Cigarette smoking and lung cancer in New Mexico

Dual Nature of Relationship between Mycobacteria and Cancer

Although the therapeutic effect of mycobacteria as antitumor agents has been known for decades, recent epidemiological and experimental studies have revealed that mycobacterium-related chronic inflammation may be a possible mechanism of cancer pathogenesis. Mycobacterium tuberculosis and non-tuberculous Mycobacterium avium complex infections have been implicated as potentially contributing to the etiology of lung cancer, whereas Mycobacterium ulcerans has been correlated with skin carcinogenesis. The risk of tumor development with chronic mycobacterial infections is thought to be a result of many host effector mechanisms acting at different stages of oncogenesis. In this paper, we focus on the nature of the relationship between mycobacteria and cancer, describing the clinical significance of mycobacteria-based cancer therapy as well as epidemiological evidence on the contribution of chronic mycobacterial infections to the increased lung cancer risk.

Clinical and radiological features of immune checkpoint inhibitor-related pneumonitis in lung cancer and non-lung cancers

OBJECTIVE

To investigate the clinical and radiological features of immune checkpoint inhibitor-related pneumonitis (ICI-P), a rare but serious pulmonary complication of cancer immunotherapy and to evaluate key differences between lung cancer (LC) and non-LC patients.

METHODS

247 patients (LC, n = 151) treated with ICI for malignancies were retrospectively screened in a single institute. The number of patients, history of other immune-related adverse events (irAE), the onset, serum KL-6 levels, and chest CT features (types of pneumonitis, symmetry, laterality, location) were recorded for the ICI-P population and compared for LC and non-LC groups.

RESULTS

ICI-P was identified in 26 patients in total (LC, n = 19; non-LC, n = 7). The incidence of other irAE was significantly higher in ICI-P group (63%) compared with patients without ICI-P (34%) (p = 0.0056). An earlier onset of ICI-P was recorded in LC (78 days) compared to non-LC patients (186 days) (p = 0.0034). Serum KL-6 was significantly elevated only in the non-LC group when ICI-P was noticed (p = 0.029). Major CT findings of ICI-P, irrespective of primary disease, were organizing pneumonia pattern and ground glass opacities. LC patients commonly exhibited consolidation and traction bronchiectasis and were prone to asymmetrical shadows (p < 0.001). Non-LC patients were more likely to exhibit symmetrical infiltrations. A small fraction of both groups experienced relapse or moving patterns of ICI-P.

CONCLUSION

ICI-P patients more often experienced other irAE prior to the development of ICI-P. The characteristics of ICI-P can differ in terms of the onset, KL-6 reliability, and chest CT findings between LC and non-LC patients.

ADVANCES IN KNOWLEDGE

In ICI-P patients, a history of other irAE can be more frequently observed. Differences in disease onset and radiological patterns between LC and non-LC patients might be helpful to make a diagnosis of ICI-P; however, longitudinal observation of chest CT scans is advised to observe the pneumonitis activity irrespective of cancer types.

Low-Dose CT Screening for Lung Cancer: Evidence from 2 Decades of Study

Lung cancer remains the overwhelmingly greatest cause of cancer death in the United States, accounting for more annual deaths than breast, prostate, and colon cancer combined. Accumulated evidence since the mid to late 1990s, however, indicates that low-dose CT screening of high-risk patients enables detection of lung cancer at an early stage and can reduce the risk of dying from lung cancer. CT screening is now a recommended clinical service in the United States, subject to guidelines and reimbursement requirements intended to standardize practice and optimize the balance of benefits and risks. In this review, the evidence on the effectiveness of CT screening will be summarized and the current guidelines and standards will be described in the context of knowledge gained from lung cancer screening studies. In addition, an overview of the potential advances that may improve CT screening will be presented, and the need to better understand the performance in clinical practice outside of the research trial setting will be discussed. © RSNA, 2020.

