Tobacco smoking, alcohol drinking and non-Hodgkin's lymphoma: A European multicenter case-control study (Epilymph)

Lifetime occupational and recreational physical activity and risk of lymphoma subtypes. Results from the European Epilymph case-control study

Physical activity is known to convey protection against several cancers. However, results on the risk of lymphoma overall and its subtypes have been inconsistent. The aim of this study was to investigate occupational and recreational physical activity in relation to risk of lymphoma subtypes adjusting for established occupational risk factors. We applied standardized tools to assess energy expenditure at work and in recreational physical activities to the questionnaire information on lifetime work and exercise history in 1117 lymphoma cases, including Hodgkin lymphoma, and B-cell (including chronic lymphocytic leukemia, and multiple myeloma) and T-cell non-Hodgkin's lymphoma (NHL) subtypes, and 1207 controls who took part in the multicentre European EpiLymph case-control study. We calculated the risk of lymphoma (all subtypes), B-cell NHL and its most represented subtypes, and Hodgkin's lymphoma (all subtypes) associated with weekly average Metabolic Equivalent of Task (MET-hours/week) and cumulative MET-hours of lifetime recreational, occupational, and total physical activity, with unconditional logistic regression and polytomous regression analysis adjusting by age, centre, sex, education, body mass index, history of farm work and solvent use. We observed an inverse association of occupational, and total physical activity with risk of lymphoma (all subtypes), and B-cell non-Hodgkin's lymphoma among women, and an upward trend in risk of Hodgkin's lymphoma with recreational and total physical activity among men, for which we cannot exclude chance or bias. Our results suggest no effect of overall physical activity on risk of lymphoma and its subtypes.

Epidemiology and etiology of diffuse large B-cell lymphoma

As the most common non-Hodgkin lymphoma subtype, diffuse large B-cell lymphoma (DLBCL) incidence patterns generally parallel that for NHL overall. Globally, DLBCL accounts for a third of all NHLs, ranging between 20% and 50% by country. Based on United States (U.S.) cancer registry data, age-standardized incidence rate for DLBCL was 7.2 per 100,000. DLBCL incidence rises with age and is generally higher in males than females; in the U.S., incidence is highest among non-Hispanic whites (9.2/100,000). Like NHL incidence, DLBCL incidence rose in the first half of the 20th century but has largely plateaued. However, there is some evidence that incidence rates are rising in areas of historically low rates, such as Asia; there are also estimates for rising DLBCL incidence in the near future due to the changing demographics in developed countries whose aging population is growing. Established risk factors for DLBCL include those that result in severe immune deficiency such as HIV/AIDS, inherited immunodeficiency syndromes, and organ transplant recipients. Factors that lead to chronic immune dysregulations are also established risk factors, and include a number of autoimmune conditions (eg, Sjögren syndrome, systemic lupus erythematosus, rheumatoid arthritis), viral infections (eg, HIV, KSHV/HHV8, HCV, EBV), and obesity. Family history of NHL/DLBCL, personal history of cancer, and multiple genetic susceptibility loci are also well-established risk factors for DLBCL. There is strong evidence for multiple environmental exposures in DLBCL etiology, including exposure to trichloroethylene, benzene, and pesticides and herbicides, with recent associations noted with glyphosate. There is also strong evidence for associations with other viruses, such as HBV. Recent estimates suggest that obesity accounts for nearly a quarter of DLBCLs that develop, but despite recent gains in the understanding of DLBCL etiology, the majority of disease remain unexplained. An understanding of the host and environmental contributions to disease etiology, and concerted efforts to expand our understanding to multiple race/ethnic groups, will be essential for constructing clinically relevant risk prediction models and develop effective strategies for disease prevention.

Occupational pesticide exposure, cancer and chronic neurological disorders: A systematic review of epidemiological studies in greenspace workers

CONTEXT

The greenspace sector includes a broad range of occupations: gardeners, landscapers, municipal workers, maintenance operators of public facilities, golf-course employees and other sports facilities, horticulturists, plant and tree nursery workers etc. The health impact of occupational pesticide exposure has mainly been studied among farmers. Other professionals such as greenspace workers are also extremely exposed, presenting specific exposure features (practices, types of pesticide used). The aim of this review was to summarize epidemiological literature that examine the relationship between pesticide exposure and the risk of cancer and long-term health effects in greenspace workers.

METHOD

Six main groups of greenspace workers were identified and examined through a systematic literature review based on PubMed and Scopus. The studies were then grouped according to their design, health outcomes and the type of population studied.

RESULTS

Forty-four articles were selected among the 1679 identified. Fifteen studies were conducted exclusively among greenspace workers, while ten also studied these workers with other pesticide applicators. Six were cohorts from the general population in which greenspace workers were identified. Elevated risks were found in several studies for leukaemia, soft-tissue sarcoma, multiple myeloma, non-Hodgkin lymphoma and Parkinson's disease.

DISCUSSION

The majority of studies used rough parameters for defining exposure such as job titles which could lead to the misclassification of exposure, with the risk of false or positive negative conclusions. Health outcomes were mainly collected through registries or death certificates, and information regarding potential confounders was often missing.

CONCLUSION

The review identified only 15 studies conducted exclusively among greenspace workers. Elevated risk was found for several sites of cancer and Parkinson's diseases. Further epidemiological research is needed, conducted specifically on these workers, to better characterize this population, its exposure to pesticides and the related health effects.

Occupational exposure to glyphosate and risk of lymphoma:results of an Italian multicenter case-control study

BACKGROUND

The International Agency for Research on Cancer (IARC) recently classified glyphosate, the most used herbicide worldwide, as a probable human carcinogen. We inquired into the association between occupational exposure to glyphosate and risk of lymphoma subtypes in a multicenter case-control study conducted in Italy.

METHODS

The Italian Gene-Environment Interactions in Lymphoma Etiology (ItGxE) study took place in 2011-17 in six Italian centres. Overall, 867 incident lymphoma cases and 774 controls participated in the study. Based on detailed questionnaire information, occupational experts classified duration, confidence, frequency, and intensity of exposure to glyphosate for each study subject. Using unconditional regression analysis, we modelled risk of major lymphoma subtypes associated with exposure to glyphosate adjusted by age, gender, education, and study centre.

RESULTS

Very few study subjects (2.2%) were classified as ever exposed to glyphosate. Risk of follicular lymphoma (FL) was elevated 7-fold in subjects classified as ever exposed to glyphosate with medium-high confidence, 4.5-fold in association with medium-high cumulative exposure level, 12-fold with medium-high exposure intensity, and 6-fold with exposure for 10 days or more per year. Significant upward trends were detected with all the exposure metrics, but duration. The overall p-value for an upward trend with four independent metrics was 1.88 × 10- 4. There was no association with risk of lymphoma (any subtype), Non Hodgkin Lymphoma, B-cell lymphoma, or the major lymphoma subtypes other than FL.

CONCLUSIONS

Our findings provide limited support to the IARC decision to classify glyphosate as Group 2A human carcinogen.

