Cigarette smoking and risk of leukemia

Second Malignancies and Richter's Syndrome in Patients with Chronic Lymphocytic Leukemia

Second malignancies are frequent complications in patients with chronic lymphocytic leukemia (CLL). Patients with this leukemia may develop large cell lymphoma (LCL) known as Richter's syndrome (RS). RS occurs in CLL patients of about 3% and may develop in a single lymph node or more often in a group of nodes. However, in some patients extranodal localization of aggressive lymphoma in RS has been observed. Besides LCL, Hodgkin's disease, prolymphocytoid leukemia, multiple myeloma and acute lymphoblastic leukemia may also occur as RS variants. The origin of lymphoid cells in RS remains tentative. However, CLL and RS originate from the same clone for some patients, whereas, in other patients cells of aggressive lymphoma do not have the features of the same clone as the CLL cells. The prognosis of RS is poor. Survival in different studies will be usually 2-5 months. The secondary development or coexistence of myeloproliferative disorders or myelodysplastic syndrome and solid tumors have also been rarely documented in CLL patients. It is of great concern that therapy may further increase the risk of a second neoplasm. However, until now, there are no clear evidence that alkylating agents or purine nucleoside analogs may be associated with an increased incidence of second malignancies in patients with CLL. In this review, epidemiology, biology, clinical characteristic and treatment approaches in RS and other secondary neoplasms in patients with CLL are discussed.

Formaldehyde as a potential human leukemogen: an assessment of biological plausibility

The International Agency for Research on Cancer (IARC, 2004) recently reevaluated the epidemiological data on formaldehyde and concluded that there was "strong but not sufficient evidence for a causal association between leukaemia and occupational exposure to formaldehyde." This conclusion was tempered since a mechanism for leukemia induction could not be identified. Chemically induced leukemia is a well-studied phenomenon with benzene and a number of cancer chemotherapeutic drugs recognized as capable of causing this effect. Abundant in vitro and in vivo data in animals and humans demonstrate that exposure to sufficient doses of these recognized leukemogens can initiate a cascade of events leading to hematopoietic toxicity and the subsequent development of leukemia. This review addresses the biological plausibility that formaldehyde might be capable of causing any type of leukemia by providing a broad overview of the scientific data that must be considered in order to support or refute a conclusion that a particular substance might be leukemogenic. Data on benzene and selected chemotherapeutic cancer drugs are used as examples and are briefly summarized to demonstrate the similar biological events thought to result in leukemogenesis. These data are compared and contrasted with the available data on formaldehyde in order to judge whether they fulfill the criteria of biological plausibility that formaldehyde would be capable of inducing leukemia as suggested by the epidemiological data. Based on the epidemiological data, it is reasonable to expect that if formaldehyde was capable of inducing leukemia, in vivo and in vitro data would offer supporting evidence for biological plausibility. In particular, there is (1) no evidence to suggest that formaldehyde reaches any target organ beyond the site of administration including the bone marrow, (2) no indication that formaldehyde is toxic to the bone marrow/hematopoietic system in in vivo or in vitro studies, and (3) no credible evidence that formaldehyde induces leukemia in experimental animals. As discussed in this review, based on the key biological events that occur in the process of chemically induced leukemia, there is inadequate biological evidence currently available to corroborate existing weak epidemiological associations. This provides an insufficient database to conclude that there is a causal relationship for formaldehyde and leukemia risk.

