Close Surveillance with Long-Term Follow-up of Subjects with Preinvasive Endobronchial Lesions.

RATIONALE: Autofluorescence bronchoscopy (AFB) and computed tomography (CT) enable lung cancer (LC) detection at the early (pre-)invasive stage. However, LC risk in patients with preinvasive endobronchial lesions is unclear. OBJECTIVES: To assess LC incidence and identify potential risk determinants in patients with preinvasive lesions. METHODS: In our tertiary care referral center, 164 subjects with preinvasive lesions were monitored up to 12.5 years by repeated AFB and CT. Occurrence of LC was monitored. Clinical management depended on histological grade, with cancer patients receiving standard care. Potential risk determinants (smoking status, baseline histology, cancer history, and chronic obstructive pulmonary disease [COPD] status) were evaluated in relation to cancer occurrence, event-free survival (EFS), and overall survival (OS). MEASUREMENTS AND MAIN RESULTS: During surveillance (median of 30 mo, range 4-152) of 164 subjects with preinvasive lesions (80 high grade and 84 low grade at inclusion), 61 LCs were detected in 55 subjects (median time to event 16.5 mo). Twenty-three LCs (38%) were detected by CT, and 38 (62%) were detected by AFB. More cancers (36 of 61; 59%) developed from separate, rather than initial lesional sites. Subjects with high-grade lesions were more likely to be diagnosed with LC at the same or another site in the lungs than those with low-grade lesions (P = 0.03). Independent risk determinants for OS were previous curatively treated cancer and COPD (P ≤ 0.05). CONCLUSIONS: Presence of preinvasive lesions, especially high-grade lesions, may serve as LC risk markers. LCs occur both at preinvasive lesion sites and elsewhere in the bronchial epithelium or lung parenchyma. Prospective validation of biomarkers and randomized intervention studies are needed to determine optimal management strategies.

Long-term follow-up after first-line bronchoscopic therapy in patients with bronchial carcinoids.

BACKGROUND: Carcinoid of the lung is considered to be a low-grade malignancy. A subgroup presents as an endobronchial tumour. Surgical resection is considered the standard approach because of its metastatic potential and the possibility of an iceberg phenomenon for the endobronchial subgroup. Advances in non-invasive and minimally invasive technologies seem to justify a more lung parenchyma-sparing approach. METHODS: In patients presenting with bronchial carcinoids, initial bronchoscopic treatment (IBT) is first attempted for complete tumour eradication and sufficient tissue sampling for the proper differentiation of typical (TC) versus atypical (AC) histological type. Furthermore in cases with postobstruction problems the desobstruction is aimed at improving the patient's condition and by that alleviate surgery if that is needed. High resolution CT is performed 6 weeks post IBT to determine local tumour growth. Surgical resection follows in case of extraluminal disease, residual carcinoid inaccessible for IBT, or late recurrences not salvaged by repeat IBT. RESULTS: Minimum follow-up was 5 years from start of treatment for 112 patients (65 women, 47 men), with a median age of 47 years (range 16-77 years). Eighty-three patients (74%) had TC, and 29 (26%) AC. IBT only was ultimately curative in 42% of the cases (47/112): 42 TC, 5 AC. Disease-specific mortality including surgical mortality has been 2.6% (3/112) in patients with extraluminal carcinoids (3 AC). CONCLUSIONS: IBT, if with unsuccessful rescue surgery, is justifiable with excellent long-term outcome. IBT made surgery unnecessary in 42% of the cases. Iceberg phenomenon and metastatic potential in this group of patients with bronchial carcinoids are clinically insignificant.

DNA copy number aberrations in endobronchial lesions: a validated predictor for cancer.