Incidence of Non-Salivary Gland Neoplasms in Patients with Warthin Tumor: A Study of 73 Cases

Warthin tumor is the second most common benign parotid neoplasm. Its association with non-salivary gland neoplasms has been sporadically reported. We reviewed clinical records of Warthin tumor diagnosed on aspiration cytology and surgical pathology to determine if there is any association with other extra-salivary gland malignant neoplasms. Computer search was made for all cases of Warthin tumor diagnosed in the parotid gland by aspiration cytology and surgical pathology at our institution between January 2007 and August 2016. Clinical records of all cases were reviewed for any associated malignant neoplasms and any surgical follow up. All available cytology and histologic material was reviewed. Seventy-three patients (mean 66.9, M:F 1.1:1, age range 43 to 87 years) with Warthin tumor were identified. 45 (62%) were diagnosed on aspiration cytology only, 19 (26%) had cytologic diagnosis as well as concordant surgical follow up, and 9 (12%) were diagnosed based on surgical pathology only. Average age for patients with and without secondary malignancy was 70.5-years, and 63.4-years, respectively (p < 0.05). Average pack years for patients with and without secondary malignancy was 45.4, and 39.8, respectively (p > 0.05). Twenty-seven (37.0%) patients harbored a malignant neoplasm. Association of extra salivary gland malignant neoplasms in 37.0% of our cases suggest that the prevalence of secondary non-salivary neoplasms in patients harboring Warthin tumor might have been underestimated. Squamous cell carcinoma was the most commonly associated non-salivary malignant neoplasm. The association of Warthin tumor with smoking plays an important role in this increased rate of malignancy, and this is supported by the fact that smoking is highly associated with head and neck and lung cancers.

Management of the Solitary Pulmonary Nodule

Context.—

Optimal management of the patient with a solitary pulmonary nodule entails early diagnosis and appropriate treatment for patients with malignant tumors, and minimization of unnecessary interventions and procedures for those with ultimately benign nodules. With the growing number of high-resolution imaging modalities and studies available, incidentally found solitary pulmonary nodules are an increasingly common occurrence.

Objective.—

To provide guidance to clinicians involved in the management of patients with a solitary pulmonary nodule, including aspects of risk stratification, workup, diagnosis, and management.

Data Sources.—

Data for this review were gathered from an extensive literature review on the topic.

Conclusions.—

Logical evaluation and management pathways for a patient with a solitary pulmonary nodule will allow providers to diagnose and treat individuals with early stage lung cancer and minimize morbidity from invasive procedures for patients with benign lesions.

A multi-institutional study of clinicopathological features and molecular epidemiology of epidermal growth factor receptor mutations in lung cancer patients living with human immunodeficiency virus infection

PURPOSE

Lung cancer has become a crucial problem among individuals living with the human immunodeficiency virus (HIV) and causes high mortality in Western countries. Japan has an increasing number of newly infected HIV patients, and lung cancer is becoming a theme in this population. However, clinical factors of this particular population in East Asian are unclear given the identification of ethnic differences in lung cancer in the general population.

METHODS

From 1986 to 2013, a retrospective nationwide study involving Japanese patients living with HIV and diagnosed with lung cancer was undertaken.

RESULTS

Forty-three lung cancer patients with HIV were identified (median age, 60.0 years; males, 97.7%; early-stage cancer, 37.2%; metastatic cancer, 34.9%), 41 (95.3%) of whom developed lung cancer in the antiretroviral era. The median CD4-positive T-cell count was 326 cells/µL. Adenocarcinoma was the most frequent histology (55.8%), followed by squamous cell carcinoma (27.9%). Epidermal growth factor receptor (EGFR) status was examined in 14 patients; five (35.7%) had EGFR mutations. The median overall survival time was 25.1 months for all stages and 7.9 months for advanced-stage cancer. Using univariate analysis, the only favorable prognostic factor for overall survival was cancer stage (p = 0.02).

CONCLUSIONS

The incidence of lung cancer among HIV patients in Japan has been increasing in the past decade. The present Japanese cohort showed similar EGFR mutation status similar to that of general population. The ethnic differences known in the general population were seen even in the population living with HIV, implying distinct clinical characteristics and outcomes from those reported in Western countries.