Second malignancies and Richter's syndrome in patients with chronic lymphocytic leukaemia treated with cladribine

The increased frequency of second malignancies in chronic lymphocytic leukaemia (CLL) is well known. Moreover, antineoplastic therapy additionally increases the risk of secondary cancers. In this study, we analysed whether treatment with cladribine (2-chlorodeoxyadenosine, 2-CdA) during the course of CLL had an impact on the subsequent occurrence of either secondary solid tumours or Richter's syndrome. There were 1487 eligible patients, 251 treated with 2-CdA alone, 913 treated with alkylating agents (AA)-based regimens alone and 323 treated with both 2-CdA and AA. Median time from the start of CLL treatment to the diagnosis of secondary malignancy was 1.9 years (0.5-5.1 years) for the 2-CdA group, 1.8 years (0.3-7.9 years) for the AA group and 3.9 years (0.3-8.4 years) for the 2-CdA+AA group. A total of 68 malignancies were reported in 65 patients. Ten events were non-melanotic skin cancers and were excluded from the analysis, leaving 58 events in 58 patients. In the group of patients treated with 2-CdA alone, there were 15 (6.0%) cases, in the group of patients treated with AA alone there were 26 (2.8%) cases, and in the group treated with 2-CdA+AA there were 17 (5.3%) cases of secondary malignancies. The differences between the frequency of secondary malignancies in the 2-CdA and 2-CdA+AA versus AA alone groups were not significant (P=0.05 and P=0.06, respectively). Only lung cancers occurred significantly more frequently in the 2-CdA (2.8%) and 2-CdA+AA (2.2%) treated groups compared with the AA patients (0.3%) (P<0.001 and P<0.01, respectively). In conclusion, 2-CdA in CLL patients does not seem to increase the risk of secondary malignancies except for lung cancers. However, further studies are necessary to establish the real risk of lung cancer in CLL patients treated with 2-CdA.

A multicenter case-control study in Italy on hematolymphopoietic neoplasms and occupation

We conducted a population-based, case-control study on hematolymphopoietic malignancies in 12 areas in Italy to investigate associations between different hematolymphopoietic malignancies and exposure to solvents and pesticides. We collected all incident cases 20-74 years of age from 12 areas, with a combined population of approximately 7 million residents. The control group was formed by a random sample of the study population. Data presented in this paper refer to 2,737 interviewed cases of 3,357 eligible cases and to 1,779 of 2,391 eligible controls. We analyzed risks associated with occupation using job-title information to evaluate disease pattern according to job category. An earlier publication presented results for women; here, we report the findings for men and discuss the overall patterns in both genders. The most consistent overall finding was an approximate doubling in relative risk for all four types of malignancies among male managers and related occupations. Several additional occupations were associated with elevated risk of one or more malignancies among men. These included cooks, waiters, and bartenders, and building caretakers and cleaners, for non-Hodgkin's lymphoma; textile workers and machinery fitters for Hodgkin's lymphoma; metal processors, material handlers, rubber workers, and painters for leukemia; and hairdressers, metal processors, tailors, electrical workers, and plumbers for multiple myeloma. The finding of increased risk of non-Hodgkin's lymphoma among both male and female cooks, waiters, and bartenders has not been previously reported; nor has the elevated risk of leukemia among material handlers. Among people engaged in agriculture, those employed as tractor drivers and as "orchard, vineyard, and related tree and shrub workers" appeared to be at increased risk for hematolymphopoietic malignancies.

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.

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.

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.

Is cigarette smoking a risk factor for non-Hodgkin's lymphoma or multiple myeloma? Results from the Lutheran Brotherhood Cohort Study

Among 17,633 U.S. white male insurance policy holders whose use of tobacco was characterized in a 1966 self-administered questionnaire, there were 49 deaths from non-Hodgkin's lymphoma (NHL) and 21 from multiple myeloma (MM) during a 20-year follow-up. Men who had ever smoked cigarettes had an elevated mortality from NHL (RR = 2.1; CI = 0.9-4.9), with risk almost four-fold greater among the heaviest smokers (RR = 3.8; CI = 1.4-10.1) compared with those who used no tobacco. In contrast, risk of MM was only slightly elevated among those who had ever smoked cigarettes (RR = 1.3; CI = 0.4-3.9) and without evidence of a dose-response trend. Since this is the first cohort study suggesting a link between cigarette smoking and NHL and findings from case-control studies have been inconsistent, additional clarification should be sought from larger incidence-based cohort investigations.

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.

[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.