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

[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.

Transcription factor genetics and biology in predisposition to bone marrow failure and hematological malignancy

Transcription factors (TFs) play a critical role as key mediators of a multitude of developmental pathways, with highly regulated and tightly organized networks crucial for determining both the timing and pattern of tissue development. TFs can act as master regulators of both primitive and definitive hematopoiesis, tightly controlling the behavior of hematopoietic stem and progenitor cells (HSPCs). These networks control the functional regulation of HSPCs including self-renewal, proliferation, and differentiation dynamics, which are essential to normal hematopoiesis. Defining the key players and dynamics of these hematopoietic transcriptional networks is essential to understanding both normal hematopoiesis and how genetic aberrations in TFs and their networks can predispose to hematopoietic disease including bone marrow failure (BMF) and hematological malignancy (HM). Despite their multifaceted and complex involvement in hematological development, advances in genetic screening along with elegant multi-omics and model system studies are shedding light on how hematopoietic TFs interact and network to achieve normal cell fates and their role in disease etiology. This review focuses on TFs which predispose to BMF and HM, identifies potential novel candidate predisposing TF genes, and examines putative biological mechanisms leading to these phenotypes. A better understanding of the genetics and molecular biology of hematopoietic TFs, as well as identifying novel genes and genetic variants predisposing to BMF and HM, will accelerate the development of preventative strategies, improve clinical management and counseling, and help define targeted treatments for these diseases.

Agent Orange and dioxin-induced myeloid leukemia: a weaponized vehicle of leukemogenesis

Agent Orange (AO) was the dominant weaponized herbicide employed by the United States (US) military during the Vietnam war. AO, however, was found to be regularly contaminated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic dioxin known; furthermore, AO was commonly diluted in the field with other aromatic hydrocarbons to assist with delivery mechanisms. Unbeknownst to the US military and the millions exposed, these events have likely contributed to the development of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) that has affected many veterans. Null studies regarding an association between AO exposure and AML/MDS are limited in their methodology and application. The acknowledgement that the known carcinogen TCDD was a contaminant in AO when paired with a strong biological plausibility for its leukemogenicity and an observed increased risk of AML/MDS in TCDD-exposed individuals should suffice to establish causal association and that veterans to whom this might apply should be awarded appropriate indemnity.

Effects of Lifestyle and Environmental Factors on the Risk of Acute Myeloid Leukemia: Result of a Hospital-based Case-Control Study

Background: Acute myeloid leukemia (AML) is a common malignancy in adults. A vast variety of environmental and lifestyle factors play a role in AML incidence. This study aimed to assess the factors related to AML.

Study design: A case-control study.

Methods: This case-control study was performed on 137 AML cases during 2018-2021 at Beheshti Hospital in Hamadan, Iran, and 137 gender/age-matched controls. A questionnaire including 12 items was used to obtain information about lifestyle and environmental factors. A univariate and multiple variate logistic regression was used to estimate the odds ratios (OR), and a 95% confidence interval (CI) was used to investigate the relationship between the studied variables and the incidence of AML.

Results: Based on findings, 62 (45.3%) out of the 137 leukemic cases were male and 75 (4.7%) were females. A statistically significant increased risk for AML was found with regard to prior usage of cytotoxic agents (OR: 8.00, 95% CI: 1.01, 63.9, P=0.050), family history of malignancies (OR: 3.62, 95% CI: 1.65, 7.92, P=0.001), exposure to electrical power (OR: 3.22, 95% CI: 1.52, 6.81, P=0.002), and history of mental diseases (OR: 8.50, 95% CI: 3.64, 19.80, P=0.001). It was found that the AML incidence had no association with age, gender, radiation therapy, cigarette smoking, prior chemotherapy, congenital disorders, exposure to chemical agents, history of infectious mononucleosis, exercise, and blood transfusion (P>0.05).

Conclusion: The current results suggested that cytotoxic agents, family history of malignancy, mental disorders, and exposure to electrical power could play a role in AML incidence.

Cumulative exposure to melphalan chemotherapy and subsequent risk of developing acute myeloid leukemia and myelodysplastic syndromes in patients with multiple myeloma

OBJECTIVES

The aim of this study was to determine risk factors for development of acute myeloid leukemia/myelodysplastic syndromes (AML/MDS) in patients with multiple myeloma (MM).

