Randomized placebo-controlled trial of isotretinoin in chemoprevention of bronchial squamous metaplasia

The Chemoprevention Effects of Two Herbal Mixtures on Chemically Induced Lung Tumorigenesis in Mice

Ruan Hua Tang (RHT) and Ruan Hua Fang (RHF) are two Chinese herbal mixtures that have been used in clinical cancer treatment for decades. This study validated our hypothesis that RHT and RHF can inhibit lung tumor development in the mouse model of Benzo(a)pyrene-induced lung tumorigenesis. An RHT oral solution was diluted to 9% and 18% in water. RHF was mixed into the diet at 15% and 30% of total food in the final doses. Two weeks after injecting BP into mice, we administered RHT and RHF for eighteen weeks. We found that 9% and 18% RHT reduced tumor multiplicity by 36.05% and 38.81% (both p < 0.05) and the tumor load by 27.13% and 55.94% (p < 0.05); 15% and 30% RHF inhibited tumor multiplicity by 12.75% and 39.84% (p < 0.01) and the tumor load by 18.38% and 61.68% (p < 0.05). Ki67 expressions in the 9% and 18% RHT groups were 19.55% and 11.51%, significantly lower than in the control (33.64%). The Ki67 levels in the 15% and 30% RHF groups were 15.56% and 14.04%, significantly lower than in the control (27.86%). Caspase 3 expressions in the 9% and 18% RHT groups were 5.24% and 7.32%, significantly higher than in the control (2.39%). Caspase 3 levels in the 15% and 30% RHF groups were 6.53% and 4.74%, significantly higher than in the control (2.07%). The bio-absorption was confirmed via a pharmacokinetic test. This study showed that RHT and RHF are safe and can inhibit lung tumor development, with anti-proliferative and pro-apoptotic effects.

Lung cancer: Premalignant biology and medical prevention

Lung cancer (both adenocarcinoma and squamous cell) progress through a series of pre-malignant histologic changes before the development of invasive disease. Each of these carcinogenic cascades is defined by genetic and epigenetic alterations in pulmonary epithelial cells. Additionally, alterations in the immune response, progenitor cell function, mutational burden, and microenvironmental mediated survival of mutated clones contribute to the risk of pre-malignant lesions progressing to cancer. Medical preventions studies have been completed and current and future trials are informed by the improved understanding of pre-malignancy. This will lead to precision chemoprevention trials based on lesional biology and histologic characteristics.

Drugs for preventing lung cancer in healthy people

BACKGROUND

This is the second update of this Cochrane Review. Some studies have suggested a protective effect of antioxidant nutrients and higher dietary levels of fruits and vegetables on lung cancer.

OBJECTIVES

To determine whether vitamins and minerals and other potential agents, alone or in combination, reduce lung cancer incidence and lung cancer mortality in healthy populations.

SEARCH METHODS

We searched CENTRAL, MEDLINE and Embase from 1974 to May 2019 and screened references included in published studies and reviews.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing vitamins or mineral supplements with placebo, administered to healthy people with the aim of preventing lung cancer.

DATA COLLECTION AND ANALYSIS

Four review authors independently selected the trials to be included in the review, assessed their methodological quality and extracted data. For dichotomous outcomes we calculated risk ratios (RRs) and 95% confidence intervals (CIs) and pooled results using the random-effects model. We assessed the risk of bias using Cochrane's 'Risk of bias' assessment tool and certainty of evidence using the GRADE approach.

MAIN RESULTS

In this update, we identified three new trials for a total of 12 studies. Six analysed vitamin A, three vitamin C, three combined vitamin D3 + calcium, four vitamin E combined with other products, one selenium supplements and nine studied combinations of two or more products. Four studies included only men and five only women. Vitamin A results in little to no difference in lung cancer incidence (RR 1.09, 95% CI 1.00 to 1.19; 5 RCTs, 212314 participants; high-certainty evidence) and lung cancer mortality (RR 1.06, 95% CI 0.81 to 1.38; 3 RCTs, 190118 participants; high-certainty evidence). But in smokers or asbestos workers vitamin A increases the risk of lung cancer incidence (RR 1.10, 95% CI 1.01 to 1.20; 3 RCTs, 43995 participants; high-certainty evidence), lung cancer mortality (RR 1.18, 95% CI 1.01 to 1.38; 2 RCTs, 29426 participants; high-certainty evidence) and all-cause mortality (RR 1.09, 95% CI 1.05 to 1.13; 2 RCTs, 32883 participants; high-certainty evidence). Vitamin A increases the risk of minor side effects, such as yellowing of the skin and minor gastrointestinal symptoms (high-certainty evidence). Vitamin C likely results in little to no difference in lung cancer incidence (RR 1.29, 95% CI 0.67 to 2.49; 2 RCTs, 14953 participants; moderate-certainty evidence). In women, vitamin C increases the risk of lung cancer incidence (RR 1.84, 95% CI 1.14 to 2.95; 1 RCT, 7627 participants; high-certainty evidence). In men, vitamin C results in little to no difference in mortality for lung cancer (RR 0.81, 95% CI 0.53 to 1.23; 1 RCT, 7326 participants; high-certainty evidence). Vitamin D + calcium may result in little to no difference in lung cancer incidence in postmenopausal women (RR 0.90, 95% CI 0.39 to 2.08; 3 RCTs, 37601 women; low-certainty evidence). Vitamin E results in little to no difference in lung cancer incidence (RR 1.01, 95% CI 0.90 to 1.14; 3 RCTs, 36841 participants; high-certainty evidence) or to lung cancer mortality (RR 0.96, 95% CI 0.77 to 1.18; 2 RCTs, 29214 participants; high-certainty evidence), but increases the risk of haemorrhagic strokes (hazard ratio (HR), 1.74, 95% CI 1.04 to 2.91; 1 RCT, 14641 participants; high-certainty evidence). Calcium results in little to no difference in lung cancer incidence in postmenopausal women (RR 0.65, 95% CI 0.13 to 3.18; 1 RCT, 733 participants) or in risk of renal calculi (RR 1.94, 95% CI 0.20 to 18.57; 1 RCT, 733 participants; low-certainty evidence). Selenium in men results in little to no difference in lung cancer incidence (RR 1.11, 95% CI 0.80 to 1.54; 1 RCT, 17448 participants; high-certainty evidence) and lung cancer mortality (RR 1.09, 95% CI 0.72 to 1.66; 1 RCT, 17448 participants; high-certainty evidence) and increases the risk for grade 1 to 2 dermatitis (RR 1.16, 95% CI 1.04 to 1.31; 1 RCT, 17448 participants; high-certainty evidence) and for alopecia (RR 1.28, 95% CI 1.07 to 1.53; 1 RCT, 17448 participants; high-certainty evidence). The combination of vitamins A, C, E + selenium + zinc results in little to no difference in lung cancer incidence (RR 0.64, 95% CI 0.28 to 1.48; 1 RCT, 12741 participants; high-certainty evidence).

AUTHORS' CONCLUSIONS

Well-designed RCTs have shown no beneficial effect of supplements for the prevention of lung cancer and lung cancer mortality in healthy people. Vitamin A supplements increase lung cancer incidence and mortality in smokers or persons exposed to asbestos. Vitamin C increases lung cancer incidence in women. Vitamin E increases the risk of haemorrhagic strokes.

Olfactory dysfunction persists after smoking cessation and signals increased cardiovascular risk

BACKGROUND

Olfaction plays a critical role in health and function in older adults, and impaired sense of smell is a strong predictor of morbidity and mortality. Smoking cigarettes causes olfactory impairment, but the mechanism of damage and ability to recover after cessation are unknown. We investigated the relationship between time since quitting and olfactory dysfunction in order to elucidate the mechanism(s) by which smoking damages the olfactory system and to inform patient counseling.

