Occupational risk for hematological malignancies

Assessment of a Systematic Screening of Occupational Exposures in Malignant Hemopathies in the Rhone-Alpes Area: Prolymphome Study

BACKGROUND

Several studies have highlighted the role of environmental exposures in malignant hemopathies etiology. Some patients with malignant hemopathies can be compensated as occupational diseases. The Prolymphome research aimed to assess a systematic screening of occupational exposures in patients with lymphoma or myeloma treated in three hospitals in the Rhône-Alpes region.

METHODS

Patients received a self-administered questionnaire to fill in at home to collect their job history and potential occupational exposures to carcinogens. A physician assessed the questionnaire to determine if a dedicated consultation was required and the possibility of claiming compensation. Patients were systematically assisted by a social worker for administrative procedures.

RESULTS

In 12 months, 754 patients were enrolled in the study, and 361 (48%) returned the questionnaire. A specialized consultation was proposed for 123 patients, and 98 patients attended the consultation. Overall, a compensation claim was proposed to 18 patients: 11 have been occupationally exposed to pesticides and seven to trichloroethylene.

CONCLUSIONS

Our results confirmed the feasibility of the systematic screening procedure. Barriers were observed at every step of the process, and it underlined that patients are rarely  nformed about occupational exposures. As the prevalence of occupational exposures in malignant hemopathies remains scarce, a systematic targeted screening could be relevant in this population.

Fertilizers and Human Health-A Systematic Review of the Epidemiological Evidence

BACKGROUND

Fertilizers are widely used to supply nutrients to crops, thereby increasing yields and soil fertility. However, the effects of their production and application on human health through occupational, residential, and environmental exposure remain unclear.

OBJECTIVE

To conduct a systematic review of epidemiological studies on the association between exposure to fertilizers and health-related outcomes.

METHODS

We searched in PubMed, Scopus, and Web of Science for cohort, case-control, cross-sectional, and ecological studies (up to May 2024) related to exposure to fertilizers and any reported human health endpoints across all age groups, without language or geographical limitations. Data were extracted for population and study characteristics, type of fertilizer used, exposure assessment, sample size, outcome and its definition, effect estimate, and quality characteristics from the eligible studies, and they were descriptively synthesized.

RESULTS

We found 65 eligible publications, with 407 postulated associations. Forty-six publications (321 associations) assessed exposure to inorganic fertilizers, and nineteen studies (93 associations) assessed organic fertilizers. Exposure assessed was related to occupation, residence, and/or proximity. The assessed outcomes were diverse, with considerable harmonization challenges. Inorganic fertilizers have been associated with an increased risk of cancerous outcomes in a small number of studies with methodological limitations and low replication validity, while organic fertilizers have been associated with infections and diarrhea.

CONCLUSIONS

The epidemiological evidence suggests possible associations between inorganic fertilizers with solid organ tumors and hematological malignancies and organic fertilizers with infections and diarrhea. However, the available evidence is limited, and heterogeneity prevails. Further research is needed to enlarge the evidence base and increase the replication validity and robustness of the results.

[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.

Monoclonal Gammopathy of Undetermined Significance: A Comprehensive Review

Monoclonal Gammopathy of Undetermined Significance (MGUS) is an asymptomatic premalignant plasma cell dyscrasia with a predominate rise of the IgG immunoglobulin fraction without end-organ damage, often diagnosed incidentally. Despite its progression into various subsequent forms of hematological malignancies, MGUS remains underdiagnosed. A literature search was conducted using the Medline, Cochrane, Embase, and Google Scholar databases, including articles published until December 2022. Keywords used encompassed "Monoclonal Gammopathy of Undetermined Significance," "Plasma Cell dyscrasia," "Monoclonal gammopathy of renal significance," and "IgM Monoclonal gammopathy of Undetermined Significance," This study aimed to conduct a critical review to update knowledge regarding the pathophysiology, risk factors, clinical features, diagnostic protocols, complications, and current and novel treatments for MGUS. We recommend a multidisciplinary approach to manage MGUS due to the complexity of the illness's etiology, diagnosis, and therapy. This comprehensive review also highlights future prospects, such as developing screening protocols for at-risk populations, prevention of disease progression by early diagnosis through genome-wide association studies, and management using Daratumumab and NSAIDs.

