Leukaemia and smoking habits among United States veterans

Lymphohaematopoietic malignancies in Scottish military veterans: Retrospective cohort study of 57,000 veterans and 173,000 non-veterans

BACKGROUND

Lymphohaematopoietic malignancies are common in the general population. There have been concerns that military service may be associated with increased risk as a result of occupational exposures. To date, few studies have demonstrated an increased risk, although a disability pension is payable to veterans who were present at nuclear tests and who develop leukaemia (other than chronic lymphocytic leukaemia). The aim of the study was to utilise data from the Scottish Veterans Health Study to examine the risk of lymphohaematopoietic malignancy following military service in a large national cohort of veterans.

METHODS

Retrospective cohort study of 57,000 veterans and 173,000 non-veterans born between 1945 and 1985 matched for age, sex and area of residence, adjusted for areal deprivation and followed up for up to 30 years, using Cox proportional hazard models to compare the risk of lymphohaematopoietic malignancy overall, by diagnosis and by sex and birth cohort.

RESULTS

We found no statistically significant difference in risk between veterans and non-veterans either for all leukaemias (Cox proportional hazard ratio 1.03, 95% confidence intervals 0.84-1.27, p=0.773), Hodgkin lymphoma (hazard ratio 1.19, 95% confidence intervals 0.87-1.61, p=0.272) or for non-Hodgkin lymphoma (hazard ratio 0.86, 95% confidence intervals 0.71-1.04, p=0.110).

CONCLUSION

Our findings provide reassurance that service in the UK Armed Forces is not associated with increased risk of lymphohaematopoietic malignancy.

Association of various risk factors with chronic lymphocytic leukemia and its cytogenetic characteristics

This study aimed to investigate whether occupational and environmental exposures, lifestyle, family, and medical history are associated with chronic lymphocytic leukemia (CLL) risk and its chromosomal abnormalities. The study included 138 CLL cases and 141 age- and sex-matched controls. Information data were collected through in-person interviews from cases and controls. Cytogenetic analysis was performed on CLL bone marrow cells. Positive associations were found between CLL and cancer family history, smoking, pneumonia, and exposure to petroleum, metals, pesticides/chemical fertilizers, detergents, and medical radiation. Chromosome deletions of 11q and 13q were more frequent in patients exposed to pesticides and rubber, respectively. This study investigated for the first time specific risk factors in relation to CLL aberrations and presented positive correlations. Moreover, it indicates the possible involvement of specific occupational and lifestyle risk factors in the onset of CLL.

Is cancer risk still reduced if you give up smoking in later life?

SUMMARY This report summarizes the experimental and epidemiological evidence examining the ability of smoking cessation to influence cancer risk reduction in later life. Available evidence suggests that smoking cessation even in later years can significantly reduce mortality and yield risk reductions for many cancers including lung, oral, head and neck, and stomach cancer, among others. More research is necessary to accurately quantify the degree of cancer risk reduction for particular age groups and to calculate the minimum time of cessation necessary to produce a significant benefit for the patient. Smoking cessation is the only approach that has been shown to effectively reduce the risk of many cancers on a mass scale. Considering this, we recommend that healthcare providers communicate these benefits to patients at every opportunity and reinforce the notion that it is never too late to quit smoking.

Risk of adult acute and chronic myeloid leukemia with cigarette smoking and cessation

BACKGROUND

Cigarette smoking is an established risk factor for adult myeloid leukemia, particularly acute myeloid leukemia (AML), but less is known about the nature of this association and effects of smoking cessation on risk.

METHODS

In a large population-based case-control study of myeloid leukemia that included 414 AML and 185 chronic myeloid leukemia (CML) cases and 692 controls ages 20-79 years, we evaluated risk associated with cigarette smoking and smoking cessation using unconditional logistic regression methods and cubic spline modeling.

RESULTS

AML and CML risk increased with increasing cigarette smoking intensity in men and women. A monotonic decrease in AML risk was observed with increasing time since quitting, whereas for CML, the risk reduction was more gradual. For both AML and CML, among long-term quitters (≥30 years), risk was comparable to non-smokers.

CONCLUSIONS

Our study confirms the increased risk of myeloid leukemia with cigarette smoking and provides encouraging evidence of risk attenuation following cessation.

Lifestyle and dietary factors in relation to risk of chronic myeloid leukemia in the NIH-AARP Diet and Health Study

BACKGROUND

Aside from exposure to ionizing radiation and benzene, little is known about lifestyle risk factors for chronic myeloid leukemia (CML) in the general population.

METHODS

We examined the relation between lifestyle and dietary risk factors for CML in 493,188 participants (294,271 males and 198,917 females) aged 50 to 71 years who completed a baseline questionnaire in the National Institutes of Health-AARP Diet and Health Study in 1995 to 1996. Over a median of 10.5 years of follow-up, 178 incident cases of CML (139 males and 39 females) were ascertained from state registries. We used Cox proportional hazards models to estimate hazard ratios and 95% confidence intervals for exposures of interest, adjusting for potential confounding variables.