METHODS

Using longitudinal data from the National Social Life Health and Aging Project (n = 3528 older adults, including 1526 former smokers), we analyzed the association between odor identification performance and time since smoking cessation using multivariate ordinal logistic regression, adjusting for cognition and demographic variables. To test whether vascular disease plays a role, we also assessed the relationship between olfactory decline and incidence of heart attack and heart disease.

RESULTS

Former smokers who quit ≤15 years before testing had significantly impaired olfaction compared to never smokers (p = 0.04), but those who quit >15 years prior did not. Olfactory decline over 5 years showed modest evidence toward predicting increased incidence of heart attack or heart disease (p = 0.08).

CONCLUSION

Olfactory impairment in smokers persists 15 years after quitting, which is consistent with a vascular mechanism of impairment. Indeed, olfactory decline is a predictor of the development of cardiovascular disease. Taken together, these data suggest that olfactory loss may be a useful sign of underlying vascular pathology. Further investigation of olfactory loss as an early biomarker for cardiovascular disease is warranted.

A Review of In Vitro Modelling Approaches to the Identification and Modulation of Squamous Metaplasia in the Human Tracheobronchial Epithelium

Squamous metaplasia in the tracheobronchial epithelium (TBE) involves the replacement of the normal pseudostratified mucociliary epithelium with a stratified squamous epithelium. Squamous metaplasia is considered to be an adaptive response that protects the lumen from the effects of inhaled airborne pollutants, but which might also feature as a pre-neoplastic lesion preceding squamous cell carcinoma. With the exception of transglutaminase I, involucrin, and cytokeratins 5, 6 and 13, few markers that contribute to the squamous phenotype have been identified in human TBE that can be used in diagnosis or to monitor its development in laboratory investigations, and current models are inadequate to provide statistically meaningful data. Therefore, new predictive markers have been identified, and new techniques established, in epithelial in vitro models capable of expressing squamous characteristics, which will be used to identify hazardous exposures and elucidate the mechanisms by which they induce their effects. A protocol for the quantitative detection of transglutaminase activity has been standardised in keratinocytes, based on the enzymatic incorporation of fluorescein–cadaverine (FC) into bis(γ-glutamyl) polyamine cross-links. The specificity of this compound as a transglutaminase substrate was demonstrated by using a range of competitive transglutaminase inhibitors, and by modulation of the squamous pathway. FC incorporation was localised to the cell membrane of terminally differentiating cells, and was not visible in basal, proliferating cells. High calcium-containing medium, nicotine and cigarette smoke condensates (CSC) induced an increase in FC incorporation, providing evidence of their role in enhancing the squamous pathway. Analysis by flow cytometry was used to provide a quantitative assessment of a range of optimised squamous differentiation markers, identified in normal human bronchial epithelia and in a bronchial cell line. Transglutaminase I was induced in a time-dependent manner, in post-confluent cells induced to differentiate down the squamous pathway, whereas involucrin was ubiquitously expressed and the levels of cytokeratins 5, 6 and 18 were reduced. The response of these and other differentiation markers to squamous-inducing conditions is being explored.

The success and the challenge of all-trans retinoic acid in the treatment of cancer

All-trans retinoic acid (ATRA), an active metabolite of vitamin A, plays important roles in cell proliferation, cell differentiation, apoptosis, and embryonic development. The effects of ATRA are mediated by nuclear retinoid receptors as well as non-genomic signal pathway, such as MAPK and PKA. The great success of differentiation therapy with ATRA in acute promyelocytic leukemia (APL) not only improved the prognosis of APL but also spurred the studies of ATRA in the treatment of other tumors. Since the genetic and physiopathological simplicity of APL is not common in human malignancies, the combination of ATRA with other agents (chemotherapy, epigenetic modifiers, and arsenic trioxide, etc) had been extensively investigated in a variety of tumors. In this review, we will discuss in details about ATRA and its role in cancer treatment.

The potential to treat lung cancer via inhalation of repurposed drugs

Lung cancer is a highly invasive and prevalent disease with ineffective first-line treatment and remains the leading cause of cancer death in men and women. Despite the improvements in diagnosis and therapy, the prognosis and outcome of lung cancer patients is still poor. This could be associated with the lack of effective first-line oncology drugs, formation of resistant tumors and non-optimal administration route. Therefore, the repurposing of existing drugs currently used for different indications and the introduction of a different method of drug administration could be investigated as an alternative to improve lung cancer therapy. This review describes the rationale and development of repositioning of drugs for lung cancer treatment with emphasis on inhalation. The review includes the current progress of repurposing non-cancer drugs, as well as current chemotherapeutics for lung malignancies via inhalation. Several potential non-cancer drugs such as statins, itraconazole and clarithromycin, that have demonstrated preclinical anti-cancer activity, are also presented. Furthermore, the potential challenges and limitations that might hamper the clinical translation of repurposed oncology drugs are described.

Inflammation and the Pathogenesis of Inverted Papilloma

Background

Despite existing clinical and histopathological evidence, the role of inflammation in the pathogenesis of inverted papilloma (IP) is not well understood. The goal of this study was to describe the inflammatory cell component present in sinonasal papilloma (SP), with the intention of further defining the existence of inflammation in IP and perhaps gaining insight into IP pathophysiology.

Methods

Computerized database analysis was performed to identify all patients with SP who underwent surgery at the Cleveland Clinic Foundation between 1995 and 2001. Histopathological features of all SP were reviewed and semiquantitative analysis of the inflammatory cells present was performed. IP was histopathologically graded into four categories by the extent of inflammatory infiltrate and cellular atypia. Statistical analysis of the inflammatory cell component present in the epithelial layer of exophytic papilloma and IP was performed.

Results

SP was classified into three types: cylindrical papilloma (5% [2/41]), exophytic squamous papilloma (34% [14/41]), and IP (61% [25/41]). Twenty-eight instances of IP in 25 patients were identified. Altogether, 11% were grade I (3/28), 54% were grade II (15/28), 25% were grade III (7/28), and 11% were grade IV (3/28). The inflammatory cell population was significantly greater in IP compared with other SPs and greater in grades I and II IP when compared with grade III and IV IP.

Conclusion

Inflammatory cells were identified as a significant cell population in IP, whereas it was less commonly encountered in other forms of SP. The proposed IP staging system may serve as the foundation for improved understanding of IP and, ultimately, may help to predict recurrence or apparent malignant transformation.

Endobronchial biopsy in the final diagnosis of chronic obstructive pulmonary disease and asthma: a clinicopathological study

BACKGROUND

Asthma and chronic obstructive pulmonary disease (COPD) are chronic conditions with an increasing prevalence in developing countries. The evaluation of endobronchial biopsies has emerged as a tool to differentiate between both conditions via the measurement of the reticular basement membrane (RBM) thickness with various conclusions drawn from different studies.

OBJECTIVES

Compare the thickness of the RBM between asthma and COPD and evaluate other histomorphological features in both groups.

DESIGN

Prospective, descriptive and analytical.

SETTING

University teaching hospital.

PATIENTS AND METHODS

The study included patients with COPD and irreversible and reversible asthma with diagnosis based on clinical assessment, pulmonary function tests and high-resolution computed tomography scans. Endobronchial biopsies were obtained from all patients and, using a light microscope and a computerized image analyzer, the thickness of the reticular basement membrane was calculated in all patients. We also made a qualitative assessment of other histo-morphological features.

MAIN OUTCOME MEASURES

Mean RBM thickness.

