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Infectious mononucleosis (IM) has been associated with an increased risk of Hodgkin lymphoma (HL), implicating a role for Epstein-Barr virus (EBV) in HL development. Although essential to the understanding of the association, it has remained uncertain if the relationship is restricted to the EBV-positive subset of HL. We collected information on mononucleosis history and childhood socioenvironmental characteristics in a population-based study of 586 patients with classic HL and 3,187 controls in Denmark and Sweden. Tumor EBV status was established for 499 cases by immunohistochemistry and in situ hybridization techniques. Odds ratios (OR) for the relationship between HL risk and mononucleosis and other risk factors were estimated by logistic regression for HL in younger (18-44 years) and older (45-74 years) adults, overall and by tumor EBV status. All analyses were adjusted for country-specific measures of maternal education and mononucleosis history. IM was associated with an increased risk of EBV-positive [OR, 3.23; 95% confidence interval (95% CI) 1.89-5.55] but not EBV-negative HL (OR, 1.35; 95% CI, 0.86-2.14). Risk of EBV-positive HL varied with time since IM and was particularly pronounced in younger adults (OR, 3.96; 95% CI, 2.19-7.18). IM-associated lymphomas occurred with a median of 2.9 years (1.8-4.9 years) after infection. The EBV specificity of the IM association was corroborated by a case-case comparison of IM history between younger adult EBV-positive and EBV-negative HL patients (OR(IM EBV+ HL versus EBV- HL), 2.68; 95% CI, 1.40-5.12). We found further evidence that IM is associated only with EBV-positive HL. This finding is compatible with the notion that EBV-positive and EBV-negative HL may have different etiologies.

Background: A possible connection between allergy and cancer has been suspected, but allergy-related conditions or atopy have been inconsistently associated with reduced risks of non-Hodgkin lymphoma. We investigated this association in a population-based case-control study and in a prospective study with prediagnostic blood specimens., Methods: We carried out a population-based study of 3055 case patients with non-Hodgkin lymphoma and 3187 control subjects in Denmark and Sweden, including questionnaire information on allergy and blood specimens, and a nested case-control study within a prospective cohort of more than 400,000 Finnish women. In the second study, serum specimens from the 198 case patients who developed non-Hodgkin lymphoma within a median of 8.9 years after the blood was drawn were matched with serum specimens from 594 control subjects. In both studies, laboratory-based evidence of allergy (atopy) was determined in serum on the basis of specific IgE reactivity to common inhalant allergens. Dissemination of disease was classified by the Ann Arbor system. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated by logistic regression., Results: In the first study, ever having hay fever, but not other allergic conditions, was associated with a reduced risk of non-Hodgkin lymphoma. In particular, subjects with specific IgE reactivity in serum had a 32% (95% CI = 20% to 42%) lower risk of overall non-Hodgkin lymphoma than those without such reactivity. However, among case patients, dissemination of the disease was strongly inversely associated with specific IgE reactivity. In the second (i.e., prospective) study, no association was found between non-Hodgkin lymphoma and specific IgE reactivity, except possibly immediately before a diagnosis of non-Hodgkin lymphoma (> or = 10 years before diagnosis, OR = 1.00, 95% CI = 0.48 to 2.09; 5-9 years before, OR = 0.95, 95% CI = 0.50 to 1.84; 1-4 years before, OR = 0.33, 95% CI = 0.11 to 1.02; and < 1 year before, OR = 0.27, 95% CI = 0.03 to 2.31)., Conclusion: Allergy may not be causally associated with the risk of non-Hodgkin lymphoma. The inverse association observed in some case-control studies may arise because non-Hodgkin lymphoma suppresses the immunologic response to allergens.

The mechanisms through which diet may influence the development of non-Hodgkin's lymphoma (NHL) are unclear but can be better understood by examining associations between nutrient consumption and NHL risk. Between 2000 and 2002, 591 NHL cases and 460 population-based controls in Sweden completed a semiquantitative food frequency questionnaire. Unconditional logistic regression was performed to estimate odds ratios and 95% confidence intervals for associations with nutrient intake; all statistical tests were two sided. Dietary intake of most macronutrients was not associated with risk of NHL or its common subtypes. Consumption of omega-3 or marine fatty acids was associated with decreased risk of NHL and chronic lymphocytic lymphoma, and dietary fiber was associated with lower risk of all subtypes examined. When the highest and the lowest quartiles of marine fat intake were compared, the odds ratio for NHL risk was 0.6 (95% confidence interval: 0.4, 0.9), ptrend=0.03; for dietary fiber intake, the corresponding odds ratio was 0.5 (95% confidence interval: 0.3, 0.7), ptrend<0.001. Dietary consumption of beta-carotene or alpha-tocopherol was associated with lower NHL risk, whereas intake of calcium or retinol was associated with increased NHL risk. Nutrients that affect inflammation, vitamin D activity, oxidative DNA damage, or DNA methylation may be associated with risk of NHL.