RESULTS

In multivariable analysis of all participants combined, female sex, years of education, and vigorous physical activity (HR for ≥3 times/week vs. <1 time/week 0.70; 95% CI, 0.49-0.99) were inversely associated with risk of CML, whereas smoking intensity (HR for smokers of ≥20 cigarettes per day vs. never smokers: 1.53; 95% CI, 1.03-2.27) and body mass (HR for BMI ≥ 30 vs. <25 kg/m(2) 1.46; 95% CI, 0.95-2.23) were associated with increased risk. A range of dietary factors was not associated with disease.

CONCLUSIONS

This study adds to the sparse information about lifestyle factors, which affect the risk of CML in the general population.

IMPACT

If these findings are confirmed, it would suggest that CML may be amenable to preventive strategies.

Cigarette smoking as a cause of cancers other than lung cancer: an exploratory study using the Surveillance, Epidemiology, and End Results Program

BACKGROUND

Cigarette smoking is causally related to several cancers, particularly lung cancer, yet for some cancers there are inconsistent associations. This study investigates the association of smoking with other cancers by correlating them with the regional incidence rates for lung cancer, which was used as a proxy for cigarette smoking. This ecologic approach relating cigarette smoking to cancer using a large database avoids the limitations and bias present in case-control and cohort studies.

METHODS

Based on the assumption that regions with a high rate of lung cancer also have a high rate of cigarette smoking, our original hypothesis is that these high-intensity regions will also have high rates of other cancers if they are associated with cigarette smoking. Linear regression and correlation analysis of regional incidence rates for lung cancer, obtained from the Surveillance, Epidemiology, and End Results (SEER) Program, were plotted with incidence rates of other cancers to determine the association between lung cancer and the other cancers.

RESULTS

Cancers that have a strong correlation with cigarette smoking in the literature also demonstrate a strong correlation with lung cancer. These cancers included urinary bladder, laryngeal, esophageal, colorectal, and kidney cancer. A number of cancers showed a weak association with cigarette smoking, such as pancreatic and liver cancer. Other cancers showed no correlation, such as ovarian and prostate cancer.

CONCLUSIONS

Cancers that respectively showed a strong or absent correlation with lung cancer in the SEER Program were similarly strongly or weakly correlated with cigarette smoking in the literature. Cancers with borderline correlations show ambiguous results or confounding variables in the literature.

Parental smoking and childhood leukemia

Childhood leukemia is the most common cancer among children, representing 31% of all cancer cases occurring in children younger than the age of 15 years in the USA. There are only few known risk factors of childhood leukemia (sex, age, race, exposure to ionizing radiation, and certain congenital diseases, such as Down syndrome and neurofibromatosis), which account for only 10% of the childhood leukemia cases. Several lines of evidence suggest that childhood leukemia may be more due to environmental rather than genetic factors, although genes may play modifying roles. Human and animal studies showed that the development of childhood leukemia is a two-step process that requires a prenatal initiating event(s) plus a postnatal promoting event(s). Despite a substantial public health effort to reduce cigarette smoking, a large proportion of the US and world population still smoke. Tobacco smoke contains at least 60 known human or animal carcinogens, with the major chemical classes being volatile hydrocarbons, aldehydes, aromatic amines, polycyclic aromatic hydrocarbons, and nitrosamines; among these chemicals, only benzene is an established leukemogen, although other chemicals in the tobacco could interact with one another in a complex way to jointly attain a significant carcinogenic effect on the development of leukemia. Although tobacco smoke is an established risk factor for adult myeloid leukemia, the studies of association between parental smoking and childhood leukemia have produced inconsistent results. The majority of the studies on maternal smoking and childhood leukemia did not find a significant positive association and some even reported an inverse association. In contrast to studies of maternal smoking, studies of paternal smoking and childhood leukemia reported more positive associations but only by less than half of the studies. Future directions to be considered for improving the study of parental smoking and childhood leukemia are: 1) consider all sources of benzene exposure in addition to smoking, including occupational exposure and traffic exhausts; 2) childhood leukemia is a heterogeneous disease and epidemiologic studies of childhood leukemia can be greatly improved by grouping childhood leukemia into more homogeneous groups by molecular techniques (e.g., structural and numerical chromosomal changes); and 3) assess gene-environment interaction. It is hoped that through the continual effort, more will be uncovered regarding the causes of childhood leukemia. In the meantime, more effort should be spent on educating the parents to quit smoking, because parental smoking is known to affect many childhood diseases (e.g., asthma, respiratory tract infection, and otitis media) that are much more prevalent than childhood leukemia.

Chronic lymphocytic leukaemia: an overview of aetiology in light of recent developments in classification and pathogenesis

This overview of the epidemiology of chronic lymphocytic leukaemia (CLL) summarizes the evolution of classification and coding systems and describes the intersection of pathogenesis and aetiology. The role of the putative precursor to CLL, monoclonal B-cell lymphocytosis (MBL), is considered, and ideas for future investigations of the MBL-CLL relationship are outlined. We discuss the epidemiology of CLL, focusing on descriptive patterns and methodological considerations. Postulated risk factors are reviewed including the role of ionizing and non-ionizing radiation, occupational and environmental chemical exposures, medical conditions and treatments, and lifestyle and genetic factors. We conclude by raising key questions that need to be addressed to advance our understanding of CLL aetiology. Recommendations for future epidemiological studies are given, including the standardization of reporting of CLL across cancer registries, the clarification of the natural history of MBL, and the circumvention of the methodological shortcomings of prior epidemiological investigations in relation to radiation, chemical exposures and infectious agents.