METHODS

We identified all patients diagnosed with MM in Sweden from January 1st, 1958 to December 31, 2011. A total of 26 627 patients were diagnosed with MM with during the study period. Of these, 124 patients (0.5%) developed subsequent AML/MDS. For each patient with MM and a subsequent AML/MDS diagnosis, we randomly selected a matched (age, sex, and date of MM diagnosis) MM patient without a subsequent second malignancy diagnosis.

RESULTS

The cumulative melphalan exposure was significantly higher (OR = 2.8, 95% CI 1.7-5.2; P < .001) among cases (median 988 mg; IQR 644-1640) compared with controls (median 578 mg; IQR 360-967). Median time to AML/MDS development was 3.8 years (IQR 2.8-5.8). Risk of AML/MDS was not statistically altered by M protein isotype, anemia, renal failure, hypercalcemia, lytic bone lesions, or radiation therapy.

CONCLUSION

In this nationwide population-based study, we show that increased cumulative doses of alkylating therapy with melphalan increases the subsequent risk of developing AML/MDS in patients with MM. Given improved survival in MM patients over the last decade future studies will be important to better define long-term risks.

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.

Challenging the concept of de novo acute myeloid leukemia: Environmental and occupational leukemogens hiding in our midst

Myeloid neoplasms like acute myeloid leukemia (AML) originate from genomic disruption, usually in a multi-step fashion. Hematopoietic stem/progenitor cell acquisition of abnormalities in vital cellular processes, when coupled with intrinsic factors such as germline predisposition or extrinsic factors such as the marrow microenvironment or environmental agents, can lead to requisite pre-leukemic clonal selection, expansion and evolution. Several of these entities have been invoked as "leukemogens." The known leukemogens are numerous and are found in the therapeutic, occupational and ambient environments, however they are often difficult to implicate for individual patients. Patients treated with particular chemotherapeutic agents or radiotherapy accept a calculated risk of therapy-related AML. Occupational exposures to benzene, dioxins, formaldehyde, electromagnetic and particle radiation have been associated with an increased risk of AML. Although regulatory agencies have established acceptable exposure limits in the workplace, accidental exposures and even ambient exposures to leukemogens are possible. It is plausible that inescapable exposure to non-anthropogenic ambient leukemogens may be responsible for many cases of non-inherited de novo AML. In this review, we discuss the current understanding of leukemogens as they relate to AML, assess to what extent the term "de novo" leukemia is meaningful, and describe the potential to identify and characterize new leukemogens.

The global burden and attributable risk factor analysis of acute myeloid leukemia in 195 countries and territories from 1990 to 2017: estimates based on the global burden of disease study 2017

BACKGROUND

Acute myeloid leukemia (AML) is a common leukemia subtype and has a poor prognosis. The risk of AML is highly related to age. In the context of population aging, a comprehensive report presenting epidemiological trends of AML is evaluable for policy-marker to allocate healthy resources.

METHODS

This study was based on the Global Burden of Disease 2017 database. We analyzed the change trends of incidence rate, death rate, and disability-adjusted life year (DALY) rate by calculating the corresponding estimated annual percentage change (EAPC) values. Besides, we investigated the influence of social development degree on AML's epidemiological trends and potential risk factors for AML-related mortality.

RESULTS

From 1990 to 2017, the incidence of AML gradually increased in the globe. Males and elder people had a higher possibility to develop AML. Developed countries tended to have higher age-standardized incidence rate and death rate than developing regions. Smoking, high body mass index, occupational exposure to benzene, and formaldehyde were the main risk factors for AML-related mortality. Notably, the contribution ratio of exposure to carcinogens was significantly increased in the low social-demographic index (SDI) region than in the high SDI region.

CONCLUSION

Generally, the burden of AML became heavier during the past 28 years which might need more health resources to resolve this population aging-associated problem. In the present stage, developed countries with high SDI had the most AML incidences and deaths. At the same time, developing countries with middle- or low-middle SDI also need to take actions to relieve rapidly increased AML burden.