Squamous Cell Carcinoma - Similarities and Differences among Anatomical Sites

Squamous cell carcinoma (SCC) is an epithelial malignancy involving many anatomical sites and is the most common cancer capable of metastatic spread. Development of early diagnosis methods and novel therapeutics are important for prevention and mortality reduction. In this effort, numerous molecular alterations have been described in SCCs. SCCs share many phenotypic and molecular characteristics, but they have not been extensively compared. This article reviews SCC as a disease, including: epidemiology, pathology, risk factors, molecular characteristics, prognostic markers, targeted therapy, and a new approach to studying SCCs. Through this comparison, several themes are apparent. For example, HPV infection is a common risk factor among the four major SCCs (NMSC, HNSC, ESCC, and NSCLC) and molecular abnormalities in cell-cycle regulation and signal transduction predominate. These data reveal that the molecular insights, new markers, and drug targets discovered in individual SCCs may shed light on this type of cancer as a whole.

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.

Clinical characteristics of Japanese lung cancer patients with human immunodeficiency virus infection

BACKGROUND

Lung cancer has emerged as a crucial problem among human immunodeficiency virus (HIV)-infected patients, contributing to significant mortality in Western countries. Japan has an increasing number of newly infected HIV patients, but clinical characteristics of lung cancer have not been well investigated in Asian populations with HIV.

PATIENTS AND METHODS

We retrospectively analyzed patients diagnosed with HIV and lung cancer simultaneously in our institution between 1985 and 2010. Data regarding HIV status, characteristics, treatment, and prognosis of lung cancer were evaluated.

RESULTS

We identified 13 consecutive patients (all men; mean age, 59.0 ± 10.2 years) since 1985, 7 of whom had been diagnosed since 2008. Mean CD4 cell count was 332 ± 159 cells/μL, and HIV viral loads were undetectable in 8 patients (61.5%) at the time of lung cancer diagnosis. The mean latency from HIV diagnosis to detection of lung cancer was 4.0 years. Histological examination demonstrated adenocarcinoma in 9 patients (69.2%), followed by squamous cell carcinoma (23.1%), and small cell carcinoma (7.7%). Among the 7 patients available for examination, 2 patients (28.6%) harbored EGFR mutation. Six patients had stage IA-IIIA, and 7 patients had stage IIIB/IV. Among 6 patients treated with chemotherapy for unresectable stages, 5 (83.3%) achieved a partial response. Median overall survival was 17 months for all stages and 14 months for advanced stages. Toxicities for treatment modalities were largely acceptable.

CONCLUSIONS

Clinical characteristics of Japanese HIV-infected patients with lung cancer resemble those of Western populations. The prognosis for patients in the metastatic stage was better than previously reported.

Effect of mustard gas exposure on incidence of lung cancer: a longitudinal study

Sulfur mustard, an agent used in chemical warfare, is an alkylating substance with carcinogenic potential. However, the precise long-term carcinogenic effects of mustard gas are unclear. Since 1952, the authors have conducted health surveys of former workers who were employed from 1929 to 1945 in a poisonous gas factory in Okuno-jima, Hiroshima, Japan. This prospective study was undertaken from 1952 to 2005 to examine the incidence of lung cancer among the workers who were exposed to mustard gas (n=480), lewisite (n=55), and/or diphenylcyanarsine (n=178), as well as the incidence among unexposed workers (n=969). The stochastic relation between exposure and lung cancer was explored on the basis of multistage carcinogenesis by using an accelerated hazard model with a transformed age scale. Mustard gas exposure was found to transform the age scale for developing lung cancer. One year of exposure in subjects ≤18 or >18 years old at first exposure shifted the age scale down by 4.9 years and 3.3 years, respectively. On the basis of the long-term follow-up of former workers in the poisonous gas factory, the authors concluded that sulfur mustard decreased the age at which people were at risk of developing lung cancer and that the effect declined with aging.

Lung cancer in never smokers: clinical epidemiology and environmental risk factors

More than 161,000 lung cancer deaths are projected to occur in the United States in 2008. Of these, an estimated 10 to 15% will be caused by factors other than active smoking, corresponding to 16,000 to 24,000 deaths annually. Thus lung cancer in never smokers would rank among the most common causes of cancer mortality in the United States if considered as a separate category. Slightly more than half of the lung cancers caused by factors other than active smoking occur in never smokers. As summarized in the accompanying article, lung cancers that occur in never smokers differ from those that occur in smokers in their molecular profile and response to targeted therapy. These recent laboratory and clinical observations highlight the importance of defining the genetic and environmental factors responsible for the development of lung cancer in never smokers. This article summarizes available data on the clinical epidemiology of lung cancer in never smokers, and several environmental risk factors that population-based research has implicated in the etiology of these cancers. Primary factors closely tied to lung cancer in never smokers include exposure to known and suspected carcinogens including radon, second-hand tobacco smoke, and other indoor air pollutants. Several other exposures have been implicated. However, a large fraction of lung cancers occurring in never smokers cannot be definitively associated with established environmental risk factors, highlighting the need for additional epidemiologic research in this area.