Tobacco use, body mass index and the risk of malignant lymphomas--a nationwide cohort study in Sweden

In the search for risk factors involved in the etiology of lymphoproliferative malignancies there is still inconsistent evidence regarding effects of smoking tobacco, and the role of smokeless tobacco is poorly investigated. New evidence indicates that excess body weight increases the risk of NHL and HD. To determine if tobacco use of various forms and high Body Mass Index (BMI) affect the occurrence of these neoplasms, we conducted a prospective cohort study on over 330,000 Swedish construction workers included in the Construction Industry Working Environment and Health program. Information on smoking, snuff dipping, height and weight was gathered by self administered questionnaires together with personal interviews. Cancer incidence was ascertained through the year 2000 by record linkage to the nationwide Swedish Cancer Registry, Migration Registry and Cause of Death Registry. At the end of follow up, 1,309 subjects had been diagnosed with NHL (including chronic lymphocytic leukemia) and 205 with HD respectively. Age adjusted incidence rate ratios were computed using Cox proportional Hazard regression modeling. Smoking cigarette, pipe or cigar was not associated with NHL or HD. There was no evidence indicating a relation between quantity and duration of smoking and NHL or HD risk. No link was found between NHL and usage of smokeless tobacco. Having a BMI of 30 or higher did not convey excess risk of developing NHL or HD compared to normal weight (BMI 18.6-24.9). We conclude that tobacco smoking and high BMI do not entail an increased risk of NHL and HD. Our findings of a relation between the duration of snuff dipping and HD need further investigation.

Overview of smoking and all cancers

Tobacco consumption has been clearly implicated in the causation of many cancer types, with irrefutable evidence to support the association in multiple organ systems. Tobacco cessation leads to reduced cancer risk and improved survival of those under treatment for their already established cancers. As understanding of the mechanisms by which tobacco products cause cancer increases, clinicians may be able to identify those at highest risk for tobacco-related malignancies and allow for more focused interventions toward risk reduction among current tobacco users. This article reviews the carcinogens present in tobacco products, the mechanisms by which tobacco causes cancer, and the various tumor types causally related to tobacco use.

Causality of myelodysplasia and acute myeloid leukemia and their genetic abnormalities

New insights into causative factors for the development of myelodysplasia (MDS) and acute myeloid leukemia (AML), with associations to specific cytogenetic and genetic abnormalities have been obtained primarily from studies of patients with the therapy-related subsets of the two diseases. Current knowledge now makes it possible to distinguish between at least seven major genetic subgroups of MDS and AML, and has directed research towards more specific causative factors also for de novo MDS and AML.

Influence of cigarette smoking on the presentation and course of acute myeloid leukemia

BACKGROUND

It is known that cigarette smoking is associated with an approximately 50% increase in leukemia risk. In order to detect a possible influence of cigarette smoking on initial characteristics at the time of presentation and on the course of the disease, we conducted a retrospective study in 643 patients with newly diagnosed acute myeloid leukemia.

PATIENTS AND METHODS

The study comprised 339 males and 304 females (median age 59 years, range 18-84 years). Two hundred and ninety-six patients (46%), smoking at least one cigarette per day for 6 months, were considered as smokers, while 347 patients (54%) were non-smokers.

RESULTS

Cigarette smoking was significantly related to male gender (P <0.0001), professional occupancy (P = 0.002), presence of organomegaly (P = 0.01), and lower peripheral blood and bone marrow leukemic cell involvement (P = 0.007 and P = 0.0001, respectively). Leukemia of French-American-British (FAB) M1 subtype was more frequent in non-smokers (P = 0.005). Although not statistically significant, smokers tended to have lower leukocyte counts than non-smokers. No difference was noted in terms of complete remission rates between smokers and non-smokers (67% compared to 64%). However, a higher rate of severe pulmonary infection was observed in smokers during induction chemotherapy (P = 0.02). Cigarette smoking (>or=20 pack-years or smoking duration >or=30 years) was significantly associated with shorter disease-free survival (P = 0.03) and overall survival (OS; P = 0.02 and P = 0.004, respectively). Other characteristics associated with poor prognosis included mainly older age, unfavorable karyotype, secondary acute myeloid leukemia (AML) and elevated World Health Organization (WHO) performance status. Cigarette smoking was associated with shorter OS in younger adults, but did not significantly influence survival in patients >60 years old. Cigarette smoking worsened the poor OS in patients with unfavorable karyotype, but did not significantly influence the prognosis of other karyotypic risk groups. In a multivariate analysis, only karyotypic grouping and age remained of prognostic value for the occurrence of disease-free and overall survival.