Modifiable Lifestyle and Medical Risk Factors Associated With Myeloproliferative Neoplasms

Despite the identification of acquired genetic mutations associated with Myeloproliferative Neoplasms (MPNs) there is a paucity of information relating to modifiable risk factors that may lead to these mutations. The MOSAICC Study was an exploratory case-control study of polycythemia vera (PV), essential thrombocythemia (ET), and Myelofibrosis (MF). MPN patients and population controls (identified by General Practitioners) and non-blood relative/friend controls were recruited from 2 large UK centers. Participants completed a telephone-based questionnaire analyzed by unconditional logistic regression analysis adjusting for potential confounders. Risk factors for MPNs identified included increasing childhood household density [odds ratio (OR) 2.55, 95% confidence interval (CI) 1.16–5.62], low childhood socioeconomic status (OR 2.30, 95%CI 1.02–5.18) and high pack years smoking (OR 2.19, 95%CI 1.03–4.66) and current smoking restricted to JAK2 positive PV cases (OR 3.73, 95%CI 1.06–13.15). Obesity was linked with ET (OR 2.59, 95%CI 1.02–6.58) confirming results in previous cohort studies. Receipt of multiple CT scans was associated with a strongly increased risk of MPN although with wide confidence intervals (OR 5.38, 95%CI 1.67–17.3). Alcohol intake was inversely associated with risk of PV (OR 0.41, 95%CI 0.19–0.92) and ET (OR 0.48, 95%CI 0.24–0.98). The associations with childhood household density, high pack years smoking and alcohol were also seen in multivariate analysis. This is the largest case control study in MPNs to date and confirms the previously reported associations with obesity and cigarette smoking from cohort studies in addition to novel associations. In particular, the role of smoking and JAK2 mutation cases merits further evaluation.

Animal farming and the risk of lymphohaematopoietic cancers: a meta-analysis of three cohort studies within the AGRICOH consortium

OBJECTIVE

Animal farming entails a variety of potential exposures, including infectious agents, endotoxins and pesticides, which may play a role in the aetiology of lymphohaematopoietic cancers (LHCs). The aim of this study was to assess whether farming specific animal species is associated with the risk of overall LHC or its subtypes.

METHODS

Data from three prospective cohort studies in the USA, France and Norway which are part of the Agricultural Cohort consortium and which collected information about animal farming and cancer were used. Analyses included 316 270 farmers and farm workers. Adjusted Cox models were used to investigate the associations of 13 histological subtypes of LHC (n=3282) with self-reported livestock (cattle, pigs and sheep/goats) and poultry (ever/never and numbers raised) farming. Cohort-specific HRs were combined using random-effects meta-analysis.

RESULTS

Ever animal farming in general or farming specific animal species was not meta-associated with overall LHC. The risk of myeloid malignancies decreased with increasing number of livestock (p trend=0.01). Increased risk of myeloproliferative neoplasms was seen with increasing number of sheep/goats (p trend <0.01), while a decreased risk was seen with increasing number of livestock (p trend=0.02). Between cohorts, we observed heterogeneity in the association of type of animal farmed and various LHC subtypes.

CONCLUSIONS

This large-scale study of three prospective agricultural cohorts showed no association between animal farming and LHC risk, but few associations between specific animal species and LHC subtypes were observed. The observed differences in associations by countries warrant further investigations.

Abnormal Plasma Cell Disorders in Refinery Waste Workers

A monoclonal gammopathy of undetermined significance (MGUS) may develop into a multiple myeloma or a correlated lymphoproliferative malignancy with a progress rate of 1% per year. The immune status, occupational-environmental risk factors, and hereditary factors may influence the risk of developing MGUS. We investigated the prevalence of MGUS in 77 refinery waste workers. They were all males, averagely aged 36, with a mean working history of 18.5 years and working in the dump for about 4.2 years. After analyzing the results of standard serum electrophoresis migrations, 16% of cases (n = 12) showed levels beyond the normal ranges. In all 12 samples we observed an increase of gamma component: 67%, IgG; 17%, IgM; 8%, IgA; 8%, oligoclonal. Workers were exposed to hazardous refinery waste. After the biological monitoring of urine samples for metals and t,t-muconic acid, no extra-range values were observed. The multivariate analysis shows, however, that cigarette smoking and residence near industrial sites are significantly (p < 0.001) associated with a high risk of MGUS development; while no association was found with occupational exposure. Additional attention might be paid in particular to these conditions in epidemiological studies and further larger, prospective, population-based researches appear warranted to evaluate the strength of any positive association.