Risk of Acute Lymphoblastic Leukemia: Results of a Case-Control Study

Background: Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. Different environmental factors might be effective in the occurrence of this malignancy during childhood. The aim of this study was to find environmental risk factors in childhood ALL in Hamadan, Iran. Methods: This case-control study was done in 2015-2018 on 125 children younger than 15 years of age suffering from ALL. Patients were matched with 130 controls with respect to age, gender, and residence location. The identification of risk factors for ALL was sought based on the comparison of studied variables between case and control individuals. Results: A statistically significant increased risk for ALL was found with regard to type of delivery (OR: 0.43, 95% CI: 0.20 - 0.92, p˂0.02), childcare (OR: 4.58, 95% CI: 0.95 - 22.20, p˂0.04), birth weight (OR: 1.44, 95% CI: 1.53 - 2.21, p˂0.006), father’s education level (OR: 2.67, 95% CI: 1.10 - 6.45, p˂0.02), and father’s job (OR: 0.2 95% CI: 0.08 - 0.51, p˂0.001). Also observed were increased odds for ALL regarding male gender, mother’s high education level, mother’s freelance job, and medium or high family income. No association with ALL incidence was observed for age, gender, breastfeeding, mother’s age at pregnancy, malignancy in first- or second-degree relatives, or mother’s use of hair dye during pregnancy (p> 0.05). Conclusion: This study showed that father’s education level, father’s job, delivery type, birth weight, and childcare can play a role in the incidence of childhood ALL.

Epidemiology of acute myeloid leukemia: Recent progress and enduring challenges

Acute myeloid leukemia (AML) is a malignant disorder of the bone marrow which is characterized by the clonal expansion and differentiation arrest of myeloid progenitor cells. The age-adjusted incidence of AML is 4.3 per 100,000 annually in the United States (US). Incidence increases with age with a median age at diagnosis of 68 years in the US. The etiology of AML is heterogeneous. In some patients, prior exposure to therapeutic, occupational or environmental DNA-damaging agents is implicated, but most cases of AML remain without a clear etiology. AML is the most common form of acute leukemia in adults and has the shortest survival (5-year survival = 24%). Curative therapies, including intensive chemotherapy and allogeneic stem cell transplantation, are generally applicable to a minority of patients who are younger and fit, while most older individuals exhibit poor prognosis and survival. Differences in patient outcomes are influenced by disease characteristics, access to care including active therapies and supportive care, and other factors. After many years without therapeutic advances, several new therapies have been approved and are expected to impact patient outcomes, especially for older patients and those with refractory disease.

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.

Cigarette smoking, dietary habits and genetic polymorphisms in GSTT1, GSTM1 and CYP1A1 metabolic genes: A case-control study in oncohematological diseases

AIM

To analyze the association between oncohematological diseases and GSTT1/GSTM1/CYP1A1 polymorphisms, dietary habits and smoking, in an argentine hospital-based case-control study.

METHODS

This hospital-based case-control study involved 125 patients with oncohematological diseases and 310 control subjects. A questionnaire was used to obtain sociodemographic data and information about habits. Blood samples were collected, and DNA was extracted using salting out methods. Deletions in GSTT1 and GSTM1 (null genotypes) were addressed by PCR. CYP1A1 MspI polymorphism was detected by PCR-RFLP. Odds ratio (OR) and 95%CI were calculated to estimate the association between each variable studied and oncohematological disease.

RESULTS

Women showed lower risk of disease compared to men (OR 0.52, 95%CI: 0.34-0.82, P = 0.003). Higher levels of education (> 12 years) were significantly associated with an increased risk, compared to complete primary school or less (OR 3.68, 95%CI: 1.82-7.40, P < 0.001 adjusted for age and sex). With respect to tobacco, none of the smoking categories showed association with oncohematological diseases. Regarding dietary habits, consumption of grilled/barbecued meat 3 or more times per month showed significant association with an increased risk of disease (OR 1.72, 95%CI: 1.08-2.75, P = 0.02). Daily consumption of coffee also was associated with an increased risk (OR 1.77, 95%CI: 1.03-3.03, P = 0.03). Results for GSTT1, GSTM1 and CYP1A1 polymorphisms showed no significant association with oncohematological diseases. When analyzing the interaction between polymorphisms and tobacco smoking or dietary habits, no statistically significant associations that modify disease risk were found.

CONCLUSION

We reported an increased risk of oncohematological diseases associated with meat and coffee intake. We did not find significant associations between genetic polymorphisms and blood cancer.

