Environmental risk factors for non-Hodgkin's lymphoma: a population-based case-control study in Languedoc-Roussillon, France

Occupational exposure to benzene and risk of non-Hodgkin lymphoma in an extended follow-up of two population-based prospective cohorts of Chinese men and women

The carcinogenicity of benzene was reevaluated by the International Agency for Research on Cancer in 2017, with the Working Group reaffirming positive yet inconclusive associations with non-Hodgkin lymphoma (NHL). To extend our previous observation of a significant exposure-response for cumulative occupational benzene exposure and NHL risk among Chinese women in a population-based cohort in Shanghai, we extended follow-up of this cohort and pooled the data with a similarly designed population-based cohort of men in Shanghai. Cumulative exposure estimates were derived for 134,449 participants in the pooled analysis by combining ordinal job-exposure matrix intensity ratings with quantitative benzene measurements from an inspection database of Shanghai factories. Associations between benzene exposure metrics and NHL (n = 363 cases including multiple myeloma [MM]) were assessed using Cox proportional hazard models. Ever occupational exposure to benzene in the pooled population was associated with NHL risk (HR = 1.5, 95% CI = 1.2-2.0), and exposure-response relationships were observed for increasing duration (ptrend = .003) and cumulative exposure (ptrend = .003). Associations with ever exposure, duration, and cumulative exposure were similar for NHL with and without MM in the case definition, including lifetime cumulative exposures in the highest quartile (HR = 1.6, 95% CI = 1.1-2.4 with MM included; HR = 1.7, 95% CI = 1.1-2.7 with MM excluded). An elevated risk of the chronic lymphocytic leukemia subtype was suggested in the pooled analyses (HR for ever vs. never exposure = 2.3, 95% CI = 0.9-5.6). These observations provide additional support for a plausible association between occupational benzene exposure and risk of NHL.

Phases and Natural History of Sjögren's Disease: A New Model for an Old Disease?

Sjögren's disease (SjD) is an archetypal and heterogenous autoimmune disorder that is characterized by exocrine glandular dysfunction. A proportion of patients develop severe extraglandular manifestations, such as cryoglobulinemia, and have an increased risk of lymphoma, both of which can adversely affect quality of life and occasionally mortality. As with most autoimmune disorders, the pathogenesis is poorly understood and difficult to predict, and, frustratingly, there is a lack of targeted therapies to cure this disease. We review the disease manifestations of SjD and propose a staged model for understanding the evolution of pathology. In longitudinal studies, most patients remain relatively stable in terms of their laboratory and clinical parameters. However, in the setting of various risk factors, a proportion of patients develop severe symptoms and/or lymphoma. We discuss potential underlying mechanisms for disease progression and the strengths and limitations of using a staged model to correlate the pathogenesis and spectrum of manifestations in SjD. Ultimately, understanding how and why some patients remain relatively stable, whereas others progress and develop florid systemic disease and a fraction develop lymphoma, is key to developing preventative and therapeutic treatments.

Systematic review of perchloroethylene and non-Hodgkin's lymphoma

We conducted a systematic review of epidemiology studies that evaluated the association between perchloroethylene (PCE) and non-Hodgkin's lymphoma (NHL). This included an independent detailed assessment of a few critical aspects of study quality (i.e., study design, exposure measurement, exposure levels, and potential confounding), and a consideration of other aspects of quality less formally. Of the identified 18 cohort studies of 15 unique cohorts, 17 case-control studies of 14 unique population groups, and 3 ecological studies, none was high quality for all four critical quality elements and each study also had other major methodological study limitations. Reported risk estimates were mostly null, ranged widely from below to above 1, and often had extremely wide confidence intervals (CIs), indicating unstable risk estimates. In addition, there was no consistent evidence of dose-response. Overall, given the low quality of the available epidemiology studies, the evidence does not support an association between PCE exposure and NHL.

Potential Correlation Between Eczema and Hematological Malignancies Risk: A Systematic Review and Meta-Analysis

Background

Eczema characterized by itch, sleeplessness, and adverse effects on quality of life is associated with a risk of hematological malignancies. However, there is a controversy pertaining to whether this association implies a greater or lesser risk of hematological cancers. We aimed to explore the link between eczema and hematological malignancies risk.

Methods

We systematically searched PubMed and Embase databases from their inception to February 17, 2022. Two reviewers independently screened articles, extracted data and assessed study quality, respectively. The odds ratios and 95% confidence intervals (CIs) were pooled by using fixed or random-effects models.

Results

29 studies involving 2,521,574 participants examined the contribution of eczema to hematological malignancies. We found that eczema significantly increased the risk of Hodgkin's lymphoma (1.44; 95% CI, 1.07–1.95), myeloma (1.15; 95% CI, 1.04–1.28), and significantly decreased the risk of lymphocytic leukemia (0.91; 95% CI, 0.84–0.99); however, it is not significantly associated with Non-Hodgkin's lymphoma, and myelocytic leukemia.

Conclusion

Eczema has been shown to be associated with the risk of hematological cancer, this association still needs to be verified in large randomized controlled trials.

Systematic Review Registration

https://inplasy.com/, INPLASY202260097.

Benzene exposure and non-Hodgkin lymphoma: a systematic review and meta-analysis of human studies

BACKGROUND

Non-Hodgkin lymphoma comprises a heterogeneous group of cancers with unresolved aetiology, although risk factors include environmental exposures to toxic chemicals. Although the ubiquitous pollutant benzene is an established leukemogen, its potential to cause non-Hodgkin lymphoma has been widely debated. We aimed to examine the potential link between benzene exposure and risk of non-Hodgkin lymphoma in humans by evaluating a wide array of cohort and case-control studies using electronic systematic review.

METHODS

We did a comprehensive systematic review and meta-analysis of all qualified human epidemiological studies that assessed the relationship between benzene exposure and non-Hodgkin lymphoma. We queried the PubMed and Embase databases for relevant articles published before June 5, 2019, and applied the SysRev platform for study selection. All peer-reviewed human cohort and case-control studies that reported non-Hodgkin lymphoma risk estimates specifically for benzene exposure were eligible for inclusion. Studies that calculated relative risks (RRs) for industries or job types without identifying those specifically exposed to benzene, that combined non-Hodgkin lymphoma with other cancer types, or that reported many different solvent exposures together were excluded. From each study, two investigators independently extracted information on the study design, location, years, sample size, participation rates, age, sex, sources of cases and controls, diagnosis, histological verification, exposure assessment, results, adjustment, and statistical analysis, and subsequently assessed study quality. We calculated the meta-analysis relative risk (meta-RR) and CIs using the fixed effect and random effect models, as well as assessing publication bias.

FINDINGS

Our search yielded 2481 articles. After screening and removal of duplicates, 20 case-control studies and eight cohort studies were included in our meta-analysis, which included a total of 9587 patients with non-Hodgkin lymphoma. We reported an increased meta-relative risk (meta-RR) of 33% in highly exposed groups, when data were available (meta-RR 1·33 [95% CI 1·13-1·57], n=28). The meta-RR rose to 1·51 (1·22-1·87, n=18) in the studies that provided results specifically for highly exposed individuals. In particular, we reported a doubling of this risk for diffuse large B-cell lymphoma, a major non-Hodgkin lymphoma subtype (1·67 [1·01-2·77]). We also detected increased risks for follicular lymphoma (1·47 [0·95-2·27]) and hairy cell leukaemia (1·77 [0·99-3·16]), though they were not statistically significant. Funnel plot, Egger's test (p=0·77) and Begg's test (p=0·98) did not show evidence of publication bias. We evaluated the major aspects of causal inference and found evidence to support all the Hill considerations for assigning causation.