CONCLUSIONS

Cigarette smoking has a deleterious effect on survival in AML by shortening complete remission duration and subsequent survival. It was associated with severe infections during aplasia. Leukemogenic compounds favoring complex karyotypic abnormalities could also be involved.

Tobacco use and cancer causation: association by tumour type

In the second part of our review we describe the association between tobacco use and risk of specific cancer types. There is evidence for an established association of tobacco use with cancer of the lung and larynx, head and neck, bladder, oesophagus, pancreas, stomach and kidney. In contrast, endometrial cancer is less common in women who smoke cigarettes. There are some data suggesting that tobacco use increases the risk for myeloid leukaemia, squamous cell sinonasal cancer, liver cancer, cervical cancer, colorectal cancer after an extended latency, childhood cancers and cancer of the gall bladder, adrenal gland and small intestine. Other forms of cancer, including breast, ovarian and prostate cancer, are unlikely to be linked to tobacco use.

The contribution of benzene to smoking-induced leukemia

Cigarette smoking is associated with an increased risk of leukemia; benzene, an established leukemogen, is present in cigarette smoke. By combining epidemiologic data on the health effects of smoking with risk assessment techniques for low-dose extrapolation, we assessed the proportion of smoking-induced total leukemia and acute myeloid leukemia (AML) attributable to the benzene in cigarette smoke. We fit both linear and quadratic models to data from two benzene-exposed occupational cohorts to estimate the leukemogenic potency of benzene. Using multiple-decrement life tables, we calculated lifetime risks of total leukemia and AML deaths for never, light, and heavy smokers. We repeated these calculations, removing the effect of benzene in cigarettes based on the estimated potencies. From these life tables we determined smoking-attributable risks and benzene-attributable risks. The ratio of the latter to the former constitutes the proportion of smoking-induced cases attributable to benzene. Based on linear potency models, the benzene in cigarette smoke contributed from 8 to 48% of smoking-induced total leukemia deaths [95% upper confidence limit (UCL), 20-66%], and from 12 to 58% of smoking-induced AML deaths (95% UCL, 19-121%). The inclusion of a quadratic term yielded results that were comparable; however, potency models with only quadratic terms resulted in much lower attributable fractions--all < 1%. Thus, benzene is estimated to be responsible for approximately one-tenth to one-half of smoking-induced total leukemia mortality and up to three-fifths of smoking-related AML mortality. In contrast to theoretical arguments that linear models substantially overestimate low-dose risk, linear extrapolations from empirical data over a dose range of 10- to 100-fold resulted in plausible predictions.

Tobacco and the risk of acute leukaemia in adults

Self-reported smoking histories were collected during face-to-face interviews with 807 patients with acute leukaemia and 1593 age- and sex-matched controls. Individuals who had smoked regularly at some time during their lives were more likely to develop acute leukaemia than those who had never smoked (odds ratio (OR) = 1.2, 95% confidence interval (CI) 1.0-1.4). The association was strongest for current smokers, defined here as smoking 2 years before diagnosis (OR = 1.4, 95% CI 1.1-1.7). With respect to the numbers of years smoked, risk estimates were raised in all groups except those who had smoked for fewer than 10 years. Similarly, the odds ratio decreased as the number of years 'stopped smoking' increased, falling to one amongst those who had given up smoking for more than 10 years. No significant linear trends were found, however, with either the numbers of years smoked or the numbers of years stopped smoking, and no significant differences were found between AML and ALL.

Second primary cancers in patients with lung carcinoma

BACKGROUND

There are only limited population-based data available regarding the risk of developing a second cancer after a diagnosis of lung carcinoma.

METHODS

Data collected from the Cancer Registry of the Swiss Canton of Vaud (comprised of approximately 600,000 inhabitants) were used to estimate the incidence of a second metachronous primary cancer following a diagnosis of lung carcinoma. Between 1974 and 1996, 5794 cases of lung carcinoma (occurring in 4728 males and 1066 females) were followed actively until the end of 1996.

RESULTS

One hundred seventy-five second primary neoplasms were registered (occurring in 146 males and 29 females). Significant excess rates were observed for all cancer sites (standardized incidence ratio [SIR] = 1.2), cancers of the oral cavity and pharynx (SIR = 2.7), and lung (SIR = 1.7). SIRs also were above unity for cancers of the esophagus (SIR = 1.8), pancreas (SIR = 1.5), bladder (SIR = 1.8), kidney (SIR = 2.3), and the female breast (SIR = 2.0). Excess rates for all cancer sites together and tobacco-related neoplasms were systematically higher at a younger age (< 60 years). The overall cumulative risk of lung cancer was 1.8% at 5 years and 4.7% at 10 years and was 5% and 11%, respectively, for any tobacco-related tumor. The estimates were consistent for squamous cell carcinoma and adenocarcinoma of the lung.

CONCLUSIONS

There were substantial excesses of second lung carcinomas as well as other major tobacco-related neoplasms, but not of colorectal carcinoma, prostate carcinoma, or lymphoid neoplasms after the diagnosis of a primary lung carcinoma. This study emphasizes the importance of smoking cessation even after a diagnosis of lung carcinoma.

