Frequency of homozygous deletion at p16/CDKN2 in primary human tumours.

Many tumour types have been reported to have deletion of 9p21 (refs 1-6). A candidate target suppressor gene, p16 (p16INK4a/MTS-1/CDKN2), was recently identified within the commonly deleted region in tumour cell lines. An increasing and sometimes conflicting body of data has accumulated regarding the frequency of homozygous deletion and the importance of p16 in primary tumours. We tested 545 primary tumours by microsatellite analysis with existing and newly cloned markers around the p16 locus. We have now found that small homozygous deletions represent the predominant mechanism of inactivation at 9p21 in bladder tumours and are present in other tumour types, including breast and prostate cancer. Moreover, fine mapping of these deletions implicates a 170 kb minimal region that includes p16 and excludes p15.

Considerations in bringing a cancer biomarker to clinical application.

Specific challenges face our application of emerging biomarkers to early lung cancer detection. These challenges might be considered frontiers to be bridged between established biomedical disciplines, requiring expertise often beyond the range of individual investigators. Cross-disciplinary research already has led to new appreciation of the mechanisms which underlie the phenotypic expression of the transformed cell and places within our grasp the tools which might lead to successful early lung cancer detection. Prior to the successful application of newly described markers, further cross-disciplinary research must (a) refine the selection of biologically appropriate markers, (b) validate such markers against acknowledged disease end points, (c) establish quantitative criteria for marker presence/absence, and (d) confirm marker predictive value in prospective population trials.

Detection of oncogene mutations in sputum precedes diagnosis of lung cancer.

The Johns Hopkins Lung Project developed an archive of sputum specimens during a randomized trial of lung cancer screening (1974-1982). We identified 15 patients from that trial who later developed adenocarcinoma of the lung. The primary lung carcinomas from 10 of these 15 patients contained either a ras or a p53 gene mutation. Using a polymerase chain reaction-based assay, stored sputum samples obtained prior to clinical diagnosis were examined for the presence of these same oncogene mutations. In 8 of 10 patients, the identical mutation identified in the primary tumor was also detected in at least one sputum sample. The earliest detection of a clonal population of cancer cells in sputum was in a sample obtained more than 1 year prior to clinical diagnosis. These results provide the basis of a novel approach for detection of lung cancer based on the evolving molecular genetics of this disease.

Biological monitoring of fire fighters: sister chromatid exchange and polycyclic aromatic hydrocarbon-DNA adducts in peripheral blood cells.

Fire fighters are exposed to potentially carcinogenic combustion and pyrolysis products during the course of their work. The present study was designed to test 43 fire fighters and matched controls for DNA damage which might be related to occupational carcinogen exposures. Using peripheral blood lymphocytes, we examined (a) baseline sister chromatid exchange (SCE) frequency and (b) SCE induction by in vitro mutagenic challenge with mitomycin C. Using nucleated peripheral blood cells, we examined (c) polycyclic aromatic hydrocarbon-DNA adduct levels by assessing benzo(a)pyrene diol epoxide (BPDE)-DNA antigenicity. Exposures were determined from histories of fire-fighting activity. The presence of confounding factors (e.g., tobacco smoking, charcoal-broiled food consumption, etc.) was determined by questionnaire. Plasma cotinine levels were measured to assess recent exposures to tobacco smoke. White fire fighters exhibited a significantly higher risk for the presence of detectable BPDE-DNA antigenicity than white controls (odds ratio, 3.4; 95% confidence interval, 1.08-10.5 after adjustment). Consumption of charcoal-broiled food less than 3 times a month was associated with a smaller proportion of individuals exhibiting measurable (positive) BPDE-DNA antigenicity, while consumption of broiled food greater than 3 times a month did not affect the proportion of positive individuals. Daily alcohol consumption was associated with a larger proportion of individuals exhibiting positive BPDE-DNA antigenicity, (P = 0.07). Tobacco smoking and charcoal-broiled food consumption, but not fire fighting, were associated with increased levels of baseline SCE. Sensitivity to SCE induced by mitomycin C in cultured peripheral lymphocytes was similar in fire fighter and control groups. However, sensitivity of individual fire fighters to mitomycin C-induced SCE was correlated with number of fires fought in the previous 24 h.