We recently identified a DNA copy number aberration (CNA)-based classifier, including changes at 3p26.3-p11.1, 3q26.2-29, and 6p25.3-24.3, as a risk predictor for cancer in individuals presenting with endobronchial squamous metaplasia. The current study was set out to validate the prediction accuracy of this classifier in an independent series of endobronchial squamous metaplastic and dysplastic lesions. The study included 36 high-risk subjects who had endobronchial lesions of various histological grades that were identified and biopsied by autofluorescence bronchoscopy and were subjected to arrayCGH in a nested case-control design. Of the 36 patients, 12 had a carcinoma in situ or invasive carcinoma at the same site at follow-up (median 11 months, range 4-24), while 24 controls remained cancer free (78 months, range 21-142). The previously defined CNA-based classifier demonstrated 92% (95% CI 77% to 98%) accuracy for cancer (in situ) prediction. All nine subjects with CNA-based classifier-positive endobronchial lesions at baseline experienced cancer outcome, whereas all 24 controls and 3 cases were classified as being low risk. In conclusion, CNAs prove to be a highly accurate biomarker for assessing the progression risk of endobronchial squamous metaplastic and dysplastic lesions. This classifier could assist in selecting subjects with endobronchial lesions who might benefit from more aggressive therapeutic intervention or surveillance.

Benefit of a second opinion: From metastatic disease to resectable lung cancer with sarcoid-like reaction.

BACKGROUND: Mediastinal lymphadenopathy in combination with lung cancer is suggestive for lymph node metastases but can also have other origins. CASE REPORT: We describe a patient diagnosed with stage IV lung cancer presenting with parenchymal lesions and enlarged mediastinal lymph nodes. A second opinion including FDG-PET scan review and a mediastinoscopy followed by surgery revealed tumor specimens originating from a single primary tumor with a sarcoid-like reaction in the mediastinal lymph nodes, changing the diagnosis from metastasized to resectable lung cancer. DISCUSSION: PET positive lesions are not always synonymous with metastatic disease in the presence of a malignant tumor. Conscientious review of FDG-PET scans and tissue sampling are therefore mandatory to determine definitive staging and subsequent interventions.

Detection and minimally invasive treatment of early squamous lung cancer.

Non-small cell lung cancer (NSCLC) is the most common cause of cancer deaths worldwide. The majority of patents presenting with NSCLC have advanced disease, which precludes curative treatment. Early detection and treatment might result in the identification of more patients with early central lung cancer and improve survival. In addition, the study of early lung cancer improves understanding of lung carcinogenesis and might also reveal new treatment targets for advanced lung cancer. Bronchoscopic investigation of the central airways can reveal both early central lung cancer in situ (stage 0) and other preinvasive lesions such as dysplasia. In the current review we discuss the detection of early squamous lung cancer, the natural history of preinvasive lesions and whether biomarkers can be used to predict progression to cancer. Finally we will review the staging and management of preinvasive lung cancer lesions and the different therapeutic modalities that are available.

Can quantifying free-circulating DNA in plasma be used to identify subjects with high-grade pre-invasive endobronchial lesions?

Increased concentrations of free-circulating plasma DNA (cpDNA) are observed in patients with invasive cancer, including lung cancer. Whether cpDNA levels are elevated in subjects with high-grade pre-invasive lesions of lung squamous cell carcinoma (SqCC) and whether its detection may be of value for identifying subjects at the highest risk of developing lung SqCC is currently unknown. The present study assessed cpDNA levels in subjects with high- and low-grade pre-invasive squamous endobronchial lesions relative to patients with clinically overt lung SqCC and healthy controls using real-time quantitative PCR methodology. The median cpDNA levels of the patients with invasive lung SqCC (n=16) were significantly higher compared with those of the healthy controls (n=16; P<0.01), whereas the cpDNA levels in the subjects with pre-invasive lesions (n=20) did not differ from those of the controls (P=0.29). The cpDNA levels in subjects with high-grade pre-invasive lesions were highly similar to those diagnosed with low-grade pre-invasive lesions (P=0.85). Our data suggest that cpDNA levels are not increased during the pre-invasive stages of lung squamous carcinogenesis.