Cancer, cigarette smoking and premature death in Europe: a review including the Recommendations of European Cancer Experts Consensus Meeting, Helsinki, October 1996

Cigarette smoking has been clearly and unambiguously identified as a direct cause of cancers of the oral cavity, oesophagus, stomach, pancreas, larynx, lung, bladder, kidney and leukaemia, especially acute myeloid leukaemia. Additionally, cigarette smoking is a direct cause of ischaemic heart disease (the commonest cause of death in western countries), respiratory heart disease, aortic aneurysm, chronic obstructive lung disease, stroke, pneumonia and cirrhosis and cancer of the liver. Cigarette smoking can kill in 24 different ways and, although smoking protects against several fatal and non-fatal conditions, the adverse effect of smoking on health is largely negative. In developed countries as a whole, tobacco is responsible for 24% of all male deaths and 7% of all female deaths: these figures rise to over 40% in men in some countries of central and eastern Europe and to 17% in women in the United States. The average loss of life of smokers is 8 years. Among United Kingdom doctors followed for 40 years, overall death rates in middle age were about three times higher among doctors who smoked cigarettes as among doctors who had never smoked regularly. About half of all regular cigarette smokers will eventually be killed by their habit. The important information is that it is never too late to stop smoking: among United Kingdom doctors who stopped smoking, even in middle age, there was a substantial improvement in life expectancy. World-wide, smoking is killing three million people each year and this figure is increasing. In most countries the worst is yet to come, since by the time the young smokers of today reach middle or old age there will be about 10 million deaths/year from tobacco. Approximately 500 million individuals alive today can expect to be killed by tobacco, 250 million of these deaths will occur in middle age. Tobacco is already the biggest cause of adult death in developed countries. Over the next few decades tobacco could well become the biggest cause of adult death in the world. For men in developed countries, the full effects of smoking can already be seen. Tobacco now causes one-third of all male deaths in middle age (plus one fifth in old age). Tobacco is a cause of about half of all male cancer deaths in middle age (plus one-third in old age). Of those who start smoking in their teenage years and keep on smoking, about half will be killed by tobacco. Half of these deaths will be in middle age (35-69) and each will lose an average of 20-25 years of non-smoker life expectancy. In non-smokers in many countries, cancer mortality is decreasing slowly and total mortality rapidly. The war against cancer is being won slowly: the effects of cigarette smoking are holding back this victory. Lung cancer now kills more women in the United States each year than breast cancer. For women in developed countries, the peak of the tobacco epidemic has not yet arrived. Tobacco now causes almost one-third of all deaths in women in middle age in the United States. Although it has only 5% of the world's female population, the United States has 50% of the world's deaths from smoking in women. Tobacco smoking is a major cause of premature death. Throughout Europe, in 1990 tobacco smoking caused three quarters of a million deaths in middle age (between 35 and 69). In the Member States of the European Union in 1990 there were over one quarter of a million deaths in middle age directly caused by tobacco smoking: there were 219700 in men and 31900 in women. There were many more deaths caused by tobacco at older ages. In countries of central and eastern Europe, including the former USSR, there were 441200 deaths in middle age in men and 42100 deaths in women. There is a need for urgent action to help contain this important and unnecessary loss of life. In formulating Recommendations, the European Cancer Experts Consensus Committee recognised that Tobacco Control depends on various parts of society and not only on the individual.

Comparing the smoking behavior of veterans and nonveterans

OBJECTIVES

The authors analyzed self-reported questionnaire data from the 1987 National Medical Expenditure Survey (NMES) to determine the smoking patterns of veterans.

METHODS

Using NMES data, the authors compared veterans versus nonveterans overall, women veterans versus women nonveterans, Vietnam-era veterans versus other veterans, and veterans whose usual source of medical care was the Department of Veterans Affairs (VA) system versus veterans who received care elsewhere.

RESULTS

The likelihood of ever having smoked cigarettes was higher for veterans than for nonveterans and for women veterans than for women nonveterans. The prevalence of current smoking was higher for veterans than for nonveterans and higher for those seeking care within the VA system than for other veterans.

CONCLUSIONS

Given the enormous health care costs associated with smoking, health promotion efforts should be developed to reduce the high rate of smoking among veterans--especially those who are consumers of VA health care.

Lymphohaematopoietic malignancies and quantitative estimates of exposure to benzene in Canadian petroleum distribution workers

OBJECTIVE

To evaluate the relation between mortality from lymphohaematopoietic cancer and long term, low level exposures to benzene among male petroleum distribution workers.

METHODS

This nested case control study identified all fatal cases of lymphohaematopoietic cancer among a previously studied cohort. Of the 29 cases, 14 had leukaemia, seven multiple myeloma, and eight non-Hodgkin's lymphoma. A four to one matching ratio was used to select a stratified sample of controls from the same cohort, controlling for year of birth and time at risk. Industrial hygienists estimated workplace exposures for benzene and total hydrocarbons, without knowledge of case or control status, for combinations of job, location, and era represented in all work histories. Average daily benzene concentrations ranged from 0.01 to 6.2 parts per million (ppm) for all jobs. Company medical records were used to abstract information on other potential confounders such as cigarette smoking, although the data were incomplete. Odds ratios (ORs) were calculated with conditional logistic regression techniques for several exposure variables.