Occupational exposure to organic dust and risk of lymphoma subtypes in the EPILYMPH case-control study

Objectives This study aimed to estimate the risk of lymphoma and its major subtypes in relation to occupational exposure to specific organic dusts. Methods We explored the association in 1853 cases and 1997 controls who participated in the EpiLymph case-control study, conducted in six European countries in 1998-2004. Based on expert assessment of lifetime occupational exposures, we calculated the risk of the major lymphoma subtypes associated with exposure to six specific organic dusts, namely, flour, hardwood, softwood, natural textile, synthetic textile, and leather, and two generic (any types) groups: wood and textile dusts. Risk was predicted with unconditional regression modeling, adjusted by age, gender, study center, and education. Results We observed a 2.1-fold increase in risk of follicular lymphoma associated with ever exposure to leather dust [95% confidence interval (CI) 1.01-4.20]. After excluding subjects who ever worked in a farm or had ever been exposed to solvents, risk of B-cell lymphoma was elevated in relation to ever exposure to leather dust [odd ratio (OR) 2.2, 95% CI 1.00-4.78], but it was not supported by increasing trends with the exposure metrics. Risk of Hodgkin lymphoma was elevated (OR 2.0, 95% CI 0.95-4.30) for exposure to textile dust, with consistent upward trends by cumulative exposure and three independent exposure metrics combined (P=0.023, and P=0.0068, respectively). Conclusions Future, larger studies might provide further insights into the nature of the association we observed between exposure to textile dust and risk of Hodgkin lymphoma.

Infectious mononucleosis, immune genotypes, and non-Hodgkin lymphoma (NHL): an InterLymph Consortium study

PURPOSE

We explored the interaction between non-Hodgkin lymphoma (NHL), infectious mononucleosis (IM) history, and immune-related genotypes in a pooled case-control analysis.

METHODS

A total of 7,926 NHL patients and 10,018 controls from 12 case-control studies were included. Studies were conducted during various time periods between 1988 and 2008, and participants were 17-96 years of age at the time of ascertainment/recruitment. Self-reported IM history and immune response genotypes were provided by the InterLymph Data Coordinating Center at Mayo Clinic. Odds ratios (OR) were estimated using multivariate logistic regression, and interactions were estimated using the empirical Bayes method. PACT was used to account for multiple comparisons.

RESULTS

There was evidence of an interaction effect between IM history and two variants on T-cell lymphoma (TCL) risk: rs1143627 in interleukin-1B (IL1B) (pinteraction = 0.04, ORinteraction = 0.09, 95% confidence interval [CI] 0.01, 0.87) and rs1800797 in interleukin-6 (IL6) (pinteraction = 0.03, ORinteraction = 0.08, 95% CI 0.01, 0.80). Neither interaction effect withstood adjustment for multiple comparisons. There were no statistically significant interactions between immune response genotypes and IM on other NHL subtypes.

CONCLUSIONS

Genetic risk variants in IL1B and IL6 may affect the association between IM and TCL, possibly by influencing T-cell activation, growth, and differentiation in the presence of IM, thereby decreasing risk of immune cell proliferation.

Serum organochlorines and non-Hodgkin lymphoma: A case-control study in Israeli Jews and Palestinians

Associations of organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) with non-Hodgkin lymphoma are controversial. We compared serum levels of 6 OC pesticides and 38 PCBs in Israeli Jews (IJ) and Palestinian Arabs (PA) and assessed possible associations with B-cell non-Hodgkin lymphoma (B-NHL). Ninety B-NHL cases (50 IJ and 40 PA) and 120 controls (65 IJ and 55 PA) were included. Median concentrations of analytes in controls were compared across ethnic groups using quantile regression, adjusting for age and sex. We used logistic regression to derive odds ratios (OR) and 95% confidence intervals (CI) for detectable analytes and B-NHL, adjusting for age, ethnic group, faming and body mass index. Median values of PCBs and dichlorodiphenyldichloroethylene (DDE) were higher in IJ vs PA controls (P = 0.0007), as were several PCBs (74, 99, 118, 138, 146, 153, 156, 163, 170, and 180). Overall, OC pesticide and PCB exposures were comparable with reports from high-income countries. B-NHL was associated with PCB 146 (OR 1.70, 95% CI: 1.02, 2.83), PCB 156 (OR 1.75, 95% CI: 1.06, 2.89), and high-chlorinated PCBs (OR 1.55, 95% CI: 1.00, 2.40) in all study subjects. These associations were robust in quantile as well as sensitivity analyses. An association of DDE with B-NHL was noted in PA (OR 1.72, 95% CI: 1.07, 2.77), but not in IJ (OR 0.87, 95% CI: 0.59, 1.27). Although high-chlorinated PCB concentrations did not indicate high exposure levels, our findings indicate that B-NHL may be associated with this exposure.

The dose-response relationship between tobacco smoking and the risk of lymphomas: a case-control study

BACKGROUND

Previous studies have provided limited support to the association between tobacco smoking and lymphomas with weak evidence of a dose-response relationship.

METHODS

We investigated the relationship between tobacco smoking and risk of non-Hodgkin lymphomas (NHL) and Hodgkin lymphomas (HL) through logistic regression spline models. Data were derived from an Italian hospital-based case-control study (1999-2014), which enrolled 571 NHLs, 188 HLs, and 1004 cancer-free controls. Smoking habits and other lifestyle factors were assessed through a validated questionnaire. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by logistic regression, adjusting for potential confounders.

RESULTS

Compared to never smokers, people smoking ≥15 cigarettes/day showed increased risks of both NHL (OR = 1.42, 95% CI: 1.02, 1.97) and HL (OR = 2.47, 95% CI: 1.25, 4.87); the risk was particularly elevated for follicular NHL (OR = 2.43; 95% CI:1.31-4.51) and mixed cellularity HL (OR = 5.60, 95% CI: 1.31, 23.97). No excess risk emerged for former smokers or people smoking <15 cigarettes/day. Spline analyses showed a positive dose-response relationship with significant increases in NHL and HL risks starting from 15 and 21 cigarettes/day, respectively, with the most evident effects for follicular NHL and mixed cellularity HL. Smoking duration was significantly associated with the HL risk only (OR = 2.15, 95% CI: 1.16, 3.99).

CONCLUSIONS

These findings support a role of tobacco smoking in the etiology of both NHL and HL, providing evidence of a direct association of risk with smoking intensity.

Ethnic variation in medical and lifestyle risk factors for B cell non-Hodgkin lymphoma: A case-control study among Israelis and Palestinians

Background

Risk factors for B-cell non-Hodgkin lymphoma (B-NHL) have not been assessed among Palestinian Arabs (PA) and Israeli Jews (IJ).

Methods

In a case-control study we investigated self-reported medical and lifestyle exposures, reporting odds ratios (ORs) and 95% confidence intervals [CIs], by ethnicity, for overall B-NHL and subtypes.