Do the smoking intensity and duration, the years since quitting, the methodological quality and the year of publication of the studies affect the results of the meta-analysis on cigarette smoking and Acute Myeloid Leukemia (AML) in adults?

BACKGROUND

The aim was to perform a systematic review and meta-analysis on the relationship between tobacco smoking and the onset of acute myeloid leukemia (AML) in adults.

METHODS

PubMed and Scopus databases were systematically searched. In the meta-analysis, random or fixed effects models were used according to the presence of heterogeneity. Study quality was assessed using the Newcastle-Ottawa Scale.

RESULTS

Twenty-seven articles were included. Case-control and cohort meta-analyses show that current, ever and former smokers have a significant increased risk to develop AML compared to never smokers [current: OR=1.36 (1.11-1.66) and RR=1.52 (1.10-2.14); ever: OR=1.25 (1.14-1.38) and RR=1.45 (1.10-1.90); former: OR=1.21 (1.03-1.41) and RR=1.45 (1.08-1.94)]. Moreover, increasing smoking intensity and duration is associated with an increase of the risk, OR shift from 1.14 (1-20 pack/years) to 2.36 (>40 pack/years).

DISCUSSION AND CONCLUSION

Smoking may have a significant role in AML onset in a multistep pathogenesis.

Clinicopathological Features and Outcome of Lung Cancer Patients with Hematological Malignancy

PURPOSE

The aim of this study was to report the incidence of lung cancer in patients with hematological malignancy (HM), as well as patient characteristics and outcome.

METHODS

We investigated 1503 consecutive patients treated for HM and 1208 patients who underwent surgical resection for lung cancer.

RESULTS

Lung cancer with HM was observed in 12 patients (0.8 % of HM cases and 1.0 % of lung cancer cases), including eight men who were smokers and four women who had never smoked. The average Brinkman index was 1010, which suggested heavy smokers. In synchronous cases, all four patients preceded to HM treatment; however, three patients died from HM. In metachronous cases, during a mean 52.7 months after treatment of lung cancer, three patients had HM. At a mean 41.4 months after HM treatment, five patients had lung cancer and underwent surgery without serious postoperative events.

CONCLUSIONS

A second cancer tended to be detected within 5 years after treatment of the first cancer. Men with a history of heavy smoking might be at risk for combined lung cancer and HM. Careful follow-up is recommended within 5 years after treatment of the first cancer. Most lung cancer detected synchronously with HM had poor prognosis. In metachronous cases, surgical resection of lung cancer after treatment of HM was feasible and safe.

Cigarette Smoking and the Risk of Adult Myeloid Disease: A Meta-Analysis

Background

The adult myeloid diseases, myelodysplastic syndrome and acute myeloid leukemia, have been reported to be associated with cigarette smoking, but the results have been conflicting. Previous studies may have ignored the relationship between myelodysplastic syndrome and acute myeloid leukemia, where approximately one-third of myelodysplastic syndrome cases will progress to acute myeloid leukemia, which could induce a serious bias in independent analyses. For the purposes of researching pathogenesis, we suggest that myelodysplastic syndrome and acute myeloid leukemia should be regarded as a single class of adult myeloid disease, and herein assessed the relationship between cigarette smoking and the risk of adult myeloid disease.

Methods

The PubMed, Cochrane Library, EBSCO, and EMBASE databases were systematically searched for reports published from 1990 to 2015. Two authors independently assessed the methodological quality and the extracted data. The odds ratios and adjusted odds ratios (OR), a sensitivity analysis, and the publication bias were analyzed using the CMA v2 (Comprehensive Meta Analysis Version 2) software program.

Results

Twenty-five studies were included in this meta-analysis. The publication dates ranged from 1990 to 2014. The pooled OR in current smokers and ever-smokers showed an increased risk of adult myeloid disease, with ORs of 1.45 (95% CI, 1.30–1.62; p<0.001) and 1.23 (95% CI 1.15–1.32; p<0.001) versus non-smokers, respectively. In the subset analyses, the OR of adult myeloid disease was increased regardless of the form of disease, geographical region, NOS (Newcastle Ottawa Scale) score, and source of controls. The smoking status was divided into <20 and ≥20 cigarettes per day, and these groups had ORs of developing adult myeloid disease of 1.24 (95% CI, 1.09–1.40; p = 0.001) and 1.32 (95% CI, 1.14–1.53; p<0.001), respectively. In the groups divided based on the number of years the subjects had smoked (<20 and ≥20 years), the ORs were 1.05 (95% CI, 0.90–1.23; p = 0.25) and 1.30 (95% CI, 1.16–1.45; p<0.001), respectively. Similarly, <20 and ≥20 pack-years were associated with ORs of 1.15 (95% CI, 1.03–1.29; p = 0.017) and 1.34 (95% CI, 1.18–1.52; p<0.001), respectively.