RESULTS

Risks of leukaemia, non-Hodgkin's lymphoma, and multiple myeloma were not associated with increasing cumulative exposure to benzene or total hydrocarbons. For leukaemia, the logistic regression model predicted an OR of 1.002 (P < 0.77) for each ppm-y of exposure to benzene. Duration of exposure to benzene was more closely associated with risk of leukaemia than other exposure variables. It was not possible to completely control for other risk factors, although there was suggestive evidence that smoking and a family history of cancer may have played a part in the risk of leukaemia.

CONCLUSION

This study did not show a relation between lymphohaematopoietic cancer and long term, low level exposures to benzene. The power of the study to detect low-such as twofold-risks was limited. Thus, further study on exposures to benzene in this concentration range are warranted.

Occupational and environmental exposures and myelodysplasia: a case-control study

A case-control study of newly diagnosed myelodysplastic syndrome patients investigated lifetime exposures through occupation, environment or hobby by questionnaire, structured and semi-structured interview. The exposure histories of 400 individually matched pairs were compared. Increased or possibly increased odds ratios were observed for radiation (2.05, 95% confidence interval 1.16-3.76), halogenated organics (1.57, 0.97-2.57), metals (1.40, 0.99-2.00), several specific radiation exposures and individual chemicals and for childlessness (1.46, 1.01-2.11). Since myelodysplasia generally carries a poor prognosis, whether or not individuals convert to leukaemia or to other cancer, these findings add to previous reports of exposures implicated in the aetiology of leukaemia and add to the case for minimizing exposures to radiation and halogenated organics.

Drinking Water Contamination and the Incidence of Leukemia and Non-Hodgkin's Lymphoma

>A study of drinking water contamination and leukemia and non-Hodgkin's lymphoma (NHL) incidence (1979-1987) was conducted in a 75-town study area. Comparing incidence in towns in the highest trichloroethylene (TCE) stratum (>5 microg/l) to towns without detectable TCE yielded an age-adjusted rate ratio (RR) for total leukemia among females of 1.43 (95% CI 1.07-1.90). For females under 20 years old, the RR for acute lymphocytic leukemia was 3.26 (95% CI 1.27-8.15). Elevated RRs were observed for chronic myelogenous leukemia among females and for chronic lymphocytic leukemia among males and females. NHL incidence among women was also associated with the highest TCE stratum (RR = 1.36; 95% CI 1.08-1.70). For diffuse large cell NHL and non-Burkitt's high-grade NHL among females, the RRs were 1.66 (95% CI 1.07-2.59) and 3.17 (95% CI 1.23-8.18), respectively, and 1.59 (95% CI 1.04-2.43) and 1.92 (95% CI 0.54-6.81), respectively, among males. Perchloroethylene (PCE) was associated with incidence of non-Burkitt's high-grade NHL among females, but collinearity with TCE made it difficult to assess relative influences. The results suggest a link between TCE/PCE and leukemia/ NHL incidence. However, the conclusions are limited by potential misclassification of exposure due to lack of individual information on long-term residence, water consumption, and inhalation of volatilized compounds.

Cigarette smoking, leukemia, and multiple myeloma

To evaluate previously reported associations with cigarette smoking, the incidence of leukemia and multiple myeloma was determined with follow-up of up to 24 years of 57,224 never-smokers, 20,928 former smokers, and 64,839 current cigarette smokers who received multiphasic health checkups. Cigarette smoking was associated with the development of acute nonlymphocytic leukemia in men only (relative risk, 2.8; 95% confidence interval, 1.2 to 6.4). Chronic myeloid leukemia showed an association with smoking of borderline significance in men only. Chronic lymphocytic leukemia and multiple myeloma were not related to cigarette smoking. In the men with acute nonlymphocytic leukemia there was a suggestion of a dose-response relation but it was not statistically significant. The association of cigarette smoking with acute nonlymphocytic leukemia was not explained by alcohol or coffee consumption or exposure to occupational hazards. This study adds to the growing body of evidence that cigarette smoking predisposes to acute nonlymphocytic leukemia in men.