Sensitive and specific monoclonal antibody recognition of human lung cancer antigen on preserved sputum cells: a new approach to early lung cancer detection.

Murine monoclonal antibodies (Mabs) to a glycolipid antigen of small-cell (SCC) and a protein antigen of non-small-cell lung cancer (NSCC) were applied to preserved sputum specimens from individuals who participated in The Johns Hopkins Lung Project (JHLP). In that study, undertaken in 1973 to evaluate the efficacy of sputum cytology screening, half of the high-risk participants (5,226 men, greater than or equal to 45 years of age, currently smoking greater than or equal to 1 pack of cigarettes per day) were randomly assigned to produce specimens for cytopathological analysis. During regular screenings over the next 5 to 8 years, 626 (12%) showed moderate (or greater) atypia. Sixty-nine of these (26 who progressed to cancer, 43 who did not) were randomly selected for a blinded improved Mab immunostaining protocol in the present study. Satisfactory specimens with morphologic atypia immunostained positively in 14 of the 22 patients who eventually progressed to cancer (sensitivity 64%), and were nonreactive in 35 of the 40 patients who did not progress to lung cancer (specificity 88%). Review of the true positive specimens (14/22 atypias) showed that they were collected 24 months in advance of diagnosis. In contrast, the 8/22 false negative atypias (failure to stain) showed that they were collected for an average of 57 months preceding the diagnosis of cancer. Subsequent specimens (average, 26 months before cancer) from participants who were originally considered "false negative" did stain positively improving sensitivity to 91% among specimens collected for an average of 2 years in advance of the clinical appearance of lung cancer. Specificity remained at 88%. Recognition of neoplastic antigen expression 2 years in advance of clinical cancer may be a valuable intermediate end point in studies of lung cancer prevention, detection, and therapy.

Genetic analysis of microsomal epoxide hydrolase gene and its association with lung cancer risk.

The human microsomal epoxide hydrolase (EH) gene contains polymorphic alleles, which may be linked to increased risk for tobacco-related lung cancer. The purpose of this study is to screen new polymorphisms and determine whether these polymorphisms can be used to predict individual susceptibility to lung cancer. The polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis was used to screen for polymorphisms in the coding region of the EH gene. Eleven polymorphisms, including previously reported polymorphisms, were identified and the prevalence of these variants was assessed in at least 50 healthy Caucasians and African-Americans. Among the 11 polymorphisms, the prevalence of the amino acid-changing EH polymorphisms in codons 43, 113 and 139 was examined in 182 Caucasian incident cases with primary lung cancer, as well as in 365 frequency-matched controls to examine the role of EH polymorphisms in lung cancer risk. A significant increase in lung cancer risk was observed for predicted high EH activity genotypes (odds ratio (OR) 2.3, 95% confidence interval (CI) 1.2-4.3) as compared with low EH activity genotypes. This association was more pronounced among patients with lung adenocarcinoma (OR 4.7, 95% CI 1.7-13.1). These results suggest that the EH polymorphism plays an important role in lung cancer risk and is linked to tobacco smoke exposure.

High frequency of K-ras codon 12 mutations in bronchoalveolar lavage fluid of patients at high risk for second primary lung cancer.

A high frequency of K-ras mutations may indicate preneoplastic changes in the bronchial epithelium as a result of genotoxic injury. With the use of sensitive detection techniques, we report a higher prevalence of K-ras mutations in bronchoalveolar lavage than has been reported previously for lung cancer. A PCR/ligase chain reaction technique was used to determine K-ras codon 12 mutations in a group of 52 bronchoalveolar lavage specimens from patients at risk of a second lung cancer. Of the specimens examined, 84% contained at least one mutation in K-ras codon 12, corroborated by an allele-specific hybridization method. These results suggest that point mutations in K-ras codon 12 are widespread in the bronchial epithelium. Based on these preliminary findings, further evaluation of this efficient sensitive assay to monitor K-ras status should be conducted in larger clinical cohorts where clinical outcomes will ultimately be available. Such a trial will define the utility of K-ras codon 12 mutation status as a marker of lung cancer.