SAMPLE SIZE

Thirty male patients.

RESULTS

The mean RBM thickness in asthmatic patients was 8.9 (2.4) micro m. The mean RBM thickness in COPD patients was 5.3 (1.1) micro m. However, there was no thickening of the RBM in patients with reversible asthma. The RBM was significantly thicker in patients with irreversible asthma than in patients with COPD or reversible asthma. There were no significant differences in epithelial desquamation or metaplasia, mucosal or submucosal inflammation, the presence of eosinophils, submucosal glandular hyperplasia or submucosal smooth muscle hyperplasia between groups.

CONCLUSIONS

The thickness of the RBM is the only reproducible histopathological feature to differentiate COPD from irreversible asthma.

LIMITATIONS

The study included a limited number of patients. A qualitative approach was used to compare epithelial cell injury, inflammation, submucosal glandular and muscular hyperplasia.

CONFLICT OF INTEREST

None.

Smoking and olfactory dysfunction: A systematic literature review and meta-analysis

OBJECTIVES/HYPOTHESIS

A systematic review and meta-analysis of the literature was undertaken, examining the association between tobacco smoking and olfactory function in humans, utilizing PubMed and Web of Science (1970-2015) as data sources.

STUDY DESIGN

Systematic literature review and meta-analysis.

METHODS

This database review of studies of smoking and olfaction, with a focus on identifying high-quality studies (based on modified versions of the Newcastle-Ottawa Scale), used validated olfactory tests among the generally healthy population.

RESULTS

We identified 11 studies meeting inclusion criteria. Of 10 cross-sectional studies, two were excluded from meta-analysis because the cohorts they studied were included in another article in the review. In meta-analysis, current smokers had substantially higher odds of olfactory dysfunction compared to never smokers (odds ratio [OR] = 1.59, 95% confidence interval [CI] = 1.37-1.85). In contrast, former smokers were found to have no difference in risk of impaired olfaction compared to never smokers (OR = 1.05, 95% CI = 0.91-1.21). The single longitudinal study reviewed found a trend toward increased risk of olfactory decline over time in ever smokers; this trend was stronger in current as compared to former smokers.

CONCLUSIONS

Current smoking, but not former smoking, is associated with significantly increased risk of olfactory dysfunction, suggesting that the effects of smoking on olfaction may be reversible. Future studies that prospectively evaluate the impact of smoking cessation on improvement in olfactory function are warranted.

LEVEL OF EVIDENCE

N/A. Laryngoscope, 127:1753-1761, 2017.

Chemoprevention studies within lung cancer screening programmes

While aggressive tobacco control and help to stop smoking are essential weapons in the fight against lung cancer, screening with low-dose computed tomography (LDCT) in high-risk populations and chemoprevention may also contribute to reducing lung cancer deaths. Persons undergoing LDCT screening are an ideal population to be tested for agents potentially able to prevent the development of lung cancer by the regression of precancerous lesions, which are routinely monitored as part of the screening process. Peripheral subsolid nodules appear as particularly suitable targets, since many are adenocarcinoma precursors.

A study on inhaled budesonide (a potential chemopreventive drug) for 1 year found that the mean size of non-solid lung nodules was significantly reduced over 5 years of follow-up, compared to inhaled placebo, in a population of high-risk individuals with indeterminate lung nodules not requiring immediate specific investigation for lung cancer and detected as part of a lung cancer screening program with LDCT.

A new randomised placebo-controlled phase-II trial to test the ability of aspirin to induce the regression of non-solid and partially solid nodules detected by LDCT screening has been started. The effect of aspirin on a miRNA signature able to predict the presence of both cancer and precancerous lesions in high-risk asymptomatic individuals is also being monitored in the trial. This signature was previously shown to predict the presence of both lung cancer and non-solid lung nodules in asymptomatic individuals.

Minireview: Familiar Faces in Unfamiliar Places: The Emerging Role of Nuclear Receptors in Lung Cancer

Nuclear hormone receptors (NRs) are a superfamily of 48 transcription factors that are frequently modulated by ligands and control various cancer-relevant cellular pathways, such as differentiation, proliferation, migration, and metabolism. These properties make them excellent therapeutic targets in cancers dependent upon their activity, and as such, 3 NRs, estrogen receptor-α, androgen receptor, and retinoic acid receptor-α (more specifically, the promyelocytic leukemia-retinoic acid receptor-α translocation), have been targeted clinically in breast cancer, prostate cancer, and acute promyelocytic leukemia, respectively. Recently, a number of studies have highlighted a putative role for NRs in nonsmall cell lung cancer (NSCLC), a highly lethal type of lung cancer with relatively few targeted agents. Here, we review the potential roles of selected NRs in NSCLC and offer insights on how NRs may be leveraged in NSCLC to improve patient outcomes.

Retinoic acid receptors: from molecular mechanisms to cancer therapy

Retinoic acid (RA), the major bioactive metabolite of retinol or vitamin A, induces a spectrum of pleiotropic effects in cell growth and differentiation that are relevant for embryonic development and adult physiology. The RA activity is mediated primarily by members of the retinoic acid receptor (RAR) subfamily, namely RARα, RARβ and RARγ, which belong to the nuclear receptor (NR) superfamily of transcription factors. RARs form heterodimers with members of the retinoid X receptor (RXR) subfamily and act as ligand-regulated transcription factors through binding specific RA response elements (RAREs) located in target genes promoters. RARs also have non-genomic effects and activate kinase signaling pathways, which fine-tune the transcription of the RA target genes. The disruption of RA signaling pathways is thought to underlie the etiology of a number of hematological and non-hematological malignancies, including leukemias, skin cancer, head/neck cancer, lung cancer, breast cancer, ovarian cancer, prostate cancer, renal cell carcinoma, pancreatic cancer, liver cancer, glioblastoma and neuroblastoma. Of note, RA and its derivatives (retinoids) are employed as potential chemotherapeutic or chemopreventive agents because of their differentiation, anti-proliferative, pro-apoptotic, and anti-oxidant effects. In humans, retinoids reverse premalignant epithelial lesions, induce the differentiation of myeloid normal and leukemic cells, and prevent lung, liver, and breast cancer. Here, we provide an overview of the biochemical and molecular mechanisms that regulate the RA and retinoid signaling pathways. Moreover, mechanisms through which deregulation of RA signaling pathways ultimately impact on cancer are examined. Finally, the therapeutic effects of retinoids are reported.

Updates and controversies in the rapidly evolving field of lung cancer screening, early detection, and chemoprevention

Lung cancer remains the leading cause of cancer-related death in the United States. Cigarette smoking is a well-recognized risk factor for lung cancer, and a sustained elevation of lung cancer risk persists even after smoking cessation. Despite identifiable risk factors, there has been minimal improvement in mortality for patients with lung cancer primarily stemming from diagnosis at a late stage when there are few effective therapeutic options. Early detection of lung cancer and effective screening of high-risk individuals may help improve lung cancer mortality. While low dose computerized tomography (LDCT) screening of high risk smokers has been shown to reduce lung cancer mortality, the high rates of false positives and potential for over-diagnosis have raised questions on how to best implement lung cancer screening. The rapidly evolving field of lung cancer screening and early-detection biomarkers may ultimately improve the ability to diagnose lung cancer in its early stages, identify smokers at highest-risk for this disease, and target chemoprevention strategies. This review aims to provide an overview of the opportunities and challenges related to lung cancer screening, the field of biomarker development for early lung cancer detection, and the future of lung cancer chemoprevention.