Results

We recruited 823 cases and 808 healthy controls. Among 307 PA/516 IJ B-NHL cases (mean age at diagnosis = 51 [±17] versus 60 [±15] years, respectively) subtype distributions differed, with diffuse large B-cell lymphoma (DLBCL) being prominent among PA (71%) compared to IJ (41%); follicular lymphoma (FL), was observed in 14% versus 28%, and marginal zone lymphoma, in 2% versus 14%, respectively. Overall B-NHL in both populations was associated with recreational sun exposure OR = 1.43 [CI:1.07–1.91], black hair-dye use OR = 1.70 [CI:1.00–2.87], hospitalization for infection OR = 1.68 [CI:1.34–2.11], and first-degree relative with hematopoietic cancer, OR = 1.69 [CI:1.16–2.48]. An inverse association was noted with alcohol use, OR = 0.46 [CI:0.34–0.62]. Subtype-specific exposures included smoking (FL, OR = 1.46 [CI:1.01–2.11]) and >monthly indoor pesticide use (DLBCL, OR = 2.01 [CI:1.35–3.00]). Associations observed for overall B-NHL in PA only included: gardening OR = 1.93 [CI:1.39–2.70]; history of herpes, mononucleosis, rubella, blood transfusion (OR>2.5, P<0.01 for all); while for IJ risk factors included growing fruits and vegetables, OR = 1.87 [CI:1.11–3.15]; and self-reported autoimmune diseases, OR = 1.99 [CI:1.34–2.95].

Conclusions

In these geographically proximate populations we found some unique risk factors for B-NHL. Heterogeneity in the observed associations by ethnicity could reflect differences in lifestyle, medical systems, and reporting patterns, while variations by histology infer specific etiologic factors for lymphoma subtypes.

Carotenoid intake and risk of non-Hodgkin lymphoma: a systematic review and dose-response meta-analysis of observational studies

Carotenoids may play a protective role in the development of non-Hodgkin lymphoma (NHL), but findings from epidemiological studies on the associations between carotenoid intake and NHL risk are inconsistent. We therefore performed a meta-analysis to systemically evaluate the associations. Eligible studies were identified by a search of PubMed, Web of Science, Embase, and article reference lists. We pooled risk estimates from individual studies using a random-effect model to quantify the associations between intakes of specific carotenoids and NHL risk. A total of 10 (7 case-control and 3 cohort) studies met our inclusion criteria. In the highest versus lowest analyses, intakes of alpha-carotene, beta-carotene, and lutein/zeaxanthin, but not lycopene or beta-cryptoxanthin, were associated with a significant reduced risk of NHL. The estimated summary relative risks (95% confidence intervals) for alpha-carotene, beta-carotene, and lutein/zeaxanthin were 0.87 (0.78-0.97), 0.80 (0.68-0.94), and 0.82 (0.69-0.97), respectively. Subgroup analyses showed that evidence supporting these protective associations was mostly based on studies with a case-control design. In addition, intakes of alpha-carotene and beta-carotene were associated with a significant decreased risk of diffuse large B-cell lymphoma, but not follicular lymphoma or small lymphocytic lymphoma/chronic lymphocytic leukemia. There was a significant inverse dose-response relationship between alpha-carotene intake and NHL risk (13% lower risk per 1000 μg/day increment of intake). In conclusion, our findings suggest that higher intakes of alpha-carotene, beta-carotene, and lutein/zeaxanthin might protect against NHL development. Further cohort studies with a control of plausible confounding are needed to confirm these associations.

Smoking is a risk factor for development of adult T-cell leukemia/lymphoma in Japanese human T-cell leukemia virus type-1 carriers

BACKGROUND AND PURPOSE

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive hematological malignancy caused by human T-cell leukemia virus type-1 (HTLV-1); no effective methods have yet been identified to prevent development of ATLL in carriers of HTLV-1. This study investigated the association between cigarette smoking and the risk of ATLL development among Japanese carriers of HTLV-1.

METHODS

This study examined the association between smoking and development of ATLL in a cohort of 1,332 Japanese HTLV-1 carriers aged 40-69 years free of ATLL at baseline from two different HTLV-1-endemic areas of Japan. Cox proportional hazards models adjusted for sex, geographic area, age at baseline, and alcohol drinking were used to estimate the effect of cigarette smoking on ATLL development.

RESULTS

Between 1993 and 2012, 25 new ATLL cases were identified among these subjects. The overall crude incidence rate for ATLL was 1.08 per 1,000 person-years among HTLV-1 carriers and was higher among male carriers than among female carriers (2.21 vs. 0.74). The risk of ATLL development increased significantly with increasing numbers of cigarettes smoked per day (hazard ratio for every increment of 20 cigarettes, 2.03; 95 % confidence interval (CI) 1.13-3.66 overall, 2.07 (95 % CI 1.13-3.73) in male carriers).

CONCLUSIONS

Cigarette smoking may influence ATLL development among HTLV-1 carriers in Japan.

Non-radiation risk factors for leukemia: A case-control study among chornobyl cleanup workers in Ukraine

BACKGROUND

Occupational and environmental exposure to chemicals such as benzene has been linked to increased risk of leukemia. Cigarette smoking and alcohol consumption have also been found to affect leukemia risk. Previous analyses in a large cohort of Chornobyl clean-up workers in Ukraine found significant radiation-related increased risk for all leukemia types. We investigated the potential for additional effects of occupational and lifestyle factors on leukemia risk in this radiation-exposed cohort.

METHODS

In a case-control study of chronic lymphocytic and other leukemias among Chornobyl cleanup workers, we collected data on a range of non-radiation exposures. We evaluated these and other potential risk factors in analyses adjusting for estimated bone marrow radiation dose. We calculated Odds Ratios and 95% Confidence Intervals in relation to lifestyle factors and occupational hazards.

RESULTS

After adjusting for radiation, we found no clear association of leukemia risk with smoking or alcohol but identified a two-fold elevated risk for non-CLL leukemia with occupational exposure to petroleum (OR=2.28; 95% Confidence Interval 1.13, 6.79). Risks were particularly high for myeloid leukemias. No associations with risk factors other than radiation were found for chronic lymphocytic leukemia.

CONCLUSIONS

These data - the first from a working population in Ukraine - add to evidence from several previous reports of excess leukemia morbidity in groups exposed environmentally or occupationally to petroleum or its products.

Risk of lymphoma subtypes and dietary habits in a Mediterranean area

BACKGROUND

Previous studies have suggested that diet might affect risk of lymphoma subtypes. We investigated risk of lymphoma and its major subtypes associated with diet in the Mediterranean island of Sardinia, Italy.

METHODS

In 1998-2004, 322 incident lymphoma cases and 446 randomly selected population controls participated in a case-control study on lymphoma etiology in central-southern Sardinia. Questionnaire interviews included frequency of intake of 112 food items. Risk associated with individual dietary items and groups thereof was explored by unconditional and polytomous logistic regression analysis, adjusting by age, gender and education.

RESULTS

We observed an upward trend in risk of lymphoma (all subtypes combined) and B-cell lymphoma with frequency of intake of well done grilled/roasted chicken (p for trend=0.01), and pizza (p for trend=0.047), Neither adherence to Mediterranean diet nor a frequent intake of its individual components conveyed protection. We detected heterogeneity in risk associated with several food items and groups thereof by lymphoma subtypes although we could not rule out chance as responsible for the observed direct or inverse associations.

CONCLUSIONS

Adherence to a Mediterranean diet does not seem to convey protection against the development of lymphoma. The association with specific food items might vary by lymphoma subtype.

Non-Hodgkin Lymphoma, Body Mass Index, and Cytokine Polymorphisms: A Pooled Analysis from the InterLymph Consortium

BACKGROUND

Excess adiposity has been associated with lymphomagenesis, possibly mediated by increased cytokine production causing a chronic inflammatory state. The relationship between obesity, cytokine polymorphisms, and selected mature B-cell neoplasms is reported.

