Molecular detection of tumor cells in bronchoalveolar lavage fluid from patients with early stage lung cancer

Early detection and prevention of lung cancer

Lung cancer remains the leading cause of cancer death in the United States and is one of the world's leading causes of preventable death. Technologic advances have brought new modalities that may be useful for the early detection of lung cancer. However, because of the large number of persons at increased risk for lung cancer, screening is a formidable task. There are several risk factors that can be identified, including potential susceptibility factors, which may aid in pinpointing individuals who need to participate in regular screening programs. Aside from recognized environmental exposures including cigarette smoking, there are a number of genetic and metabolic susceptibility factors that have been examined. These include polymorphisms in the cytochrome p450 enzymes and the metabolizing capability of glutathione s-transferase or acetylation. Additionally, defects in DNA repair and in bleomycin sensitivity assays may also aid in identifying individuals who are at an increased risk for lung cancer. Additional work has been done in the area of characterizing the molecular alterations in the bronchial epithelium in high-risk smokers. This manuscript addresses only selected molecular alterations that have been examined in preneoplastic bronchial epithelium. In addition to mutations in the k-ras oncogene and the p53 gene, which are frequently seen in malignancy, alterations in the p16 gene, microsatellite instability and loss of heterozygocity are also promising potential markers of preneoplasia. The hnRNP A2/B1 gene also shows some promising increased expression in preneoplasia. Lung cancer prevention has made some strides. A number of trials with molecular and morphologic intermediate endpoints have been conducted and have suggested that some of the molecular alterations and morphologic alterations are reversible. However, the rate of spontaneous regression of these lesions is, as yet, uncharacterized. Two recent large studies, the beta-carotene and retinol efficacy trial (CARET) trial conducted in the United States and the Alpha-Tocopherol Beta Carotene (ATBC) trial conducted in Finland, both demonstrated an unexpected increased risk for lung cancer associated with beta-carotene supplementation. The EUROSCAN trial evaluation of vitamin A and N-acetylcystine also showed no benefit to supplementation in reducing risk for lung cancer. Results from the Intergroup study of 1 3-cis-retinoic acid are pending, and plans are underway for an Intergroup trial studying high selenium yeast to reduce lung cancer risk. Hopefully, the combination of identifying markers of increased risk among the numerous current and former smokers will identify high-risk populations to participate in future trials of promising agents that may lead to reduction in incidence and mortality of the leading cause of cancer death.

Cancer screening in the elderly population

This article reviews the current state of knowledge regarding cancer screening in the geriatric population. Care of the elderly requires knowledge of underlying physiologic changes, comorbidities, quality-of-life factors, and life expectancies. There is always the danger that ageism may prevent elderly cancer patients from receiving the proper treatment. On the other hand, overzealous treatment can lead to adverse results if elderly patients are not properly targeted based on current evidence of the benefits and risks of specific screening practices.

Potential biomarkers for the early detection of lung cancer

Lung cancer remains the leading cause of cancer death among men and women in the United States. Early detection of premalignant lesions provides the possibility of treatment at earlier stages. Because malignancy develops from genetic alterations, the early detection of these genetic changes should be associated with the earliest clues to transformation. This article presents an overview of detection of molecular markers and their relevance to lung cancer. In the future, such molecular markers may play a role in guiding therapy for lung cancer.

Early glandular neoplasia of the lung

Although bronchogenic carcinomas progress through a very well defined sequence of metaplasia, dysplasia and carcinoma in situ, very little is known about the early progression of glandular neoplasms of the lung. In particular, the early precursor lesion from which fully malignant adenocarcinomas arise has effectively eluded recognition, at least until recently. Several lines of evidence now implicate atypical adenomatous hyperplasia (AAH) as an initial morphologic stage in multistep lung tumorigenesis. Despite its small size, AAH can be appreciated at the light microscopic level and characterized at the molecular genetic level. Indeed, the genetic characterization of AAH promises to further our understanding of lung cancer development and might facilitate the design of novel strategies for early detection of lung cancer.

Molecular pathogenesis of lung cancer

Lung cancer is the largest cancer killer of men and women in the united states. In addition to the progress made from antismoking primary prevention measures, new tools to help treat patients with lung cancer are emerging from the rapid advances in knowledge of the molecular pathogenesis of lung cancer. These tools include molecular and cellular biology and are starting to provide an insight into how the tumor cell, by altering oncogenes and tumor suppressor genes, achieves growth advantage, uncontrolled proliferation and metastatic behavior via disruption of key cell-cycle regulators and signal transduction cascades. Moreover, new knowledge is being developed in terms of the molecular definition of individual susceptibility to tobacco smoke carcinogens. These tools are being translated into clinical strategies to complement surgery, radiotherapy, and chemotherapy and also to assist in primary and secondary prevention efforts. This review summarizes current knowledge of the molecular pathogenesis of lung cancer. From this we know that respiratory epithelial cells require many genetic alterations to become invasive and metastatic cancer. We can detect cells with a few such changes in current and former smokers, offering the opportunity to intercede with a biomarker-monitored prevention and early detection effort. This will be coupled with new advances in computed tomography-based screening. Finally, because the molecular alterations are known, new mechanism-based therapies are being developed and brought to the clinic, including new drugs, vaccines, and gene therapy, which also must be integrated with standard therapies.

Molecular and genetic targets in early detection

Recent research has revealed the existence of specific mutations in cancer. These mutations are being investigated as targets to find subjects at high risk for cancer, to detect early cancer, to detect the early recurrence of established cancer, and to find micrometastasis. These mutations are reviewed for the major anatomic sites. Some of the clinical issues related to the application of these mutations and the limitations of using molecular targets are also considered. Current methods for determining the risk of cancer are reviewed. Risk assessment is essential for defining cohorts for chemoprevention and other interventions. The concept of using surrogate anatomic and functional sites for estimating risk is introduced. Finally, the increasing complexity of molecular genetic analysis and the biologic heterogeneity of cancer are discussed in relation to early detection.

Microsatellite instability and p53 mutations in hepatocellular carcinoma

We have studied 27 hepatocellular carcinomas (HCCs) to identify possible relationships between microsatellite instability (MSI), p53 mutations, and HBV infection in hepatocarcinogenesis. MSI was assessed using 19 polymorphic markers and the poly(A) tract BAT-26. All coding regions of p53 were examined for mutations. Tumors were also examined for presence of hepatitis B virus (HBV) DNA sequences; 66.6% of the samples exhibit MSI in at least one microsatellite locus and 44% in two or three loci. None of the tumors examined showed alterations in BAT-26. Moreover, 73.3% of samples with indication of HBV infection showed instability in at least one marker. No association between MSI and pathological profile was found. Five (18.5%) samples harbored mutations in p53, three missense, and two insertions, all in exons 5 and 8 not previously reported. No mutations were detected in codon 249, which has been linked with dietary intake of aflatoxins. Our results support the hypothesis that HCC is a "low" MSI tumor. Only 1/5 samples with MSI in more than two markers harbored a mutation in p53. Although the number of samples is too small to support a statistical significance, this finding may indicate an inverse relationship between p53 mutations and MSI in HCC.

Molecular genetic characteristics of lung cancer--useful as real' tumor markers?

The increased knowledge about the molecular mechanisms leading to the development of a tumor has opened new horizons for basic and applied research. Lung cancer is among the tumor entities with the highest incidence and mortality rates. Recently new drugs and therapeutic options for patients with lung cancer were developed. These developments demand new and improved techniques for the sensitive and specific detection of lung tumor cells. Some of the molecular genetic features of lung tumor cells are summarized and the possibilities to use these characteristics as new tumor markers are discussed.