

BACKGROUND

Endobronchial ultrasound (EBUS) was introduced in the last decade, enabling real-time guidance of transbronchial needle aspiration (TBNA) of mediastinal and hilar structures and parabronchial lung masses. The many publications produced about EBUS-TBNA have led to a better understanding of the performance characteristics of this procedure. The goal of this document was to examine the current literature on the technical aspects of EBUS-TBNA as they relate to patient, technology, and proceduralist factors to provide evidence-based and expert guidance to clinicians.

METHODS

Rigorous methodology has been applied to provide a trustworthy evidence-based guideline and expert panel report. A group of approved panelists developed key clinical questions by using the PICO (population, intervention, comparator, and outcome) format that addressed specific topics on the technical aspects of EBUS-TBNA. MEDLINE (via PubMed) and the Cochrane Library were systematically searched for relevant literature, which was supplemented by manual searches. References were screened for inclusion, and well-recognized document evaluation tools were used to assess the quality of included studies, to extract meaningful data, and to grade the level of evidence to support each recommendation or suggestion.

RESULTS

Our systematic review and critical analysis of the literature on 15 PICO questions related to the technical aspects of EBUS-TBNA resulted in 12 statements: 7 evidence-based graded recommendations and 5 ungraded consensus-based statements. Three questions did not have sufficient evidence to generate a statement.

CONCLUSIONS

Evidence on the technical aspects of EBUS-TBNA varies in strength but is satisfactory in certain areas to guide clinicians on the best conditions to perform EBUS-guided tissue sampling. Additional research is needed to enhance our knowledge regarding the optimal performance of this effective procedure.

Evaluation of a Steerable Tube Thoracostomy System Compatible with a Flexible Bronchoscope

Tube thoracostomy is effective at draining the pleural space; however, when fluid or air is loculated, drainage may be compromised. For this reason, a steerable chest tube with a redirecting stylet was developed. This tube also allows use of a flexible bronchoscope in the pleural space without significant limitations in mobility as seen in prior studies.Methods:We tested the ability of a steerable tube thoracostomy system in a porcine subject to change position, drain fluid, and utilize a flexible bronchoscope in the pleural space. Fiducial markers were implanted into the parietal pleura to demonstrate maneuverability of the bronchoscope and the ability to take forceps biopsies.Results:Bronchoscope positions in the pleural space were confirmed fluoroscopically: apical, medial, lateral, anterior diaphragm, and posterior diaphragm. All fiducial markers and tissue along the parietal pleura were located and biopsied via flexible forceps with the bronchoscope. The tube was repositioned into all dependent areas where fluid collected.Conclusions:This steerable tube and a flexible bronchoscope can access and visualize the pleural space, locate and biopsy implanted markers on the parietal pleural surface, and drain fluid from the pleural space. Further studies will be needed to evaluate the usefulness of this procedure in the clinical setting.

Adult Bronchoscopy Training: Current State and Suggestions for the Future: CHEST Expert Panel Report

BACKGROUND

The determination of competency of trainees in programs performing bronchoscopy is quite variable. Some programs provide didactic lectures with hands-on supervision, other programs incorporate advanced simulation centers, whereas others have a checklist approach. Although no single method has been proven best, the variability alone suggests that outcomes are variable. Program directors and certifying bodies need guidance to create standards for training programs. Little well-developed literature on the topic exists.

METHODS

To provide credible and trustworthy guidance, rigorous methodology has been applied to create this bronchoscopy consensus training statement. All panelists were vetted and approved by the CHEST Guidelines Oversight Committee. Each topic group drafted questions in a PICO (population, intervention, comparator, outcome) format. MEDLINE data through PubMed and the Cochrane Library were systematically searched. Manual searches also supplemented the searches. All gathered references were screened for consideration based on inclusion criteria, and all statements were designated as an Ungraded Consensus-Based Statement.

RESULTS

We suggest that professional societies move from a volume-based certification system to skill acquisition and knowledge-based competency assessment for trainees. Bronchoscopy training programs should incorporate multiple tools, including simulation. We suggest that ongoing quality and process improvement systems be introduced and that certifying agencies move from a volume-based certification system to skill acquisition and knowledge-based competency assessment for trainees. We also suggest that assessment of skill maintenance and improvement in practice be evaluated regularly with ongoing quality and process improvement systems after initial skill acquisition.

CONCLUSIONS

The current methods used for bronchoscopy competency in training programs are variable. We suggest that professional societies and certifying agencies move from a volume- based certification system to a standardized skill acquisition and knowledge-based competency assessment for pulmonary and thoracic surgery trainees.