METHOD

Data on 4,979 cases and 4,752 controls from nine American/European studies from the InterLymph consortium (1988-2008) were pooled. For diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), joint associations of body mass index (from self-reported height and weight) and 12 polymorphisms in cytokines IL1A (rs1800587), IL1B (rs16944, rs1143627), IL1RN (rs454078), IL2 (rs2069762), IL6 (rs1800795, rs1800797), IL10 (rs1800890, rs1800896), TNF (rs1800629), LTA (rs909253), and CARD15 (rs2066847) were investigated using unconditional logistic regression. BMI-polymorphism interaction effects were estimated using the relative excess risk due to interaction (RERI).

RESULTS

Obesity (BMI ≥ 30 kg/m(2)) was associated with DLBCL risk [OR = 1.33; 95% confidence interval (CI), 1.02-1.73], as was TNF-308GA+AA (OR = 1.24; 95% CI, 1.07-1.44). Together, being obese and TNF-308GA+AA increased DLBCL risk almost 2-fold relative to those of normal weight and TNF-308GG (OR = 1.93; 95% CI, 1.27-2.94), with a RERI of 0.41 (95% CI, -0.05-0.84; Pinteraction = 0.13). For FL and CLL/SLL, no associations with obesity or TNF-308GA+AA, either singly or jointly, were observed. No evidence of interactions between obesity and the other polymorphisms were detected.

CONCLUSIONS

Our results suggest that cytokine polymorphisms do not generally interact with BMI to increase lymphoma risk but obesity and TNF-308GA+AA may interact to increase DLBCL risk.

IMPACT

Studies using better measures of adiposity are needed to further investigate the interactions between obesity and TNF-308G>A in the pathogenesis of lymphoma.

Medical history, lifestyle, family history, and occupational risk factors for lymphoplasmacytic lymphoma/Waldenström's macroglobulinemia: the InterLymph Non-Hodgkin Lymphoma Subtypes Project

BACKGROUND

Lymphoplasmacytic lymphoma/Waldenström's macroglobulinemia (LPL/WM), a rare non-Hodgkin lymphoma subtype, shows strong familial aggregation and a positive association with chronic immune stimulation, but evidence regarding other risk factors is very limited.

METHODS

The International Lymphoma Epidemiology Consortium (InterLymph) pooled data from 11 predominantly population-based case-control studies from North America, Europe, and Australia to examine medical history, lifestyle, family history, and occupational risk factors for LPL/WM. Age-, sex-, race/ethnicity-, and study-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression for a total of 374 LPL/WM cases and 23 096 controls.

RESULTS

In multivariate analysis including all putative risk factors, LPL/WM risk was associated with history of Sjögren's syndrome (OR = 14.0, 95% CI = 3.60 to 54.6), systemic lupus erythematosus (OR = 8.23, 95% CI = 2.69 to 25.2), hay fever (OR = 0.73, 95% CI = 0.54 to 0.99), positive hepatitis C serology (OR = 2.51, 95% CI = 1.03 to 6.17), hematologic malignancy in a first-degree relative (OR = 1.64, 95% CI = 1.02 to 2.64), adult weight (OR = 0.61, 95% CI = 0.44 to 0.85 for highest vs. lowest quartile), duration of cigarette smoking (OR = 1.46, 95% CI = 1.04 to 2.05 for ≥ 40 years vs. nonsmokers), and occupation as a medical doctor (OR = 5.54, 95% CI = 2.19 to 14.0). There was no association with other medical conditions, lifestyle factors, or occupations.

CONCLUSIONS

This pooled analysis confirmed associations with immune conditions and family history of hematologic malignancy, and identified new associations with hay fever, weight, smoking, and occupation, and no association with other lifestyle factors. These findings offer clues to LPL/WM biology and prevention.

Rationale and Design of the International Lymphoma Epidemiology Consortium (InterLymph) Non-Hodgkin Lymphoma Subtypes Project

BACKGROUND

Non-Hodgkin lymphoma (NHL), the most common hematologic malignancy, consists of numerous subtypes. The etiology of NHL is incompletely understood, and increasing evidence suggests that risk factors may vary by NHL subtype. However, small numbers of cases have made investigation of subtype-specific risks challenging. The International Lymphoma Epidemiology Consortium therefore undertook the NHL Subtypes Project, an international collaborative effort to investigate the etiologies of NHL subtypes. This article describes in detail the project rationale and design.

METHODS

We pooled individual-level data from 20 case-control studies (17471 NHL cases, 23096 controls) from North America, Europe, and Australia. Centralized data harmonization and analysis ensured standardized definitions and approaches, with rigorous quality control.

RESULTS

The pooled study population included 11 specified NHL subtypes with more than 100 cases: diffuse large B-cell lymphoma (N = 4667), follicular lymphoma (N = 3530), chronic lymphocytic leukemia/small lymphocytic lymphoma (N = 2440), marginal zone lymphoma (N = 1052), peripheral T-cell lymphoma (N = 584), mantle cell lymphoma (N = 557), lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (N = 374), mycosis fungoides/Sézary syndrome (N = 324), Burkitt/Burkitt-like lymphoma/leukemia (N = 295), hairy cell leukemia (N = 154), and acute lymphoblastic leukemia/lymphoma (N = 152). Associations with medical history, family history, lifestyle factors, and occupation for each of these 11 subtypes are presented in separate articles in this issue, with a final article quantitatively comparing risk factor patterns among subtypes.

CONCLUSIONS

The International Lymphoma Epidemiology Consortium NHL Subtypes Project provides the largest and most comprehensive investigation of potential risk factors for a broad range of common and rare NHL subtypes to date. The analyses contribute to our understanding of the multifactorial nature of NHL subtype etiologies, motivate hypothesis-driven prospective investigations, provide clues for prevention, and exemplify the benefits of international consortial collaboration in cancer epidemiology.

Epidemiology and etiology of non-hodgkin lymphoma

Non-Hodgkin lymphoma (NHL) consists of many histologically and biologically distinct lymphoid malignancies with poorly understood, but possibly distinct, etiologies. The patterns of incidence and time trend vary not only by age, sex, and race/ethnicity in the USA, but also show significant geographic differences, suggesting the potential role of infectious agents, environmental factors, and lifestyle factors in addition to host genetic status in the development of NHL. Important pathogenetic mechanisms include immune modulation and chronic antigen stimulation. Epidemiologic studies in the past two decades have provided intriguing new insights on the possible causes of lymphoma and support the idea that there is some mechanistic commonality of lymphomagenesis, but significant etiologic heterogeneity clearly exists. This review presents a summary of the current understanding of the descriptive epidemiology and etiology of NHL and suggests areas of focus for future epidemiologic research.

Medical history, lifestyle, and occupational risk factors for hairy cell leukemia: the InterLymph Non-Hodgkin Lymphoma Subtypes Project

BACKGROUND

Little is known about the etiology of hairy cell leukemia (HCL), a rare B-cell lymphoproliferative disorder with marked male predominance. Our aim was to identify key risk factors for HCL.

METHODS

A pooled analysis of individual-level data for 154 histologically confirmed HCL cases and 8834 controls from five case-control studies, conducted in Europe and Australia, was undertaken. Age-, race and/or ethnicity-, sex-, and study-adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression.