Shanghai Health Study (2001-2009): What was learned about benzene health effects?

The Shanghai Health Study (SHS) was a large epidemiology study conducted as a joint effort between the University of Colorado and Fudan University in Shanghai, China. The study was funded by members of the American Petroleum Institute between 2001 and 2009 and was designed to evaluate the human health effects associated with benzene exposure. Two arms of the SHS included: an occupational-based molecular epidemiology study and several hospital-based case control studies. Consistent with historical literature, following sufficient exposure to relatively high airborne concentrations and years of exposure, the SHS concluded that exposure to benzene resulted in an increased risk of various blood and bone marrow abnormalities such as benzene poisoning, aplastic anemia (AA), myelodysplastic syndrome (MDS), and acute myeloid leukemia (AML). Non-Hodgkin lymphoma (NHL) was not significantly increased for the exposures examined in this study. Perhaps the most important contribution of the SHS was furthering our understanding of the mechanism of benzene-induced bone marrow toxicity and the importance of identifying the proper subset of MDS relevant to benzene. Investigators found that benzene-exposed workers exhibited bone marrow morphology consistent with an immune-mediated inflammatory response. Contrary to historic reports, no consistent pattern of cytogenetic abnormalities was identified in these workers. Taken together, findings from SHS provided evidence that the mechanism for benzene-induced bone marrow damage was not initiated by chromosome abnormalities. Instead, chronic inflammation, followed by an immune-mediated response, is likely to play a more significant role in benzene-induced disease initiation and progression than previously thought.

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.

Working environment and myeloproliferative neoplasm: A population-based case-control study following a cluster investigation

BACKGROUND

Occupational exposures, including those to polycyclic aromatic hydrocarbons (PAH), are suspected risk factors for myeloproliferative neoplasms (MPN).

METHODS

We investigated occupational exposures and MPN risk (54 cases and 472 controls) in a population-based case-control study in three rural Pennsylvania counties. Occupational histories, coded to SIC/SOC 1980, were linked to a previously created PAH job-exposure matrix. Odds ratios for industry (17 categories), occupation (26 categories), and PAH exposure were adjusted using logistic regression.

RESULTS

No industries or occupations were strongly or consistently associated with increased MPN risk. Analysis of employment duration found that being employed for 5 or more years in transportation, communications, and other public utilities was associated with MPN risk. There was no indication of an association with cumulative PAH exposure.

CONCLUSIONS

These few associations did not appear to have a common exposure. This exploratory study does not support the hypothesis that occupational exposure, including PAH, are strong risk factors for MPNs.

The role of genotypes that modify the toxicity of chemical mutagens in the risk for myeloproliferative neoplasms

BACKGROUND

The etiology of myeloproliferative neoplasms (MPN) (polycythemia vera; essential thrombocythemia; primary myelofibrosis) is unknown, however they are associated with a somatic mutation--JAK2 V617F--suggesting a potential role for environmental mutagens.

METHODS

We conducted a population-based case-control study in three rural Pennsylvania counties of persons born 1921-1968 and residing in the area between 2000-2008. Twenty seven MPN cases and 292 controls were recruited through random digit dialing. Subjects were genotyped and odds ratios estimated for a select set of polymorphisms in environmentally sensitive genes that might implicate specific environmental mutagens if found to be associated with a disease.

RESULTS

The presence of NAT2 slow acetylator genotype, and CYP1A2, GSTA1, and GSTM3 variants were associated with an average 3-5 fold increased risk.

CONCLUSIONS

Exposures, such as to aromatic compounds, whose toxicity is modified by genotypes associated with outcome in our analysis may play a role in the environmental etiology of MPNs.

Evaluation of monoclonal and oligoclonal gammopathies in a pediatric population in a major urban center

OBJECTIVES

A growing body of literature has documented monoclonal proteins in children. Little is known about their associated diagnoses.

METHODS

We retrospectively evaluated all patients (aged 0-21 years) with abnormal findings on serum immunofixation electrophoresis (SIFE) from 2005 to 2011. We also documented the monoclonal immunoglobulin classes and light chain types involved and then correlated these data with the clinical diagnoses.

