A case-control study of myelodysplastic syndromes among Japanese men and women

[Environmental and occupational risk factors for myelodysplastic syndrome]

Chemotherapy and radiotherapy for a previous cancer can lead to subsequent myelodysplastic syndrome (MDS). However, these therapy-related cases are hypothesized to explain only 5 % of diagnosed MDS cases. Environmental or occupational exposure to chemicals or radiations has also been reported to be associated with higher risk of MDS. The present review analyses those studies evaluating the association of MDS with environmental or occupational risk factors. There is sufficient evidence that environmental or occupational exposure to ionizing radiation or benzene can cause MDS. Tobacco smoking is also a sufficiently documented riskfactor for MDS. A positive association has been reported between exposure to pesticides and MDS. However, there is only limited evidence that this association could be causal.

The Impact of Sedentary Lifestyle, High-fat Diet, Tobacco Smoke, and Alcohol Intake on the Hematopoietic Stem Cell Niches

Hematopoietic stem and progenitor cells maintain hematopoiesis throughout life by generating all major blood cell lineages through the process of self-renewal and differentiation. In adult mammals, hematopoietic stem cells (HSCs) primarily reside in the bone marrow (BM) at special microenvironments called “niches.” Niches are thought to extrinsically orchestrate the HSC fate including their quiescence and proliferation. Insight into the HSC niches mainly comes from studies in mice using surface marker identification and imaging to visualize HSC localization and association with niche cells. The advantage of mouse models is the possibility to study the 3-dimensional BM architecture and cell interactions in an intact traceable system. However, this may not be directly translational to human BM. Sedentary lifestyle, unhealthy diet, excessive alcohol intake, and smoking are all known risk factors for various diseases including hematological disorders and cancer, but how do lifestyle factors impact hematopoiesis and the associated niches? Here, we review current knowledge about the HSC niches and how unhealthy lifestyle may affect it. In addition, we summarize epidemiological data concerning the influence of lifestyle factors on hematological disorders and malignancies.

The importance of evaluating specific myeloid malignancies in epidemiological studies of environmental carcinogens

INTRODUCTION

Although myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), myeloproliferative neoplasms (MPN) - including chronic myeloid leukemia (CML) - and myelodysplastic/myeloproliferative neoplasms (MDS/MPN) are largely clinically distinct myeloid malignancies, epidemiological studies rarely examine them separately and often combine them with lymphoid malignancies, limiting possible etiological interpretations for specific myeloid malignancies.

METHODS

We systematically evaluated the epidemiological literature on the four chemical agents (1,3-butadiene, formaldehyde, benzene, and tobacco smoking, excluding pharmaceutical, microbial and radioactive agents, and pesticides) classified by the International Agency for Research on Cancer as having sufficient epidemiological evidence to conclude that each causes "myeloid malignancies." Literature searches of IARC Monographs and PubMed identified 85 studies that we critically assessed, and for appropriate subsets, summarized results using meta-analysis.

RESULTS

Only two epidemiological studies on 1,3-butadiene were identified, but reported findings were inadequate to evaluate specific myeloid malignancies. Studies on formaldehyde reported results for AML and CML - and not for MDS or MPN - but reported no increased risks. For benzene, several specific myeloid malignancies were evaluated, with consistent associations reported with AML and MDS and mixed results for CML. Studies of tobacco smoking examined all major myeloid malignancies, demonstrating consistent relationships with AML, MDS and MPN, but not with CML.

CONCLUSIONS

Surprisingly few epidemiological studies present results for specific myeloid malignancies, and those identified were inconsistent across studies of the same exposure, as well as across chemical agents. This exercise illustrates that even for agents classified as having sufficient evidence of causing "myeloid malignancies," the epidemiological evidence for specific myeloid malignancies is generally limited and inconsistent. Future epidemiological studies should report findings for the specific myeloid malignancies, as combining them post hoc - where appropriate - always remains possible, whereas disaggregation may not. Furthermore, combining results across possibly discrete diseases reduces the chances of identifying important malignancy-specific causal associations.

Risk factors for de novo and therapy-related myelodysplastic syndromes (MDS)

PURPOSE

Myelodysplastic syndromes (MDS) are classified as de novo and therapy-related (tMDS). We evaluated associations between MDS risk factors separately for de novo and tMDS.