Multiple primary cancers in the Vaud Cancer Registry, Switzerland, 1974-89

Data collected by the Cancer Registry of the Swiss Canton of Vaud (whose population in 1980 was about 530,000 inhabitants) were used to estimate the incidence of second metachronous primary cancers following any specific neoplasm. Among 34,615 cases of incident neoplasms registered between 1974 and 1989 and followed through integrated active follow-up to the end of 1989, for a total of 118,241 person-years at risk, there were 2,185 second primaries (1,280 males, 905 females). For both sexes, the standardised incidence ratios (SIR) were significantly elevated by about 20%. Overall significantly elevated ratios were registered for cancers of the oral cavity and pharynx (SIR = 1.6 for males, 2.0 for females), oesophagus in males (SIR = 1.5), lung in males (SIR = 1.4), skin melanoma (SIR = 1.7 for males, 1.5 for females), non-melanomatous skin cancers (SIR = 1.6 for males, 1.5 for females), female breast (SIR = 1.3), kidney (SIR = 1.5 for males, 1.9 for females), and thyroid in males (SIR = 2.4). When specific first cancer sites were considered, the SIR following a cancer of the oral cavity and pharynx was around 3 in both sexes, mainly on account of a substantial excess of second primaries of the oral cavity, oesophagus, larynx and lung. The overall SIR following laryngeal cancer was 3.0, and significant excesses were observed for oral cavity and pharynx, oesophagus and lung. After lung cancer, the overall SIR was 1.7 for males and 2.6 for females, and significantly elevated SIRs were observed for oral cavity, lung and oesophagus. Following non-melanomatous skin cancers, elevated SIRs were observed in both sexes for skin melanoma and non-melanomas. The incidence of any cancer after breast cancer was significantly elevated (SIR = 1.2), mainly on account of an elevated risk of subsequent breast cancer (SIR = 1.7). With reference to cervical cancer, there was a significant excess for any subsequent primary (SIR = 1.6), and for lung cancer (SIR = 7.8). Significantly elevated SIRs were observed for kidney following bladder cancer, and for bladder after kidney cancer. In both sexes, the incidence of cancers of any site was elevated following leukaemias (SIR = 1.7 for males, 2.5 for females), and a significant excess was registered for lung in males and non-melanomatous skin cancers in both sexes.(ABSTRACT TRUNCATED AT 400 WORDS)

Chronic leukaemias

In recent years many subtypes of CLL and some CML variants have been recognized throughout the world by means of careful clinical, epidemiological, immunological, molecular biological and viral studies. Most striking has been the establishment of a close association between certain immunophenotypical subtypes of CLL and infection with HTLV-I and possibly HTLV-II. CLL has consistently been shown to have a strong genetic component and a low incidence among Asians, but a growing body of evidence also links this major leukaemia type with environmental factors including solvents, unidentified farming and other occupational exposures. In contrast, CML is characterized by few genetic associations, relatively homogenous world-wide distribution, greater frequency in Blacks than in Whites, little evidence of viral aetiology, and evidence that exposures to ionizing radiation, benzene and possibly other chemical agents are important aetiological factors. Most studies suggest that acquired rather than genetic factors are of greater importance in the aetiology of CML, but this conclusion is somewhat difficult to reconcile with the relatively small variation in incidence rates internationally. Common to both disorders in most populations are an increasing incidence with age, male predominance, and stability of incidence, survival and mortality over the years, exclusive of improved survival of CML following allogeneic bone marrow transplantation.

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.

Professional and consumer concerns about the environment, lifestyle, and cancer

Although it cannot be said that "everything causes cancer," our environment will never be carcinogen-free. As a result, there are many substances we come in contact with daily that could be potentially harmful to our health. Even with the growing knowledge of the mechanisms of carcinogenesis, it is difficult to single out the exact cancer-causing or -promoting effects of single substances. The confusion that exists about the environment, lifestyle, and cancer can be overwhelming for everyone. Garfinkel offered the following suggestions for health care providers to use in putting this issue into better perspective for consumers: (1) no single study of cancer risk factors should be used as a basis for writing or changing public health policy; (2) animal studies should be supportive of findings in epidemiological studies; (3) any environmental factor-cancer effect relationship should be demonstrated biologically; (4) regulatory agencies such as the EPA tend to be conservative in their interpretation of study results, and may suggest caution even when the risk of developing cancer is low; (5) regulatory agencies have been known to extrapolate future effects of carcinogen exposure from current incomplete or limited information about the carcinogen in question. With the knowledge that we do have, we must strive to take personal control over life-style factors that may cause cancer.

Perspectives on risk assessment impact of recent reports on benzene

Very sensitive methods that can detect the benzene metabolite muconic acid (MA) in the urine of virtually all members of the general population have recently become available and have been used in a few occupational studies as a marker of benzene exposure. Preliminary findings from these studies suggest that urinary MA may be a reliable marker of occupational exposure to greater than 5 ppm benzene. It was also consistently observed that a certain proportion of the general population have urinary MA levels compatible with those seen in persons occupationally exposed to greater than 1 ppm benzene. It is unlikely that these elevated levels can be explained solely as being artifactual. The frequency with which they occur for a given individual, and the duration with which they are maintained, are not known. Information on these two factors is needed in order to adequately assess whether or not these levels present a significant risk for a segment of the general population.

Cigarette smoking and leukemia: results from the Lutheran Brotherhood Cohort Study

In a 20-year follow-up (1966-86) of 17,633 White males who described tobacco use in a mailed questionnaire sent in 1966, there were 74 deaths from leukemia (including 30 myeloid, 30 lymphatic, and 14 other and unspecified leukemia). Among men who ever smoked cigarettes, increased risks were observed for lymphatic (relative risk [RR] = 2.7), and other and unspecified leukemia (RR = 1.5); risks rose with increasing number of cigarettes smoked, although the dose-response relationship was statistically significant only for total leukemia. Mortality from myeloid leukemia was not elevated, except among those smoking over a pack of cigarettes per day. Results from this cohort support a relationship between cigarette smoking and leukemia. Further studies are needed to elucidate subtype associations with cigarette smoking.