RESULTS

The usual patterns for age and sex in HCL were observed, with a median age of 55 years and sex ratio of 3.7 males to females. Cigarette smoking was inversely associated with HCL (OR = 0.51, 95% CI = 0.37 to 0.71) with dose-response relationships observed for duration, frequency, and lifetime cigarette smoking (P(trend) < .001). In contrast, occupation as a farmer was positively associated with HCL (OR = 2.34, 95% CI = 1.36 to 4.01), with a dose-response relationship observed for duration (OR = 1.82, 95% CI = 0.85 to 3.88 for ≤ 10 years vs never; and OR = 2.98, 95% CI = 1.50 to 5.93 for >10 years vs never; P(trend) = .025). Adult height was also positively associated with HCL (OR = 2.69, 95% CI = 1.39 to 5.29 for upper vs lower quartile of height). The observed associations remained consistent in multivariate analysis.

CONCLUSIONS

Our observations of an increased risk of HCL from farming exposures and decreased risk from smoking exposures, independent of one another, support a multifactorial origin and an etiological specificity of HCL compared with other non-Hodgkin lymphoma subtypes. The positive association with height is a novel finding that needs replication.

Multiple myeloma and occupation: a pooled analysis by the International Multiple Myeloma Consortium

OBJECTIVE

We investigated occupational risk of multiple myeloma (MM) in a pooled analysis of five international case-control studies.

METHODS

We calculated the odds ratio and its 95% confidence interval for selected occupations with unconditional regression analysis in 1959 MM cases and 6192 controls, by pooling study-specific risks using random-effects meta-analysis. Exposure to organic solvents was assessed with a job-exposure matrix (JEM).

RESULTS

Gardeners and nursery workers combined, most likely exposed to pesticides, showed a 50% increase in risk (OR = 1.50, 95% CI 0.9-2.3), while other farming jobs did not. Metal processors (OR = 1.55, 95% CI 0.9-2.3), female cleaners (OR = 1.32, 95% CI 1.0-1.8), and high level exposure to organic solvents (OR = 1.38, 95% CI 0.96-1.8) also showed moderately increased risks.

CONCLUSIONS

Additional case-control studies of MM aetiology are warranted to further investigate the nature of the repeatedly reported increase in MM risk in several occupational groups.

Smoking, variation in N-acetyltransferase 1 (NAT1) and 2 (NAT2), and risk of non-Hodgkin lymphoma: a pooled analysis within the InterLymph consortium

PURPOSE

Studies of smoking and risk of non-Hodgkin lymphoma (NHL) have yielded inconsistent results, possibly due to subtype heterogeneity and/or genetic variation impacting the metabolism of tobacco-derived carcinogens, including substrates of the N-acetyltransferase enzymes NAT1 and NAT2.

METHODS

We conducted a pooled analysis of 5,026 NHL cases and 4,630 controls from seven case-control studies in the international lymphoma epidemiology consortium to examine associations between smoking, variation in the N-acetyltransferase genes NAT1 and NAT2, and risk of NHL subtypes. Smoking data were harmonized across studies, and genetic variants in NAT1 and NAT2 were used to infer acetylation phenotype of the NAT1 and NAT2 enzymes, respectively. Pooled odds ratios (ORs) and 95 % confidence intervals (95 % CIs) for risk of NHL and subtypes were calculated using joint fixed effects unconditional logistic regression models.

RESULTS

Current smoking was associated with a significant 30 % increased risk of follicular lymphoma (n = 1,176) but not NHL overall or other NHL subtypes. The association was similar among NAT2 slow (OR 1.36; 95 % CI 1.07-1.75) and intermediate/rapid (OR 1.27; 95 % CI 0.95-1.69) acetylators (p (interaction) = 0.82) and also did not differ by NAT1*10 allelotype. Neither NAT2 phenotype nor NAT1*10 allelotype was associated with risk of NHL overall or NHL subtypes.

CONCLUSION

The current findings provide further evidence for a modest association between current smoking and follicular lymphoma risk and suggest that this association may not be influenced by variation in the N-acetyltransferase enzymes.

Lymphoma risk in livestock farmers: results of the Epilymph study

We explored the risk of lymphoma and its most prevalent subtypes associated with occupational contact with livestock, and whether risk was modified by age at first contact, in 2,348 incident lymphoma cases and 2,462 controls who participated in the EPILYMPH case-control study. A detailed occupational history was collected in cases and controls, including working in a livestock farm, species of livestock, its approximate number and circumstances of contact. For each disease outcome, and each type of livestock, odds ratios (OR) and their 95% confidence intervals (95% CI) were calculated using unconditional logistic regression, adjusting for age, gender, education and center. Lymphoma risk (all subtypes combined) was not increased amongst those exposed to contact with any livestock (OR = 1.0, 95% CI 0.8-1.2). Overall, we did not observe an association between occupational contact with livestock and risk of lymphoma (all types) and B-cell lymphoma. The risk of diffuse large B cell lyphoma (DLBCL) was significantly lower amongst subjects who started occupational contact with any species of livestock before or at age 12 (OR = 0.5, 95% CI 0.2-0.9), but not at older ages. A significant heterogeneity in risk of B cell lymphoma by age at first contact was detected for contact with cattle, poultry and swine. Early occupational contact with livestock might be associated with a decrease in risk of B cell lymphoma.

Alcohol drinking and non-Hodgkin lymphoma risk: a systematic review and a meta-analysis

BACKGROUND

Whether an association between alcohol drinking and non-Hodgkin lymphoma (NHL) risk exists is an open question. In order to provide quantification of the issue, we carried out a meta-analysis of published data.

METHODS

We identified 21 case-control and 8 cohort studies, including a total of 18,759 NHL cases. We derived meta-analytic estimates using random-effects models, taking into account correlation between estimates.

RESULTS

The overall relative risk (RR) of NHL for drinkers versus non-drinkers was 0.85 [95% confidence interval (CI) 0.79-0.91]. Compared with non-drinkers, the pooled RRs were 0.88 for light (≤1 drink per day), 0.87 for moderate (1 to <4 drinks per day), and 0.84 for heavy (≥4 drinks per day) alcohol drinking. There was no association for light drinkers in cohort studies, whereas for moderate and heavy drinkers, the RRs were similar in case-control (0.85 for moderate, 0.92 for heavy) and cohort (0.89 for moderate, 0.79 for heavy) studies. The inverse relation with alcohol consumption (drinkers versus non-drinkers) was similar in men (RR = 0.83) and women (RR = 0.86), but apparently stronger in studies from Asia (RR = 0.69) than other world areas (RR = 0.88).

CONCLUSION

This meta-analysis provides quantitative evidence of a favourable role of alcohol drinking on NHL risk, though the lack of a biological explanation suggests caution in the interpretation of results.

Current understanding of lifestyle and environmental factors and risk of non-hodgkin lymphoma: an epidemiological update

The incidence rates of non-Hodgkin lymphoma (NHL) have steadily increased over the last several decades in the United States, and the temporal trends in incidence can only be partially explained by the HIV epidemic. In 1992, an international workshop sponsored by the United States National Cancer Institute concluded that there was an “emerging epidemic” of NHL and emphasized the need to investigate the factors responsible for the increasing incidence of this disease. Over the past two decades, numerous epidemiological studies have examined the risk factors for NHL, particularly for putative environmental and lifestyle risk factors, and international consortia have been established in order to investigate rare exposures and NHL subtype-specific associations. While few consistent risk factors for NHL aside from immunosuppression and certain infectious agents have emerged, suggestive associations with several lifestyle and environmental factors have been reported in epidemiologic studies. Further, increasing evidence has suggested that the effects of these and other exposures may be limited to or stronger for particular NHL subtypes. This paper examines the progress that has been made over the last twenty years in elucidating the etiology of NHL, with a primary emphasis on lifestyle factors and environmental exposures.