DNA copy number alterations in endobronchial squamous metaplastic lesions predict lung cancer.

RATIONALE: Autofluorescence bronchoscopy (AFB) is a valid strategy for detecting premalignant endobronchial lesions. However, no biomarker can reliably predict lung cancer risk of subjects with AFB-visualized premalignant lesions. OBJECTIVES: The present study set out to identify AFB-visualized squamous metaplastic (SqM) lesions with malignant potential by DNA copy number profiling. METHODS: Regular AFB examinations in 474 subjects at risk of lung cancer identified six subjects with SqM lesions at baseline, and carcinoma in situ or carcinoma (carcinoma in situ or greater) at the initial SqM site at follow-up bronchoscopy. These progressive SqM lesions were compared for immunostaining pattern and array comparative genomic hybridization-based chromosomal profiles with 23 SqM lesions of subjects who remained cancer-free. Specific DNA copy number alterations (CNAs) linked to cancer risk were identified and accuracy of CNAs to predict endobronchial cancer in this series was determined. MEASUREMENTS AND MAIN RESULTS: At baseline, p53, p63, and Ki-67 immunostaining were not predictive for a differential clinical outcome of SqM lesions. The mean number of CNAs in baseline SqM of cases was significantly higher compared with control subjects (P < 0.01). Chromosomal regions significantly more frequently altered in SqM of cases were 3p26.3-p11.1, 3q26.2-q29, 9p13.3-p13.2, and 17p13.3-p11.2 (family-wise error rate <0.10). CNAs were specifically detected at the site of future cancer. In cases, baseline-detected CNAs persisted in subsequent biopsies taken from the initial site, and levels increased toward cancer progression. In this series, a model based on CNAs at 3p26.3-p11.1, 3q26.2-29, and 6p25.3-24.3 predicted cancer with 97% accuracy. CONCLUSIONS: The data suggest that the presence of specific CNAs in SqM lesions predict endobronchial cancer.

Early detection and treatment of squamous cell lung cancer / Diagnóstico precoce e tratamento do carcinoma escamoso de pulmão

In this review, we discuss the detection, staging, and treatment of early-stage squamous cell lung cancer, with a focus on bronchoscopic techniques, including electrocauterization, argon plasma coagulation, cryotherapy, neodymium: yttriumaluminum-garnet laser therapy, photodynamic therapy, and intraluminal brachytherapy.The cure rate achieved with bronchoscopic techniques is 43-97%. Most bronchoscopic strategies are less morbid and less toxic than is non-bronchoscopic radiation therapy. Success depends on the application of stringent selection criteria forappropriate tumors, smaller tumors responding better. In some cases, electrocauterization, argon plasma coagulation, and cryotherapy can be conducted safely in an outpatient setting. There is sufficient technology available for the detection and treatment of early-stage squamous cell lung cancer. The greatest challenge is to determine whether early detection and treatment improves survival in high-risk populations and is cost-effective.

Neste artigo de revisão, discutimos os métodos para detecção, estadiamento e tratamento do carcinoma epidermoideprecoce com foco em técnicas broncoscópicas, como eletrocautério, coagulação com plasma de argônio, crioterapia, laser neodímio:ítrio-alumínio-granada, terapia fotodinâmica e braquiterapia intraluminal. A taxa de cura com as técnicas broncoscópicas é 43-97%. A maioria das estratégias broncoscópicas apresenta menor morbidade e toxicidade que a radioterapia. O sucesso depende da aplicação rigorosa de critérios de seleção de acordo com o tumor, sendo que aqueles menores apresentam melhor resposta. Em alguns casos, o eletrocautério, a coagulação com plasmade argônio e a crioterapia podem ser utilizados ambulatorialmente com segurança. Há suficiente tecnologia disponível para a detecção e tratamento precoce do câncer de pulmão epidermoide. O maior desafio é determinar se a detecção e o tratamento precoces melhoram a sobrevida em coortes de alto risco e se tal abordagem é custo-efetiva.