INTERPRETATION

Our findings suggest a causal link between benzene exposure and non-Hodgkin lymphoma, especially for diffuse large B-cell lymphoma.

FUNDING

National Institute of Environmental Health Sciences.

5G mobile networks and health-a state-of-the-science review of the research into low-level RF fields above 6 GHz

The increased use of radiofrequency (RF) fields above 6 GHz, particularly for the 5 G mobile phone network, has given rise to public concern about any possible adverse effects to human health. Public exposure to RF fields from 5 G and other sources is below the human exposure limits specified by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). This state-of-the science review examined the research into the biological and health effects of RF fields above 6 GHz at exposure levels below the ICNIRP occupational limits. The review included 107 experimental studies that investigated various bioeffects including genotoxicity, cell proliferation, gene expression, cell signalling, membrane function and other effects. Reported bioeffects were generally not independently replicated and the majority of the studies employed low quality methods of exposure assessment and control. Effects due to heating from high RF energy deposition cannot be excluded from many of the results. The review also included 31 epidemiological studies that investigated exposure to radar, which uses RF fields above 6 GHz similar to 5 G. The epidemiological studies showed little evidence of health effects including cancer at different sites, effects on reproduction and other diseases. This review showed no confirmed evidence that low-level RF fields above 6 GHz such as those used by the 5 G network are hazardous to human health. Future experimental studies should improve the experimental design with particular attention to dosimetry and temperature control. Future epidemiological studies should continue to monitor long-term health effects in the population related to wireless telecommunications.

Increased Regulatory T Cells and Decreased Myeloid-Derived Suppressor Cells Induced by High CCL17 Levels May Account for Normal Incidence of Cancers among Patients with Atopic Dermatitis

The incidence of cancers in atopic dermatitis (AD) is not increased, although the Th2-dominant environment is known to downregulate tumor immunity. To gain mechanistic insights regarding tumor immunity in AD, we utilized CCL17 transgenic (TG) mice overexpressing CCL17, which is a key chemokine in AD. Tumor formation and lung metastasis were accelerated in CCL17 TG mice when melanoma cells were injected subcutaneously or intravenously. Flow cytometric analysis showed increases in regulatory T cells (Tregs) in lymph nodes in CCL17 TG mice with high mRNA levels of IL-10 and Foxp3 in tumors, suggesting that Tregs attenuated tumor immunity. The frequency of myeloid-derived suppressor cells (MDSCs), however, was significantly decreased in tumors of CCL17 TG mice, suggesting that decreased MDSCs might promote tumor immunity. Expression of CXCL17, a chemoattractant of MDSCs, was decreased in tumors of CCL17 TG mice. Depletion of Tregs by the anti-CD25 antibody markedly reduced tumor volumes in CCL17 TG mice, suggesting that tumor immunity was accelerated by the decrease in MDSCs in the absence of Tregs. Thus, CCL17 attenuates tumor immunity by increasing Tregs and Th2 cells, while it decreases MDSCs through reductions in CXCL17, which may work as a “safety-net” to reduce the risk of malignant tumors in the Th2-dominant environment.

Determinants of non-Hodgkin's lymphoma at Felegehiwot specialized hospital, North West Ethiopia: A case-control study

BACKGROUND

The global burden of cancer continues to increase largely because of the aging and growth of the world population alongside an increasing adoption of cancer-causing behaviors. Hence, the purpose of this study was to identify determinants of Non-Hodgkin lymphoma cancer among individuals who diagnosed at the Felegehiwot specialized hospital, North West Ethiopia, 2019.

METHODS

An institution-based unmatched case-control study was conducted at the Felegehiwot Specialized hospital from December 2018 up to June 2019. The sample size calculated using the two-population proportion formula. The final sample size was 486, (162 cases and 324 controls). The simple random sampling method was employed to catch up with the estimated samples. The collected data entered into the Epi-data version 3.1 software and analyzed using SPSS version 21 software. Descriptive statistics computed. Simple logistic analysis was run (at 95% CI and p-value < 0.05) to identify the determinants of non-Hodgkin's lymphoma.

RESULT

A total of 486 patients participated. Nearly one-third of the cases and controls were in the age group of 46-60 years. About 90% of cases and 91% of controls were orthodox Christian. Monthly income of ≤28 dollars (AOR = 2. 73, 95%CI: 1. 8, 4.2), male sex (AOR = 1. 8, 95%CI: 1.2, 2.8), ever had chemical exposure, (AOR = 11. 9, 95%CI: 7.6, 18.8), no regular physical exercise (AOR = 15. 5, 95%CI: 5.7, 42.3), and having hypertension [AOR = 0. 03; 95%CI:0.005, 0.2), lung disease (AOR = 0. 2; 95%CI: 0.06, 0.7), and chronic kidney and cardiac diseases (AOR = 0. 06; 95%CI: 0.01, 0.2) were the determinants of non-Hodgkin's lymphoma.

CONCLUSIONS

The findings in this study suggest that having a low monthly income, being male sex, ever had chemical exposure, not engaged in regular physical exercise, and being diabetic were the determinants of non-Hodgkin's lymphoma.

Noncutaneous and Cutaneous Cancer Risk in Patients With Atopic Dermatitis: A Systematic Review and Meta-analysis

Importance

Impaired skin barrier and aberrant immune function in atopic dermatitis (AD) may alter immune response to malignant cancer. Conflicting data exist on the risk of cancer in patients with AD.

Objective

To assess the risk of noncutaneous and cutaneous cancers in patients with AD compared with the general population without AD.

Data Sources

Studies identified from searches of MEDLINE and Embase that were published from 1946 and 1980, respectively, to January 3, 2019. The following search terms were used: [(exp NEOPLASMS/ OR neoplas*.tw. OR tumo*.tw. OR cancer*.tw. OR malignanc*.tw.) AND (exp Dermatitis, Atopic/ OR (atopic adj1 (dermatit* or neurodermatit*)).tw. OR eczema.tw. OR disseminated OR neurodermatit*.tw.)].

Study Selection

Included were observational studies (cohort and case-control designs) reporting a risk estimate for cancer in patients with AD compared with a control group (general population or patients without AD).

Data Extraction and Synthesis

Two independent reviewers extracted data and assessed the risk of bias using the Risk of Bias in Nonrandomized Studies of Interventions (ROBINS-I) assessment tool, modified for observational exposure studies. Data were pooled using a random-effects model and expressed as standardized incidence ratios (SIRs) or odds ratios (ORs) with 95% CIs. Heterogeneity was assessed using the Cochrane Q statistic and the I2 statistic.

Main Outcomes and Measures

The main outcome of the study was risk of cancer measured by SIRs or ORs.