Menstrual and reproductive factors, and hormonal contraception use: associations with non-Hodgkin lymphoma in a pooled analysis of InterLymph case-control studies

BACKGROUND

The two most common forms of non-Hodgkin lymphoma (NHL) exhibit different sex ratios: diffuse large B-cell lymphoma (DLBCL) occurs more frequently in men and follicular lymphoma (FL) more frequently in women. Looking among women alone, this pooled analysis explores the relationship between reproductive histories and these cancers.

MATERIALS AND METHODS

Self-reported reproductive histories from 4263 women with NHL and 5971 women without NHL were pooled across 18 case-control studies (1983-2005) from North America, Europe and Japan. Study-specific odd ratios (ORs) and confidence intervals (CIs) were estimated using logistic regression and pooled using random-effects meta-analyses.

RESULTS

Associations with reproductive factors were found for FL rather than NHL overall and DLBCL. In particular, the risk of FL decreased with increasing number of pregnancies (pooled OR(trend) = 0.88, 95% CI 0.81-0.96). FL was associated with hormonal contraception (pooled OR = 1.30, 95% CI 1.04-1.63), and risks were increased when use started after the age of 21, was used for <5 years or stopped for >20 years before diagnosis. DLBCL, on the other hand, was not associated with hormonal contraception (pooled OR = 0.87, 95% CI 0.65-1.16).

CONCLUSIONS

Hormonal contraception is associated with an increased risk of FL but not of DLBCL or NHL overall.

Alcohol drinking, tobacco smoking and subtypes of haematological malignancy in the UK Million Women Study

BACKGROUND

Previous research suggests associations of lower alcohol intake and higher tobacco consumption with increased risks of haematological malignancy. The prospective Million Women Study provides sufficient power for reliable estimates of subtype-specific associations in women.

METHODS

Approximately 1.3 million middle-aged women were recruited in the United Kingdom during 1996-2001 and followed for death, emigration and cancer registration until 2009 (mean 10.3 years per woman); potential risk factors were assessed by questionnaire. Adjusted relative risks were estimated by Cox regression.

RESULTS

During follow-up, 9162 incident cases of haematological malignancy were recorded, including 7047 lymphoid and 2072 myeloid cancers. Among predominantly moderate alcohol drinkers, higher intake was associated with lower risk of lymphoid malignancies, in particular diffuse large B-cell lymphoma (relative risk 0.85 per 10 g alcohol per day (95% confidence interval 0.75-0.96)), follicular lymphoma (0.86 (0.76-0.98)) and plasma cell neoplasms (0.86 (0.77-0.96)). Among never- and current smokers, higher cigarette consumption was associated with increased risk of Hodgkin lymphoma (1.45 per 10 cigarettes per day (1.22-1.72)), mature T-cell malignancies (1.38 (1.10-1.73)) and myeloproliferative/myelodysplastic disease (1.42 (1.31-1.55)).

CONCLUSION

These findings confirm and extend existing evidence for associations of subtypes of haematological malignancy with two common exposures in women.

Alcohol intake and the incidence of non-hodgkin lymphoid neoplasms in the cancer prevention study II nutrition cohort

Although several studies have shown a lower risk of non-Hodgkin lymphoma (NHL) in alcohol drinkers compared with nondrinkers, the dose-response relation and potential differences between former and current drinking and across beverage types and subtypes are unclear. The authors examined associations of alcohol intake with risk of NHL and NHL subtypes in the Cancer Prevention Study II Nutrition Cohort, a prospective study of US men and women aged 50-74 years. Between 1992 and 2007, there were 1,991 incident NHL cases among 143,124 participants. Multivariable-adjusted relative risks and 95% confidence intervals were computed using Cox proportional hazards regression. Compared with nondrinkers, the relative risk of NHL associated with former drinking was 0.90 (95% confidence interval (CI): 0.75, 1.10); the relative risks associated with current intakes of <1, 1-2, and >2 drinks/day were 0.93 (95% CI: 0.83, 1.03), 0.91 (95% CI: 0.78, 1.06), and 0.78 (95% CI: 0.65, 0.93), respectively. Associations did not differ by sex (P-interaction = 0.45) or beverage type (P-difference = 0.22). Alcohol intake was more strongly associated with B-cell lymphoma (P-trend = 0.005) than with T-cell lymphoma (P-trend = 0.76), and associations were similar among B-cell lymphoma subtypes. In this prospective study, current heavy alcohol intake was associated with a reduced risk of NHL. Associations did not differ by beverage type and were slightly stronger for B-cell tumors than for T-cell tumors.

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.

A comprehensive study of polymorphisms in the ABCB1, ABCC2, ABCG2, NR1I2 genes and lymphoma risk

Owing to their role in controlling the efflux of toxic compounds, transporters are central players in the process of detoxification and elimination of xenobiotics, which in turn is related to cancer risk. Among these transporters, ATP-binding cassette B1/multidrug resistance 1 (ABCB1/MDR1), ABCC2/multidrug resistance protein 2 (MRP2) and ABCG2/breast cancer resistance protein (BCRP) affect susceptibility to many hematopoietic malignancies. The maintenance of regulated expression of these transporters is governed through the activation of intracellular "xenosensors" like the nuclear receptor 1I2/pregnane X receptor (NR1I2/PXR). SNPs in genes encoding these regulators have also been implicated in the risk of several cancers. Using a tagging approach, we tested the hypothesis that common polymorphisms in the transporter genes ABCB1, ABCC2, ABCG2 and the regulator gene NR1I2 could be implicated in lymphoma risk. We selected 68 SNPs in the four genes, and we genotyped them in 1,481 lymphoma cases and 1,491 controls of the European case-control study (EpiLymph) using the Illumina GoldenGate™ assay technology. Carriers of the SNP rs6857600 minor allele in ABCG2 was associated with a decrease in risk of B-cell lymphoma (B-NHL) overall (p < 0.001). Furthermore, a decreased risk of chronic lymphocytic leukemia (CLL) was associated with the ABCG2 rs2231142 variant (p = 0.0004), which could be replicated in an independent population. These results suggest a role for this gene in B-NHL susceptibility, especially for CLL.

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.