Physical activity among lung cancer survivors: changes across the cancer trajectory and associations with quality of life

BACKGROUND

Regular physical activity may offer benefits to lung cancer survivors, many of whom experience quality-of-life (QOL) impairments. However, little is know about lung cancer survivors' engagement in physical activity across the cancer trajectory. The current study addressed this research gap and also examined the association between lung cancer survivors' physical activity and their QOL.

METHODS

The study participants were 175 individuals who completed surgical treatment for early-stage non-small cell lung cancer 1 to 6 years previously. Participants completed a one-time survey regarding their current QOL and their engagement in physical activities currently, during the 6 months after treatment, and during the 6 months before diagnosis.

RESULTS

Participants' reported engagement in both moderate and strenuous intensity activities was lower during the post-treatment period compared with before diagnosis and at the current time. Engagement in light intensity activities did not differ for the three time points. Almost two-thirds of participants did not engage in sufficient activity to meet national physical activity guidelines for any of the three time points. Lung cancer survivors who currently met physical activity guidelines reported better QOL in multiple domains than less active individuals.

CONCLUSIONS

Engagement in physical activity among lung cancer survivors is particularly low during the early post-treatment period. Current engagement in physical activity is associated with better QOL. However, most lung cancer survivors do not meet physical activity guidelines and may benefit from interventions to promote engagement in regular physical activities.

Factores etiológicos del cáncer de pulmón: fumador activo, fumador pasivo, carcinógenos medioambientales y factores genéticos

Every year, in Spain 18,000 new cases of lung cancer (LC) are diagnosed. Approximately, 80-90% LC in men and women are directly attributable to tobacco abuse. Cigarette smoke contains over 300 chemicals, 40 of which are known to be potent carcinogens. In the last decade, as in Spain, prevalence of smoking in women has generally increased in the European Union. LC risk can be substantially reduced after smoking cessation, yet never reaches baseline. On the other hand, environmental tobacco smoke exposure (passive smoking) in nonsmokers appears to have a significantly increased risk of LC. An updated of etiology factors of LC, risk related to duration as well as intensity of smoking, relationship between environmental tobacco smoke exposure and LC risk, genetic predisposition and a variety of occupational and environmental exposures implicated as potential risk factors for the development of LC will be reviewed here.

Circulating tumour-derived DNA and RNA markers in blood: a tool for early detection, diagnostics, and follow-up?

BACKGROUND

Lung cancer is the most common cause of cancer death in developed countries. The prognosis is poor with only 10-15% of patients surviving 5 years after diagnosis. This dismal prognosis is attributed to the lack of efficient diagnostic methods for early detection and lack of successful treatment for metastatic disease. Within the last decade, rapid advances in molecular biology and radiology have provided a rational basis for improving early detection and patients' outcome. A non-invasive blood test effective in detecting preneoplastic changes or early lung cancer in high risk individuals has been perceived as a holy grail by cancer researchers.

METHODS

The introduction of polymerase chain reaction (PCR)-based technology in the late 1980s and its refinement over the last 10 years have allowed us to detect and quantify extremely small amounts of tumour-derived nucleic acids. This has led to an increased knowledge of the molecular pathogenesis of lung cancer and a basis for the use of DNA and RNA markers in blood for early cancer detection, diagnostics, and follow-up. Common genetic alterations in lung carcinogenesis are already well known. We reviewed published literature on DNA and RNA in plasma or serum in lung cancer patients up to 2004, with particular emphasis on reports published since 1995.