The finding of premalignant lesions is not associated with smoking cessation in chemoprevention study volunteers.

BACKGROUND AND STUDY AIMS: Screening programs for lung cancer may lead to a heightened awareness of the risks of smoking and enhance quitting. The aim of this study was to evaluate whether the participation on a chemoprevention study for premalignant lesions could influence smoking cessation. METHODS: Two hundred one volunteers, current (n = 188) and former smokers (n = 13) with more than 20 pack years had been screened for the chemoprevention study. One hundred forty-six of the current smokers at time of chemoprevention study screening have been retrospectively interviewed about their smoking behavior > or =1 year after their first contact for the chemoprevention study. Structured questionnaires were used, and interviews were held by telephone. The quitters at the time of these first interviews were contacted again 4 years after the initial interview about their current smoking behavior. RESULTS: Of the 146 smoking volunteers, 83 were diagnosed with premalignant lesions of the bronchial mucosa and participated in the chemoprevention study, and 63 had no premalignant lesions and were not included in that study.The majority of participants were men: 87 (60%). The mean age of the participants was 52 +/- 9 years, and the mean age at which volunteers started smoking was 15 +/- 3. Mean number of pack years was 47 +/- 27. Ten volunteers in the group without premalignant lesions and 19 in the group with premalignant lesions had quit smoking at time of the first interview. The smoking cessation rate of the total study group was 20%.Univariate logistic regression analysis demonstrated that smoking cessation was only significantly associated with male gender. No significant associations were found between smoking cessation and the finding of premalignant lesions, sex, age, level of addiction, educational level, marital condition, history of cancer/pulmonary diseases, age at start smoking, previous attempts to quit smoking, and motivation to quit smoking.Within the group of subjects who had quit smoking at the time of the first interview, 15 of 29 persons who had stopped smoking at the time of the first interview have reported that participation in the bronchoscopy screening and/or the trial has been of major influence on their decision to stop smoking. CONCLUSIONS: A smoking cessation rate of 20% has been found among volunteers for a chemopreventive trial investigating smoking-related premalignant lesions after almost 2 years after initial contact has been found. Volunteers experienced screening and trial participation as having influenced their smoking cessation. Smoking cessation was significantly associated with male gender, whereas the finding of premalignant lesions by bronchoscopy was not.

Detection and localization of intraepithelial neoplasia and invasive carcinoma using fluorescence-reflectance bronchoscopy: an international, multicenter clinical trial.