Chemoprevention of lung cancer: concepts and strategies

Lung cancer develops in a stepwise fashion, with an accumulation of molecular alterations progressing through preinvasive steps to invasive disease. This progression could be arrested or reversed through pharmacologic treatments, which are known as cancer chemoprevention. Preclinical and clinical findings relating to different classes of candidate chemopreventive agents provide support for this strategy as an active and promising approach for controlling this disease.

Randomized, double-blind, placebo-controlled, phase III chemoprevention trial of selenium supplementation in patients with resected stage I non-small-cell lung cancer: ECOG 5597

PURPOSE

Selenium has been reported to have chemopreventive benefits in lung cancer. We conducted a double-blind, placebo-controlled trial to evaluate the incidence of second primary tumors (SPTs) in patients with resected non-small-cell lung cancer (NSCLC) receiving selenium supplementation.

PATIENTS AND METHODS

Patients with completely resected stage I NSCLC were randomly assigned to take selenized yeast 200 μg versus placebo daily for 48 months. Participation was 6 to 36 months postoperatively and required a negative mediastinal node biopsy, no excessive vitamin intake, normal liver function, negative chest x-ray, and no other evidence of recurrence.

RESULTS

The first interim analysis in October 2009, with 46% of the projected end points accumulated, showed a trend in favor of the placebo group with a low likelihood that the trial would become positive; thus, the study was stopped. One thousand seven hundred seventy-two participants were enrolled, with 1,561 patients randomly assigned. Analysis was updated in June 2011 with the maturation of 54% of the planned end points. Two hundred fifty-two SPTs (from 224 patients) developed, of which 98 (from 97 patients) were lung cancer (38.9%). Lung and overall SPT incidence were 1.62 and 3.54 per 100 person-years, respectively, for selenium versus 1.30 and 3.39 per 100 person-years, respectively, for placebo (P = .294). Five-year disease-free survival was 74.4% for selenium recipients versus 79.6% for placebo recipients. Grade 1 to 2 toxicity occurred in 31% of selenium recipients and 26% of placebo recipients, and grade ≥ 3 toxicity occurred in less than 2% of selenium recipients versus 3% of placebo recipients. Compliance was excellent. No increase in diabetes mellitus or skin cancer was detected.

CONCLUSION

Selenium was safe but conferred no benefit over placebo in the prevention of SPT in patients with resected NSCLC.

Lung cancer chemoprevention: current status and future prospects

Lung cancer is the leading cause of cancer death worldwide, making it an attractive disease for chemoprevention. Although avoidance of tobacco use and smoking cessation will have the greatest impact on lung cancer development, chemoprevention could prove to be very effective, particularly in former smokers. Chemoprevention is the use of agents to reverse or inhibit carcinogenesis and has been successfully applied to other common malignancies. Despite prior studies in lung cancer chemoprevention failing to identify effective agents, we now have the ability to identify high-risk populations, and our understanding of lung tumour and premalignant biology continues to advance. There are distinct histological lesions that can be reproducibly graded as precursors of non-small-cell lung cancer and similar precursor lesions exist for adenocarcinoma. These premalignant lesions are being targeted by chemopreventive agents in current trials and will continue to be studied in the future. In addition, biomarkers that predict risk and response to targeted agents are being investigated and validated. In this Review, we discuss the principles of chemoprevention, data from preclinical models, completed clinical trials and observational studies, and describe new treatments for novel targeted pathways and future chemopreventive efforts.

Chemoprevention of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Lung cancer is the most common cause of cancer death in men and women in the United States. Cigarette smoking is the main risk factor. Former smokers are at a substantially increased risk of developing lung cancer compared with lifetime never smokers. Chemoprevention refers to the use of specific agents to reverse, suppress, or prevent the process of carcinogenesis. This article reviews the major agents that have been studied for chemoprevention.

METHODS

Articles of primary, secondary, and tertiary prevention trials were reviewed and summarized to obtain recommendations.

RESULTS

None of the phase 3 trials with the agents β-carotene, retinol, 13-cis-retinoic acid, α-tocopherol, N-acetylcysteine, acetylsalicylic acid, or selenium has demonstrated beneficial and reproducible results. To facilitate the evaluation of promising agents and to lessen the need for a large sample size, extensive time commitment, and expense, surrogate end point biomarker trials are being conducted to assist in identifying the most promising agents for later-stage chemoprevention trials. With the understanding of important cellular signaling pathways and the expansion of potentially important targets, agents (many of which target inflammation and the arachidonic acid pathway) are being developed and tested which may prevent or reverse lung carcinogenesis.

CONCLUSIONS

By integrating biologic knowledge, additional early-phase trials can be performed in a reasonable time frame. The future of lung cancer chemoprevention should entail the evaluation of single agents or combinations that target various pathways while working toward identification and validation of intermediate end points.

Assessing tobacco use by cancer patients and facilitating cessation: an American Association for Cancer Research policy statement

When diagnosed with cancer, patients can immediately make a meaningful positive impact on their health by stopping their tobacco use. Scientific evidence clearly shows that tobacco use in patients with cancer leads to poorer outcomes. The specific biological processes driving tobacco consumption's interference in cancer therapy are the subject of continuing research, but the evidence is clear that tobacco use in patients with cancer leads to decreased treatment efficacy and safety, decreased survival, decreased quality of life, increased treatment-related toxicity, and increased risk of cancer recurrence and second primary tumors. Data suggest that tobacco cessation can improve outcomes and survival in patients with cancer, yet full execution of evidence-based cessation interventions is infrequent in oncology settings. Therefore, both improved provision of cessation assistance to all patients with cancer who use tobacco or have recently quit and further study of the deleterious effects of tobacco use and benefits of tobacco cessation on cancer progression and treatment are needed and recommended by the American Association for Cancer Research. Progress on both fronts begins with universal assessment and documentation of tobacco use as a standard of quality cancer care regardless of treatment setting and will be further facilitated through the development of reliable, valid, and standard measures of tobacco use, incorporation of evidence-based procedures into quality and accreditation procedures, and the development of appropriate training, clinical infrastructure, and incentives for delivery of tobacco cessation interventions.

Trials and tribulations of interrogating biomarkers to define efficacy of cancer risk reductive interventions

The challenges of clinical screening of cancer risk reductive interventions ("chemopreventive") have slowed progress in deployment of therapeutics to reverse or delay the carcinogenesis process. The preoperative or window-of-opportunity design clinical trial design enrolls subjects rapidly, has short study periods, and quantifies tissue biomarkers that reflect both anti-carcinogenesis mechanism of the risk reductive intervention and key molecular events of the carcinogenesis process for a specific epithelial target. High subject screened to on study ratios reduce the efficiency and increase cost of this research strategy. Small-sized tissue samples obtained by minimally invasive endoscopic technologies limit the number of biomarkers that can be detected and quantified, forcing investigators into choosing either a broad-based but superficial multi-mechanism exploration of signaling intermediates or a more focused analysis of multiple molecular events in a linear signaling-specific pathway. More efficient strategies of the future might involve isolation and expansion of pluripotent cells from at-risk epithelium or intraepithelial neoplastic lesions. Such a strategy would allow interrogation of key carcinogenesis-associated pathways and mechanisms in representative primary single-cell cultures amenable to genomic, proteomics, or transfection-based technologies.