METHODS

The study population included 346 de novo MDS cases, 37 tMDS cases and 682 population controls frequency matched by age and sex. Polytomous logistic regression was performed to calculate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

After adjustment, former smoking status (OR = 1.45, 95% CI: 1.10-1.93), personal history of autoimmune disease (OR = 1.34, 95% CI: 0.99-1.82) and exposure to benzene (OR = 1.48, 95% CI: 1.00-2.19) were associated with de novo MDS. Risk estimates for the associations between smoking, autoimmune disease, and benzene exposure were similar in magnitude but non-significant in tMDS cases. Among individuals with a previous diagnosis of cancer, de novo MDS cases and controls were more likely to have had a previous solid tumor, while tMDS cases more commonly had a previous hematologic malignancy.

CONCLUSIONS

We observed similar associations between smoking, history of autoimmune disease and benzene exposure in de novo and tMDS although estimates for tMDS were imprecise due to small sample sizes. Future analyses with larger sample sizes will be required to confirm whether environmental factors influence risk of tMDS.

Alcohol use is not a significant contributor to myelodysplastic syndromes

PURPOSE

Myelodysplastic syndromes (MDS) are a class of clonal neoplastic disorders of largely unknown etiology, and published data remain inconclusive regarding the association between lifetime alcohol consumption and MDS risk. In these analyses, data from a population-based case-control study were used to investigate this association.

METHODS

Eligible cases of MDS were identified through the Minnesota Cancer Reporting System; controls were matched by sex and age-decile. A central review process was used to confirm MDS diagnosis and classify subtypes. Unconditional and polytomous logistic regression were used to calculate odds ratios (OR) and 95% confidence intervals (CI). Kaplan-Meier curves were used to compare survival by category of lifetime alcohol consumption.

RESULTS

In total, 398 cases of MDS and 698 controls were included. Alcohol consumption at 23-30, 31-49, and 50-65 years of age, recent consumption 1 year before diagnosis/interview, and lifetime consumption were not found to be significantly associated with MDS in males (OR range 0.63-0.99) or females (OR range 0.58-1.70). Analysis by MDS subtype further suggested there was not a significant association between recent alcohol consumption and odds of disease by subtype (OR range 0.39-1.13). Lifetime alcohol consumption was not significantly associated with survival after diagnosis of MDS CONCLUSIONS: Previously reported associations between alcohol consumption and MDS risk were inconsistent. Results from our analyses by sex and disease subtype do not support alcohol as a significant contributor to risk of MDS.

Occupational, dietary, and other risk factors for myelodysplastic syndromes in Western Greece

PURPOSE

We have observed an increasing incidence of myelodysplastic syndromes (MDS) in the geographic area of Western Greece during the past two decades. The objective of this study was to investigate potential risk factors for the manifestation of MDS in this area of Greece.

METHODS

A hospital-based case-control study was conducted in the public hospitals of the region. Participants were interviewed based on a questionnaire regarding demographics, occupational exposures, smoking, alcohol consumption, dietary, and domestic factors.

RESULTS

A total of 228 individuals (126 cases, 102 controls) were recruited in this study. Univariate analysis showed that risk of MDS was associated with a family history of hematologic malignancy or solid tumor, exposure to pesticides, insecticides, herbicides, increased weekly intake of meat and eggs, and increased alcohol intake, whereas fruit intake had a protective effect. Analysis by pesticide ingredient showed a weak association of exposure to paraquat and glyphosate with the occurrence of MDS. Multivariate analysis showed that independent risk factors for the manifestation of MDS were family history of solid tumor (OR 2.47, 95% CI 1.32-4.65), meat intake for ≥5 days/week (OR 2.67, 95% CI 1.05-6.80) and exposure to pesticides (OR 3.25, 95% CI 1.73-6.11).

CONCLUSIONS

Exposure to pesticides is a major risk factor of MDS in Western Greece. Family history of solid tumor and increased meat intake also appear to play a role in the pathogenesis of MDS. Public health authorities should implement policies to advise and protect farmers from the harmful effects of agrochemicals. Emphasis should also be given to health promotion advice including healthy eating.