RESULTS

A total of 695 SIFE tests were performed on this patient population. Of these, 95 SIFE tests (14%) identified a gammopathy (from 83 different patients), and of these, 74 (11%) demonstrated only a monoclonal gammopathy (from 63 different patients). The most common associated diagnosis in the study interval was ataxia-telangiectasia (22%). No patient in the study population was diagnosed with multiple myeloma or Waldenström macroglobulinemia.

CONCLUSIONS

The significance and presence of a monoclonal or oligoclonal gammopathy in pediatric and young adult populations is distinct from that seen in adults.

Pesticide induced alterations in marrow physiology and depletion of stem and stromal progenitor population: an experimental model to study the toxic effects of pesticide

Long-term exposure of agriculturally used organochloride and organophosphate pesticides have been shown to cause long-lasting hematotoxicity and increased incidence of aplastic anemia in humans. The mechanisms involved in pesticide induced hematotoxicity and the features of toxicity that may play a major role in bone marrow suppression are not known. The aim of the present study was to investigate the hematological consequences of pesticide exposure in swiss albino mice exposed to aqueous mixture of common agriculturally used pesticides for 6 h/day, 5 days/week for 13 weeks. After the end of last exposure, without a recovery period, the strong hematotoxic effect of pesticide was assessed in mice with long-term bone marrow explant culture (LTBMC-Ex) system and cell colony forming assays. Bone marrow explant culture from the pesticide exposed group of mice failed to generate a supportive stromal matrix and did not produce adequate number of hematopoietic cells and found to contain largely the adipogenic precursors. The decreased cell colony numbers in the pesticide exposed group indicated defective maturational and functional status of different marrow cell lineages. As a whole, exposure of mice to the mixture of pesticides reduced the total number of bone marrow cells (granulocytes are the major targets of pesticide toxicity), hematopoietic, and non-hematopoietic progenitor cells and most of the hematological parameters. Replication of primitive stem/progenitor cells in the marrow was decreased following pesticide exposure with G0/G1-phase arrest of most of the cells. The progenitor cells showed decreased percentage of cells in S/G2/M-phase. The increased apoptosis profile of the marrow progenitors (Increased CD95 expression) and primitive stem cells (High Annexin-V positivity on Sca1+ cells) with an elevated intracellular cleaved caspase-3 level on the Sca1+ bone marrow cells provided the base necessary for explaining the deranged bone marrow microenvironmental structure which was evident from scanning electron micrographs. These results clearly indicate a strong, long lasting toxic effect of pesticides on the bone marrow microenvironment and different microenvironmental components which ultimately leads to the formation of a degenerative disease like aplastic anemia.

Anthropometric, medical history and lifestyle risk factors for myeloproliferative neoplasms in the Iowa Women's Health Study cohort

Classical myeloproliferative neoplasms (MPNs) are composed of essential thrombocythemia (ET), polycythemia vera (PV) and myelofibrosis (MF), the etiology of which is largely unknown. We investigated the role of anthropometric, medical and lifestyle factors with risk of MPN in a prospective cohort of 27,370 women aged 55-69 years at enrollment. After >250,000 person-years of follow-up, 257 cases of MPN were identified (172 ET, 64 PV, 21 MF). Risk factor profiles were mostly unique for the two most common types, ET and PV. ET was associated with energy balance factors including body mass index (RR = 1.52 for >29.3 vs. <23.4 kg/m(2) ; p-trend = 0.042), physical activity (RR = 0.66 for high vs. low; p-trend = 0.04) and adult onset diabetes (RR = 1.82; p = 0.009), while PV was not. PV was associated with current smoking (RR = 2.83; p-trend = 0.016), while ET was not. Regular use of aspirin was associated with lower risk of ET (RR = 0.68; p = 0.017). These results broadly held in multivariate models. Our results suggest distinct etiologies for these MPN subtypes and raise mechanistic hypotheses related to obesity-related inflammatory pathways for ET and smoking-related carcinogenic pathways for PV. Regular aspirin use may lower risk for ET.

Precursors to lymphoproliferative malignancies

We review monoclonal B-cell lymphocytosis (MBL) as a precursor to chronic lymphocytic leukemia and monoclonal gammopathy of undetermined significance (MGUS) as a precursor to plasma cell disorders. These conditions are present in the general population and increase with age. These precursors aggregate with lymphoproliferative malignancies in families suggesting shared inheritance. MBL and MGUS may share some of the same risk factors as their related malignancies but data are limited. Although these conditions are characterized by enhanced risk for the associated malignancy, the majority of individuals with these conditions do not progress to malignancy. A key focus for current work is to identify markers that predict progression to malignancy.