Molecular pathways: current role and future directions of the retinoic acid pathway in cancer prevention and treatment

Retinoids and their naturally metabolized and synthetic products (e.g., all-trans retinoic acid, 13-cis retinoic acid, bexarotene) induce differentiation in various cell types. Retinoids exert their actions mainly through binding to the nuclear retinoic acid receptors (α, β, γ), which are transcriptional and homeostatic regulators with functions that are often compromised early in neoplastic transformation. The retinoids have been investigated extensively for their use in cancer prevention and treatment. Success has been achieved with their use in the treatment of subtypes of leukemia harboring chromosomal translocations. Promising results have been observed in the breast cancer prevention setting, where fenretinide prevention trials have provided a strong rationale for further investigation in young women at high risk for breast cancer. Ongoing phase III randomized trials investigating retinoids in combination with chemotherapy in non-small cell lung cancer aim to definitively characterize the role of retinoids in this tumor type. The limited treatment success observed to date in the prevention and treatment of solid tumors may relate to the frequent epigenetic silencing of RARβ. Robust evaluation of RARβ and downstream genes may permit optimized use of retinoids in the solid tumor arena.

Drugs for preventing lung cancer in healthy people

BACKGROUND

This is an updated version of the original review published in Issue 2, 2003. Some studies have suggested a protective effect of antioxidant nutrients on lung cancer. Observational epidemiological studies suggest an association between higher dietary levels of fruits and vegetables containing beta-carotene and a lower risk of lung cancer.

OBJECTIVES

To determine whether vitamins, minerals and other potential agents, alone or in combination, reduce incidence and mortality from lung cancer in healthy people.

SEARCH METHODS

For this update we have used a search strategy adapted from the design in the original review. The following electronic databases have been searched up to December 2011: MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL). References included in published studies and reviews were also screened.

SELECTION CRITERIA

Included studies were randomised controlled clinical trials comparing different vitamins, mineral supplements or supplements with placebo, administered to healthy people with the aim of preventing lung cancer.

DATA COLLECTION AND ANALYSIS

Two authors independently selected the trials to be included in the review, assessed the methodological quality of each trial and extracted data using a standardised form. For each study, relative risk and 95% confidence limits were calculated for dichotomous outcomes and pooled results were calculated using the random-effect model.

MAIN RESULTS

In the first version of this review four studies were included; in this review update, an additional five studies have been included. Four studies included only males and two only females; two studies included only participants considered at high risk, namely smokers or exposed to asbestos, and one study included people deficient in many micronutrients. Six studies analysed vitamin A, three vitamin C, four vitamin E, one selenium supplements, and six studied combinations of two or more products. All the RCTs included in this review were classified as being of low risk of bias.For people not at high risk of lung cancer and compared to placebo, none of the supplements of vitamins or minerals or their combinations resulted in a statistically significant difference in lung cancer incidence or mortality, except for a single study that included 7627 women and found a higher risk of lung cancer incidence for those taking vitamin C but not for total cancer incidence, but that effect was not seen in males or when the results for males and females were pooled.For people at high risk of lung cancer, such as smokers and those exposed to asbestos and compared to placebo, beta-carotene intake showed a small but statistically significant higher risk of lung cancer incidence, lung cancer mortality and for all-causes mortality.

AUTHORS' CONCLUSIONS

There is no evidence for recommending supplements of vitamins A, C, E, selenium, either alone or in different combinations, for the prevention of lung cancer and lung cancer mortality in healthy people. There is some evidence that the use of beta-carotene supplements could be associated with a small increase in lung cancer incidence and mortality in smokers or persons exposed to asbestos.

The dawn of a revolution in personalized lung cancer prevention

Lung cancer prevention and early detection, which have fallen on hard times for more than the past 20 years, seem to have turned a corner toward better times ahead. Exciting new results of randomized controlled trials that targeted the arachidonic acid pathway, including a celecoxib trial reported by Mao and colleagues in this issue of the journal (beginning on page 984) and a trial of the prostacyclin analog iloprost, complement recently reported 20%-30% lung cancer mortality reductions, either with aspirin in targeting the arachidonic acid pathway or with computed tomography screening. The new results show encouraging activity personalized to former smokers and/or people expressing predictive biomarkers. These trials and technological advances in molecular profiling and imaging herald substantial clinical advances on the horizon of this field.

Altered histology provides a positive clinical signal in the bronchial epithelium

The history of lung cancer chemoprevention trials has been uniformly disappointing in that the large phase III studies showed no effect or harm in actively smoking participants, and smaller phase II studies have also been negative. In this issue of the journal (beginning on page 793), Keith and colleagues report their randomized, placebo-controlled trial of the oral prostacyclin analogue iloprost, the first trial to show an improvement in bronchial histology (i.e., regression), which occurred in former, but not current, smokers with sputum atypia. This Perspective discusses the strength of the clinical signal provided by this observation and its implications for further drug development.

Randomized controlled trial of acitretin versus placebo in patients at high-risk for basal cell or squamous cell carcinoma of the skin (North Central Cancer Treatment Group Study 969251)

BACKGROUND

Chemoprevention with systemic retinoids has demonstrated promise in decreasing the incidence of new primary nonmelanoma skin cancers (NMSCs) in immunocompromised post-transplantation recipients. There is limited evidence for the use of systemic retinoids in the nontransplantation patient. To the authors' knowledge, this is the first randomized controlled trial to assess the efficacy of acitretin as a chemopreventive agent in nontransplantation patients at high-risk for NMSC.

METHODS

The study was designed as a prospective, randomized, double-blind, placebo-controlled clinical trial. To test the possible skin cancer-preventing effect of a 2-year treatment with acitretin, 70 nontransplantation patients aged ≥18 years who had a history of ≥2 NMSCs within 5 years of trial onset were randomized to receive either placebo or acitretin 25 mg orally 5 days per week. The primary outcome measure was the rate of new NMSC development.

RESULTS

Seventy patients were randomized to receive either acitretin alone (N = 35) or placebo (N = 35). During the 2-year treatment period, the patients who received acitretin did not have a statistically significant reduction in the rate of new primary NMSCs (odds ratio, 0.41; 95% confidence interval, 0.15-1.13; 54% vs 74%; P = .13). However, using the incidence of new NMSC, the time to new NMSC, and total NMSC counts, an umbrella test indicated a significant trend that favored the use of acitretin (chi-square statistic, 3.94; P = .047). The patients who received acitretin reported significantly more mucositis and skin toxicities compared with the patients who received placebo.

CONCLUSIONS

Although there was not a statistically significant benefit observed with the use of acitretin, this may have been the result of low statistical power.

Randomized phase II trial of inhaled budesonide versus placebo in high-risk individuals with CT screen-detected lung nodules

Screening CT identifies small peripheral lung nodules, some of which may be pre- or early invasive neoplasia. Secondary end point analysis of a previous chemoprevention trial in individuals with bronchial dysplasia showed reduction in size of peripheral nodules by inhaled budesonide. We performed a randomized, double-blind, placebo-controlled phase IIb trial of inhaled budesonide in current and former smokers with CT-detected lung nodules that were persistent for at least 1 year. A total of 202 individuals received inhaled budesonide, 800 μg twice daily or placebo for 1 year. The primary endpoint was the effect of treatment on target nodule size in a per person analysis after 1 year. The per person analysis showed no significant difference between the budesonide and placebo arms (response rate 2% and 1%, respectively). Although the per lesion analysis revealed a significant effect of budesonide on regression of existing target nodules (P = 0.02), the appearance of new lesions was similar in both groups and thus the significance was lost in the analysis of all lesions. The evaluation by nodule type revealed a nonsignificant trend toward regression of nonsolid and partially solid lesions after budesonide treatment. Budesonide was well tolerated, with no unexpected side effects identified. Treatment with inhaled budesonide for 1 year did not significantly affect peripheral lung nodule size. There was a trend toward regression of nonsolid and partially solid nodules after budesonide treatment. Because a subset of these nodules is more likely to represent precursors of adenocarcinoma, additional follow-up is needed.