[Management of myelodysplastic syndromes]

Myelodysplastic syndromes are heterogeneous diseases whose molecular characteristics have only been identified in recent years. Better identification of prognostic factors, larger access to allogeneic stem cell transplantation and the advent of new drugs notably hypomethylating agents (azacitidine, decitabine) and lenalidomide have improved patient outcome.

Alcohol consumption and risk of myelodysplastic syndromes: A meta-analysis of epidemiological studies

Previous studies on the association between alcohol intake and the risk of myelodysplastic syndromes (MDS) have been inconclusive. We conducted a meta-analysis to evaluate alcohol intake as a risk factor for MDS. We performed a systematic literature search of articles published before March, 2014 using Web of Science, PubMed and the Cochrane Library. Two evaluators independently selected and reviewed studies based on predetermined selection criteria. The fixed- or random-effects models were used to summarize the estimates of odds ratios (ORs) with 95% confidence intervals (CIs). A total of 9 studies (8 case-control and 1 cohort) met the inclusion criteria of this meta-analysis. No significant association was observed between alcohol consumption and MDS when comparing drinkers to non-drinkers (OR=1.16, 95% CI: 0.88-1.53) or between subgroups stratified by alcohol history, gender, ethnicity, study design, source of patients or MDS subtypes. However, the data indicated a stronger association of alcohol with MDS in individuals who consumed ≥10 g/day (OR=1.55, 95% CI: 1.08-2.21) vs. those who consumed <10 g/day (OR=1.09, 95% CI: 0.78-1.53). This meta-analysis suggests that alcohol intake may increase the risk of MDS in a dose-dependent manner. However, additional well-designed, prospective cohort studies are required to verify these findings and identify other risk factors associated with MDS.

A Meta-Analysis of the Relationship between Cigarette Smoking and Incidence of Myelodysplastic Syndromes

BACKGROUND

In recent years, epidemiologic studies have reported controversial results relating cigarette smoking to myelodysplastic syndromes (MDS) risk. A meta-analysis was performed to assess such potential relationship between cigarette smoking and incidence of MDS.

METHODS

A search of literature published before October 2012 for observational studies evaluating the association between cigarette smoking and MDS, returned 123 articles and of these, 14 were selected for this study. The outcomes from these studies were calculated and reported as odds ratios (OR). Quality assessments were performed with the Newcastle-Ottawa Scale. Heterogeneity was evaluated by the I(2) index and source of heterogeneity was detected by sensitivity analyses. Finally, publication bias was assessed through visual inspection of funnel plots and Egger's test.

RESULTS

The pooled OR of developing MDS in ever-smokers was 1.45 (95% CI, 1.25 to 1.68) versus non-smokers. Current and former smokers had increased risks of MDS, with ORs of 1.81 (95% CI, 1.24 to 2.66) and 1.67 (95% CI, 1.42 to 1.96), respectively. In subset analyses, ever-smokers had increased risks of developing MDS if they were living in the United States, or in Europe, female in gender, had refractory anemia (RA)/RA with ringed sideroblasts (RARS) or RA with excess blasts (RAEB)/RAEB in transformation (RAEBt), respectively. Our results demonstrated that the association was stronger in individuals who smoked ≥20 cigarettes/day (OR, 1.62; 95% CI, 1.03 to 2.55) versus those who smoked <20 cigarettes/day (OR, 1.36; 95% CI, 1.13 to 1.64). Moreover, individuals who smoked more than 20 pack-years had increased MDS risk (OR, 1.94; 95% CI, 1.29 to 2.92).

CONCLUSION

Our outcomes show that smoking increases the risk of developing MDS in ever-smokers who are current or former smokers. We also demonstrate here that positive association between cigarette smoking and risk of MDS exists, and occurs in a dose-dependent manner.

Epidemiology of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) comprise a heterogeneous group of clonal hematopoietic stem cell malignancies with significant morbidity and high mortality. The incidence of MDS increases markedly with age, and the disease is most prevalent in individuals who are white and male. It is conservatively estimated that >10,000 new cases of MDS occur in the United States annually, and that ≥ 60,000 individuals with MDS currently reside in the country. With an aging population and an improving awareness of the disease, the documented disease burden is expected to escalate in the near future. Recent studies have identified new or inconsistent etiologic factors that warrant further research. Given the poor survival of individuals with MDS, it is important to identify prognostic factors to better risk-stratify patients for more effective treatment. The relevance of different comorbidities to MDS prognosis and the potential interaction between various comorbidities represents an interesting area of research.