Prospective detection of preclinical lung cancer: results from two studies of heterogeneous nuclear ribonucleoprotein A2/B1 overexpression.

The United States lung cancer epidemic has not yet been controlled by present prevention and treatment strategies. Overexpression of a Mr 31,000 protein, heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1, had shown promise as a marker of lung cancer. In a pilot study of archived preneoplastic sputum specimens, hnRNP A2/B1 overexpression more accurately detected preclinical lung cancer than standard cytomorphology. In separate, ongoing prospective studies, sputum is collected annually from stage I resected non-small cell lung cancer patients at high risk of developing a second primary lung cancer and Yunnan tin miners at high risk of primary lung cancer. After the first year of follow-up, preclinical detection of lung cancer by routine cytology was compared with hnRNP A2/B1 overexpression as measured by quantitative densitometry of immunostained slides. Up-regulation of hnRNP A2/B1 in sputum specimens accurately predicted the outcome in 32 of 40 primary lung cancer and control patients within 12 months, whereas cytological change suggestive of lung cancer was found in only 1 patient. In the primary lung cancer study, overexpressed hnRNP A2/B1 accurately predicted the outcome in 69 of 94 primary lung cancer and control miners, whereas only 10 with primary lung cancer were diagnosed cytologically. These two prospective studies accurately predicted that 67 and 69% of those with hnRNP A2/B1 up-regulation in their sputum would develop lung cancer in the first year of follow-up, compared with background lung cancer risks of 2.2 and 0.9% (35- and 76-fold increase, respectively). Using sputum cells to monitor hnRNP A2/B1 expression may greatly improve the accuracy of preclinical lung cancer detection.

Rational targets for the early detection of lung cancer.

The fact that routinely effective treatments for disseminated lung cancer are not available has prompted the search for effective early detection systems. It is important to identify lung cancer while it is still confined to the bronchial epithelium and is potentially curable with local modalities. We have previously reported on an immunologically based assay to identify antigens expressed on shed bronchial epithelial cells. This assay resulted in a statistically significant correlation of immunostaining with the eventual development of lung cancer 2-4 years prior to routine clinical detection. Attempts to further improve this approach require an understanding of the basis for its success. Based on the work of Hakomori and coworkers, this difucosylated Lewis X structure would be a likely marker of carcinogenic transformation of the bronchial epithelium. In fact, an antibody to this structure was useful for sputum immunocytochemistry analysis for early lung cancer detection. Other carbohydrate structures would also be reasonable markers to evaluate for early detection application, based on the known pattern of expression of these structures in fetal, dysplastic, and neoplastic lung tissue. Another antibody used for sputum immunostaining recognizes a 31-kd protein structure; the antibody is not a known member of a likely class of early detection targets. The reported cases of lung cancer missed by the immunostaining approach included principally adenocarcinoma of the lung, suggesting that the addition of a marker(s) of that type of morphologic differentiation should be considered. Markers to dissect the various forms of lung adenocarcinoma are being characterized and are available for evaluation in early detection applications.(ABSTRACT TRUNCATED AT 250 WORDS)

A case-cohort study of an early biomarker of lung cancer in a screening cohort of Yunnan tin miners in China.

We initiated the present study to evaluate the accuracy of a new epithelial biomarker of early lung cancer. We tested the hypothesis that expression of a tumor-associated antigen by exfoliated sputum epithelial cells has greater accuracy (sensitivity and specificity) for the detection of preclinical, localized lung cancer than do routine clinical detection methods. Monoclonal antibody (MAb) 703D4 recognizes heterogeneous nuclear ribonuclear protein (hnRNP) A2/B1. We compared the accuracy of hnRNP up-regulation with cytology and radiographic screening for lung cancer detection in miners who were highly exposed to tobacco smoke, radon, and arsenic in southwestern China. The results showed that MAb 703D4 detection of hnRNP expression by sputum epithelial cells had greater accuracy for the detection of lung cancer than did routine screening methods, particularly for early (localized) disease. Among 57 cases and 76 noncases at the first screening, overall MAb detection of hnRNP was more sensitive (74 versus 21% for cytology and 42% for chest x-ray) but had lower specificity (70 versus 100% for cytology and 90% for chest x-ray) than standard methods. Recognizing hnRNP up-regulation resulted in detection of approximately one-third more early cases than did the combination of X-ray and cytology. Detection of hnRNP A2/B1 expression appears to be a good initial screening test for lung carcinogenesis, as it identified 74% of those who developed subsequent clinical lung cancer. Future studies might separate individuals with high lung cancer risk by MAb detection, confirming the positives with markers having greater specificity (e.g., clinical studies that become positive later in the morphological progression).