Racial Differences in Outcomes within the National Lung Screening Trial. Implications for Widespread Implementation

RATIONALE

Black individuals with lung cancer (LC) experience higher mortality because they present with more advanced disease and are less likely to undergo curative resection for early-stage disease. The National Lung Screening Trial (NLST) demonstrated improved LC mortality by screening high-risk patients with low-dose computed tomography (LDCT). The benefit of LDCT screening in black individuals is unknown.

OBJECTIVES

Examine results of the NLST by race.

METHODS

This was a secondary analysis of a randomized trial (NCT00047385) performed in 33 U.S. centers.

MEASUREMENTS AND MAIN RESULTS

Overall and lung cancer-specific mortality were measured. Screening with LDCT reduced LC mortality in all racial groups but more so in black individuals (hazard ratio [HR], 0.61 vs. 0.86). Smoking increased the likelihood of death from LC, and when stratified by race black smokers were twice as likely to die as white smokers (HR, 4.10 vs. 2.25). Adjusting for sociodemographic and behavioral characteristics, black individuals experienced higher all-cause mortality than white individuals (HR, 1.35; 95% confidence interval, 1.22-1.49); however, black individuals screened with LDCT had a reduction in all-cause mortality. Black individuals were younger, were more likely to be current smokers, had more comorbidities, and had fewer years of formal education than white individuals (P < 0.05).

CONCLUSIONS

Black individuals screened with LDCT had decreased mortality from lung cancer. However, the demographics associated with improved LC survival were less commonly found in black individuals. The overall mortality in the NLST was higher for black individuals than white individuals, but improved in black individuals screened, suggesting that this subgroup may have had improved access to care. To realize the reductions in mortality from LC screening, dissemination efforts need to be tailored to meet the needs of this community.

A Bronchial Genomic Classifier for the Diagnostic Evaluation of Lung Cancer

BACKGROUND

Bronchoscopy is frequently nondiagnostic in patients with pulmonary lesions suspected to be lung cancer. This often results in additional invasive testing, although many lesions are benign. We sought to validate a bronchial-airway gene-expression classifier that could improve the diagnostic performance of bronchoscopy.

METHODS

Current or former smokers undergoing bronchoscopy for suspected lung cancer were enrolled at 28 centers in two multicenter prospective studies (AEGIS-1 and AEGIS-2). A gene-expression classifier was measured in epithelial cells collected from the normal-appearing mainstem bronchus to assess the probability of lung cancer.

RESULTS

A total of 639 patients in AEGIS-1 (298 patients) and AEGIS-2 (341 patients) met the criteria for inclusion. A total of 43% of bronchoscopic examinations were nondiagnostic for lung cancer, and invasive procedures were performed after bronchoscopy in 35% of patients with benign lesions. In AEGIS-1, the classifier had an area under the receiver-operating-characteristic curve (AUC) of 0.78 (95% confidence interval [CI], 0.73 to 0.83), a sensitivity of 88% (95% CI, 83 to 92), and a specificity of 47% (95% CI, 37 to 58). In AEGIS-2, the classifier had an AUC of 0.74 (95% CI, 0.68 to 0.80), a sensitivity of 89% (95% CI, 84 to 92), and a specificity of 47% (95% CI, 36 to 59). The combination of the classifier plus bronchoscopy had a sensitivity of 96% (95% CI, 93 to 98) in AEGIS-1 and 98% (95% CI, 96 to 99) in AEGIS-2, independent of lesion size and location. In 101 patients with an intermediate pretest probability of cancer, the negative predictive value of the classifier was 91% (95% CI, 75 to 98) among patients with a nondiagnostic bronchoscopic examination.

CONCLUSIONS

The gene-expression classifier improved the diagnostic performance of bronchoscopy for the detection of lung cancer. In intermediate-risk patients with a nondiagnostic bronchoscopic examination, a negative classifier score provides support for a more conservative diagnostic approach. (Funded by Allegro Diagnostics and others; AEGIS-1 and AEGIS-2 ClinicalTrials.gov numbers, NCT01309087 and NCT00746759.).

High yield of bronchoscopic transparenchymal nodule access real-time image-guided sampling in a novel model of small pulmonary nodules in canines

BACKGROUND

Bronchoscopic transparenchymal nodule access (BTPNA) is a novel approach to accessing pulmonary nodules. This real-time, image-guided approach was evaluated for safety, accuracy, and yield in the healthy canine model.