OBJECTIVES: The primary objective of this study was to evaluate the benefit of using a new fluorescence-reflectance imaging system, Onco-LIFE, for the detection and localization of intraepitheal neoplasia and early invasive squamous cell carcinoma. A secondary objective was to evaluate the potential use of quantitative image analysis with this device for objective classification of abnormal sites. DESIGN: This study was a prospective, multicenter, comparative, single arm trial. Subjects for this study were aged 45 to 75 years and either current or past smokers of more than 20 pack-years with airflow obstruction, forced expiratory volume in 1 second/forced vital capacity less than 75%, suspected to have lung cancer based on either sputum atypia, abnormal chest roentgenogram/chest computed tomography, or patients with previous curatively treated lung or head and neck cancer within 2 years. MATERIALS AND METHODS: The primary endpoint of the study was to determine the relative sensitivity of white light bronchoscopy (WLB) plus autofluorescence-reflectance bronchoscopy compared with WLB alone. Bronchoscopy with Onco-LIFE was carried out in two stages. The first stage was performed under white light and mucosal lesions were visually classified. Mucosal lesions were classified using the same scheme in the second stage when viewed with Onco-LIFE in the fluorescence-reflectance mode. All regions classified as suspicious for moderate dysplasia or worse were biopsied, plus at least one nonsuspicious region for control. Specimens were evaluated by the site pathologist and then sent to a reference pathologist, each blinded to the endoscopic findings. Positive lesions were defined as those with moderate/severe dysplasia, carcinoma in situ (CIS), or invasive carcinoma. A positive patient was defined as having at least one lesion of moderate/severe dysplasia, CIS, or invasive carcinoma. Onco-LIFE was also used to quantify the fluorescence-reflectance response (based on the proportion of reflected red light to green fluorescence) for each suspected lesion before biopsy. RESULTS: There were 115 men and 55 women with median age of 62 years. Seven hundred seventy-six biopsy specimens were included. Seventy-six were classified as positive (moderate dysplasia or worse) by pathology. The relative sensitivity on a per-lesion basis of WLB + FLB versus WLB was 1.50 (95% confidence interval [CI], 1.26-1.89). The relative sensitivity on a per-patient basis was 1.33 (95% CI, 1.13-1.70). The relative sensitivity to detect intraepithelial neoplasia (moderate/severe dysplasia or CIS) was 4.29 (95% CI, 2.00-16.00) and 3.50 (95% CI, 1.63-12.00) on a per-lesion and per-patient basis, respectively. For a quantified fluorescence reflectance response value of more than or equal to 0.40, a sensitivity and specificity of 51% and 80%, respectively, could be achieved for detection of moderate/severe dsyplasia, CIS, and microinvasive cancer. CONCLUSIONS: Using autofluorescence-reflectance bronchoscopy as an adjunct to WLB with the Onco-LIFE system improves the detection and localization of intraepitheal neoplasia and invasive carcinoma compared with WLB alone. The use of quantitative image analysis to minimize interobserver variation in grading of abnormal sites should be explored further in future prospective clinical trial.

CT detected indeterminate pulmonary nodules in a chemoprevention trial of fluticasone.

INTRODUCTION: In animal models of lung carcinogenesis, inhaled corticosteroids appear to reduce the number of new lung tumors. In a trial of budesonide in smokers with bronchial dysplasia, the proportion of indeterminate CT detected pulmonary nodules that resolved was larger in the treatment group. We performed a secondary analysis of CT data of subjects at risk of lung cancer enrolled in a chemoprevention trial of fluticasone. METHODS: Subjects with bronchial squamous metaplasia or dysplasia had a baseline chest CT scan. They were randomized to fluticasone or a placebo. After 6 months a repeat CT was performed and the change in number and size of nodules was evaluated. RESULTS: Two hundred and one subjects were screened. Of the 108 volunteers included in the study, 74 were male, mean age was 53 years and mean number of pack years 48. Baseline: 35 subjects had 91 nodules in total, 62% <4mm. In the fluticasone arm more subjects had a decrease and fewer had an increase in number of nodules, however this trend did not reach statistical significance. CONCLUSION: In this preliminary study there was a tendency of nodules to resolve, however, studies with CT detected nodules as inclusion criterion are needed.

The influence of fluticasone inhalation on markers of carcinogenesis in bronchial epithelium.

RATIONALE: Bronchial epithelium exposed to cigarette smoke undergoes a series of histologic changes that may ultimately lead to invasive cancer. Inhaled corticosteroids reduce the number of lung tumors developing in rats exposed to cigarette smoke. OBJECTIVES: We studied the effect of inhaled fluticasone on premalignant lesions in smokers and patients curatively treated for head and neck cancer or lung cancer. METHODS: Participants were screened for premalignant lesions by bronchoscopy. Biopsies were taken from three to five locations and classified using WHO criteria. In case of a metaplasia index of > 15%, participants were randomized to receive a powder inhalation device containing either fluticasone 500 microg or a placebo, to be used twice a day. After 6 months, biopsies were obtained from the same locations as previously sampled. Efficacy of treatment was assessed by reversal of metaplasia/dysplasia; secondary endpoints were reversal of increased p53 and KI-67 immunoreactivity and expression of human telomerase reverse transcriptase. MEASUREMENTS AND MAIN RESULTS: Of the 201 subjects that were screened, 108 were included. Mean age was 53 yr (35-71), mean number of pack-years 48 (18-99), mean metaplasia index 48%, and 32% had some degree of dysplasia at baseline. The two treatment arms did not differ with respect to response or change in either metaplasia index or the expression of the markers p53, KI-67, or human telomerase reverse transcriptase. CONCLUSIONS: Inhaled fluticasone in a dose of 500 mug twice a day does not affect the natural course of premalignant lesions in the central airways.