Results

This systematic review and meta-analysis included 8 population-based cohort studies (n = 5 726 692 participants) and 48 case-control studies (n = 114 136 participants). Among cohort studies, a statistically significant association was found between AD and keratinocyte carcinoma (5 studies; pooled SIR, 1.46; 95% CI, 1.20-1.77) as well as cancers of the kidney (2 studies; pooled SIR, 1.86; 95% CI, 1.14-3.04), central nervous system (2 studies; pooled SIR, 1.81; 95% CI, 1.22-2.70), and pancreas (1 study; SIR, 1.90; 95% CI, 1.03-3.50). Among 48 case-control studies, pooled effects showed patients with AD had statistically significantly lower odds of central nervous system cancers (15 studies; pooled OR, 0.76; 95% CI, 0.70-0.82) and pancreatic cancer (5 studies; pooled OR, 0.81; 95% CI, 0.66-0.98), contrary to the higher incidence found in cohort studies. Case-control studies also demonstrated lower odds of lung and respiratory system cancers (4 studies; pooled OR, 0.61; 95% CI, 0.45-0.82). No evidence of association was found between AD and other cancer types, including melanoma. There was substantial heterogeneity between studies for many other cancers, which precluded pooling of data, and there was moderate to serious risk of bias among included studies.

Conclusions and Relevance

Observational evidence suggests potential associations between AD and increased risk of keratinocyte carcinoma and kidney cancer as well as lower odds of lung and respiratory system cancers. Further research is needed to address the heterogeneity and limitations of current evidence and to better understand the mechanisms underlying a possible association between AD and cancer risk.

Influence of Rurality, Race, and Ethnicity on Non-Hodgkin Lymphoma Incidence

INTRODUCTION

Exposure to lymphomagens vary by geography. The extent to which these contribute to racial and ethnic disparities in non-Hodgkin lymphoma (NHL) incidence is not well understood. We sought to evaluate the association between urban-rural status and racial and ethnic disparities in the 3 major NHL subtypes: diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), and chronic lymphocytic leukemia (CLL).

PATIENTS AND METHODS

We used data on NHL incidence from 21 Surveillance, Epidemiology, and End Results (SEER) population-based registries for the period 2000 to 2016. Population characteristics were compared by NHL subtype and urban-rural status, using rural-urban continuum codes from the US Department of Agriculture. Incidence rate ratios were calculated, and Poisson regression was used to assess the association between incidence and rurality.

RESULTS

A total of 136,197 DLBCL, 70,882 FL, and 120,319 CLL incident cases aged ≥ 20 years were reported. The majority of DLBCL patients were non-Hispanic white (73.5%), with 11.9% Hispanic and 7.3% non-Hispanic black, with a similar distribution observed in FL and CLL. Adjusting for age, sex, and family poverty, we found increased DLBCL incidence among Hispanics in increasingly urban areas compared to rural areas (rural incidence rate ratio [IRR] = 1.00; nonmetropolitan urban IRR = 1.32, 95% CI 1.16, 1.51; metropolitan urban IRR = 1.55, 95% CI 1.36, 1.76). Among non-Hispanic blacks, urban areas, relative to rural areas, were associated with increased CLL incidence (IRR = 1.48; 95% CI 1.27, 1.72).

CONCLUSION

Urban-rural incidence patterns suggest that environmental exposures in urban areas associated with DLBCL and CLL pathogenesis may disproportionately affect Hispanics and non-Hispanic blacks.

Modeling Gene-Environment Interaction for the Risk of Non-hodgkin Lymphoma

Background: Non-hodgkin lymphoma (NHL) is one of the most common and deadly cancers. There is limited analysis of gene-environment interactions for the risk of NHL. This study intends to explore the interactions between genetic variants and environmental factors, and how they contribute to NHL risk.

Methods: A case-control study was performed in Shanghai, China. The cases were diagnosed between 2003 and 2008 with patients aged 18 years or older. Samples and SNPs which did not satisfy quality control were excluded from the analysis. Weighted and unweighted genetic risk scores (GRS) and environmental risk scores were generated using clustering analysis algorithm. Univariate and multivariable logistic regression analyses were conducted. Moreover, genetics and environment interactions (G × E) were tested on the NHL cases and controls.

Results: After quality control, there are 22 SNPs, 11 environmental variables and 5 demographical variables to be explored. For logistic regression analyses, 5 SNPs (rs1800893, rs4251961, rs1800630, rs13306698, rs1799931) and environmental tobacco smoking showed statistically significant associations with the risk of NHL. Odds ratio (OR) and 95% confidence interval (CI) was 10.82 (4.34–28.88) for rs13306698, 2.84 (1.66–4.95) for rs1800893, and 2.54 (1.43–4.58) for rs4251961. For G × E analysis, the interaction between smoking and dichotomized weighted GRS showed statistically significant association with NHL (OR = 0.23, 95% CI = [0.09, 0.61]).

Conclusions: Several genetic and environmental risk factors and their interactions associated with the risk of NHL have been identified. Replication in other cohorts is needed to validate the results.

Non-Hodgkin lymphoma among Brazilian agricultural workers: A death certificate case-control study

To estimate the non-Hodgkin lymphoma (NHL) mortality risk among agricultural workers in Brazil's southern states, we used death certificates to identify cases of NHL between the ages of 20 and 69 years from residents of nonurban municipalities between 1996 and 2005 (n = 1,317). Controls were randomly selected from those whose underlying cause of death did not include neoplasm or hematological diseases and paired with cases by sex, age, year of death, and state of residence (n = 2,634). Odds of being an agricultural worker among cases and controls were estimated by conditional logistic regression, stratified and adjusted by sex, state, education, and race. An increased risk of death by NHL was observed among agricultural workers 20-39 years old (OR_adj = 2.06; 95% CI 95%, 1.20-3.14). Our results suggest that the young agricultural workers from southern Brazil were more likely to die of NHL compared to nonagricultural workers.

Allergic conditions are not associated with the risk of non-Hodgkin's lymphoma or Hodgkin's lymphoma: a systematic review and meta-analysis

We aimed to systematically evaluate the association between allergic conditions and the risk of Hodgkin’s lymphoma (HL) and non-HL (NHL). Systematic literature searches in PubMed and Embase were conducted up to October 2015 to identify eligible studies. Either a fixed-effects model or a random-effects model was adopted to estimate overall odds ratios (ORs) according to heterogeneity across studies. Subgroup and publication bias analyses were applied. A total of 24 case–control studies and 13 cohort studies (conducted from 1987 to 2015) were included in the analysis of the risk of NHL. History of any allergic condition was inversely associated with the risk of NHL in case–control studies (OR =0.83, 95% CI 0.76–0.91), while the reduction in the risk of NHL was not observed in cohort studies (OR =1.18, 95% CI 0.98–1.42). Significant association with the risk of NHL was found for asthma, hay fever, food allergy, allergic rhinitis, and hives. In the pooled analysis of the risk of HL, 12 studies (two were cohort studies) were included. The pooled OR was 0.96 (95% CI 0.84–1.09) for case–control studies and 1.46 (95% CI 0.63–3.38) for cohort studies. For specific allergic condition, we observed a reduced risk of HL in individuals with hay fever and food allergy. In conclusion, history of any allergic condition was not significantly associated with the risk of NHL or HL. Several specific allergic conditions, including asthma, hay fever, food allergy, and allergic rhinitis, might be associated with a reduced risk of NHL, while individuals with hay fever or food allergy may have a reduced risk of HL.