Hair dye use and risk of human cancer

Over 50% of the adult population will use hair dyes at some point in their lifetimes. Hair dyes consist of various chemicals and the composition of these chemicals vary by hair dye types. Chemicals p-phenylenediamine and aminophenyl have been suggested as possible carcinogens or mutagens in experimental studies. The scientific community has been interested in this potential public health impact and the results of published epidemiological studies are summarized here. The current evidence provides limited evidences on the association between personal hair dye use and human cancer risk, except for the possibility of hematopoietic cancers and to a lesser extent, bladder cancer. Risk appears to be affected by time period of use and by specific genetic polymorphisms. Future studies should investigate potential gene and environment interaction to assess possible genetic susceptibility. Several methodological issues should also be considered in future studies including completed hair dye use information such as on timing, duration, frequency and type of hair dye product use.

Case-control study of risk factors of myelodysplastic syndromes according to World Health Organization classification in a Chinese population

Risk factors of mydelodysplastic syndromes (MDS) remain largely unknown. We conducted a hospital-based case-control study consisting of 403 newly diagnosed MDS patients according to World Health Organization classification and 806 individually gender and age-matched patient controls from 27 major hospitals in Shanghai, China, to examine relation of lifestyle, environmental, and occupational factors to risk of MDS. The study showed that all MDS (all subtypes combined) risk factors included anti tuberculosis drugs [odds ratio (OR)(adj) = 3.15; 95% confidence interval (CI) = 1.22-8.12] as an independent risk factor, benzene (OR(adj) = 3.73; 95% CI = 1.32-10.51), hair dye use (OR = 1.46; 95% CI = 1.03-2.07), new building and renovations (OR = 1.69; 95% CI = 1.11-2.00), pesticides (OR = 2.16; 95% CI = 1.22-3.82), and herbicides (OR = 5.33; 95% CI = 1.41-20.10) as relative risk factors. Risk factors of MDS subtype refractory cytopenia with multiple dysplasia (RCMD) were benzene (OR(adj) = 5.99; 95% CI = 1.19-30.16) and gasoline (OR(adj) = 11.44; 95% CI = 1.31-100.03) as independent risk factors, and traditional Chinese medicines (OR = 2.17; 95% CI = 1.15-4.07), pesticides (OR = 2.92; 95% CI = 1.37-6.25), and herbicides (OR = 12.00; 95% CI = 1.44-99.67) as relative risk factors. Smoking tobacco was significantly associated with refractory anemia with excess of blasts (RAEB) (OR(adj) = 2.43; 95% CI = 1.02-5.77). Education is shown as an independent protective factor against all MDS (OR(adj) = 0.90; 95% CI = 0.83-0.99) and RCMD (OR(adj) = 0.89; 95% CI = 0.79-0.99). These findings suggest that multiple modifiable behavioral, environmental, and occupational factors play a role in MDS etiology, and various MDS subtypes may have different susceptibility.

Alcohol, signaling, and ECM turnover

Alcohol is recognized as a direct hepatotoxin, but the precise molecular pathways that are important for the initiation and progression of alcohol-induced tissue injury are not completely understood. The current understanding of alcohol toxicity to organs suggests that alcohol initiates injury by generation of oxidative and nonoxidative ethanol metabolites and via translocation of gut-derived endotoxin. These processes lead to cellular injury and stimulation of the inflammatory responses mediated through a variety of molecules. With continuing alcohol abuse, the injury progresses through impairment of tissue regeneration and extracellular matrix (ECM) turnover, leading to fibrogenesis and cirrhosis. Several cell types are involved in this process, the predominant being stellate cells, macrophages, and parenchymal cells. In response to alcohol, growth factors and cytokines activate many signaling cascades that regulate fibrogenesis. This mini-review brings together research focusing on the underlying mechanisms of alcohol-mediated injury in a number of organs. It highlights the various processes and molecules that are likely involved in inflammation, immune modulation, susceptibility to infection, ECM turnover and fibrogenesis in the liver, pancreas, and lung triggered by alcohol abuse.