RESULTS

Twenty-two clinical studies have evaluating the role of DNA and RNA aberrations in the blood of lung cancer patients. A total of 1618 (range 10-163/study) cases and 595 (range 10-120/study) control cases were evaluated, and overall plasma/serum abnormalities were found in 43% (range 0-78%) of cases and 0.8% of healthy controls. For (1) total DNA and gene expression levels, 61% (range 53-71%) of cases and 0.9% of controls; (2) oncogene mutations, 16% (range 0-30%) and 0%; (3) microsatellite alterations, 46% (range 24-71%) and 21% (controls with non-malignant pulmonary disease); (4) promoter methylation, 42% (range 5-73%) and 0%; (5) tumour-related RNAs, 54% (range 39-78%) and 6%. In general, the studies contain small series of lung cancer patients and even smaller or missing case control groups.

CONCLUSION

The analysis of circulating DNA or RNA in plasma is a promising non-invasive diagnostic tool, requiring only a limited blood sample. Its wide applicability and potential importance will possibly lead to increasing clinical impact in the near future. However, large prospective clinical studies are needed to validate and standardise any tests for DNA or RNA alteration in plasma or serum of high risk individuals or patients with established lung cancer.

BMD at multiple sites and risk of fracture of multiple types: long-term results from the Study of Osteoporotic Fractures

In a large cohort of U.S. women aged 65 and older, we report the relationships of BMD measured at several sites, and subsequent fracture risk at multiple sites over > 8 years of follow-up. Although we found almost all fracture types to be related to low BMD, the overall proportion of fractures attributable to low BMD is modest.

INTRODUCTION

Although several studies have reported the relationship between bone mineral density (BMD) and subsequent fracture risk, most have been limited by short follow-up time, BMD measures at only one or two sites, or availability of data for only select fracture types.

MATERIALS AND METHODS

In the multicenter Study of Osteoporotic Fractures (SOF), we studied the relationship of several different BMD measures to fracture risk of multiple types in 9704 non-black women aged 65 and older. We previously reported on the relationship of peripheral BMD measures to risk of several types of fracture during an average 2.2-year follow-up period. In this expanded analysis, we present results of the relationship of both peripheral and central BMD measures and fractures of multiple types during 10.4 and 8.5 years of follow-up, respectively. We also report population attributable risk (PAR) estimates for osteoporosis and risk of several types of fracture.

RESULTS

Our results show that almost all types of fractures have an increased incidence in women with low BMD. However, hip BMD is somewhat more strongly related to most of the fracture types studied than spine or peripheral BMD measures. Nonetheless, the proportion of fractures attributable to osteoporosis (based on a standard definition of osteoporosis) is modest, ranging from < 10% to 44% based on the most commonly used definition of osteoporosis (BMD T-score < -2.5).

CONCLUSION

Finding effective prevention strategies for fractures in older women will require additional interventions beside preventions for bone loss, such as prevention of falls and other fracture risk factors.

Smoking and the Risk of Lung Cancer

BACKGROUND

GSTP1 is a gene that helps detoxify foreign substances in the body. Functional polymorphisms of GSTP1 have been studied as risk factors for lung cancer. Past studies have compared the effect of the "at risk" polymorphism in two strata of smoking pack-years (usually defined by the median among controls). We examined the interaction between GSTP1 polymorphisms and cumulative exposure to smoking and their association with lung cancer risk.

METHODS

Data are from a large hospital-based case-control study of persons treated for primary lung cancer at the Massachusetts General Hospital since 1992. Controls were drawn from friends and nonrelated family members. We genotyped 1,042 cases and 1,161 controls for GSTP1 using polymerase chain reaction-restriction fragment length polymorphism techniques.

FINDINGS

The GSTP1 GG genotype approximately doubled the lung cancer risk associated with pack-years. This interaction was stronger among current smokers. At 26 pack-years (median among controls with a smoking history), the adjusted odds ratio for the association between pack-years and lung cancer risk was 13 (95% confidence interval = 6.5-25) among current smokers with the GSTP1 GG genotype compared with 6.1 (95% confidence interval = 4.9-7.5) among those with the GSTP1 AA genotype.

CONCLUSIONS

GSTP1 GG increases the lung cancer risk associated with pack-years of smoking.

Progress in lung cancer chemoprevention

BACKGROUND

Lung cancer is one of the major causes of cancer-related deaths. Lung cancer mortality figures argue powerfully for new approaches to control this disease. The term chemoprevention can be defined as the use of specific natural or synthetic chemical agents to reverse, suppress, or prevent premalignancy from progressing to invasive cancer.