The natural history of carcinoma in situ involving bronchial resection margins.

STUDY OBJECTIVES: Microscopic residual disease in the bronchial resection margins after surgical resection of lung cancer is rare, and its clinical significance remains unsettled. We studied the natural history of patients with carcinoma in situ (CIS) at their bronchial resection margins to focus on the issue of stump recurrence. METHODS: Eleven individuals who had undergone radical surgery for N0M0 lung tumors were found to have CIS at the bronchial resection margins. All of the resection specimens were reviewed with respect to the pattern of CIS extension and reclassified as follows: superficial CIS, involving surface epithelium only (CIS-S), CIS extending into the submucosal gland ducts but not deeper (CIS-D), and CIS extending into submucosal gland acini (CIS-A). Patients were followed using autofluorescence bronchoscopy and high-resolution computer tomography. Clinical parameters and the local extent of CIS at histology review were correlated with outcome. RESULTS: Median follow-up was 35 months (range, 15 to 89). Histology review showed two CIS-S cases, six CIS-D cases, and three CIS-A cases. All of the patients with CIS-A developed stump recurrences in contrast with those with only CIS-S. Three patients with CIS-D have developed metachronous primaries in the contralateral lung, whereas the stump region remained free of tumor. CONCLUSIONS: The presence of CIS in the bronchial resection margin after resection of lung cancers is associated with stump recurrences. Although absolute numbers are too small for firm conclusions, our data suggest that those with deep glandular extension of CIS bear the highest risk of early recurrence. However, the development of new primaries away from the stump region and the possible development of distant disease are equally relevant considerations with respect to the choice of additional therapy.

The natural course of preneoplastic lesions in bronchial epithelium.

PURPOSE: To study the natural history of preneoplastic lesions in the bronchial mucosa of the individuals at risk. PATIENTS AND METHODS: White light and autofluorescence bronchoscopy examinations have been done in 52 individuals harboring 134 preneoplastic lesions (WHO criteria). End points were the development of carcinoma in situ (CIS) or squamous cell cancer (SCC) or the highest category of dysplasia up until March 1, 2003 for the remaining preneoplastic lesions. RESULTS: Distribution and outcome of preneoplastic lesions have been found to be unrelated to various risk factors such as smoking history, past history of cancer, or chronic obstructive pulmonary disease. Nonstepwise changes of preneoplastic lesions are seen. Regression rate has been 54%. Progression to CIS/SCC has been 13.4% (18 of 134) and was for severe dysplasia, significantly higher (P < 0.003) than preneoplastic lesions showing lower-grade dysplasia (squamous metaplasia, mild and moderate dysplasia). Time to progression was not significantly different. However, when analyzed per individual, no significant difference of progression rate between individuals with or without severe dysplasia was seen (39% versus 26%; P = 0.36). CONCLUSIONS: The 54% regression rate of all preneoplastic lesions, 26% to 39% progression rate to CIS/SCC of individuals with lower-grade dysplasia or severe dysplasia with no significant difference in progression rate and time to progression combined with nonstepwise histologic changes unrelated to the initial histologic grading indicate that one cannot differentiate the potentially more malignant preneoplastic lesions among the many preneoplastic lesions present in the bronchial mucosa. The initial WHO classification of any preneoplastic lesion cannot be reliably used for accurate risk assessment of field carcinogenesis.