Environmental, lifestyle, and familial/ethnic factors associated with myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) are characterized by overproduction of mature functional blood cells and are often associated with an acquired genetic mutation of Janus Kinase 2(V617F). The etiology of MPNs remains unknown. The aim of this article was to review and collate all known published data investigating environmental and lifestyle factors associated with MPNs. Medline, Embase, PubMed, Cochrane, and Web of Science were systematically searched using terms for MPNs and observational study designs to identify studies investigating the risk factors for MPNs published before March 2010. Of 9,156 articles identified, 19 met the selection criteria. Although the studies exhibited heterogeneity, in case definitions, study design, and risk factors investigated, several themes emerged. A strong association was found with Jewish descent, and with a family history of MPNs. Autoimmune conditions, specifically Crohn's disease, were more common in patients with MPNs. Certain occupational groups were significantly associated with MPNs including occupations with potential exposure to benzene and/or petroleum. Blood donation was associated with an increased risk of polycythemia vera specifically. The vast heterogeneity in studies identified as part of this review suggests that large scale systematic assessment of etiological factors associated with MPNs is warranted.

Prevalence of monoclonal gammopathy of undetermined significance: a systematic review

Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant plasma cell disorder that is associated with a lifelong risk of multiple myeloma. We conducted a systematic review of all studies investigating the prevalence and incidence of MGUS in the online database PubMed. The review was conducted from January 6, 2009, through January 15, 2010. The following MeSH search headings were used: monoclonal gammopathy, benign and prevalence; monoclonal gammopathy, benign and incidence; paraproteinemia and prevalence; and paraproteinemia and incidence. Articles were limited to those written in English and published by January 2009. Fourteen studies that met prespecified criteria were included and systematically assessed to identify the most accurate prevalence estimates of MGUS based on age, sex, and race. On the basis of our systematic review, we estimate that the crude prevalence of MGUS in those older than 50 years is 3.2% in a predominantly white population. Studies in white and Japanese populations demonstrate a clear increase in prevalence with age. The prevalence is also affected by sex: 3.7% and 2.9% in white men and women, respectively; and 2.8% and 1.6% in Japanese men and women, respectively. Additionally, MGUS is significantly more prevalent in black people (5.9%-8.4%) than in white people (3.0%-3.6%). We conclude that MGUS is a common premalignant plasma cell disorder in the general population of those older than 50 years. The prevalence increases with age and is affected by race, sex, family history, immunosuppression, and pesticide exposure. These results are important for counseling, clinical care, and the design of clinical studies in high-risk populations.

Occupational exposures and non-Hodgkin's lymphoma: Canadian case-control study

BACKGROUND

The objective was to study the association between Non-Hodgkin's Lymphoma (NHL) and occupational exposures related to long held occupations among males in six provinces of Canada.

METHODS

A population based case-control study was conducted from 1991 to 1994. Males with newly diagnosed NHL (ICD-10) were stratified by province of residence and age group. A total of 513 incident cases and 1506 population based controls were included in the analysis. Conditional logistic regression was conducted to fit statistical models.

RESULTS

Based on conditional logistic regression modeling, the following factors independently increased the risk of NHL: farmer and machinist as long held occupations; constant exposure to diesel exhaust fumes; constant exposure to ionizing radiation (radium); and personal history of another cancer. Men who had worked for 20 years or more as farmer and machinist were the most likely to develop NHL.

CONCLUSION

An increased risk of developing NHL is associated with the following: long held occupations of faer and machinist; exposure to diesel fumes; and exposure to ionizing radiation (radium). The risk of NHL increased with the duration of employment as a farmer or machinist.

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.

Occupational exposure to pesticides and risk of hematopoietic cancers: meta-analysis of case–control studies

OBJECTIVE

In this study we conducted a meta-analysis of 13 case-control studies that examined the occurrence of hematopoietic cancers in pesticide related occupations in order to undertake a qualitative and quantitative evaluation of a possible relationship.

METHODS

Pubmed databases were searched for case-control studies published between 1990 and 2005 investigating the relation between hematopoietic cancers and occupational exposure to pesticides. Fixed and random effect meta-analysis models were used depending on the presence of heterogeneity between studies.