Budesonide versus placebo in high-risk population with screen-detected lung nodules: rationale, design and methodology

BACKGROUND

Screening-CT is able to discover small peripheral lung nodules. The nature of these nodules is uncertain but it is reasonable that some of them, in particular the non-solid ones, could represent precancerous lesions. A previous trial showed a reduction in size of peripheral nodules by inhaled budesonide in subjects with bronchial dysplasia.

OBJECTIVE

The primary objective of the study was the evaluation of the effect of budesonide as a chemopreventive agent for lung lesions. The primary endpoint was the modification of lung lesions at ld-CT scan (according to RECIST criteria) after one year of treatment in a person-specific analysis.

METHODS

We performed a randomized, double-blind, placebo controlled trial to evaluate whether inhaled budesonide was able to reduce size and number of persistent, undetermined CT-detected lung nodules in high-risk asymptomatic subjects currently undergoing a five-year CT scan screening program at the European Institute of Oncology.

RESULTS

Trial enrollment started in April 2006 and ended in July 2007 with the randomization of 202 current or former smokers with stable CT-detected lung nodules set to receive budesonide 800 μg or placebo twice daily for 12 months.

CONCLUSION

Our trial represents the first phase II study of a chemopreventive intervention focusing on the peripheral lung, where the majority of lung cancers arise. The research was nested into a screening project with clear advantages in participant accrual and reduction of costs. This paper describes the rationale and design of the study, thus focusing on the methodology and operational aspects of the clinical trial. (Clinicaltrials.gov number. NCT00321893).

Chemoprevention of lung squamous cell carcinoma in mice by a mixture of Chinese herbs

Antitumor B (ATB) is a Chinese herbal mixture of six plants. Previous studies have shown significant chemopreventive efficacy of ATB against human esophageal and lung cancers. We have recently developed a new mouse model for lung squamous cell carcinomas (SCC). In this study, lung SCC mouse model was characterized using small-animal imaging techniques (magnetic resonance imaging and computed tomography). ATB decreased lung SCC significantly (3.1-fold; P < 0.05) and increased lung hyperplastic lesions by 2.4-fold (P < 0.05). This observation suggests that ATB can block hyperplasia from progression to SCC. ATB tissue distribution was determined using matrine as a marker chemical. We found that ATB is rapidly absorbed and then distributes to various tissues including the lung. These results indicate that ATB is a potent chemopreventive agent against the development of mouse lung SCCs.

Impact of smoking cessation on global gene expression in the bronchial epithelium of chronic smokers

Cigarette smoke is the major cause of lung cancer and can interact in complex ways with drugs for lung cancer prevention or therapy. Molecular genetic research promises to elucidate the biological mechanisms underlying divergent drug effects in smokers versus nonsmokers and to help in developing new approaches for controlling lung cancer. The present study compared global gene expression profiles (determined via Affymetrix microarray measurements in bronchial epithelial cells) between chronic smokers, former smokers, and never smokers. Smoking effects on global gene expression were determined from a combined analysis of three independent data sets. Differential expression between current and never smokers occurred in 591 of 13,902 measured genes (P < 0.01 and >2-fold change; pooled data)--a profound effect. In contrast, differential expression between current and former smokers occurred in only 145 of the measured genes (P < 0.01 and >2-fold change; pooled data). Nine of these 145 genes showed consistent and significant changes in each of the three data sets (P < 0.01 and >2-fold change), with eight being down-regulated in former smokers. Seven of the eight down-regulated genes, including CYP1B1 and three AKR genes, influence the metabolism of carcinogens and/or therapeutic/chemopreventive agents. Our data comparing former and current smokers allowed us to pinpoint the genes involved in smoking-drug interactions in lung cancer prevention and therapy. These findings have important implications for developing new targeted and dosing approaches for prevention and therapy in the lung and other sites, highlighting the importance of monitoring smoking status in patients receiving oncologic drug interventions.

The prevalence of human papilloma virus infection in sinonasal inverted papilloma specimens classified by histological grade

BACKGROUND

Histological analysis suggests that inverted papilloma (IP) tumorigenesis may occur through a stepwise series of discrete events. The association between human papilloma virus (HPV) and IP has been described at varying incidences. The purpose of this study was to evaluate the prevalence of the HPV subtypes in a large series of IP specimens classified by histological grade.

METHODS

Fifty-seven paraffin-embedded specimens of Korean population were available for study. Each specimen was graded according to a four-stage histological grading system (stages I and II, benign IP; stage III, dysplastic IP; stage IV, carcinoma arising from IP). A representative section of IP specimen was isolated through laser capture microdissection (7.5- to 10-mum laser spot size). Subsequently, DNA extraction and HPV genotyping with the HPV DNA chip test (Biomed Lab Co., Seoul, Korea) was performed. The HPV DNA chip contained 22 type-specific probes that consisted of 15 high-risk subtypes and 7 low-risk subtypes.

RESULTS

Histological grading was as follows: 5, grade I; 23, grade II; 22, grade III; and 7, grade IV. Seven of 57 specimens (12.3%) showed HPV DNA. All of the HPV(+) cases showed HPV DNA in early grade (grades I and II) IP lesions. No higher grade (grades III and IV) IP tumors showed HPV DNA. Among the seven HPV(+) cases, five were high-risk subtypes and two were unspecified subtypes.

CONCLUSION

HPV infection, mainly high-risk subtypes, occurs in benign IP as an early event during the multistep tumorigenesis of IP. Cumulative other genetic insults may be required to progress from benign IP (grades I and II) to dysplastic IP (grade III) and carcinoma arising from IP (grade IV).

Proliferative changes in the bronchial epithelium of former smokers treated with retinoids

BACKGROUND

Retinoids have shown antiproliferative and chemopreventive activity. We analyzed data from a randomized, placebo-controlled chemoprevention trial to determine whether a 3-month treatment with either 9-cis-retinoic acid (RA) or 13-cis-RA and alpha-tocopherol reduced Ki-67, a proliferation biomarker, in the bronchial epithelium.

METHODS

Former smokers (n = 225) were randomly assigned to receive 3 months of daily oral 9-cis-RA (100 mg), 13-cis-RA (1 mg/kg) and alpha-tocopherol (1200 IU), or placebo. Bronchoscopic biopsy specimens obtained before and after treatment were immunohistochemically assessed for changes in the Ki-67 proliferative index (i.e., percentage of cells with Ki-67-positive nuclear staining) in the basal and parabasal layers of the bronchial epithelium. Per-subject and per-biopsy site analyses were conducted. Multicovariable analyses, including a mixed-effects model and a generalized estimating equations model, were used to investigate the treatment effect (Ki-67 labeling index and percentage of bronchial epithelial biopsy sites with a Ki-67 index > or = 5%) with adjustment for multiple covariates, such as smoking history and metaplasia. Coefficient estimates and 95% confidence intervals (CIs) were obtained from the models. All statistical tests were two-sided.

RESULTS

In per-subject analyses, Ki-67 labeling in the basal layer was not changed by any treatment; the percentage of subjects with a high Ki-67 labeling in the parabasal layer dropped statistically significantly after treatment with 13-cis-RA and alpha-tocopherol treatment (P = .04) compared with placebo, but the drop was not statistically significant after 9-cis-RA treatment (P = .17). A similar effect was observed in the parabasal layer in a per-site analysis; the percentage of sites with high Ki-67 labeling dropped statistically significantly after 9-cis-RA treatment (coefficient estimate = -0.72, 95% CI = -1.24 to -0.20; P = .007) compared with placebo, and after 13-cis-RA and alpha-tocopherol treatment (coefficient estimate = -0.66, 95% CI = -1.15 to -0.17; P = .008).