Mortality among petrochemical science and engineering employees

This is a study of a dynamic cohort of 13 250 commercial research and development personnel for whom information on occupational and educational background and smoking was available. Their age-, sex-, race-, and period-adjusted death rates were compared with New Jersey rates and with an internal comparison population. The overall results were favorable. The study groups had significantly fewer deaths from most major disease categories compared with other New Jersey residents. Among white male scientists and engineers, age-adjusted overall mortality and ischemic heart disease mortality were comparable to white male managers and support staff studied, whereas mortality from leukemia and lymphatic cancer was significantly elevated. Mechanics, however, had a significantly lower leukemia and lymphatic cancer mortality rate than did the comparison group. In a Poisson regression model in which white males and females from the study population were used, and for which the effects of age, smoking, college education category, period of hire, and years employed were controlled, scientists, engineers, and research technicians had elevated (nonsignificantly) mortality rates for leukemia and lymphatic cancer compared with managers and support staff. Smoking was an independent risk factor for leukemia and lymphatic cancer. Further work is needed to assess if specific environmental factors, such as benzene, other aromatics, radiation, medical treatment, and smoking habits, might have contributed to the above findings.

[Tobacco and leukemia]

Although some epidemiological studies have published findings supporting the hypothesis that smokers are at a higher risk of developing leukemia, the causal relationship between tobacco and leukemia has not been considered conclusive due to the weak association found, to the lack of a dose-response relationship and to the inconsistencies found throughout the different studies. However, most of these studies were not specifically designed to establish the tobacco-leukemia relationship and therefore their capacity to evaluate this hypothesis is rather limited. This hypothesis could be supported by the fact that tobacco causes cancer in sites which are not in direct contact with tobacco smoke. Likewise, the presence of benzene and radioactive compounds would provide some biologic plausibility to the hypothesis that tobacco could be a cause of leukemia. However, since the etiology of leukemia is not well understood, the small excess risk detected may be confounded by some uncontrolled factor.

Association between smoking and leukemia in two American Cancer Society prospective studies

The association between smoking and leukemia in men and women was analyzed from the data of two prospective studies. Myeloid leukemia was positively associated with smoking in men in both studies (standardized mortality ratios [SMR], 2.44 and 1.32; P less than 0.05), but not with smoking in women. Lymphatic leukemia showed no elevation in risk in men and women in both studies. Animal studies suggest a real biologic difference in leukemogenic effect between the sexes, but further analyses are needed to characterize the smoking effect of leukemia in women.

Cigarette smoking, blast crisis, and survival in chronic myeloid leukemia

We reviewed the records of all patients with chronic myeloid leukemia (CML) seen in the CML Clinic of the University of Colorado Health Sciences Center between 1968 and 1987 for a history of cigarette smoking. Patients who smoked for five or more pack/years within the ten years preceding, or after the diagnosis of CML, were defined as smokers. Adequate smoking histories were obtained on 122 patients. Eighty-seven of these were non-smokers and 35 were smokers by the above criteria. The smoking group had a higher predominance of males, an older median age, and were diagnosed earlier in the course of the 20 year study. Seventy-two patients had died at the time of analysis. All but one, a non-smoker, died from the development of blast crisis. The overall median actuarial survival was significantly reduced for smokers (35 months) as compared to non-smokers (47 months). This was particularly striking for patients who had succumbed to the disease, with a median survival of 30 months in smokers versus 46 months in non-smokers. Although various explanations could explain the differences noted, we conclude that cigarette smoking has an adverse effect on the development of blast crisis and survival in chronic myeloid leukemia.

Determination of benzene, toluene and 1,3-butadiene in cigarette smoke by GC-MDS

An analytical procedure was devised for the determination of selected gas phase constituents in cigarette smoke utilizing capillary gas chromatography and mass selective detection (GC-MSD); the MSD was used in the selective ion monitoring mode (SIM). The gas of freshly generated mainstream smoke was analyzed via a 10-port gas sampling valve on a puff-by-puff basis. Benzene, toluene, and 1,3-butadiene were found in the range of 6-73, 5-88, and 16-75 micrograms/cigarette, respectively. The gas phase of sidestream smoke was trapped in methanol using 3 midget impingers at -78 degrees C. Benzene in sidestream smoke was found in the range of 490-840 micrograms/cigarette; toluene and 1,3-butadiene levels were 1,090-1,690 and 300-470 micrograms/cigarette, respectively. Environmental tobacco smoke (ETS), sampled in a smoke-filled bar, was analyzed using the cold trap method. The concentrations of benzene and toluene in this indoor air were found to be 26-36 and 41-80 micrograms/m3, respectively, while 1,3-butadiene was present at 3.3-4.5 micrograms/m3.