Obesity, lifestyle factors, and risk of myelodysplastic syndromes in a large US cohort

The etiology of myelodysplastic syndromes (MDS) is not well understood. The authors examined the relations of obesity and lifestyle factors to MDS in a cohort of 471,799 persons aged 50-71 years who were recruited into the National Institutes of Health-AARP Diet and Health Study, a large US prospective study, in 1995-1996. Incident MDS was diagnosed in 193 persons during 2001-2003. A significant positive association was observed between body mass index (BMI; weight (kg)/height (m)(2)) at baseline and MDS. Compared with persons with a BMI less than 25.0, the hazard ratios for persons with BMIs of 25.0-<30.0 and >or=30.0 were 1.15 (95% confidence interval (CI): 0.81, 1.64) and 2.18 (95% CI: 1.51, 3.17; P for trend < 0.001), respectively. The association was not affected by physical activity, cigarette smoking, or alcohol intake. As reported in previous studies, the risk of MDS was elevated among former smokers (hazard ratio = 1.68, 95% CI: 1.17, 2.41) and current smokers (hazard ratio = 3.17, 95% CI: 2.02, 4.98) as compared with never smokers. Physical activity, alcohol consumption, meat intake, and fruit and vegetable intake did not appear to significantly influence the risk of MDS in this analysis. This prospective investigation of MDS implicates both obesity and smoking as modifiable risk factors.

Personal use of hair dye and cancer risk in a prospective cohort of Chinese women

Although widely studied over the past 40 years, personal use of hair dye generally has not been associated with overall cancer risk. The association between hair dye use and risk of bladder and hematopoietic cancers has been less conclusive. Most hair dye studies have been case-control studies conducted in Caucasian populations. We examined the relationship between personal hair dye use and cancer risk in a prospective cohort of 70,366 Chinese women. After an average of 7 years of follow up, 2437 women were newly diagnosed with cancer by 31 December 2005. Cox proportional hazard models were used to estimate relative risks (RR) and 95% confidence intervals (CI) of cancer risk associated with hair dye use, adjusting for potential confounding factors. Compared with women who reported no hair dye use, ever users had an overall cancer risk of 0.89 (95% CI 0.82, 0.97). No significant association was observed for several common cancers, including cancers of the breast (RR 0.93, 95% CI 0.78, 1.09), lung (RR 0.81, 95% CI 0.62, 1.09), stomach (RR 0.90, 95% CI 0.66, 1.21), and colorectum (RR 1.04, 95% CI 0.84, 1.28). We also found no significant association with most other cancers, including bladder cancer (RR 1.14, 95% CI 0.56, 2.35) and hematopoietic cancers overall (RR 0.89, 95% CI 0.59, 1.35) or their subtypes, including non-Hodgkin lymphoma, multiple myeloma, and leukemia. We generally found no evidence of an association between personal use of hair dye and cancer risk, although our study is limited by small numbers for certain cancer types.

Smoking as a risk factor for myelodysplastic syndromes and acute myeloid leukemia and its relation to cytogenetic findings: a case-control study

In this case-control study, interview data on smoking habits were available for 179 de novo cases (116 with cytogenetic data) of acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS). Smoking habits were compared with a pooled set of population controls and hospital controls (diagnosed with malignant melanoma). Each pack-year of smoking increased the risk of MDS with 1.3% (95% CI 0.1-2.6%), corresponding to an estimated excess risk of 71% (95% CI 3-180%) for 40 pack-years. Associations between smoking and the specific aberrations -5/5q-, -7/7q-, and +8 in AML and MDS were indicated but the estimates were imprecise.

Epidemiology of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are one of the most common hematological conditions among the elderly. Differences in disease classification and diagnosis have made population-based studies an arduous endeavor. A variety of risk factors have been linked with increased risk (smoking and exposure to solvents and agrochemicals) or decreased risk of MDS (wine drinking), but the majority of cases remain unexplained. One area that has not been explored is the influence of diet in MDS development. Much still needs to be learned about what causes MDS and the genetic factors that increase susceptibility. Multi-institutional studies with a molecular-epidemiologic approach are necessary to develop a MDS risk predictive model.