METHODS

A novel, inorganic model of subcentimeter pulmonary nodules was developed, consisting of 0.25-cc aliquots of calcium hydroxylapatite (Radiesse) implanted via transbronchial access in airways seven generations beyond the main bronchi to represent targets for evaluation of accuracy and yield. Thoracic CT scans were acquired for each subject, and from these CT scans LungPoint Virtual Bronchoscopic Navigation software provided guidance to the region of interest. Novel transparenchymal nodule access software algorithms automatically generated point-of-entry recommendations, registered CT images, and real-time fluoroscopic images and overlaid guidance onto live bronchoscopic and fluoroscopic video to achieve a vessel-free, straight-line path from a central airway through parenchymal tissue for access to peripheral lesions.

RESULTS

In a nine-canine cohort, the BTPNA procedure was performed to sample 31 implanted Radiesse targets, implanted to simulate pulmonary nodules, via biopsy forceps through a specially designed sheath. The mean length of the 31 tunnels was 35 mm (20.5-50.3-mm range). Mean tunnel creation time was 16:52 min, and diagnostic yield was 90.3% (28 of 31). No significant adverse events were noted in the status of any of the canine subjects post BTPNA, with no pneumothoraces and minimal bleeding (all bleeding events < 2 mL in volume).

CONCLUSIONS

These canine studies demonstrate that BTPNA has the potential to achieve the high yield of transthoracic needle aspiration with the low complication profile associated with traditional bronchoscopy. These results merit further study in humans.

Derivation of a bronchial genomic classifier for lung cancer in a prospective study of patients undergoing diagnostic bronchoscopy

BACKGROUND

The gene expression profile of cytologically-normal bronchial airway epithelial cells has previously been shown to be altered in patients with lung cancer. Although bronchoscopy is often used for the diagnosis of lung cancer, its sensitivity is imperfect, especially for small and peripheral suspicious lesions. In this study, we derived a gene expression classifier from airway epithelial cells that detects the presence of cancer in current and former smokers undergoing bronchoscopy for suspect lung cancer and evaluated its sensitivity to detect lung cancer among patients from an independent cohort.

METHODS

We collected bronchial epithelial cells (BECs) from the mainstem bronchus of 299 current or former smokers (223 cancer-positive and 76 cancer-free subjects) undergoing bronchoscopy for suspected lung cancer in a prospective, multi-center study. RNA from these samples was run on gene expression microarrays for training a gene-expression classifier. A logistic regression model was built to predict cancer status, and the finalized classifier was validated in an independent cohort from a previous study.

RESULTS

We found 232 genes whose expression levels in the bronchial airway are associated with lung cancer. We then built a classifier based on the combination of 17 cancer genes, gene expression predictors of smoking status, smoking history, and gender, plus patient age. This classifier had a ROC curve AUC of 0.78 (95% CI, 0.70-0.86) in patients whose bronchoscopy did not lead to a diagnosis of lung cancer (n = 134). In the validation cohort, the classifier had a similar AUC of 0.81 (95% CI, 0.73-0.88) in this same subgroup (n = 118). The classifier performed similarly across a range of mass sizes, cancer histologies and stages. The negative predictive value was 94% (95% CI, 83-99%) in subjects with a non-diagnostic bronchoscopy.

CONCLUSION

We developed a gene expression classifier measured in bronchial airway epithelial cells that is able to detect lung cancer in current and former smokers who have undergone bronchoscopy for suspicion of lung cancer. Due to the high NPV of the classifier, it could potentially inform clinical decisions regarding the need for further invasive testing in patients whose bronchoscopy is non diagnostic.

Lung cancer screening

The United States Preventive Services Task Force recommends lung cancer screening with low-dose computed tomography (LDCT) in adults of age 55 to 80 years who have a 30 pack-year smoking history and are currently smoking or have quit within the past 15 years. This recommendation is largely based on the findings of the National Lung Screening Trial. Both policy-level and clinical decision-making about LDCT screening must consider the potential benefits of screening (reduced mortality from lung cancer) and possible harms. Effective screening requires an appreciation that screening should be limited to individuals at high risk of death from lung cancer, and that the risk of harm related to false positive findings, overdiagnosis, and unnecessary invasive testing is real. A comprehensive understanding of these aspects of screening will inform appropriate implementation, with the objective that an evidence-based and systematic approach to screening will help to reduce the enormous mortality burden of lung cancer.

Screening and early detection efforts in lung cancer

Lung cancer is the leading cause of cancer-related death in the United States. Since publication of results from the National Lung Screening Trial, several professional organizations, including the US Preventive Services Task Force, have published guidelines recommending low-dose computed tomography for screening in asymptomatic, high-risk individuals. The benefits of screening include detection of cancer at an early stage when a definitive cure is possible, but the risks include overdiagnosis, false-positive results, psychological distress, and radiation exposure. The current review covers the scope of low-dose computed tomography screening, potential risks, costs, and future directions in the efforts for early detection of lung cancer.