Atopy and Specific Cancer Sites: a Review of Epidemiological Studies

Mounting evidence appears to link asthma and atopy to cancer susceptibility. This review presents and discusses published epidemiological studies on the association between site-specific cancers and atopy. PubMed was searched electronically for publications between 1995 and 2015, and cited references were researched manually. Quantitative studies relating to atopy, allergy, or asthma and cancer were identified and tabulated. Despite many exposure-related limitations, patterns in the studies were observed. Asthma, specifically, has been observed to be a risk factor for lung cancer. A protective effect of atopic diseases against pancreatic cancer has been shown consistently in case-control studies but not in cohort studies. Allergy of any type appears to be protective against glioma and adult acute lymphoblastic leukemia. Most studies on atopic diseases and non-Hodgkin lymphoma or colorectal cancer reported an inverse association. The other sites identified had varying and non-significant outcomes. Further research should be dedicated to carefully defined exposure assessments of "atopy" as well as the biological plausibility in the association between atopic diseases and cancer.

Reach: An Unprecedented European Initiative for Regulating Industrial Chemicals

In February 2001, the European Commission (EC) released a White Paper, REACH 2001, detailing unique and unprecedented legislative proposals for the regulation of industrial chemicals, based on the Precautionary Principle. The object of these proposals was to reverse the escalating incidence of avoidable cancers, a wide range of other industrial diseases, and environmental contamination. However, REACH was aggressively opposed by the European and U.S. chemical industries, and even more so by the U.S. administration. The EC responded by making major concessions in its October 2003 REACH-based legislative proposals. This report critically analyzes REACH, and its 2003 revised proposals, and recommends that REACH be strengthened, not weakened. Furthermore, the report urges that regulatory policies of the United States and other industrialized nations be drastically reformed to comply with those of REACH.

Occupation and Risk of Non-Hodgkin Lymphoma and Its Subtypes: A Pooled Analysis from the InterLymph Consortium

BACKGROUND

Various occupations have been associated with an elevated risk of non-Hodgkin lymphoma (NHL), but results have been inconsistent across studies.

OBJECTIVES

We investigated occupational risk of NHL and of four common NHL subtypes with particular focus on occupations of a priori interest.

METHODS

We conducted a pooled analysis of 10,046 cases and 12,025 controls from 10 NHL studies participating in the InterLymph Consortium. We harmonized the occupational coding using the 1968 International Standard Classification of Occupations (ISCO-1968) and grouped occupations previously associated with NHL into 25 a priori groups. Odds ratios (ORs) adjusted for center, age, and sex were determined for NHL overall and for the following four subtypes: diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), and peripheral T-cell lymphoma (PTCL).

RESULTS

We confirmed previously reported positive associations between NHL and farming occupations [field crop/vegetable farm workers OR = 1.26; 95% confidence interval (CI): 1.05, 1.51; general farm workers OR = 1.19; 95% CI: 1.03, 1.37]; we also confirmed associations of NHL with specific occupations such as women's hairdressers (OR = 1.34; 95% CI: 1.02, 1.74), charworkers/cleaners (OR = 1.17; 95% CI: 1.01, 1.36), spray-painters (OR = 2.07; 95% CI: 1.30, 3.29), electrical wiremen (OR = 1.24; 95% CI: 1.00, 1.54), and carpenters (OR = 1.42; 95% CI: 1.04, 1.93). We observed subtype-specific associations for DLBCL and CLL/SLL in women's hairdressers and for DLBCL and PTCL in textile workers.

CONCLUSIONS

Our pooled analysis of 10 international studies adds to evidence suggesting that farming, hairdressing, and textile industry-related exposures may contribute to NHL risk. Associations with women's hairdresser and textile occupations may be specific for certain NHL subtypes.

CITATION

't Mannetje A, De Roos AJ, Boffetta P, Vermeulen R, Benke G, Fritschi L, Brennan P, Foretova L, Maynadié M, Becker N, Nieters A, Staines A, Campagna M, Chiu B, Clavel J, de Sanjose S, Hartge P, Holly EA, Bracci P, Linet MS, Monnereau A, Orsi L, Purdue MP, Rothman N, Lan Q, Kane E, Seniori Costantini A, Miligi L, Spinelli JJ, Zheng T, Cocco P, Kricker A. 2016. Occupation and risk of non-Hodgkin lymphoma and its subtypes: a pooled analysis from the InterLymph Consortium. Environ Health Perspect 124:396-405; http://dx.doi.org/10.1289/ehp.1409294.

Occupational Exposure to Benzene and Non-Hodgkin Lymphoma in a Population-Based Cohort: The Shanghai Women's Health Study

BACKGROUND

The association between benzene exposure and non-Hodgkin lymphoma (NHL) has been the subject of debate as a result of inconsistent epidemiologic evidence. An International Agency for Research on Cancer (IARC) working group evaluated benzene in 2009 and noted evidence for a positive association between benzene exposure and NHL risk.

OBJECTIVE

We evaluated the association between occupational benzene exposure and NHL among 73,087 women enrolled in the prospective population-based Shanghai Women's Health Study.

METHODS

Benzene exposure estimates were derived using a previously developed exposure assessment framework that combined ordinal job-exposure matrix intensity ratings with quantitative benzene exposure measurements from an inspection database of Shanghai factories collected between 1954 and 2000. Associations between benzene exposure metrics and NHL (n = 102 cases) were assessed using Cox proportional hazard models, with study follow-up occurring from December 1996 through December 2009.

RESULTS

Women ever exposed to benzene had a significantly higher risk of NHL [hazard ratio (HR) = 1.87, 95% CI: 1.19, 2.96]. Compared with unexposed women, significant trends in NHL risk were observed for increasing years of benzene exposure (p(trend) = 0.006) and increasing cumulative exposure levels (p(trend) = 0.005), with the highest duration and cumulative exposure tertiles having a significantly higher association with NHL (HR = 2.07, 95% CI: 1.07, 4.01 and HR = 2.16, 95% CI: 1.17, 3.98, respectively).

CONCLUSIONS

Our findings, using a population-based prospective cohort of women with diverse occupational histories, provide additional evidence that occupational exposure to benzene is associated with NHL risk.

Common immune-related exposures/conditions and risk of non-Hodgkin lymphoma: a case-control study of disease-discordant twin pairs

We evaluated the association between common immune system-altering experiences and non-Hodgkin lymphoma (NHL) risk using a case-control study of 162 like-sex twin pairs discordant for NHL, identified from the International Twin Study. Information on medical history and evidence of childhood exposure to microbes was obtained by questionnaire from 1998 to 2002. Conditional logistic regression was used to estimate odds ratios and 95% confidence intervals. Intra-twin-pair agreement between twins on individual exposures was high (76%-97%). A negative association between NHL and seasonal hay fever (odds ratio (OR) = 0.28, 95% confidence interval (CI): 0.10, 0.75) and certain allergies (OR = 0.29, 95% CI: 0.13, 0.68) was observed. The number of atopic diseases was negatively associated with NHL (P for trend = 0.0003). A history of infectious mononucleosis was negatively associated with NHL risk (OR = 0.35, 95% CI: 0.14, 0.90). NHL risk was associated with more frequent childhood exposure to microbes during early life (P for trend = 0.04). No differences in association by NHL subtype were observed, although statistical power for these comparisons was low. These observations support the hypothesis that immune-related exposures, especially atopy, are associated with decreased NHL risk. Use of the within-twin-pair study design mitigates confounding by genome, family structure, and unmeasured characteristics of early childhood factors.