Personal hair dye use and cancer: a systematic literature review and evaluation of exposure assessment in studies published since 1992

Hair dyes are widely used, and permanent hair dye is the most commonly used type of product. Permanent hair dye colors are formed by an oxidative process involving arylamines, giving rise to concerns about the potential adverse health effects of long-term exposure, especially cancer. A 1993 International Agency for Cancer Research (IARC) review concluded that evidence was inadequate to evaluate the carcinogenicity of personal hair dye use. This systematic review synthesizes the results from studies of personal hair dye use and cancer published since 1993, taking into consideration the quality of exposure assessment. Thirty-one English-language articles published in January 1992-February 2005 that investigated the association between personal hair dye use and cancer were identified through the PubMed search engine. Quality of exposure assessment was rated between 1+ (lowest quality: assessed ever use of hair dyes) and 4+ (highest quality: assessed dye type [permanent/nonpermanent], dye color/shade, frequency and duration of use). Because of the heterogeneity of the exposure assessment across the studies, a formal meta-analysis was not conducted. Associations between personal hair dye use and non-Hodgkin's lymphoma, multiple myeloma, acute leukemia, and bladder cancer were observed in at least one well-designed study with detailed exposure assessment (rated 3+ or 4+), but were not consistently observed across studies. Results for bladder cancer studies suggest that subsets of the population may be genetically susceptible to hair dye exposures, but these findings are based on small subgroups in one well-designed case-control study. Replication of these findings is needed to determine whether the reported associations are real or spurious.

A case-control study of myelodysplastic syndromes in Belgrade (Serbia Montenegro)

The objective of the study was to investigate factors related to the occurrence of myelodysplatic syndromes (MDS) in the population of Belgrade (Serbia Montenegro). The case-control study was conducted during the period 2000-2003. The study group consisted of 80 newly diagnosed MDS patients and 160 sex- and age-matched hospital controls with nonmalignant and noninfectious diseases. The disease categories in the control group were circulatory (51 patients, 32%), gastrointestinal (53 patients, 33%), and ophthalmological (56 patients, 35%) disorders. Conditional univariate and multivariate logistic regression analyses were applied. Multivariate analysis showed the following factors to be significantly related to MDS: exposure to chemicals (OR = 10.8, 95%CI 3.2-36.2, p = 0.0001), viral upper respiratory tract infections (twice a year or more, OR = 5.8, 95%CI 2.5-13.6, p = 0.0001), exposure to insecticides, pesticides and herbicides (OR = 5.2, 95%CI 1.8-15.1, p = 0.003), coffee (OR = 5.1, 95%CI 1.9-13.7, p = 0.001), and alcohol consumption (OR = 2.2, 95%CI 1.1-4.6, p = 0.033). The findings support the hypotheses that exposure to chemical agents, pesticides, insecticides, and herbicides, certain lifestyle factors (alcohol and coffee consumption), and frequent viral infections may be involved in the etiology of MDS, but these results should be confirmed by further investigations.

Occupational exposures and haematological malignancies: overview on human recent data

OBJECTIVE

Occupational causes of haematological malignancies are relatively uncommon, under-studied and under-identified. They are also often unrecognized by clinicians. This review summarizes the principal epidemiologic studies on this topic.

METHODS

We analyzed the recent relevant human data found in the Medline, the Pascal and the BDSP databases.

RESULTS

Benzene and ionizing radiation are the only agents conclusively demonstrated to be carcinogenic to the haematopoietic system. In particular, both exposures are strongly associated with acute myeloid leukaemia. Low doses of both may also be related to myeloid malignancies. Infectious agents and pesticides are also thought to induce lymphoproliferative cancers. Some studies show an association between haematological malignancies and low-frequency electromagnetic fields and organic solvents. All of these suspected occupational causes must be confirmed by further studies.

CONCLUSIONS

Better knowledge and understanding of occupational causes of haematological malignancies are necessary to improve their prevention and compensation.