Association of JAK-STAT pathway related genes with lymphoma risk: results of a European case-control study (EpiLymph)

Previous studies have suggested an important role for the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signalling pathway in tumour development. Therefore, we explored genetic variants in JAK-STAT pathway associated genes with lymphoma risk. In samples of the EpiLymph case-control study we genotyped 1536 single nucleotide polymorphisms (SNPs) using GoldenGate BeadArray™ Technology (Illumina, San Diego, CA, USA). Here, we report the associations between selected SNPs and haplotypes of the JAK-STAT pathway and risk of Hodgkin lymphoma (HL), B-cell non-Hodgkin lymphoma (B-NHL) and most frequent B-NHL subtypes. Among 210 relevant JAK-STAT pathway-related SNPs, polymorphisms in nine genes (BMF, IFNG, IL12A, SOCS1, STAT1, STAT3, STAT5A, STAT6, TP63) were significantly associated with lymphoma risk. At a study-wise significance level, we obtained a risk reduction of 28% among carriers of the heterozygous genotype of the STAT3 variant (rs1053023) for B-NHL. For six other variants within the STAT3 gene we observed an inverse association with different lymphoma subtypes. A reduced risk for HL was observed for the heterozygous genotype of the STAT6 SNP (rs324011). This is an explorative investigation to examine associations between JAK-STAT signalling related genes and lymphoma risk. The results implicate a relevant role of certain pathway-related genes in lymphomagenesis, but still need to be approved by independent studies.

Alcohol consumption over time and risk of lymphoid malignancies in the California Teachers Study cohort

Several previous studies found inverse associations between alcohol consumption and risk of non-Hodgkin lymphoma (NHL) and multiple myeloma. However, most studies were retrospective, and few distinguished former drinkers or infrequent drinkers from consistent nondrinkers. Therefore, the authors investigated whether history of alcohol drinking affected risks of NHL and multiple myeloma among 102,721 eligible women in the California Teachers Study, a prospective cohort study in which 496 women were diagnosed with B-cell NHL and 101 were diagnosed with multiple myeloma between 1995-1996 and December 31, 2007. Incidence rate ratios and 95% confidence intervals were estimated using Cox proportional hazards regression. Risk of all types of B-cell NHL combined or multiple myeloma was not associated with self-reported past consumption of alcohol, beer, wine, or liquor at ages 18-22 years, at ages 30-35 years, or during the year before baseline. NHL subtypes were inconsistently associated with alcohol intake. However, women who were former alcohol drinkers at baseline were at elevated risk of overall B-cell NHL (rate ratio = 1.46, 95% confidence interval: 1.08, 1.97) and follicular lymphoma (rate ratio = 1.81, 95% confidence interval: 1.00, 3.28). The higher risk among former drinkers emphasizes the importance of classifying both current and past alcohol consumption and suggests that factors related to quitting drinking, rather than alcohol itself, may increase B-cell NHL risk.

Birth order and risk of non-hodgkin lymphoma--true association or bias?

There is inconsistent evidence that increasing birth order may be associated with risk of non-Hodgkin lymphoma (NHL). The authors examined the association between birth order and related variables and NHL risk in a pooled analysis (1983-2005) of 13,535 cases and 16,427 controls from 18 case-control studies within the International Lymphoma Epidemiology Consortium (InterLymph). Overall, the authors found no significant association between increasing birth order and risk of NHL (P-trend = 0.082) and significant heterogeneity. However, a significant association was present for a number of B- and T-cell NHL subtypes. There was considerable variation in the study-specific risks which was partly explained by study design and participant characteristics. In particular, a significant positive association was present in population-based studies, which had lower response rates in cases and controls, but not in hospital-based studies. A significant positive association was present in higher-socioeconomic-status (SES) participants only. Results were very similar for the related variable of sibship size. The known correlation of high birth order with low SES suggests that selection bias related to SES may be responsible for the association between birth order and NHL.

A hospital-based case-control study of non-Hodgkin lymphoid neoplasms in Shanghai: analysis of personal characteristics, lifestyle, and environmental risk factors by subtypes of the WHO classification

OBJECTIVES

To investigate potential risk factors (personal characteristics, lifestyle, and environmental factors) of non-Hodgkin lymphoid neoplasms (NHLN), including lymphomas and lymphocytic leukemia, according to the World Health Organization classification.

MATERIALS AND METHODS

The investigation was a hospital-based case-control study consisting of 649 confirmed NHLN cases and 1298 individually gender-age-matched patient controls at 25 hospitals in Shanghai. A 17-page questionnaire was used to obtain information on demographics, medical history, family history, lifestyle risk factors, employment history, residential history, and occupational and non-occupational exposures. Risk estimates were calculated using conditional logistic regression models.

RESULTS

Potential risk factors of NHLN (all subtypes combined) or individual subtypes included low-level education, home or workplace renovation, living on a farm, planting crops, and raising livestock or animals. Some risk factors applied to all or most subtypes (such as lowlevel education, living on a farm, and raising livestock or animals), whereas others did not (such as the use of traditional Chinese medicines, which was associated with a reduced risk). Blood transfusions, hair dyes, or living near high-voltage power lines were not associated with an increased risk.

CONCLUSIONS

The study identified a number of risk factors for NHLN overall and specific subtypes. Some risk factors were subtype-specific. The difference in risk by subtype underscores the etiologic commonality and heterogeneity of NHLN subtypes.

Genetic polymorphisms in cytochrome P450s, GSTs, NATs, alcohol consumption and risk of non-Hodgkin lymphoma

The aim of this study was to investigate whether genetic polymorphisms in cytochrome P450s (CYPs), glutathione S-transferases (GSTs), and N-acetyltransferases (NATs) genes modify the relationship between alcohol consumption and risk of non-Hodgkin's lymphoma (NHL) in a population-based, case-control study including 1,115 Connecticut women. Although we did not find strong evidence that the genetic polymorphisms modify the relationship between alcohol consumption and risk of NHL, we identified significant interactions for multiple GSTs and NATs and alcohol intake among persons with DLBCL. Our results confer support investigation of the gene-environment interaction in a larger study population of DLBCL.

Association of alcohol intake with the risk of malignant lymphoma and plasma cell myeloma in Japanese: a population-based cohort study (Japan Public Health Center-based Prospective Study)

Few studies have evaluated the association between alcohol intake and the risk of the lymphoid neoplasms malignant lymphoma (ML) and plasma cell myeloma (PCM) among Asian populations. We conducted a large-scale population-based cohort study of 95,520 Japanese subjects (45,453 men and 50,067 women; age 40-69 years at baseline) with an average 13 years of follow-up, during which a total of 257 cases of ML and 89 of PCM were identified. Hazard ratios and 95% confidence intervals were estimated using a Cox regression model adjusted for potential confounders. Alcohol intake of > or = 300 g/week was associated with a significantly lower risk of lymphoid neoplasms (hazard ratio, 0.60; 95% confidence interval, 0.37-0.98) than occasional drinking at a frequency of <1 day/month, and the trend for alcohol consumption was significant (P = 0.028). A similar trend was observed for the subcategories of ML, PCM, and non-Hodgkin lymphoma (NHL), albeit that the results were significant only for alcohol consumption at > or = 300 g/week in NHL patients, probably due to the small number of subjects in each category. In conclusion, we found that alcohol had an inverse association with the risk of lymphoid neoplasms, particularly the risk of NHL, among a Japanese population.