Polymorphisms of the DNA repair gene XRCC1 and lung cancer risk.

We explored the association between polymorphisms of the DNA repair gene XRCC1 (codons 194, 280, and 399) and lung cancer risk in a case-control study nested within a cohort of tin miners. Cases were those diagnosed with lung cancer over 6 years of follow-up (n = 108). Two controls, matched on age and sex, were selected for each case by incidence density sampling. Of the three polymorphisms, only the XRCC1 Arg280His allele was associated with increased lung cancer risk (odds ratio, 1.8; 95% confidence interval, 1.0-3.4) after adjustment for radon and tobacco exposure. In addition, individuals with the variant Arg280His allele who were alcohol drinkers seemed to be at higher risk for lung cancer compared with those with the homozygous wild-type genotype. Conversely, individuals with the variant Arg194Trp allele who were alcohol drinkers seemed to be at lower risk for lung cancer compared with those with the homozygous wild-type genotype. Polymorphisms of XRCC1 appear to influence risk of lung cancer and may modify risk attributable to environmental exposures.

Risk factors and early detection of lung cancer in a cohort of Chinese tin miners.

PURPOSE: To examine risk factors and establish a biologic specimen and data bank for the study of early markers of lung cancer. METHODS: We designed a dynamic cohort using an ongoing lung cancer screening program among radon- and arsenic-exposed tin miners in Yunnan China. Through the first four years of the study, 8,346 miners aged 40 years and older with over 10 years of occupational exposure have been enrolled, risk factors have been assessed, annual sputum and chest radiographs have been obtained, and numerous biologic specimens have been collected. RESULTS: A total of 243 new lung cancer cases have been identified through 1995. Radon and arsenic exposures are the predominant risk factors, but lung cancer risk is also associated with chronic bronchitis and silicosis, as well as a number of exposure to tobacco smoke, including early age of first use, duration, and cumulative exposure. Tumor and sputum samples are being examined for early markers of lung cancer. CONCLUSION: A cohort of occupationally-exposed tin miners with an extensive biologic specimen repository has been successfully established to simultaneously study the etiology and early detection of lung cancer.

Biomarkers of carcinogen exposure and cancer risk in a coke plant.

To evaluate the association between an indicator of carcinogen exposure (peripheral blood leukocyte DNA adducts of polycyclic aromatic hydrocarbons) and an early indicator of neoplastic transformation (sputum epithelial cell membrane antigens binding by monoclonal antibodies against small cell lung cancer and against nonsmall cell lung cancer), a survey of 350 coke-oven workers and 100 unexposed workers was planned. This paper reports a pilot investigation on a subgroup of 23 coke-oven workers and 8 unexposed controls. A "gas regulator" worker with positive tumor antigen binding was identified. Results show that smokers, subjects with decreased pulmonary function (forced expiratory volume in 1 sec/forced vital capacity% < 80), and those with morphological dysplasia of sputum cells have higher levels of DNA adducts. The gas regulators showed the highest values for adducts; however, no significant difference of adduct levels was found between the coke-oven group and unexposed controls.

Consensus statements from the Second International Lung Cancer Molecular Biomarkers Workshop: a European strategy for developing lung cancer molecular diagnostics in high risk populations.