CONCLUSIONS

In per-subject analyses, treatment with 13-cis-RA and alpha-tocopherol, compared with placebo, was statistically significantly associated with reduced bronchial epithelial cell proliferation; treatment with 9-cis-RA was not. In per-site analyses, statistically significant associations were obtained with both treatments.

Lung Cancer Chemoprevention

BACKGROUND

Lung cancer is the most common cause of cancer death in the United States. Cigarette smoking is the main risk factor. Former smokers are at a substantially increased risk for lung cancer compared with lifetime never-smokers. Chemoprevention is the use of specific agents to reverse, suppress, or prevent the process of carcinogenesis. This article reviews the major agents that have been studied for chemoprevention.

METHODS

Articles of primary, secondary, and tertiary prevention trials were reviewed and summarized to obtain recommendations.

RESULTS

None of the phase III trials with the agents beta carotene, retinol, 13-cis-retinoic acid, alpha-tocopherol, N-acetylcysteine, or acetylsalicylic acid has demonstrated beneficial, reproducible results. For facilitating the evaluation of promising agents and for lessening the need for a large sample size, extensive time commitment, and expense, focus is now turning toward the assessment of surrogate end point biomarkers for lung carcinogenesis. With the understanding of important cellular signaling pathways, various inhibitors that may prevent or reverse lung carcinogenesis are being developed.

CONCLUSIONS

By integrating biological knowledge, more trials can be performed in a reasonable time frame. The future of lung cancer chemoprevention should entail the evaluation of single agents or combinations that target various pathways while working toward identification and validation of intermediate end points.

Inhibition of lung carcinogenesis by 1alpha,25-dihydroxyvitamin D3 and 9-cis retinoic acid in the A/J mouse model: evidence of retinoid mitigation of vitamin D toxicity

9-cis-Retinoic acid (9cRA) and 1alpha,25-dihydroxyvitamin D3 (1,25D) show promise as potential chemopreventive agents. We examined 9cRA and 1,25D, alone and in combination, for their potential to inhibit carcinogen (NNK)-induced lung carcinogenesis in A/J mice. A/J mice (n=14/group) were treated with 9cRA (7.5, 15, or 30 mg/kg diet), 1,25D (2.5 or 5.0 microg/kg diet), or a combination of 9cRA (15 mg/kg diet) plus 1,25D (2.5 microg/kg diet) for 3 weeks before and 17 weeks after carcinogen injection. Lung tumor incidence, tumor multiplicity, plasma 1,25D levels and kidney expression of vitamin D 24-hydroxylase (CYP24) were determined. Compared to carcinogen-injected controls, mice receiving 9cRA supplementation had significantly lower tumor multiplicity at all doses (decreased 68-85%), with body weight loss at the higher doses of 9cRA. Mice receiving 1,25D supplementation had significantly lower tumor incidence (decreased 36 and 82%) and tumor multiplicity (decreased 85 and 98%), but experienced significant body weight loss, kidney calcium deposition, elevated kidney CYP24 expression and decreased fasting plasma 1,25D levels. Although, there was no apparent influence on chemopreventive efficacy, addition of 9cRA to 1,25D treatment effectively prevented the weight loss and kidney calcification associated with 1,25D treatment alone. These data demonstrate that 9cRA and 1,25D, alone or combined, can inhibit lung tumor promotion in the A/J mouse model. Combining 1,25D with 9cRA has the potential to mitigate the toxicity of 1,25D, while preserving the significant effect of 1,25D treatment against lung carcinogenesis. The underlying mechanism behind this effect does not appear to be related to retinoid modulation of vitamin D catabolism.

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.

Biomarkers to assess the utility of potential reduced exposure tobacco products

To date, we have no valid biomarkers that serve as proxies for tobacco-related disease to test potential reduced exposure products. This paper represents the deliberations of four workgroups that focused on four tobacco-related heath outcomes: Cancer, nonmalignant pulmonary disease, cardiovascular disease, and fetal toxicity. The goal of these workgroups was to identify biomarkers that offer some promise as measures of exposure or toxicity and ultimately may serve as indicators for future disease risk. Recommendations were based on the relationship of the biomarker to what is known about mechanisms of tobacco-related pathogenesis, the extent to which the biomarker differs among smokers and nonsmokers, and the sensitivity of the biomarker to changes in smoking status. Other promising biomarkers were discussed. No existing biomarkers have been demonstrated to be predictive of tobacco-related disease, which highlights the importance and urgency of conducting research in this area.

Biomarkers to assess the utility of potential reduced exposure tobacco products

To date, we have no valid biomarkers that serve as proxies for tobacco-related disease to test potential reduced exposure products. This paper represents the deliberations of four workgroups that focused on four tobacco-related heath outcomes: Cancer, nonmalignant pulmonary disease, cardiovascular disease, and fetal toxicity. The goal of these workgroups was to identify biomarkers that offer some promise as measures of exposure or toxicity and ultimately may serve as indicators for future disease risk. Recommendations were based on the relationship of the biomarker to what is known about mechanisms of tobacco-related pathogenesis, the extent to which the biomarker differs among smokers and nonsmokers, and the sensitivity of the biomarker to changes in smoking status. Other promising biomarkers were discussed. No existing biomarkers have been demonstrated to be predictive of tobacco-related disease, which highlights the importance and urgency of conducting research in this area.

Serum retinoic acid, retinol and retinyl palmitate levels in patients with lung cancer

OBJECTIVES

Epidemiological studies have shown an inverse relationship between dietary vitamin A intake and the risk of developing lung cancer. The aim of this study was to investigate the vitamin A status in patients with lung cancer, by determining the serum levels of retinoic acid, retinol and retinyl palmitate.

METHODS

In total, 36 patients with lung cancer and 27 controls were assessed. Of the patients 14 had squamous cell carcinoma, 3 adenocarcinoma, 15 non-small cell lung cancer and 4 small cell lung cancer. Serum retinoic acid, retinol and retinyl palmitate levels were determined with HPLC and UV detection, after liquid extraction.

RESULTS

Serum retinol levels did not differ between patients (733.5 +/- 326.4 ng/mL) and controls (734.5 +/- 337.1 ng/mL). The retinyl palmitate concentration tended to be lower in patients (14.3 +/- 9.7 ng/mL) than in controls (16.7 +/- 13.7 ng/mL). The serum retinoic acid levels were significantly lower in patients (1.9 +/- 0.6 ng/mL) than in controls (2.5 +/- 1.1 ng/mL, P < 0.05). A positive correlation was observed between the retinol and retinoic acid levels and retinyl palmitate and retinoic acid levels.

CONCLUSIONS

The lower levels of retinoic acid in patients with lung cancer suggest there may be a deficiency or impairment in retinol metabolism in these patients. Further studies with larger numbers of patients are needed to evaluate the possible relationship between serum retinoid levels and lung cancer.

Chemoprevention in lung carcinogenesis--an overview

Lung cancer ranks among the most commonly occurring malignancies and is currently the leading cause of cancer-related death worldwide. This is due to its late diagnosis and relative resistance to standard oncological treatment approaches. The heavy burden of lung cancer and its treatment resistance have elicited an intense interest in the promising approach of chemoprevention. Chemoprevention is defined as a pharmacologic intervention to suppress or reverse the carcinogenic process and the lung is one of the most studied sites for cancer chemoprevention. This review, with a short update on pulmonary carcinogenesis, will summarize the available knowledge of chemoprevention trials and agents with a preventive potential in the 'lung field'.

Lung cancer: genetics of risk and advances in chemoprevention

PURPOSE OF REVIEW

The current article reviews recent advances in genetic susceptibility and chemoprevention of lung cancer.