Polymorphisms of drug-metabolizing genes and risk of non-Hodgkin lymphoma

Drug metabolizing genes are involved in the detoxification of chemical carcinogens. Polymorphisms in drug-metabolizing genes affect the risk of some forms of cancer. We analyzed six polymorphisms to evaluate their association with risk for non-Hodgkin lymphoma (NHL), and to examine whether smoking modifies these associations in population-based study in Korea (713 cases and 1,700 controls). The GSTP1 rs1695 AG and the combined AG/GG genotypes were associated with decreased risk of NHL (odds ratio (OR)(AG) = 0.67, 95% confidence interval (CI) = 0.55-0.82; OR(AG/GG) = 0.66, 95% CI = 0.54-0.80) and DLBCL (OR(AG) = 0.63, 95% CI = 0.49-0.82; OR(AG/GG) = 0.64, 95% CI = 0.50-0.82). For T-cell lymphoma, only the combined AG/GG genotype was associated with decreased risk (OR(AG/GG) = 0.65, 95% CI = 0.44-0.96). The CYP1A1 rs1048943 AG genotype and the combined AG/GG genotypes were associated with increased risk of NHL (OR(AG) = 1.28, 95% CI = 1.07-1.54; OR(AG/GG) = 1.26, 95% CI = 1.06-1.51) and DLBCL (OR(AG) = 1.32, 95% CI = 1.04-1.66; OR(AG/GG) = 1.30, 95% CI = 1.03-1.63), but not T-cell lymphoma. Smoking does not modify the association between these polymorphisms and NHL risk. Our data provide evidence that the GSTP1 rs1695 and the CYP1A1 rs1048943 genotypes affect the risk of NHL in Korea.

Association of alcohol intake and smoking with malignant lymphoma risk in Japanese: a hospital-based case-control study at Aichi Cancer Center

Given the lower incidence and differences in distribution of malignant lymphoma in Asian than western populations, the association of alcohol intake and smoking with malignant lymphoma risk in Asian populations merits investigation. Here, we conducted a sex- and age-matched case-control study of a Japanese population using two data sets, the first and second versions of the Hospital-based Epidemiological Research Program at Aichi Cancer Center Hospital (HERPACC-I and HERPACC-II, respectively), in 452 and 330 cases of histologically diagnosed malignant lymphoma and 2,260 and 1,650 noncancer controls, respectively. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using a conditional logistic regression model that incorporated smoking exposure and alcohol intake. Compared with nondrinking, consumption of >or=50 g/d by frequent drinkers was associated with significantly decreased risk in both data sets [OR (95% CI), 0.70 (0.53-0.93) for HERPACC-I and 0.40 (0.23-0.68) for HERPACC-II]. Given similar findings among groups, we used pooled data sets in subsequent analyses. For any alcohol intake versus nondrinking, point estimates of OR were less than unity for all four malignant lymphoma subtypes. In contrast, pack-years of smoking were associated with increased malignant lymphoma risk: relative to the reference (0-4 pack-years), OR (95% CI) were 1.32 (1.02-1.71), 1.39 (1.07-1.80), and 1.48 (1.12-1.95) for 5 to 19, 20 to 39, and >or=40 pack-years, respectively. This association with smoking was less apparent for all subtypes, except Hodgkin's lymphoma. In conclusion, we found that alcohol had an inverse association with malignant lymphoma risk across all malignant lymphoma subtypes in our Japanese subjects. Smoking appeared to be positively associated with malignant lymphoma risk, but this finding may vary by subtype.

Exposure to ultraviolet radiation and risk of malignant lymphoma and multiple myeloma--a multicentre European case-control study

BACKGROUND

Three recent studies have reported a decreased risk of non-Hodgkin lymphoma (NHL) for high ultraviolet (UV) radiation exposure.

METHODS

We conducted a multicentre case-control study during 1998-2004 in France, Germany, Ireland, Italy and Spain, comprising 1518 cases of NHL, 268 cases of Hodgkin lymphoma, 242 cases of multiple myeloma and 2124 population or hospital controls. We collected information on sensitivity to sun and personal exposure to UV radiation in childhood and adulthood via interview, and assessed occupational exposure to UV radiation from the occupational history.

RESULTS

The risk of Hodgkin and NHL was increased for increasing skin sensitivity to the sun [odds ratio (OR) for no suntan vs very brown 2.35, 95% CI 0.94-5.87 and 1.39, 95% CI 1.03-1.87, respectively]. The risk of diffuse large B-cell lymphoma was reduced for increasing adult personal (OR for highest vs lowest quartile of exposure in free days 0.62, 95% CI 0.44-0.87) and for occupational exposure to UV radiation (OR for highest vs lowest exposure tertile 0.63, 95% CI 0.37-1.04). The risk of multiple myeloma was increased for personal exposure to UV radiation during adulthood (OR for highest vs lowest quartile of exposure in free days 1.49, 95% CI 0.88-2.50). A protective effect was observed for use of sun lamps for diffuse large B-cell lymphoma (OR for 25+ times vs never 0.63, 95% CI 0.38-1.03).

CONCLUSIONS

The hypothesis of a protective effect of UV radiation on lymphoma is supported by our results. The underlying mechanisms might differ from those operating in skin carcinogenesis. The increased risk of multiple myeloma is worth replication.

The impact of tobacco smoking and alcohol drinking on survival of patients with non-Hodgkin lymphoma

Tobacco smoking and alcohol consumption have not been clearly related to the risk of non-Hodgkin lymphoma (NHL), and the impact of these two factors on survival of NHL patients has received little attention. Cases were 268 subjects with incident histologically-confirmed NHL, admitted as inpatients to the Division of Medical Oncology, between 1983 and 2002. These individuals were enrolled as cases in case-control studies conducted at the same institution over the same period. For all patients clinical (histological subtype, major prognostic factors and treatment) and epidemiological data (smoking and drinking habits) were available. Survival analysis was performed using Kaplan-Meier methods. Hazard ratio (HR) was estimated by Cox proportional hazard model. Compared to never smokers, patients who smoked >or=20 cigarettes/day had higher risks of death (HR = 1.70, 95% confidence interval (CI): 1.06-2.73) and lower survivals at 5 years (60 and 46%, respectively). Likewise, patients who drunk >or=4 drinks/day showed 1.69-fold higher probability of death (95% CI: 1.04-2.76) in comparison to drinkers of <2 drinks/day (5-year survival: 47 and 67%, respectively). When combining exposure to alcohol and tobacco, no excess of death emerged in light drinkers (<4 drinks/day), irrespective of their smoking habits, but higher risks of death emerged among heavy drinkers. In the present study, heavy tobacco smoking, and particularly, heavy alcohol drinking were associated with poor survival in NHL patients. Our findings strongly encourage physicians to advice NHL patients to stop smoking and diminish alcohol consumption to obtain improvements in the course of NHL.

Birth order, allergies and lymphoma risk: results of the European collaborative research project Epilymph

Lymphomas are a heterogeneous group of malignancies of the immune system. Recent studies suggest that immunological conditions which are modulated by lifestyle-dependent environmental determinants might affect lymphoma risk. We used data from Epilymph, a European multi-centric case-control study with 2,480 cases and 2,540 controls, to analyse the relationship between lifestyle-dependent immunological determinants and risk of lymphomas. We found an inverse relationship between risk of lymphoma and allergies, mainly respiratory (OR=0.86, CI=0.89-1.01) and food allergies (OR=0.67, CI=0.52-0.85), a slightly elevated lymphoma risk for first-born children (OR=1.17, CI=0.99-1.39) and only children (OR=1.10, CI=0.86-1.39). The inverse relationship between atopic disorders and risk of lymphomas is consistent with earlier observations. Our findings on birth order and lymphoma increase the inconsistency of findings across studies and suggest a critical reappraisal of potential underlying mechanisms.