Risk factors of myelodysplastic syndromes: a case-control study

Little is known about the etiology of myelodysplastic syndromes (MDS). A hospital-based case-control study of 354 adult de novo MDS cases and 452 controls was conducted to investigate associations between lifestyle characteristics and MDS risk. The distribution by French-American-British (FAB) type was 67 (19%) refractory anemia (RA), 38 (11%) refractory anemia with ringed sideroblasts (RARS), 43 (12%) chronic myelomonocytic leukemia (CMML), 136 (38%) RA with excess blasts (RAEB), and 70 (20%) RAEB in transformation (RAEBT). Multivariate logistic regression analyses were performed among all MDS cases and among each FAB type and gender. For all MDS combined, family history of hematopoietic cancer (odds ratio (OR) = 1.92), smoking (OR = 1.65), and exposure to agricultural chemicals (OR = 4.55) or solvents (OR = 2.05) were associated with MDS risk. Among RA/RARS cases, smoking (OR = 2.23) and agricultural chemical exposure (OR = 5.68) were the only risk factors identified. For RAEB/RAEBT cases, family history of hematopoietic cancer (OR = 2.10), smoking (OR = 1.52), and exposure to agricultural chemicals (OR = 3.79) or solvents (OR = 2.71) were independent risk factors. Drinking wine reduced risk for all FAB types by almost 50% (OR = 0.54). We found a joint effect between smoking and chemical exposure with the highest risk among smokers exposed to solvents/agricultural chemicals (OR = 3.22). Results from this large study suggest that several factors play a role in MDS predisposition with possible joint effects. Risk profiles seem to differ by FAB type and gender.

Oxidative stress and the myelodysplastic syndromes

The evolution of higher organisms from anaerobic to aerobic living has promoted an elaborate mechanism of defense against potentially toxic oxidants. Many environmental toxicants implicated in the pathogenesis of myelodysplastic syndromes (MDS), including benzene and ionizing radiation, exert toxicity via pro-oxidant mechanisms. The emerging data suggest a probable genetic susceptibility to environmental carcinogenesis through functional polymorphic variants in enzymes that metabolize toxicants and/or protect against oxidative stress. The most studied enzyme is NAD(P)H:quinone oxidoreductase (NQO1). CD34+ cells from individuals homozygous for the NQO1 C609T nonfunctional allelic variant are incapable of enzyme induction following exposure to benzene, thus potentially increasing the hematotoxicity of benzene metabolites. Serologic and molecular markers of oxidative stress are present in many patients with MDS and include an increased concentration of the lipid peroxidation product malondialdehyde and the presence of oxidized bases in CD34+ cells. Potential mechanisms of oxidative stress include mitochondrial dysfunction via iron overload and mitochondrial DNA mutation, systemic inflammation, and bone marrow stromal defects. The biological activity of the antioxidant aminothiol amifostine in vivo suggests that these pathways may be meaningful targets for future therapy in MDS patients.

Stem cell transplantation for leukemias following myelodysplastic syndromes or secondary to cytotoxic therapy

Two main forms of therapy-related myelodysplastic syndrome and acute myeloid leukemia (t-MDS/AML) have been recognized. The most frequent type, occurring after treatment with alkylating agents, is characterized by abnormalities of chromosomes 5 and/or 7 and t-MDS/AML following treatment with topoisomerase II inhibitors and is associated with molecular aberrations of MLL (11q23) and AML-1 (21q22). Individuals with certain polymorphisms associated with impaired detoxification of cytotoxic agents have an increased risk of developing MDS or AML after treatment of unrelated cancers. Multidrug chemotherapy is less effective for patients with MDS, or AML following MDS, or t-MDS/AML when compared with primary AML, and results in lower complete remission (CR) rates and lower long-term survival. Patients with good risk cytogenetic features, such as t(15; 17), t(8; 21) and inversion 16 are an exception as their treatment outcome is comparable with primary AML patients. Patients who attain a polyclonal and/or a cytogenetic CR may be candidates for autologous stem cell transplantation. For the remaining patients, the only curative option is allogeneic stem cell transplantation with stem cells from a histocompatible sibling or an alternative donor. Reduced intensity conditioning regimens may be considered for patients older than 50 years or patients with comorbidities. The advice is to treat patients early after diagnosis and preferably before progression as these patients have the highest chance of a favorable outcome.