Risk of lymphoma in patients with atopic dermatitis and the role of topical treatment: A systematic review and meta-analysis

BACKGROUND

There is controversy regarding a potential increased risk of lymphoma in patients with atopic dermatitis (AD).

OBJECTIVE

To assess the risk of lymphoma and the role of topical treatments in patients with AD.

METHODS

A systematic literature search and a separate meta-analysis were performed on case control and cohort studies.

RESULTS

Of the 3979 articles retrieved, 24 references met the inclusion criteria. In cohort studies, the risk of lymphoma was slightly increased, with a relative risk (RR) of 1.43 (95% confidence interval [CI], 1.12-1.81). In case control studies, no significant increased risk of lymphoma was found, with an odds ratio (OR) of 1.18 (95% CI, 0.94-1.47). Severity of AD was a significant risk factor. Highly potent topical steroids were associated with an increased risk of lymphoma. For topical calcineurin inhibitors (TCIs), a significant association between tacrolimus and mostly skin lymphoma was found in 1 study.

LIMITATIONS

Confusion between severe AD and cutaneous T-cell lymphoma may account for part of the increased risk of lymphoma in patients with AD.

CONCLUSION

This systematic literature review shows a slightly increased risk of lymphoma in patients with AD. Severity of AD appears to be a significant risk factor. The role of topical steroids and TCIs is unlikely to be significant.

Allergy and risk of hematologic malignancies: associations and mechanisms

Increasing evidence indicates that a dysregulated immune system, as the one found in allergic disorders, can affect survival of tumor cells. A possible association between allergies and risk of hematologic malignancies has been examined in several epidemiological studies; however, results were not always consistent. The aim of this review is to report the preclinical and clinical data, which support a correlation between allergy and hematologic neoplasms. Immune system modulation could represent a powerful tool in the prevention and treatment of hematologic malignancies.

Exploring risk factors for follicular lymphoma

Follicular lymphoma (FL) is an indolent malignancy of germinal center B cells with varied incidence across racial groups and geographic regions. Improvements in the classification of non-Hodgkin lymphoma subtypes provide an opportunity to explore associations between environmental exposures and FL incidence. Our paper found that aspects of Western lifestyle including sedentary lifestyle, obesity, and diets high in meat and milk are associated with an increased risk of FL. Diets rich in fruits and vegetables, polyunsaturated fatty acids, vitamin D, and certain antioxidants are inversely associated with FL risk. A medical history of Sjogren's syndrome, influenza vaccination, and heart disease may be associated with FL incidence. Associations between FL and exposure to pesticides, industrial solvents, hair dyes, and alcohol/tobacco were inconsistent. Genetic risk factors include variants at the 6p21.32 region of the MHC II locus, polymorphisms of the DNA repair gene XRCC3, and UV exposure in individuals with certain polymorphisms of the vitamin D receptor. Increasing our understanding of risk factors for FL must involve integrating epidemiological studies of genetics and exposures to allow for the examination of risk factors and interactions between genes and environment.

Cigarette smoking is associated with a small increase in the incidence of non-Hodgkin lymphoma: a meta-analysis of 24 observational studies

Previous studies have evaluated the association between cigarette smoking and incidence of non-Hodgkin lymphoma (NHL) with inconclusive results. Our main objective was to evaluate this relationship using a meta-analysis of observational studies. A literature search was undertaken through October 2011 looking for pertinent studies. Seven prospective cohort and 17 case-control studies were included in this meta-analysis. Outcomes were calculated using the random-effects model and are reported as odds ratio (OR). Meta-regression was used to evaluate the dose-response of intensity and duration of smoking in NHL incidence. Our study found an OR of 1.40 (95% confidence interval [CI] 1.14-1.73; p = 0.001) in current female smokers seen only in case-control studies. No increased odds of NHL was seen in men. There was no association between smoking and the most common NHL subtypes, with the exception of a statistical trend toward a higher incidence of T-cell lymphoma. In conclusion, there appears to be an increase in the odds of NHL in current female smokers.

Allergy-associated symptoms in relation to childhood non-Hodgkin's as contrasted to Hodgkin's lymphomas: a case-control study in Greece and meta-analysis

An increase of the prevalence of childhood allergic diseases and the incidence of childhood Hodgkin's (HL) and non-Hodgkin's lymphoma (NHL) were reported in the late 20th century. Among adults, several studies point to an inverse association with lymphoma; it remains to be confirmed whether allergy is also related to childhood lymphomas and whether the association, if any, is of an aetiologic nature. Between 1996 and 2008, 277 children (aged 0-14 years) with HL (N = 111) or NHL (N = 166) were enrolled in Nationwide Registry for Childhood Hematological Malignancies (NARECHEM), a Greek hospital-based-registry of childhood hematological malignancies. Hospital controls were individually matched to cases on age and sex. Multivariate conditional logistic regression was used to estimate odds ratios (ORs) with 95%confidence intervals (CIs) for associations of allergic diseases and other covariates with childhood HL or NHL risk. Subsequently, we combined our results with those of a French case-control study in a meta-analysis amounting to a total of 330 NHL cases/1478 controls and 239 HL cases/959 controls. After controlling for sociodemographic, perinatal and environmental factors, childhood NHL was less prevalent among children with allergy-associated symptoms overall (OR:0.50, 95%CI:0.27-0.92) or a history of asthma (OR:0.43, 95%CI:0.21-0.88). By contrast, allergy did not seem to be associated with childhood HL risk, although statistical power was limited. Fewer seaside holidays and higher birth weight were also associated with increased childhood NHL risk. The combined OR of the two studies for the association of asthma with NHL risk was: 0.52, 95%CI:0.32-0.84, whereas for HL: 0.86, 95%CI:0.51-1.45. Allergy seems to be strongly and inversely associated with childhood NHL. It remains to be elucidated in future investigations comprising larger populations, focusing on specific disease subtypes and employing more pertinent study-designs, whether this association is genuinely protective.

Cigarette smoking, passive smoking, and non-Hodgkin lymphoma risk: evidence from the California Teachers Study

Epidemiologic studies conducted to date have shown evidence of a causal relation between smoking and non-Hodgkin lymphoma (NHL) risk. However, previous studies did not account for passive smoking exposure in the never-smoking reference group. The California Teachers Study collected information about lifetime smoking and household passive smoking exposure in 1995 and about lifetime exposure to passive smoking in 3 settings (household, workplace, and social settings) in 1997-1998. Multivariable-adjusted relative risks and 95% confidence intervals were estimated by fitting Cox proportional hazards models with follow-up through 2007. Compared with never smokers, ever smokers had a 1.11-fold (95% confidence interval (CI): 0.94, 1.30) higher NHL risk that increased to a 1.22-fold (95% CI: 0.95, 1.57) higher risk when women with household passive smoking were excluded from the reference category. Statistically significant dose responses were observed for lifetime cumulative smoking exposure (intensity and pack-years; both P 's for trend = 0.02) when women with household passive smoking were excluded from the reference category. Among never smokers, NHL risk increased with increasing lifetime exposure to passive smoking (relative risk = 1.51 (95% CI: 1.03, 2.22) for >40 years vs. ≤5 years of passive smoking; P for trend = 0.03), particularly for follicular lymphoma (relative risk = 2.89 (95% CI: 1.23, 6.80); P for trend = 0.01). The present study provides evidence that smoking and passive smoking may influence NHL etiology, particularly for follicular lymphoma.