What is early lung cancer? A review of the literature.

The dismal cure rate of patients with lung cancer and the stage shift hypothesis have propelled the interest to perform screening at large, despite that previous randomized clinical trials failed to show any mortality benefit and the controversial issue of overdiagnosis. Due to early detection programs, a larger number of individuals at risk will be found to harbor small and potentially malignant early stage lesions. The application of non- and minimal invasive techniques for early detection, staging and treatment will become increasingly important. This review deals with the available clinical, surgical and pathological data focusing on early lung cancer lesions < or =1 cm. Literature data from both centrally located and parenchymal lesions < or =3 cm. have been analyzed. For all sub-centimeter lesions, minimal invasive staging and treatment approaches must still be considered inappropriate. Less invasive and less extensive treatment methods may be considered in high risk individuals with < or =1 cm. peripheral lesion showing > or =50 ground glass opacity on high resolution CT scan and those with superficial lesion in their central airways without deeper tumor invasion in the bronchial wall. Caution is necessary, however, as clinical staging remains inferior to pathological staging which is based on tissue samples collected after complete tumor removal and mediastinal lymph nodes dissection have been performed.

Elevated hTERT mRNA levels: A potential determinant of bronchial squamous cell carcinoma (in situ).

Expression levels of hTERT mRNA were investigated by RT-PCR in tissue specimens of patients with (Group A) and without (Group B) clinically overt bronchial carcinoma, respectively. Bronchial carcinoma (n = 9) and distant normal (n = 9) specimens were analyzed in Group A. The chance of carcinoma seemed to increase with increasing hTERT mRNA levels (OR = 6.04, 95% CI = 1.02-37). Group B was comprised of 21 patients who underwent autofluorescence bronchoscopy. After analysis of 66 bronchial biopsies the chance of prevalent carcinoma in situ or carcinoma increased with increasing hTERT mRNA levels (OR = 6.19, 95% CI = 1.55-25). Variables like age, gender, smoking history, history of cancer within the airways or the degree of lymphocyte infiltrate in the specimens did not modify this relation. In 7 Group B patients in whom bronchial cancer was diagnosed during follow-up, biopsies taken before cancer diagnosis from both the area of the newly developed tumor and distantly from this area had been analyzed for hTERT expression. The median hTERT mRNA level in the biopsies from the area of future cancer was significantly higher than in biopsies taken from distant sites (p < 0.03). These data indicate that elevated hTERT mRNA is associated with an increased relative risk of prevalent and incident bronchial squamous cell carcinoma (in situ).

Increased expression of the EZH2 polycomb group gene in BMI-1-positive neoplastic cells during bronchial carcinogenesis.

Polycomb group (PcG) genes are responsible for maintenance of cellular identity and contribute to regulation of the cell cycle. Recent studies have identified several PcG genes as oncogenes, and a role for PcG proteins in human oncogenesis is suspected. We investigated the expression of BMI-1 and EZH2 PcG oncogenes in human bronchial squamous cell carcinomas (SCCs) and bronchial premalignant precursor lesions (PLs). Whereas normal bronchial epithelium was associated with widespread expression of BMI-1 in resting EZH2-negative cells, neoplastic cells in lung carcinomas displayed altered expression of both BMI-1 and EZH2. Two patterns of abnormal PcG expression were observed: increased expression of BMI-1 in dividing neoplastic cells of PLs and SCCs, and enhanced expression of EZH2 and Ki-67 in BMI-1-positive cells according to severity of the histopathologic stage. We propose that altered expression of BMI-1 and EZH2 is an early event that precedes high rates of proliferation in lung cancer. Because PcG complexes are normally involved in the maintenance of cell characteristics, abnormal PcG expression may contribute to loss of cell identity.