Conclusions

This meta-analysis, for the first time, combined myelodysplastic syndrome with acute myeloid leukemia to assess the overall risk of adult myeloid disease, and it demonstrated that cigarette smoking is associated with a significantly increased risk of adult myeloid disease.

ABCB1 C3435T polymorphism is associated with leukemia susceptibility: evidence from a meta-analysis

INTRODUCTION AND OBJECTIVE

Many studies have been conducted on the association between the adenosine triphosphate-binding cassette, subfamily B, member 1 (ABCB1) gene C3435T polymorphism and leukemia risk, however, the previously published findings remain controversial. Thus, a meta-analysis was carried out to accurately evaluate the effect of this polymorphism on leukemia susceptibility.

METHODS

A computerized literature search was conducted of PubMed, Elsevier database, the China National Knowledge Infrastructure database, and Wanfang Database, to find published case-control studies exploring the relationship between ABCB1 C3435T polymorphism and leukemia risk. Odds ratios (ORs) with 95% confidence intervals (CIs) were applied to assess the strength of association.

RESULTS

A total of 17 studies of 2,431 cases and 3,028 controls were included in this meta-analysis. The results of overall comparisons suggest that there is a significant association between ABCB1 C3435T polymorphism and leukemia risk under two genetic models (TT vs CC: OR=1.39, 95% CI=1.04-1.84, P=0.02; CT+TT vs CC: OR=1.20, 95% CI=1.06-1.36, P=0.004). In the subgroup analyses by ethnicity, age, and leukemia subtype, a significant association was found in Caucasian (CT vs CC: OR=1.22, 95% CI=1.03-1.45, P=0.02; TT vs CC: OR=1.34, 95% CI=1.10-1.64, P=0.004; CT+TT vs CC: OR=1.27, 95% CI=1.08-1.49, P=0.004), adult leukemia (CT vs CC: OR=1.46, 95% CI=1.17-1.83, P=0.001; CT+TT vs CC: OR=1.43, 95% CI=1.01-2.03, P=0.04), and lymphocytic leukemia (TT vs CC: OR=1.73, 95% CI=1.19-2.51, P=0.004; TT vs CC+CT: OR=1.62, 95% CI=1.10-2.38, P=0.01; CT+TT vs CC: OR=1.28, 95% CI=1.10-1.48, P=0.001).

CONCLUSION

The meta-analysis suggests that ABCB1 C3435T polymorphism is associated with increased risk of leukemia.

Association between the MDM2 T309G polymorphism and leukemia risk: a meta-analysis

Several studies have suggested associations between MDM2 (mouse double minute 2 homolog) polymorphisms and leukemia risk, but they reported contradictory results. For better understanding of the effect of MDM2 T309G polymorphism on leukemia risk, we performed a meta-analysis. All eligible studies were identified through a search of PubMed, Web of Science, EMBASE, and Chinese Biomedical Literature (CBM) databases before May 2014. Assessment of associations between the MDM2 T309G polymorphism and leukemia risk was conducted by odds ratios (ORs) and 95% confidence intervals (95% CIs). Finally, a total of 11 publications covering 12 case-control studies with 2, 362 cases and 5, 562 controls concerning MDM2 T309G polymorphism with respect to leukemia were included in the meta-analysis. Significant associations were found between MDM2 T309G polymorphism and leukemia risk in four models in overall populations (G vs T: OR=1.29, 95% CI=1.11- 1.49, p=0.001; GG vs TT: OR=1.67, 95% CI=1.21-2.30, p=0.002; GG vs TG/TT: OR=1.56, 95% CI=1.21-2.00, p=0.001; GG/TG vs TT: OR=1.28, 95% CI=1.05-1.57, p=0.015). In the sub-group analysis according to ethnicity, increased leukemia risks were observed in three genetic models among Asians but not Caucasians. In conclusion, the results of our meta-analysis suggest that the MDM2 T309G polymorphism can increase the risk of leukemia, especially among Asian populations.