METHODS

Issues related to lung cancer chemoprevention are reviewed, including risk factors and identification of high-risk cohorts, endpoint biomarkers, and current and new chemopreventive agents. Also, important findings from chemoprevention randomized, controlled trials are summarized.

RESULTS

Trials in lung cancer chemoprevention have so far produced either neutral or harmful primary endpoint results, whether in the primary, secondary, or tertiary settings. Lung cancer was not prevented by beta-carotene, alpha-tocopherol, retinol, retinyl palmitate, N-acetylcysteine, or isotretinoin in smokers. Secondary results from the phase III trials involving selenium and vitamin E, as well as results from the US Intergroup NCI I91-0001 trial supporting treatment with isotretinoin in never and former smokers, are promising and may help define new avenues for chemoprevention.

CONCLUSIONS

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. Molecular markets of risk, drug activity and targeting, improved imaging techniques, and new drug delivery systems are being evaluated.

Genetic testing for lung cancer risk: if physicians can do it, should they?

Advances in genetics have increased our ability to assess an individual's genetic risk for disease. There is a hypothesis that genetic test results will motivate high-risk individuals to reduce harmful exposures, to increase their surveillance for disease, or to seek preventive treatments. However, genetic testing for genes associated with an increased risk of lung cancer would not change physicians' recommendations regarding smoking cessation. Limited studies suggest that test results that demonstrate an increased risk of lung cancer do not improve smoking cessation success. These test results may even distort an individual's risk perceptions. Before recommending genetic testing to assess risk for disease, physicians need to consider whether knowledge about genetic susceptibility will alter patient management.

Lung cancer screening by spiral CT. What is the optimal target population for screening trials?

The purpose of this document is to provide recommendations for the selection of the optimal target population for lung cancer screening trials with Spiral Computer Tomography based on an analysis of risk factors and high-risk populations. Our recommendations are to include current or ex-smokers (<5 years) with a smoking history of at least 30 years and an average consumption of at least 20 cigarettes a day. When these selection criteria are applied there is no need for a lower age cut-off. Elderly people can be included as long as their life expectancy is more than 10 years. Participants should be fit enough to undergo thoracic surgery. They may have a history of previous cancer, provided that the cancer has been curatively treated at least 5 years ago without evidence of relapse, except for breast cancer, melanoma and hypernephroma. People with an inability to lie flat, who are unable to hold their breath for 20 s, with a body weight above 140 kg, a chest CT scan within 1 year before enrolment or a previous pneumonectomy should not be invited. The inadequacy of the unit 'Pack-Years' (PY) to estimate the individual lung cancer risk is recognised, and future initiatives to develop an appropriate lung cancer risk model are encouraged.

The epidemiology of lung cancer

Lung cancer continues to be the leader in cancer deaths in the United States. The incidence of lung cancer in men has slowly decreased since the late 1980s, but has just now begun to plateau in women at the end of this decade. Despite modest advances in chemotherapy for treating lung cancer, it remains a deadly disease with overall 5-yr survival rates having not increased significantly over the last 25 years, remaining at approximately 14%. Tobacco smoking causes approximately 85-90% of bronchogenic carcinoma. Environmental tobacco exposure or a second-hand smoke also may cause lung cancer in life-long non-smokers. Certain occupational agents such as arsenic, asbestos, chromium, nickel and vinyl chloride increase the relative risk for lung cancer. Smoking has an additive or multiplicative effect with some of these agents. Familial predisposition for lung cancer is an area with advancing research. Developments in molecular biology have led to growing interest in investigation of biological markers, which may increase predisposition to smoking-related carcinogenesis. Hopefully, in the future we will be able to screen for lung cancer by using specific biomarkers. Finally, dietary factors have also been proposed as potential risk modulators, with vitamins A, C and E proposed as having a protective effect. Despite the slow decline of smoking in the United States, lung cancer will likely continue its devastation for years to come.

Early diagnosis of lung cancer

Recent advances in computer-assisted image analysis, tumor biology, PCR-based assays, fluorescence bronchoscopy, spiral CT, endobronchial treatment modalities, and chemoprevention make it possible to re-examine the strategy of early detection in the comprehensive management of lung cancer.