RESULTS

The overall meta-odds ratio obtained after pooling 44 ORs from 13 studies was 1.3 (95% CI: 1.3-1.5). We realized stratified analysis on three different types of hematopoietic cancers (non-Hodgkin lymphoma (NHL), leukemia and multiple myeloma). A significant increased risk of NHL was found (OR = 1.35; 95% CI = 1.2-1.5). Moreover, increased risks of Leukemia (OR = 1.35; 95% CI = 0.9-2) and multiple myeloma (OR = 1.16; 95% CI = 0.99-1.36) were also detected but these results were not statistically significant. Significant heterogeneity existed among the different studies and a publication bias was detected. Therefore, a meta-regression was carried out. Our results showed that a long period of exposure (more than 10 years) provided an increase in the risk of all hematopoietic cancers and for NHL by fractions of 2.18 (95% CI = 1.43-3.35) and 1.65 (95% CI = 1.08-2.51), respectively.

CONCLUSIONS

The overall meta-odds ratio suggests that there is a significantly positive association between occupational exposure to pesticides and all hematopoietic cancers as well as NHL. A major limitation of our meta-analysis is the lack of sufficient data about exposure information and other risk factors for hematopoietic cancer (genetic predisposition, ethnic origin, immunodepression...). In addition, data concerning specific subtypes of hematopoietic cancers are often confusing. Thus, future epidemiological studies should undertake a major effort to assess the identity and the level of pesticides exposure and should control for the most likely potential confounders.

The myelodysplastic syndromes

The myelodysplastic syndrome(s) (MDS), bone marrow stem cell malignancies that share pathogenetic overlap with acute myeloid leukemia, are characterized by peripheral blood cytopenias and, in more advanced subtypes, varied degrees of maturation arrest. Premature apoptosis of bone marrow cellular elements contributes to ineffective hematopoiesis, which is exacerbated by stromal production of inflammatory cytokines. Abrogation of the effects of these cytokines represents an area of active clinical research, particularly in the treatment of low-risk MDS. In high-risk MDS, the activation of oncogenes and the inactivation of tumor suppressor genes predominate over inhibitory cytokines as proliferation predominates over apoptosis. Agents such as thalidomide, lenalidomide and the hypomethylating drugs 5-azacytidine and decitabine have shown promising efficacy and tolerability in clinical trials, and may represent a springboard for future treatment combinations.

Immunomodulation in myelodysplastic syndromes

The myelodysplastic syndromes (MDS) - bone-marrow stem-cell malignancies that share pathogenetic overlap with acute myeloid leukemia - are characterized by peripheral-blood cytopenias and, in more advanced subtypes, varied degrees of maturation arrest. Premature apoptosis of bone-marrow cellular elements contributes to ineffective hematopoiesis, which is exacerbated by stromal production of inflammatory cytokines. Abrogation of the effects of these cytokines represents an area of active clinical research, particularly in the treatment of low-risk MDS. Agents such as thalidomide, lenalidomide, and infliximab have shown promising efficacy and tolerability in clinical trials, and may represent a springboard for future treatment combinations.

Causal Relationship between Non-Hodgkin's Lymphoma and Exposure to Benzene and Benzene-Containing Solvents

Non-Hodgkin's lymphoma (NHL) is a malignant neoplasm of the lymphatic system made up of mainly B cell lymphocytes. A large number of studies have shown significant associations between NHL and benzene or benzene-containing solvents and products. This article summarizes studies detailing these associations and indicates those that are significant. Based on an analysis of the literature and the weight of evidence from numerous studies, it is reasonable to conclude that exposure to benzene or to solvents or products containing benzene is causally related to NHL.

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.

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.

Does asbestos exposure cause non-Hodgkin's lymphoma or related hematolymphoid cancers? A review of the epidemiologic literature

Asbestos exposure has been linked to non-Hodgkin's lymphoma (NHL) and other types of hematolymphoid cancer (HL-CA) in several case reports and epidemiologic studies. This review covers the scientific and medical literature on the issue of whether asbestos exposure is a cause of NHL or other HL-CAs. Studies of animals exposed to asbestos have not shown an increase in NHL or other types of HL-CA. Although some patients with asbestosis have mild immunologic abnormalities, 32 of 35 epidemiologic studies of asbestos exposure in humans are negative for NHL or other HL-CAs. Therefore, it can be concluded that there is no increased risk of NHL or other HL-CAs associated with asbestos exposure.