Occupational and environmental risk factors of the myelodysplastic syndromes in the North of France

Aetiological factors of the myelodysplastic syndromes (MDS) are largely unknown, with the exception of alkylating agents, ionizing radiation and benzene. Some other risk factors have been suggested by the few epidemiological studies reported (solvents, ammonia, exhaust gases, metals, pesticides, alcohol). We performed a case-control study to assess the relationship between occupational or environmental factors and MDS. Two hundred and four patients with newly diagnosed MDS, and 204 sex- and age-matched controls were included. Medical history, demographic data, lifetime exposure and hobbies were obtained. Qualitative and quantitative exposure to chemical and physical hazards were evaluated with the patients and reviewed by a group of experts in occupational exposure. The median age was 70 years and 62% of the patients were men. In univariate analyses, we found relationships between MDS and smoking habits, gardening, occupations such as health professionals, technical and sale representatives, machine operators, agricultural workers, textile workers, qualitative occupational exposures (exposed/non-exposed) to oil, solvents, ammonia, pesticides, fertilizers, cereal dusts, contact with poultry or livestock and infective risk, and lifetime cumulative exposure to solvents, oil, textile dust and infective risk. The main risk factors of MDS determined by multivariate analyses (conditional logistic regression) were, being an agricultural worker [odds ratio (OR) = 3.66; 95% confidence interval (CI) 1.9-7.0], textile operator (OR = 3.66; 95% CI 1.9-7.9), health professional (OR = 10.0; 95% CI 2.1-48.7), commercial and technical sale representative (OR = 4.45; 95% CI 1.4-14.6), machine operator (OR = 2.69; 95% CI 1.2-6.0), living next to an industrial plant (OR = 2.45; 95% CI 1.5-4.1), smoking (OR = 1.74; 95% CI 1.1-2.7) and lifetime cumulative exposure to oil (OR = 1.1; 95% CI 1.0-1.2). Further studies should be performed to assess specific exposures more precisely and it would be of interest to develop a map of haematological malignancies according to industrial background.

Use of hair dyes, hematopoietic neoplasms, and lymphomas: a literature review. I. Leukemias and myelodysplastic syndromes

We review published epidemiologic studies on personal use of hair dyes and leukemias and myelodysplastic syndromes (MDS). A subsequent article will review studies on lymphomas and multiple myeloma. A computerized literature search for the years 1966 through 1996 was completed using MEDLINE. Data were extracted using a standardized form that recorded study design, study population, type of cases, comparison group, sources of data on personal exposure to hair dyes, method of data collection, type of exposure data collected, covariates, and results. The above search identified 13 epidemiologic studies on the possible association between personal use of hair dyes and leukemias and MDS. Although there are some reports of positive associations, overall the evidence linking personal use of hair dyes to various leukemia and MDS subgroups is weak. One cannot definitively rule out an association, however, because of the methodologic limitations, such as small numbers of exposed cases and lack of detailed exposure information. Any further research would need much better assessment of hair dye use, including product type, color frequency, duration, and changes in use over time, and adequate statistical power.

Smoking and myelodysplastic syndromes

The purpose of this case-control study was to investigate tobacco smoking as a risk factor for myelodysplastic syndromes, emphasizing karyotypic aberrations as markers for exposure and risk differentiation with respect to morphology. We obtained smoking history by interview of 330 cytogenetically investigated adult myelodysplastic syndrome cases and 337 controls, matched with respect to sex, year of birth, and county of living. Smoking for at least 1 year at some time 20 years or less before diagnosis was associated with an elevated relative risk (RR) for primary myelodysplastic syndromes (odds ratio (OR) 1.8; 95% confidence interval (CI) = 1.2-2.7). The results indicated a relation with intensity and duration of smoking as well as a decrease in risk a few years after cessation of smoking. Smoking was associated with an increased RR for primary myelodysplastic syndromes with chromosome 7 abnormalities (OR 5.0; 95% CI = 1.1-23). Elevated RRs were also seen for refractory anemia (OR 2.5; 95% CI = 1.2-5.6) and for refractory anemia with ringed sideroblasts (OR 3.2; 95% CI = 0.88-12). The findings suggest that smoking is a risk factor for myelodysplastic syndromes.

Hair dye use and occupational exposure to organic solvents as risk factors for myelodysplastic syndrome

To investigate the relationships of personal hair dye use and environmental factors to myelodysplastic syndromes (MDS), we conducted a case-control study in Japan. A total of 111 MDS cases and 830 controls randomly selected from the residents in the same prefecture of cases using telephone directories responded to a health questionnaire. The odds ratio (OR) for ever having used hair dye was 1.99 (95% confidence interval (CI) 1.17-3.38) and there were statistically significant trends in risk with increasing duration and number of hair dye use. Occupational exposure to organic solvents was marginally associated with the risk of MDS (OR = 1.99; 95% CI 0.97-4.10).