Bronchogenic cancer in patients under 40 years old. The experience of a Latin American country

Lung cancer in young patients is increasing in frequency, as documented by data from the United States, Canada, Japan, and European countries. However, to date and to our knowledge, there have not been any reports from Latin America on this topic. The published reports show that lung cancer in young patients is associated with smoking habit and family history of lung cancer. Its clinical course seems to be more aggressive than in older patients and the histologic type is less often squamous type. We describe 48 patients, aged 40 years or younger, who were diagnosed as having lung cancer in the Instituto Nacional de Cancerología from 1980 to 1990. The patients were equally divided between men and women. Smoking was documented for only 46 percent of the cases. The histologic type most frequently diagnosed was adenocarcinoma (N = 26) followed by squamous cell carcinoma (N = 12). Almost all the cases (46 cases) were staged IV according to the TNM classification. A group of 33 patients older than 40 years (56 to 82 years) were used for comparison. The differences in sex ratio that were higher for men in the elder (m/f, 2.7:1) were family history for cancer in six patients elder; positive smoking habit in all the aged patients (100 percent) compared with only 43.7 percent in the younger group; histologic type (26 adenocarcinomas and 4 squamous in the younger compared with 14 and 12, respectively, in the elder).

Occupational lung cancer

Exposure to certain industrial agents has been thought to have carcinogenic potential, both for employees who work closely with such agents and for the general population that comes in contact with them. Although case reports, laboratory studies, and epidemiologic analyses help to determine the carcinogenicity of implicated agents, each of these types of investigation has limitations and deficiencies in distinguishing causal from noncausal associations. Asbestos has been linked with bronchogenic carcinoma, but several controversial factors--the degree of risk relative to exposure dose, the synergistic effect of cocarcinogens, and the question of existence of a threshold dose--complicate the understanding of the magnitude of the risk for exposed persons. Several other physical and chemical agents (such as chromium, nickel, and radon) have also been associated with an increased incidence of lung cancer in epidemiologic and animal studies. As with asbestos, the specific type of the agent and exposure conditions are important in determining the degree of carcinogenicity. In studies of exposure to man-made mineral fibers, formaldehyde, and silica, the findings have been inconsistent. Because the degree of health hazard attributable to asbestos and other known and suspected lung carcinogens is controversial, a wide range of opinions exists about the importance of occupational exposures to the overall incidence of lung cancers. Nevertheless, attempting to prevent lung cancers by minimizing or eliminating exposure to carcinogens is preferable to treating existent cases.

The health consequences of smoking. Cancer

Smoking has now been identified as a definite cause of cancer at many sites (Table 2). Of all cancers in the United States, 30% could be prevented if cigarette smoking were eliminated. Organs in direct contact with smoke--the oral cavity, esophagus, lung, and bronchus--are at the greatest risk of malignancy among smokers. As many as 90% of these cancers are attributable to smoking. Organs and tissues distant from smoke are also at some increased risk. Among smokers, rates of cancer of the cervix, pancreas, bladder, kidney, stomach, and hematopoietic tissue are increased 50% to 200% over rates in nonsmokers. Risk of cancer at all sites increases with increasing exposure to cigarette smoke. Cigarette smoke contains potent carcinogens that influence carcinogenesis at both early and late stages. These carcinogens can interact with other exposures, such as alcohol, to synergistically increase the risk of cancer. The adverse carcinogenic effects of cigarette smoking, however, can be reduced for all smokers if tobacco use is stopped. The prevalence of smoking among the US population as a whole has declined from 40% in 1965 to 29% in 1987. This progress against the epidemic of tobacco use has already produced a decrease in the occurrence of the most common tumor among men, lung cancer. Unfortunately, the decline in smoking prevalence and cancer incidence has not occurred equally across US populations. Death rates of lung cancer in women continue to rise, and, based upon current smoking patterns, these rates will continue to increase into the next century. The challenge to physicians and public health workers is compelling and immediate: Abstaining from smoking is the single most effective way to reduce an individual's risk of cancer.

The health benefits of smoking cessation

Extensive evidence has now accumulated on the health benefits of smoking cessation. With few exceptions, disease risks are reduced following smoking cessation and continue to drop as abstinence is maintained. The review of the evidence in the 1990 Report of the Surgeon General led to major conclusions that establish smoking cessation as a clear priority for health care providers.