The relation between cigarette smoking and risk of acute myeloid leukemia: an updated meta-analysis of epidemiological studies

Smoking has been postulated as an environmental risk factor for acute myeloid leukemia (AML). The primary objective of this meta-analysis of observational studies was to evaluate the epidemiologic relationship between smoking and the risk of development of AML. Twenty-three studies published between January 1993 and December 2013 were included in our analysis, and accounted for 7,746 cases of AML. The outcome of interest was the relative risk (RR) with 95% confidence interval (CI) of developing AML in adult cigarette smokers in comparison with non-smokers, and was estimated using the random-effects model. Our results showed that current and ever smokers have 40% (RR 1.40, 95% CI 1.22-1.60; P < 0.001) and 25% (RR 1.25, 95% CI 1.15-1.36; P < 0.001) increased risk of developing AML when compared with non-smokers. The increased RR of AML was increased regardless of sex, study design, geographical region, and quality of the studies. Intensity of smoking of <10, 10-20, 20-30, and >30 cigarettes per day was associated with RRs of AML of 1.27, 1.36, 1.55, and 1.77, respectively (P < 0.001 for trend). Duration of smoking of <20 and >20 years was associated with RRs of 1.07 and 1.44, respectively (P < 0.001 for trend). Cumulative smoking of <10, 10-20, 20-30, and >30 pack-years was associated with RRs of 1.13, 1.23, 1.39, and 1.71, respectively (P < 0.001 for trend). Overall, cigarette smoking proves to be a significant risk factor for the development of AML in adults.

Tobacco smoke exposure and the risk of childhood acute lymphoblastic and myeloid leukemias by cytogenetic subtype

BACKGROUND

Tobacco smoke contains carcinogens known to damage somatic and germ cells. We investigated the effect of tobacco smoke on the risk of childhood acute lymphoblastic leukemia (ALL) and myeloid leukemia (AML), especially subtypes of prenatal origin such as ALL with translocation t(12;21) or high-hyperdiploidy (51-67 chromosomes).

METHODS

We collected information on exposures to tobacco smoking before conception, during pregnancy, and after birth in 767 ALL cases, 135 AML cases, and 1,139 controls (1996-2008). Among cases, chromosome translocations, deletions, or aneuploidy were identified by conventional karyotype and fluorescence in situ hybridization.

RESULTS

Multivariable regression analyses for ALL and AML overall showed no definite evidence of associations with self-reported (yes/no) parental prenatal active smoking and child's passive smoking. However, children with history of paternal prenatal smoking combined with postnatal passive smoking had a 1.5-fold increased risk of ALL [95% confidence interval (CI), 1.01-2.23], compared to those without smoking history (ORs for pre- or postnatal smoking only were close to one). This joint effect was seen for B-cell precursor ALL with t(12;21) (OR = 2.08; 95% CI, 1.04-4.16), but not high hyperdiploid B-cell ALL. Similarly, child's passive smoking was associated with an elevated risk of AML with chromosome structural changes (OR = 2.76; 95% CI, 1.01-7.58), but not aneuploidy.

CONCLUSIONS

Our data suggest that exposure to tobacco smoking was associated with increased risks of childhood ALL and AML; and risks varied by timing of exposure (before and/or after birth) and cytogenetic subtype, based on imprecise estimates.

IMPACT

Parents should limit exposures to tobacco smoke before and after the child's birth.

Association between RAD51 gene polymorphism (-135G/C) and susceptibility of myelodysplastic syndrome and acute leukemia: evidence based on a meta-analysis

Study results on the association between RAD51 gene -135G/C polymorphism and risk of myelodysplastic syndrome (MDS) or acute leukemia are inconsistent. A meta-analysis was conducted to identify the association. A systematic search was performed in PubMed, Embase, CNKI, VIP, Wanfang databases to collect all relevant studies until January 2013. Meta-analysis was carried out using fixed/random model by Review Manager 5.1 and STATA10.0. A total of 10 eligible studies with 2,656 patients and 3,725 controls were included in meta-analysis. Significant association was detected between -135G/C polymorphism and increased MDS risk (CC + GC vs. GG: OR = 1.46, 95% CI = 1.11-1.92; CC vs. GC + GG: OR = 2.45, 95% CI = 1.23-4.89), while no association was observed for acute leukemia. Subgroup analysis by subtypes of acute leukemia and ethnicity showed no significant results either. Our meta-analysis indicated that the -135G/C polymorphism might be associated with increased susceptibility of MDS. However, lack of evidence supported association of this polymorphism with acute leukemia. Additional well-designed studies with larger samples are required to verify our results.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