The Second Molecular Biomarkers Workshop was held at the Roy Castle International Centre for Lung Cancer Research in Liverpool, in June 2001 and it brought together experts in the clinical, epidemiological and molecular-pathology of lung cancer from Europe and the USA, to address issues surrounding the development of a European strategy for early lung cancer detection. The 2001 Workshop Breakout Groups concentrated on the current challenges in the early detection of lung cancer which need to be addressed in the light of the recent surge in interest in many countries for mounting new clinical trials to evaluate the utility of Spiral CT in early lung cancer detection. If population-based trials of CT screening are mounted it will also be a favorable clinical environment in which to evaluate efficiently recent advances in molecular screening and genotyping. The Workshop focused specifically on: a) clinical and molecular biomarkers, b) sputum as an early detection and diagnostic tool, c) validation of molecular markers prior to their use in early detection trials and d) ethical issues that have to be considered in early lung cancer detection trials. A distillation of the Workshop discussions is given in this article.

Smoking, leukocyte count, and ventilatory lung function in working men.

Results of a cross-sectional study of ventilatory lung function (VLF) in a group of 307 working men showed that the leukocyte count in peripheral blood is more closely associated with the relative position (percentile) of a person in the frequency distribution of VLF than is smoking intensity. Leukocyte count is significantly (and inversely) correlated with VLF in nonsmokers as well as in smokers. A multiple regression analysis indicated that, after accounting for the effect of height and age, white blood cell (WBC) count explains more of the VLF variance than many other health determinants. Moreover, WBC count is the only variable, apart from height and age, that contributes significantly to the regression. Current smokers with elevated leukocyte count in peripheral blood may constitute a defined high-risk group because they demonstrate more negative regression age coefficients when compared with smokers without elevated WBC or with nonsmokers. Mechanisms that may explain these findings are discussed.

The early detection of second primary lung cancers by sputum immunostaining. LCEWDG Investigators. Lung Cancer Early Detection Group.

STUDY OBJECTIVE: To determine whether monoclonal antibody (Mab) detection of tumor-associated antigen expressed on sputum epithelial cells precedes clinical presentation of second primary lung cancer. DESIGN SETTING/PARTICIPANTS: Eleven oncology centers collaborate in the accrual of 1,000 patients with stage I non-small cell lung cancer (NSCLC) who had undergone resection. The Mabs examined in this study (624H12, 703D4) detect two promising oncofetal/differentiation markers (ie, a difucosylated Lewis X and a 31-Kd glycoprotein antigen). INTERVENTIONS: Induced sputum specimens are evaluated for quality, then are Papanicolaou and immunostained by independent central laboratories at enrollment and annually thereafter. The predictive value of Mab markers is compared with routine morphologic study for detection of second primary lung cancer during an anticipated 3 years of accrual and 1 year of follow-up. MEASUREMENTS AND RESULTS: Five hundred eighty of an anticipated 1,000 patients have been accrued on schedule. Patients are primarily white (88.6%), former smokers (75.9%), men (55.6%), with a median age of 66.7, and joined the study at an average of 3.7 years following resection of a stage 1 NSCLC (34.4% squamous, 43.6% adenocarcinoma). Central laboratories found less dysplasia and more unsatisfactory specimens (27.3%) than do the accrual institution laboratories. Immunostaining identifies more suspicious cells than does morphologic study. However, only two second primary lung cancers (eight total deaths) have occurred to date. CONCLUSIONS: Halfway through the accrual, we describe the study design and preliminary observations. This study illustrates rational selection of carcinogenesis markers by linkage of marker expression on preneoplastic specimens with subsequent expression on tumor tissue.

Expression of early lung cancer detection marker: hnRNP-A2/B1 and its relation to microsatellite alteration in non-small cell lung cancer.