Evaluation of cancer risk related to atopic dermatitis and use of topical calcineurin inhibitors

Cases of lymphoma or cutaneous cancer have been observed following use of topical calcineurin inhibitors (TCIs), but it is unclear whether TCI use increases cancer risk. We used published literature to assess the extent to which atopic dermatitis (AD) or TCI use is associated with lymphoma, melanoma, basal cell carcinoma and squamous cell carcinoma. We searched the literature and summarized the results of all studies that provided data on the absolute or relative frequency of any malignancy among patients with AD or eczema or among patients using TCIs. The relative risk for all lymphoma in broad populations of AD or eczema ranged from 0·7 to 1·8. Available data on lymphoma following TCI use were inconsistent and insufficient to draw a conclusion about the causal role of TCIs. We found no evidence indicating that melanoma or nonmelanoma skin cancer is associated with TCI use. A bias analysis showed that cutaneous T-cell lymphomas initially misdiagnosed and treated as AD would lead to overestimation of the association between TCI use and lymphoma. However, there are only sparse data on specific malignancies among TCI-treated patients. The short duration of typical TCI exposure hinders conclusions about longer exposure. There is insufficient evidence in the epidemiological literature to infer whether TCIs do or do not cause malignancy.

Polychlorinated biphenyls and non-Hodgkin's lymphoma: a case-control study in Northern Italy

BACKGROUND

Polychlorinated biphenyls (PCBs) have been hypothesized to increase the risk of non-Hodgkin lymphoma (NHL), although conclusive evidence is still lacking. High levels of PCBs were found in soil in some areas close to a PCB-producing factory in Brescia, North Italy. We conducted a population-based case-control study among residents of the town to investigate the possible association between PCB pollution and NHL in this area.

METHODS

We included both incident and deceased NHL cases, and a random sample of the town residents as controls, frequency matched to cases as regards age and gender. Exposure to PCBs was estimated on the basis of the lifetime residential history of cases and controls in four different areas of the town-A, B and C (polluted areas) and D (control area).

RESULTS

A total of 495 cases (287 incident cases) and 1467 controls were enrolled. Positive associations were found between NHL and having resided for at least 10 years in the area A, the most polluted area (odds ratio, OR=1.8; p=0.02) and for having resided in any of the polluted areas considered together (A+B+C) (OR=1.4; p=0.08). However, no associations were evident for having resided 20 years or longer in the polluted areas or when analyzing the association with each subject's main residence in his/her lifetime.

CONCLUSION

This study provides some evidence for an association between PCB exposure and NHL, though results should be considered with caution in the absence of individual biological measures of exposure.

Incidence of cancer in the general population and in patients with or without atopic dermatitis in the U.K

BACKGROUND

Atopic dermatitis (AD) affects approximately 20% of children and 1-3% of adults in developed countries.

OBJECTIVE

To study the incidence of cancer in patients with AD in the U.K. general population.

METHODS

We conducted a follow-up study in the U.K. using The Health Improvement Network (THIN) database. We calculated the incidence rate (IR) of the first occurrence of overall cancer, lymphoma, melanoma and nonmelanoma skin cancer (NMSC) in the general population, in patients with AD and in individuals without AD. In addition we calculated the IR ratio (IRR) of overall cancer and subtypes of cancer in patients with AD vs. those without.

RESULTS

The study population included 4,518,131 patients [2,336,230 (51·7%) female]. There were 129,972 subjects [68,688 (52·8%) female] with a diagnosis of cancer (excluding NMSC). The IR (per 10,000 person-years) of cancer (excluding NMSC) was 42·41 [95% confidence interval (CI) 42·18-42·64]; of lymphoma 1·70 (95% CI 1·65-1·74); of skin melanoma 1·71 (95% CI 1·67-1·76) and of NMSC 11·76 (95% CI 11·64-11·88). The age- and sex-adjusted IRR for cancer (excluding NMSC) was 1·49 (95% CI 1·39-1·61); for lymphoma 2·21 (95% CI 1·65-2·98); for melanoma 1·74 (95% CI 1·25-2·41); and for NMSC 1·46 (95% CI 1·27-1·69).

CONCLUSIONS

Our results indicate an increased incidence of cancer overall as well as of specific cancer subtypes, including lymphoma, in patients with AD. Further studies are needed to disentangle the effects of treatment for AD from AD itself.

History of asthma or eczema and cancer risk among men: a population-based case-control study in Montreal, Quebec, Canada

BACKGROUND

Epidemiologic evidence regarding the association between a history of allergic diseases and different cancer types has been inconsistent.

OBJECTIVE

To examine whether a history of asthma or eczema is associated with various cancers among Canadian men in a population based case-control study conducted in the 1980s.

METHODS

Questionnaire-based interviews were performed by a team of trained interviewers from August 1979 to March 1986. Information collected included self-reported history of a prior medical diagnosis of asthma and of eczema, medication use, and several covariates among 3,300 cancer cases and 512 population controls. Logistic regression models were used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the association between asthma or eczema and more than 20 cancer types combined, as well as for each of the 8 most common cancer types (stomach, colon, rectum, lung, prostate, bladder, skin, and lymph nodes).

RESULTS

Considering study participants who reported a prior medical diagnosis of the disease and medication use, a history of asthma was negatively associated with all cancer types combined (OR, 0.72; 95% CI, 0.5-1.1) and similarly for a history of eczema (OR, 0.66; 95% CI, 0.4-1.1). Although ORs between asthma and eczema and most individual types were below 1.0, only 2 ORs were significantly below 1.0: that between asthma and stomach cancer (OR, 0.27; 95% CI, 0.1-0.9) and that between eczema and lung cancer (OR, 0.34; 95% CI, 0.2-0.7).

CONCLUSION

Allergic conditions that result from a hyperreactive immune system might lead to a more efficient elimination of abnormal cells, thus lowering cancer risks.