De novo acute myeloid leukemia risk factors: a Texas case-control study

BACKGROUND

Acute myeloid leukemia (AML) is comprised of several bone marrow-based cancers and is the most common type of leukemia in the United States. The etiology of AML is not well understood. A case-control study was conducted at The University of Texas M. D. Anderson Cancer Center to investigate associations between lifestyle characteristics and the risk of AML in Texas.

METHODS

This study included 638 adult patients with de novo AML (cases) and a group of 636 matched controls. Interviewer-administered questionnaires were used to collect demographic and occupational data. The distribution of cases by World Health Organization (WHO) subtype was 71 patients (11%) with recurrent cytogenetic abnormalities (AML-RCA), 134 patients (21%) with multilineage dysplasia (AML-MD), and 389 patients (61%) with AML not otherwise categorized (AML-NOC). Multivariate logistic regression analyses were performed among all AML cases and among both sexes and each WHO subgroup.

RESULTS

Among men, heavy smoking (≥30 pack-years; odds ratio [OR], 1.86) and occupational solvent exposure at low levels (OR, 2.87) or moderate/high levels (OR, 4.13) statistically significantly increased the risk of AML. Among women, obesity (OR, 1.62) and solvent exposure to low levels (OR, 2.73) or moderate/high levels (OR, 3.90) increased the risk of AML. Across WHO subtypes, obesity was associated with a statistically significantly increased risk of AML-RCA (OR, 3.15), whereas solvent exposure increased the risk in all subtypes at low levels (AML-RCA: OR, 4.11; AML-MD: OR, 2.54) and moderate/high levels (AML-RCA: OR, 5.13; AML-MD: OR, 3.02). A joint effect between smoking and solvent exposure was observed, and the highest risk was observed among smokers who had solvent exposure (OR, 4.51).

CONCLUSIONS

The current results suggested that several factors play a role in AML predisposition with possible joint effects. Risk profiles for AML differed by sex and WHO subtype.

Retinoid differentiation therapy for common types of acute myeloid leukemia

Many cancers arise in a tissue stem cell, and cell differentiation is impaired resulting in an accumulation of immature cells. The introduction of all-trans retinoic acid (ATRA) in 1987 to treat acute promyelocytic leukemia (APL), a rare subtype of acute myeloid leukemia (AML), pioneered a new approach to obtain remission in malignancies by restoring the terminal maturation of leukemia cells resulting in these cells having a limited lifespan. Differentiation therapy also offers the prospect of a less aggressive treatment by virtue of attenuated growth of leukemia cells coupled to limited damage to normal cells. The success of ATRA in differentiation therapy of APL is well known. However, ATRA does not work in non-APL AML. Here we examine some of the molecular pathways towards new retinoid-based differentiation therapy of non-APL AML. Prospects include modulation of the epigenetic status of ATRA-insensitive AML cells, agents that influence intracellular signalling events that are provoked by ATRA, and the use of novel synthetic retinoids.

MDM2 SNP309 variation contributes to leukemia risk: meta-analyses based on 7259 subjects