A case-referent study of cancer mortality among sulfate mill workers in Sweden

OBJECTIVES

To investigate whether workers in Swedish sulfate mills have an increased risk of death from certain malignancies that have previously been linked to the pulping process.

METHODS

Subjects of the study (n=2480) were men aged 40-75 at death during 1960-89 in the parishes surrounding four sulfate mills. Exposure assessment was based on information from the personnel files in the mills- 35% of the subjects were recognised there, and work categories were created.

RESULTS

Among all sulfate mill workers, the odds ratio (OR) (90% confidence interval (90% CI)) for death from lung cancer was 1.6 (1.1 to 2.3), pleural mesotheliomas 9.5 (1.9 to 48), brain tumours 2.6 (1.2 to 5.3), and liver or biliary tract cancer 2.3 (1.0 to 5.2). There was an increased mortality from leukaemia among workers in the soda recovery plant (5.9 (2.6 to 13)) and bleaching plant and digester house (2.8 (1.0 to 7.5)).

CONCLUSIONS

Sulfate mill workers were at increased risk of dying from lung cancer and pleural mesotheliomas, probably due to exposure to asbestos. Increased risks of brain tumours and cancers of the liver or biliary tract were also found but the aetiology is not obvious.

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).

Non-Hodgkin's lymphoma risk derived from exposure to organic solvents: a review of epidemiologic studies

The rate of non-Hodgkin's lymphomas (NHL) has increased around the world during the last decades. Apart from the role of the human immunodeficiency virus (HIV) infection in the development of NHL, exposure to chemical agents like phenoxyacetic pesticides, hair dyes, metal fumes and organic solvents are suspected to be involved. The present review evaluates the results of studies that directly or indirectly searched for an association between solvent exposure and NHL. The selected studies comprised those published from 1979 to 1997, designed to investigate risk factors for NHL, whether specifically looking for solvent exposure or for general risks in which solvent exposure could be included. In 25 of the 45 reviewed studies (55.5%), fifty-four statistically significant associations between NHL and solvent exposure related occupations or industries were reported. Statistical significance was more frequently shown in studies where solvent exposure was more accurately defined. In eighteen of such studies, 13 (72.2%) defined or suggested organic solvents as possible risk factors for NHL.

Hematopoietic and lymphatic malignancies in vehicle mechanics

Although it is generally acknowledged that benzene causes leukemia, especially acute myeloid leukemia, considerable divergences persist in the assessment of the leukemia risk due to occupational low-level benzene exposure. Specifically, the risk for vehicle mechanics is considered by some authors as being nondetectable with epidemiologic methods, whereas others calculated that the incidence rate of leukemia (all types) in vehicle mechanics is increased more than 60 times. The purpose of this review is to examine the publications on this topic in light of criteria for causal inference and to discuss the possible role of bias, confounding factors, and chance. The results of this analysis reveal that there are surprisingly few epidemiologic observations supporting an increased incidence of leukemia in vehicle mechanics. Apparently, publications suggesting a leukemogenic effect of low-level benzene exposure in garage mechanics are more often quoted than their negative counterparts, although they are not better designed.

Risk of malignant transformation in patients with monoclonal gammopathy of undetermined significance

The acturial probability of malignant transformation was analyzed in a series of 263 patients with monoclonal gammopathy of undetermined significance (MGUS) over a 15-year period and followed from 5 to 20 years. At a median follow-up of 11.5 years, 157 patients (59.7%) had died of causes unrelated to MGUS, 47 (17.9%) were still alive and presented no increase in monoclonal component, 11 (4.1%) presented an increase in monoclonal component without evidence of malignant immunoproliferative disease, and 48 (18.3%) had developed a malignant transformation of MGUS. In particular, MGUS evolved into 35 cases of multiple myeloma, two of solitary plasmacytoma of the bone, four of macroglobulinemia, three of malignant lymphoma, two of amyloidosis, one of chronic lymphocytic leukemia, and one of plasma cell leukemia. The cumulative incidence of malignant transformation was 18.3%; and the actuarial risk of malignant transformation was 6.1, 15.4, and 31.3% at 5, 10 and 20 years, respectively. The multivariate regression analysis according to Cox's proportional hazard model selected among 22 different variables established at initial diagnosis of MGUS only age as the factor significantly (P < 0.011) and negatively (b = -1.104) related to the risk of developing a malignant immunoproliferative disease. Therefore, patients with MGUS present an increased risk of developing a malignant lymphoproliferative or plasma cell proliferative disease, and MGUS could be considered a pre-neoplastic condition. Since no clinical or laboratory features are able to identify in advance the patients at high risk of disease progression, each patient must be followed up periodically and over an indefinite period.