We have reported that a mouse monoclonal antibody, 703D4, which recognizes heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP-A2/B1) can frequently detect lung cancer in exfoliated sputum epithelial cells 1-2 years earlier than routine chest X-ray or sputum cytomorphology. We along with others have shown that microsatellite alteration (MA) at selected loci can be recognized in sputum cells prior to clinical lung cancer. The present study was undertaken to determine how frequently the expression of hnRNP-A2/B1 message is associated with neoplastic clonal expansion as shown by MA in 41 cases of non-small cell lung cancer (NSCLC). We used Northern blotting to evaluate hnRNP-A2/B1 mRNA expression in lung tumor and remote noninvolved lung. We evaluated microsatellite instability (i.e. shifts; MI) or loss of heterozygosity (LOH) with a panel of 13 microsatellite markers at loci identified previously as susceptible in NSCLC. Of the 41 tumors, 25 (61%) over-expressed hnRNP-A2/B1 and 33 (80%) demonstrated MA in at least one of 13 loci (58% in at least two loci). The association between MA (one locus) and the overexpression of hnRNP-A2/B1 is statistically significant (P=0.0082), and those lung tumors with MA at two or more loci were significantly more likely to over-express hnRNP-A2/B1 mRNA (P=0.004). MA of loci on 3p were the only MA statistically associated with hnRNP-A2/B1 message overexpression (P=0.001). We conclude that lung tumor cells undergoing clonal expansion frequently upregulate hnRNP-A2/B1.

Moving to the routine management of pre symptomatic lung cancer.

Lung cancer is the world's leading cause of cancer death. Since progress in the treatment of this cancer has been exceedingly slow, the upswing in tobacco consumption in many sectors becomes even more tragic. One area for cautious optimism is the recent pilot reports of improved early lung cancer detection using new spiral CT techniques from institutions in Japan and New York. The prospect of improved early detection in a major cancer raises a number of public health concerns and highlights the importance of critical validation of this proposed new tool. From experience with early detection-based management of other cancers, it is evident that the entire process of detection, case validation, intervention, monitoring and public education needs to be carefully developed. The International Association for the Study of Lung Cancer has worked with the National Cancer Institute over the last decade to nurture interest and expertise in conducting population-based management of early lung cancer. A distillation of this process up to the current time is reviewed in this manuscript.

Peptide amidating activity in human bronchoalveolar lavage fluid.

Monitoring respiratory epithelial biology may reveal individuals with incipient lung cancer. The expression of neuroendocrine (NE) markers in pulmonary epithelium is thought to be central to lung development, repair of injury and may contribute to carcinogenesis. In this study, we evaluate several candidate NE markers to determine the feasibility of prospective analysis of clinical specimens. The potential NE markers include the enzyme L-DOPA decarboxylase (DDC), the neuropeptide gastrin releasing peptide (GRP), and peptidyl-glycine alpha-amidating monooxygenase (PAM), the bifunctional enzyme responsible for the final bioactivation step of many neuropeptides. A comparison of PAM activity and DDC levels in 30 lung cancer cell lines indicated that peptide amidating activity may be an indicator of NE status. Bronchoalveolar lavage (BAL) fluid from subjects at risk of developing second primary lung cancer and from volunteers was obtained. The activity of the first PAM enzyme, peptidylglycine alpha-hydroxylating monooxygenase (PHM), ranged from not detectable to 507 pmol/h/mg protein in 57 specimens. The second PAM enzyme, peptidylamidoglycolate lyase (PAL), ranged from not detectable to 414 pmol/h/mg protein in 56 specimens. Using cluster analysis by the average linkage method, a group of enzyme values with PHM greater than 230 pmol/h/mg protein was determined. Long-term follow-up of these patients for new second primary lung cancers may help to determine the potential predictive value of PAM detected in the BAL fluid.

New approaches to the integrated management of early lung cancer.

We have briefly surveyed some the developments in the field of molecular diagnostics that provide a basis for cautious optimism about progress in population-based early lung cancer screening. The sound lung cancer management strategies that were formulated several decades ago failed in clinical trials because the necessary tools to implement the strategies were not yet available. Technology is beginning to emerge that makes population-based screening achievable. This same technology may be used to define a comprehensive marker panel including the most informative markers from the long list of candidate markers. Validation studies will define more clearly the strengths and limitations of new molecular diagnostics and provide leads for further research attention. The clinical community can expedite this process if these validation efforts are aggressively pursued. Parallel developments are clearly needed in refining the range of therapeutic intervention for early cancer management. The success of both diagnostic and intervention tools is interwoven in the ultimate goal of reducing lung cancer mortality. This article is an invitation to think expansively about new approaches to cancer care that integrate the fruits of our hard-learned lessons.