Genetic variation in N-acetyltransferases 1 and 2, cigarette smoking, and risk of non-Hodgkin lymphoma

Cigarette smoke contains many carcinogens that are metabolically activated through xenobiotic metabolism by phase I and II enzymes, including N-acetyltransferases 1 and 2 (NAT1 and NAT2). We investigated non-Hodgkin lymphoma risk in general and by subtype in relation to NAT1 and NAT2 genotypes and cigarette smoking in a population-based case-control study in Connecticut. Of the 535 controls, 53.1% reported ever smoking, and of the 461 cases, 55.7% reported ever smoking. We found a two-fold increased risk of T-cell lymphoma among those possessing the NAT1*10 genotype compared to those with other NAT1 genotypes; including an OR of 2.0 (95% CI: 1.0-2.4) for those heterozygous or homozygous for NAT1*10 genotypes. Rapid acetylator NAT2 phenotype increased the risk of both T-cell lymphoma (OR = 3.2; 95% CI: 1.1-9.5) and marginal zone lymphoma (OR = 3.0; 95% CI: 1.0-8.7), though these results were based on a small number of cases. When smoking status and risk of NHL was stratified by NAT1 and NAT2 genotypes, an increased risk of NHL overall was observed in current (OR = 1.7; 95% CI: 1.2-2.4) smokers without the NAT1*10 genotype but not among smokers with the NAT1*10 genotype (p-interaction < 0.01). No association between history of cigarette smoking and risk of NHL overall was observed with any NAT2 genotype. Our results present modest evidence that acetylation rate is associated with risk of NHL for specific subtypes and that the NAT1*10 genotype is an "at-risk" allele. Additionally, our results suggest that the relationship between NHL and smoking status may be modified by common genetic variation in NAT1 but not NAT2. We conclude that these findings require replication in larger studies and ultimately in pooled analyses.

Atopic disease and risk of non-Hodgkin lymphoma: an InterLymph pooled analysis

We performed a pooled analysis of data on atopic disease and risk of non-Hodgkin lymphoma (NHL) from 13 case-control studies, including 13,535 NHL cases and 16,388 controls. Self-reported atopic diseases diagnosed 2 years or more before NHL diagnosis (cases) or interview (controls) were analyzed. Pooled odds ratios (OR) and 95% confidence intervals (95% CI) were computed in two-stage random-effects or joint fixed-effects models, and adjusted for age, sex, and study center. When modeled individually, lifetime history of asthma, hay fever, specific allergy (excluding hay fever, asthma, and eczema), and food allergy were associated with a significant reduction in NHL risk, and there was no association for eczema. When each atopic condition was included in the same model, reduced NHL risk was only associated with a history of allergy (OR, 0.80; 95% CI, 0.68-0.94) and reduced B-cell NHL risk was associated with history of hay fever (OR, 0.85; 95% CI, 0.77-0.95) and allergy (OR, 0.84; 95% CI, 0.76-0.93). Significant reductions in B-cell NHL risk were also observed in individuals who were likely to be truly or highly atopic-those with hay fever, allergy, or asthma and at least one other atopic condition over their lifetime. The inverse associations were consistent for the diffuse large B-cell and follicular subtypes. Eczema was positively associated with lymphomas of the skin; misdiagnosis of lymphoma as eczema is likely, but progression of eczema to cutaneous lymphoma cannot be excluded. This pooled study shows evidence of a modest but consistent reduction in the risk of B-cell NHL associated with atopy.

Genetic and environmental risk indicators in canine non-Hodgkin's lymphomas: breed associations and geographic distribution of 608 cases diagnosed throughout France over 1 year

BACKGROUND

The etiology of non-Hodgkin's lymphomas (NHL) is multifactorial. Environmental and genetic factors are frequently incriminated both in humans and dogs.

OBJECTIVES

Our purpose was to study the geographic distribution of canine NHL (CNHL) in France and to evaluate genetic and environmental influences.

ANIMALS

Six hundred and eight cases of CNHL, diagnosed throughout France over 1 year, were collected from 7 Veterinary Histopathologic Laboratories.

METHODS

Retrospective study. Breeds affected by lymphomas were compared with the national population and associations between breed and immunophenotype were studied. The distribution of CNHL and canine T-cell NHL per 100,000 dogs per department was compared with the distribution of waste incinerators, polluted sites, and radioactive waste.

RESULTS

The breeds significantly overrepresented among lymphoma cases were Boxer, Setter, and Cocker Spaniel (P < .001). There was a significant association between Boxer and T-cell NHL (P < .001), and between German Shepherd and Rottweiler and B-cell NHL (P < .01). The geographic distribution of CNHL and canine T-cell NHL indicated significant heterogeneity. Significant association between distributions of CNHL and waste incinerators (rho= 0.25, P < .05), polluted sites (rho= 0.36, P < .001), and radioactive waste (rho= 0.51, P < .001) was found.

CONCLUSIONS AND CLINICAL IMPORTANCE

Influence of genetics in the development of CNHL was supported by the existence of an association between breed and immunophenotype. Waste incinerators, polluted sites, and radioactive waste could just be considered as risk indicators of CNHL, but not as risk factors. Case-control studies around critical sites are necessary to confirm the implication of those environmental factors in the development of CNHL.

Occupational exposure to solvents and risk of non-Hodgkin lymphoma in Connecticut women

A population-based case-control study involving 601 incident cases of non-Hodgkin lymphoma (NHL) and 717 controls was conducted in 1996-2000 among Connecticut women to examine associations with exposure to organic solvents. A job-exposure matrix was used to assess occupational exposures. Increased risk of NHL was associated with occupational exposure to chlorinated solvents (odds ratio (OR) = 1.4, 95% confidence interval (CI): 1.1, 1.8) and carbon tetrachloride (OR = 2.3, 95% CI: 1.3, 4.0). Those ever exposed to any organic solvent in work settings had a borderline increased risk of NHL (OR = 1.3, 95% CI: 1.0, 1.6); moreover, a significantly increased risk was observed for those with average probability of exposure to any organic solvent at medium-high level (OR = 1.5, 95% CI: 1.1, 1.9). A borderline increased risk was also found for ever exposure to formaldehyde (OR = 1.3, 95% CI: 1.0, 1.7) in work settings. Risk of NHL increased with increasing average intensity (P = 0.01), average probability (P < 0.01), cumulative intensity (P = 0.01), and cumulative probability (P < 0.01) level of organic solvent and with average probability level (P = 0.02) and cumulative intensity level of chlorinated solvent (P = 0.02). Analyses by NHL subtype showed a risk pattern for diffuse large B-cell lymphoma similar to that for overall NHL, with stronger evidence of an association with benzene exposure. Results suggest an increased risk of NHL associated with occupational exposure to organic solvents for women.

Occupational exposure to pesticides and lymphoid neoplasms among men: results of a French case-control study

OBJECTIVES

Investigating the relationship between occupational exposure to pesticides and the risk of lymphoid neoplasms (LNs) in men.

METHODS

A hospital-based case-control study was conducted in six centres in France between 2000 and 2004. The cases were incident cases with a diagnosis of LN aged 18-75 years. During the same period, controls of the same age and sex as the cases were recruited in the same hospital, mainly in the orthopaedic and rheumatological departments. Exposures to pesticides were evaluated through specific interviews and case-by-case expert reviews. Four hundred and ninety-one cases (244 cases of non-Hodgkin's lymphoma (NHL), 87 of Hodgkin's lymphoma (HL), 104 of lymphoproliferative syndromes (LPSs) and 56 of multiple myeloma (MM) cases) and 456 controls were included in the analyses. The odds ratios (ORs) and 95% CI were estimated using unconditional logistic regressions.