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

To determine the risk factors of the myelodysplastic syndromes (MDS) we conducted a case-control study in Japan. One hundred and sixteen MDS patients were diagnosed from 1 September to 31 October 1992 and from 1 August to 31 October 1993 in the 32 hospitals enrolled in the idiopathic Disorders of Hematopoietic Organs Research Committee. Age, sex, and hospital-matched controls were selected for each case. Information on cigarette smoking and drinking habits, hair dye use, history of keeping pet animals, and occupational exposures to organic solvents, lead and radiation was obtained from self-administered questionnaires. Conditional logistic regression was applied to this individually matched case-control study and odds ratios (ORs) were computed to estimate association between each exposure variable and risk of MDS. Alcohol drinking was associated with increased risk of MDS (OR = 2.15; 95% confidence interval = 1.12-4.16) and there was a significant trend in risk with increasing amounts of ethanol consumed per week (P < 0.05). We also found elevated ORs for cigarette smokers (OR = 1.80), users of hair dye products (OR = 1.77), and workers exposed to organic solvents (OR = 1.50), although these ratios were not statistically significant. Exposure to pet animals was not associated with risk of MDS. The association observed between alcohol drinking and MDS was still eminent even after adjusted with other variables of cigarette smoking, hair dye use and occupational exposure to organic solvents, and the dose-response relationship was also confirmed.

Risk of monoclonal gammopathy of undetermined significance: a case-referent study

A retrospective study was conducted in 285 cases of monoclonal gammopathy of undetermined significance (MGUS) and in 570 sex- and age-matched hospital controls in order to investigate the possible association between socioeconomic status, residence, alcohol and tobacco habits, occupation, occupational exposure to toxic substances, chronic antigenic stimulation, and risk of MGUS. Significant associations with the risk of MGUS were found for farmers (P < 0.005) and for workers in industry (P < 0.025). Occupational exposure to asbestos, fertilizers, mineral oils and petroleum, paints and related products, pesticides, and radiation was significantly (P < 0.05) associated with an increase in risk of MGUS. Chronic immune-stimulating conditions, when considered as a group, presented a significant (P < 0.025) association with the risk of MGUS, but no specific disease has been found to be significantly associated. These data are in agreement with the previous reports on multiple myeloma, suggesting that these factors may play an important role in the development of monoclonal gammopathies. However, these findings need to be confirmed in prospective larger population-based studies.

Asbestos and erionite fibres can induce mutations in human lymphocytes that result in loss of heterozygosity

Although asbestos and erionite are proven human carcinogens, most studies have concluded that these fibres are not mutagenic to mammalian cells in vitro. We have studied the potential of these fibres and chrysotile fibres to induce mutations in human peripheral lymphocytes, using a mutation assay that measures mutation at the autosomal HLA-A locus. Exposure of lymphocytes in culture to 400 micrograms/ml of crocidolite or erionite for 72 hr did not result in a statistically significant increase in the mutation frequency (MF) in the HLA-A assay, although a trend towards increased MF was observed. Exposure to 400 micrograms/ml chrysotile resulted in no increase in MF; however a significant increase was observed at 50 micrograms/ml. Mutations in somatic cells can be classified according to their molecular basis. Molecular analysis of mutants obtained following exposure of lymphocytes to crocidolite and erionite demonstrated a statistically significant increase in the class of mutations arising from loss-of-heterozygosity (LOH) events involving the selection locus (HLA-A) and more distal loci. Mutations following exposure to crocidolite and erionite showed a greater frequency of LOH than did spontaneous mutants (p < 0.02 and p < 0.005 respectively). Mutants following exposure to chrysotile did not display a significant difference in LOH when compared with spontaneous mutants. Thus, although an increase in overall mutation frequency following fibre exposure did not achieve statistical significance, the modest increase seen following exposure to erionite and crocidolite is translated into a highly significant change in those components of the spectrum of mutations which result in LOH.