RECENT FINDINGS

Linkage analysis has identified a locus on chromosome 6q23-25 that determines susceptibility to lung cancer in families with multiple members with cancer of the lung, throat, and larynx. Obligate gene carriers are sensitive to even small tobacco smoke exposure in terms of increased lung cancer risk. Variation in other genes, particularly those regulating the activation or inactivation of carcinogens, has been implicated in determining lung cancer risk. Epidemiologic and preclinical studies suggest that chemoprevention of lung cancer is an achievable goal. Early trials with beta-carotene supplementation, however, have revealed a harmful effect. Promising new agents must be evaluated in both preclinical models and in intermediate end point biomarker trials before being taken to large primary prevention trials, and lung cancer chemoprevention should only be attempted within controlled clinical trials.

SUMMARY

We are poised to learn a great deal about the genetic susceptibility to lung cancer, which will not only allow definition of groups with extremely high risk, but may also yield new insights into processes that determine innate susceptibility or resistance to lung carcinogenesis. Chemoprevention of lung cancer is not yet ready for clinical application. As a result of the large number of lung cancer deaths and the large number of at-risk individuals, even modestly effective chemoprevention could save many lives.

Chemoprevention: From research to clinical oncology

Chemoprevention is by now an emerging area of clinical oncology addressed to healthy individuals at higher risk for cancer, subjects with precancerous conditions, and patients who are at risk for a second primary cancer. The important results of large trials with various agents and the more accurate methods of risk assessment have already had implications in clinical practice. Recently, a number of compounds have shown to be clinically effective at various organ levels, often covering all the three settings of primary, secondary and tertiary prevention. There is proof today that at least 3 of the 4 'big killers' in oncology--breast, colon and prostate cancer--and oral cancer are to a certain extent preventable by chemopreventive drugs. The missing piece so far is lung cancer. The expanding molecular drug development is providing the tools for a more effective and safer molecular-targeted prevention. Combination chemoprevention and the use of agents with multiple effects are other particularly promising chemoprevention strategies.

Chemoprevention Strategies for Patients with Lung Cancer in the Context of Screening

Despite major advances in the treatment and management of lung cancer, most patients with lung cancer eventually die of this disease. Because conventional therapies have failed to make a major impact on survival, newer approaches are necessary in the battle against lung cancer. Better understanding of molecular biology of several tumors has led to novel targeted therapeutic approaches with potential utility in cancer treatment in general and lung cancer in particular. In addition to smoking cessation, targeting individuals at high risk by use of early detection or aiming at reversal of premalignant lesions seem like attractive strategies. In light of the noted improvement in molecular diagnostic tools and targeted therapies, the question of chemoprevention in the context of early detection deserves a closer look. In this article, we review what has been achieved in the area of chemoprevention and discuss possible prospects that may help reduce lung cancer mortality in the context of early detection.

Advances in the Biology of Lung Cancer Chemoprevention

The heavy burden of lung cancer, which includes the highest worldwide mortality of any cancer, and its resistance to standard approaches (smoking cessation, screening, and therapy), have motivated an intense interest in chemoprevention of this disease. Randomized controlled trials of agents (including retinoids, beta-carotene, and vitamin E) to prevent lung cancer have produced only disappointing clinical results to date. New, molecular-targeted approaches are advancing rapidly, however, with many promising targets and interactive signaling pathways for developing novel agents and combinatorial approaches in this setting. This promise is illustrated by recent studies of 15-hydroxyprostaglandin dehydrogenase, which plays a critical role in polyunsaturated fatty acid metabolism and (like another important target, prostacyclin) is downstream of cyclooxygenase-2. 15-hydroxyprostaglandin dehydrogenase degrades prostaglandin E2, appears to have tumor suppressor activity, and can be induced both by peroxisome proliferator-activated receptor-gamma ligands and an epidermal growth factor receptor inhibitor. Other important targets/pathways include the insulin-like growth factor axis, phosphoinositide 3-kinase pathway, cyclin D and E family members, and epigenetic events. Defining highest lung cancer risk (eg, establishing molecular risk models through long-term analyses of high-risk cohorts) will facilitate the clinical development of molecular-targeted prevention that will potentially reduce the enormous burden of lung cancer.

9-cis-Retinoic Acid Treatment Increases Serum Concentrations of α-Tocopherol in Former Smokers

PURPOSE

Low serum concentrations of antioxidants may be associated with an increased risk of cancer. Based on the accumulated evidence, we hypothesized that retinoids would elevate serum alpha-tocopherol. This study was designed to determine whether 9-cis-retinoic acid (9-cis-RA), the most common chemopreventive agent, could alter serum alpha-tocopherol in former smokers. Because hyperlipidemia is a known side effect of retinoids, we also evaluated the association between serum alpha-tocopherol and lipids in the same population.

EXPERIMENTAL DESIGN

Subjects who had stopped smoking at least 12 months before the study were randomly assigned to receive oral 9-cis-RA or placebo daily for 3 months. Clinical information and blood samples were obtained monthly; serum alpha-tocopherol concentrations were measured by high-performance liquid chromatography and lipid levels by enzymatic assays before treatment and every month during the treatment.

RESULTS

Of the 149 subjects in the study, 113 completed 3 months of treatment and provided samples for evaluation of serum alpha-tocopherol. Serum alpha-tocopherol levels in the 9-cis-RA group (n = 52) were higher after treatment (r = 0.445, P < 0.01) than before. The incidences of grade > or =2 hypertriglyceridemia and hypercholesterolemia were higher in the 9-cis-RA group than in the placebo group (P = 0.0005 and P = 0.01, respectively), but there were no serious complications related to hyperlipidemia.

CONCLUSIONS

Treatment of former smokers with 9-cis-RA significantly increased their serum alpha-tocopherol levels, and this could be a benefit. In addition, serum alpha-tocopherol could serve as a biomarker for 9-cis-RA treatment.

Chemoprevention of lung cancer

PURPOSE OF REVIEW

Lung cancer is one of the major causes of cancer-related deaths. Grim mortality figures argue powerfully for new approaches to control this disease. Chemoprevention is the use of specific natural or synthetic chemical agents to reverse, suppress, or prevent carcinogenic progression to invasive cancer. The current article focuses on the field of lung cancer chemoprevention and recent advances. Lung cancer biology and general principles of prevention strategies are also described.

RECENT FINDINGS

Trials in lung cancer chemoprevention have so far produced either neutral or harmful primary end point results whether in the primary, secondary and tertiary settings. The data suggest that lung cancer was not prevented by beta-carotene, alpha-tocopherol, retinal, retinyl palmitate, N-acetylcysteine, or isotretinoin in smokers. The results from the recently completed Canadian study of anethole dithiolethione in smokers with bronchial dysplasia as well secondary analyses of the phase III trials involving selenium and data from the US Intergroup NCI-91-0001 supporting treatment with isotretinoin in never and former smokers are hopeful and may help define new avenues of chemopreventive treatment after scientists and clinicians analyze the information generated.

SUMMARY

The concept of chemoprevention in lung cancer is still in its infancy but one day may have a significant impact on the incidence and mortality of this leading cancer threat. An improved understanding of carcinogenesis and cancer prevention mechanisms will no doubt aid in the design of future clinical trials and in the validation of candidate agents as well as the development of new targets. Planned or ongoing trials currently are targeting important molecular markers of lung carcinogenesis and progression including cyclooxygenase-2, the ras-signaling pathway through farnesyl transferase inhibitors and the tyrosine kinase/epidermal growth factor receptor pathway. Until such studies are completed however, no drug or drug combination should be used for lung cancer prevention outside of a clinical study.