RESULTS

Positive associations between HL and occupational exposure to triazole fungicides and urea herbicides were observed (OR = 8.4 (2.2 to 32.4), 10.8 (2.4 to 48.1), respectively). Exposure to insecticides, fungicides and herbicides were linked to a threefold increase in MM risk (OR = 2.8 (1.2 to 6.5), 3.2 (1.4 to 7.2), 2.9 (1.3 to 6.5)). For LPS subtypes, associations restricted to hairy-cell leukaemia (HCL) were evidenced for exposure to organochlorine insecticides, phenoxy herbicides and triazine herbicides (OR = 4.9 (1.1 to 21.2), 4.1 (1.1 to 15.5), 5.1 (1.4 to 19.3)), although based on small numbers. Lastly, despite the increased ORs for organochlorine and organophosphate insecticides, carbamate fungicides and triazine herbicides, no significant associations were evidenced for NHL.

CONCLUSIONS

The results, based on case-by-case expert review of occupation-specific questionnaires, support the hypothesis that occupational pesticide exposures may be involved in HL, MM and HCL and do not rule out a role in NHL. The analyses identified specific pesticides that deserve further investigation and the findings were consistent with those of previous studies.

Meta-analysis of benzene exposure and non-Hodgkin lymphoma: biases could mask an important association

OBJECTIVES

Benzene is a widely recognised cause of leukaemia but its association with non-Hodgkin's lymphoma (NHL) is less well established. The goal of this project is to review the current published literature on this association.

METHODS

We performed a meta-analysis of cohort and case-control studies of benzene exposure and NHL and a meta-analysis of NHL and refinery work, a potential source of benzene exposure.

RESULTS

In 22 studies of benzene exposure, the summary relative risk for NHL was 1.22 (95% CI 1.02 to 1.47; one-sided p value = 0.01). When studies that likely included unexposed subjects in the "exposed" group were excluded, the summary relative risk increased to 1.49 (95% CI 1.12 to 1.97, n = 13), and when studies based solely on self-reported work history were excluded, the relative risk rose to 2.12 (95% CI 1.11 to 4.02, n = 6). In refinery workers, the summary relative risk for NHL in all 21 studies was 1.21 (95% CI 1.00 to 1.46; p = 0.02). When adjusted for the healthy worker effect, this relative risk estimate increased to 1.42 (95% CI 1.19 to 1.69).

CONCLUSIONS

The finding of elevated relative risks in studies of both benzene exposure and refinery work provides further evidence that benzene exposure causes NHL. In addition, the finding of increased relative risks after removing studies that included unexposed or lesser exposed workers in "exposed" cohorts, and increased relative risk estimates after adjusting for the healthy worker effect, suggest that effects of benzene on NHL might be missed in occupational studies if these biases are not accounted for.

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.

Immunoglobulin E levels and risk of lymphoma in a case-control study in Spain

Epidemiologic studies have shown an inverse association between atopy and malignant lymphoma, but results are inconsistent. We investigated levels of IgE, before and after commencement of treatment, and evaluated lymphoma risk in relation to total and specific IgE levels. Serum levels of IgM, IgA, and IgG were also measured. We enrolled 467 newly diagnosed lymphoma cases and 544 hospital controls, matched for age, sex, and hospital. Lymphomas were histologically confirmed and categorized according to the WHO classification. Subjects provided blood for analysis of total and specific IgE levels, and total IgM, IgA, and IgG levels. Additional information was collected by interviewer-administered questionnaire. Controlling for age, sex, center, smoking status, and any treated asthma or eczema, we found that the overall risk of lymphoma was significantly lower in the high [odds ratio (OR), 0.39; 95% confidence interval (95% CI), 0.28-0.54] and middle (OR, 0.55; 95% CI, 0.40-0.74) tertiles for total serum IgE compared with the low tertile. Specific IgE to common aeroallergens (defined as >or=0.35 kU/L) was also inversely associated with risk of lymphoma (OR, 0.67; 95% CI, 0.45-1.00). Lymphoma was associated with IgA and IgM but not IgG. Mean levels of all immunoglobulins were decreased with more advanced malignancy, and total serum IgE levels were lower before treatment. The data suggest that the low levels of immunoglobulins seen in a wide range of lymphoma cases is likely to be linked to a lymphogenesis process rather than resulting from a selective protection due to an atopic process. Long-term cohort studies may be fundamental to fully evaluate these associations.

The non-Hodgkin lymphomas: a review of the epidemiologic literature

The non-Hodgkin lymphomas (NHL) are a heterogeneous group of B-cell and T-cell neoplasms that arise primarily in the lymph nodes. NHL incidence rates in the US doubled between about 1970 and 1990, and stabilized during the 1990s. NHL accounts for approximately 3.4% of cancer deaths in the US. Although some of the observed patterns in NHL have been related to HIV/AIDS, these conditions cannot fully explain the magnitude of the changes; neither do changes in classification systems nor improved diagnostic capabilities. Studies of occupational and environmental exposures (e.g., pesticides, solvents) have produced no consistent pattern of significant positive associations. Inverse associations with ultraviolet radiation exposure and alcohol and fish intake, and positive associations with meat and saturated fat intake have been reported in several studies; additional studies are needed to confirm or refute these associations. Family history of NHL or other hematolympho-proliferative cancers and personal history of several autoimmune disorders are associated with increased risk of NHL, but are not likely to account for a large proportion of cases. HIV and other infectious agents, such as human herpesvirus 8 and Epstein-Barr, appear to be associated with differing types of NHL, such as some B-cell lymphomas. Future epidemiologic studies should evaluate associations by NHL type, enhance exposure information collected, and elucidate factors that may identify susceptible (or resistant) subpopulations because of genetic, immunologic or other characteristics. The extent to which the etiology of NHL types may differ is important to resolve in ongoing and future studies.

Occupation and the risk of non-Hodgkin lymphoma

Although thus far no occupational agents have been classified as established causes of non-Hodgkin lymphoma (NHL), employment as a farmer, teacher, dry cleaner, meat worker, printer, or wood worker has been associated with elevated risk in the peer-reviewed literature. We conducted several meta-analyses to assess risk in these occupations and industries from articles published in MEDLINE up to August 1, 2006. The summary risk estimates suggest a homogeneous excess risk for NHL among workers in the printing industry [relative risk (RR), 1.86; 95% confidence interval (95% CI), 1.37-2.52] and wood workers (RR, 1.15; 95% CI, 1.00-1.31). Considerable heterogeneity but elevated risks were found for farmers (RR, 1.11; 95% CI, 1.05-1.17), especially in animal husbandry (RR, 1.31; 95% CI, 1.08-1.60), and teaching (RR, 1.47; 95% CI, 1.34-1.61). An increased risk was absent for employment in the meat processing industry (RR, 0.99; 95% CI, 0.77-1.29). These results suggest that although excess risk is found for employment in the printing industry, wood processing industry, teaching, and farming, it is unlikely that occupation represents a major risk factor for NHL in most populations. At present, no conclusive evidence of causal relations between occupations and increased NHL risk exists; this can be ascribed to methodologic problems in studying the link between NHL risk and occupation, including heterogeneity of disease and exposure circumstances and low statistical power. Implementing state-of-the-art exposure assessment technologies, including biomarker-based assessment, and aiming to identify susceptible subgroups can increase the statistical power enough to analyze etiologically relevant NHL subtypes and provide clues on possible causal agents in future studies. These goals can be best attained within the framework of large-scale, international collaborative projects.