Evidence implicates MDM2 (murine double minute-2) T309G polymorphism as a risk factor for several cancers. Increasing numbers of studies have been carried out on the association of MDM2 T309G polymorphism with susceptibility to leukemia and have generated conflicting results. The aim of the present study was to derive a more precise estimation of the relationship. Meta-analyses assessing the association of MDM2 T309G variation with leukemia were conducted. Separate analyses on ethnicity and clinical types were also performed. Eligible studies were identified for the period up to February 2012. Consequently, seven publications including eight case-control studies with 1777 cases and 5482 controls were selected for analysis. The overall data indicated a significant association of the MDM2 T309G polymorphism with leukemia risk (GG vs. TT: odds ratio [OR] = 1.62; 95% confidence interval [CI] = 1.14-2.29; dominant model: OR = 1.20; 95% CI = 1.06-1.36; recessive model: OR = 1.47; 95% CI = 1.07-2.03). In subgroup analysis by ethnicity, the G allele may increase leukemia susceptibility among Asians (GG vs. TT: OR = 3.06; 95% CI = 2.05-4.56; dominant model: OR = 1.82; 95% CI = 1.31-2.51; recessive model: OR = 2.32; 95% CI = 1.69-3.19) but not Caucasians. In subgroup analysis by clinical types, data suggested increased risk for acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) under additive and recessive models, respectively. Similarly, elevated risk for chronic lymphocytic leukemia (CLL) was shown under the dominant model. Collectively, the results of the present study suggest that MDM2 T309G polymorphism might be a low-penetrant risk factor for leukemia among Asians but not Caucasians. The G allele might increase CLL susceptibility and homozygous GG might elevate AML and CML risk.

NAD(P)H: quinone oxidoreductase 1 deficiency conjoint with marginal vitamin C deficiency causes cigarette smoke induced myelodysplastic syndromes

Background

The etiology of myelodysplastic syndromes (MDS) is largely unknown. Exposure to cigarette smoke (CS) is reported to be associated with MDS risk. There is inconsistent evidence that deficiency of NAD(P)H-quinone: oxidoreductase 1 (NQO1) increases the risk of MDS. Earlier we had shown that CS induces toxicity only in marginal vitamin C-deficient guinea pigs but not in vitamin C-sufficient ones. We therefore considered that NQO1 deficiency along with marginal vitamin C deficiency might produce MDS in CS-exposed guinea pigs.

Methodology and Principal Findings

Here we show that CS exposure for 21 days produces MDS in guinea pigs having deficiency of NQO1 (fed 3 mg dicoumarol/day) conjoint with marginal vitamin C deficiency (fed 0.5 mg vitamin C/day). As evidenced by morphology, histology and cytogenetics, MDS produced in the guinea pigs falls in the category of refractory cytopenia with unilineage dysplasia (RCUD): refractory anemia; refractory thrombocytopenia that is associated with ring sideroblasts, micromegakaryocytes, myeloid hyperplasia and aneuploidy. MDS is accompanied by increased CD34(+) cells and oxidative stress as shown by the formation of protein carbonyls and 8-oxodeoxyguanosine. Apoptosis precedes MDS but disappears later with marked decrease in the p53 protein. MDS produced in the guinea pigs are irreversible. MDS and all the aforesaid pathophysiological events do not occur in vitamin C-sufficient guinea pigs. However, after the onset of MDS vitamin C becomes ineffective.

Conclusions and Significance

CS exposure causes MDS in guinea pigs having deficiency of NQO1 conjoint with marginal vitamin C deficiency. The syndromes are not produced in singular deficiency of NQO1 or marginal vitamin C deficiency. Our results suggest that human smokers having NQO1 deficiency combined with marginal vitamin C deficiency are likely to be at high risk for developing MDS and that intake of a moderately large dose of vitamin C would prevent MDS.

Cigarette smoking shortens the survival of patients with low-risk myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a group of hematological malignancies with poor survival. Although previous studies have identified the prognostic role of multiple demographic and clinical characteristics, the potential role of lifestyle factors has not been evaluated. In this study, we conducted an extensive assessment of the predictors of MDS survival, with a special focus on lifestyle factors. A total of 616 patients (median survival = 4.1 years) were included in the analysis, and multivariate Cox proportional hazard models were utilized to estimate hazard ratios. Compared with non-smokers, MDS patients who smoked at the initial clinical encounter had a significantly increased risk of death [hazard ratio (HR) = 1.46, 95% confidence intervals (CI): 1.07-2.00]. The elevated risk was restricted to men (HR = 1.76, 95% CI: 1.21-2.56) and not observed among women (HR = 0.98, 95% CI: 0.51-1.85). When patients were stratified by the IPSS categorization, a near three fold increased risk of death was associated with smoking among patients with low-risk MDS (HR = 2.83, 95% CI: 1.48-5.39), whereas smoking did not appear to influence the survival of patients with intermediate- or high-risk MDS. This study was the first to identify smoking as a significant and independent predictor of MDS survival, particularly among low-risk patients.