Certain autoimmune and chronic inflammatory conditions, such as Sjögren's syndrome and rheumatoid arthritis (RA), have consistently been associated with an increased risk of malignant lymphomas, but it is unclear whether elevated lymphoma risk is a phenomenon that accompanies inflammatory conditions in general. Likewise, it is debated whether the increased risk identified in association with some disorders pertains equally to all individuals or whether it varies among groups of patients with different phenotypic or treatment-related characteristics. It is similarly unclear to what extent the increased lymphoma occurrence is mediated through specific lymphoma subtypes. This update reviews the many findings on risks, risk levels, and lymphoma characteristics that have been presented recently in relation to a broad range of chronic inflammatory, including autoimmune, conditions. Recent results clearly indicate an association between severity of chronic inflammation and lymphoma risk in RA and Sjögren's syndrome. Thus, the average risk of lymphoma in RA may be composed of a markedly increased risk in those with most severe disease and little or no increase in those with mild or moderate disease. The roles of immunosuppressive therapy and EBV infection seem to be limited. Furthermore, RA, Sjögren's syndrome, systemic lupus erythematosus, and possibly celiac disease may share an association with risk of diffuse large B-cell lymphoma, in addition to well-established links of Sjögren's syndrome with risk of mucosa-associated lymphoid tissue lymphoma and of celiac disease with risk of small intestinal lymphoma. However, there is also obvious heterogeneity in risk and risk mediators among different inflammatory diseases.

The reasons for the positive association between skin cancer and non-Hodgkin's lymphoma are not known but may be due to common susceptibility involving suboptimal DNA repair. Therefore, we investigated selected polymorphisms and haplotypes in three DNA repair genes, previously associated with skin cancer and DNA repair capacity, in risk of follicular lymphoma, including possible gene interaction with cigarette smoking and sun exposure. We genotyped 19 single nucleotide polymorphisms (SNP) in the ERCC2, XRCC1, and XRCC3 genes in 430 follicular lymphoma patients and 605 controls within a population-based case-control study in Denmark and Sweden. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated using unconditional logistic regression and haplotype associations were assessed with a global score test. We observed no associations between variation in the ERCC2 and XRCC1 genes and follicular lymphoma risk. In XRCC3, increased risk of follicular lymphoma was suggested for rare homozygotes of three SNPs [Rs3212024: OR, 1.8 (95% CI, 1.1-2.8); Rs3212038: OR, 1.5 (95% CI, 1.0-2.4); Rs3212090: OR, 1.5 (95% CI, 1.0-2.5)]. These results were strengthened in current cigarette smokers. However, evidence of differences in XRCC3 haplotype distributions between follicular lymphoma cases and controls was weak, both overall and in current smokers. We conclude that polymorphic variation in the XRCC3 gene, but not in ERCC2 or XRCC1, may be of importance for susceptibility to follicular lymphoma, perhaps primarily in current smokers. The link between skin cancer and follicular lymphoma is unlikely to be mediated through common variation in the studied DNA repair gene polymorphisms.

Background: Case-control studies of familial cancer risk traditionally rely on self-reported family history of cancer, which may bias results due to differential recall between case patients and control subjects. To evaluate the reliability of self-reported data, we analyzed questionnaire and registry-based data on familial cancer from a population-based case-control study of malignant lymphoma., Methods: All 1508 lymphoma case patients and 1229 control subjects completed a telephone interview assessing cancer in family members. Participants were linked to the Swedish Multi-Generation Register and Cancer Register to identify confirmed cancer diagnoses in first-degree relatives. The sensitivity and specificity of self-reported familial cancer were calculated among case patients and control subjects and were compared using logistic regression. All statistical tests were two-sided., Results: Lymphoma case patients reported a family history of any cancer with statistically significantly higher sensitivity than control subjects (0.85, 95% confidence interval [CI] = 0.83 to 0.87 and 0.80, 95% CI = 0.77 to 0.82, respectively) but with marginally lower specificity (0.89, 95% CI = 0.87 to 0.91 and 0.92, 95% CI = 0.90 to 0.94, respectively). The sensitivity of self-reporting familial cancers by site ranged from less than 0.20 for rare malignancies to nearly 0.75 for more common types, whereas specificity was generally 0.98 or greater. For most sites, the reliability of self-report was similar in patients and control subjects. However, patients reported familial hematopoietic cancer with statistically significantly higher sensitivity (0.60, 95% CI = 0.57 to 0.62) than control subjects (0.38, 95% CI = 0.35 to 0.40). Odds ratios for the association between familial cancer and risk of non-Hodgkin lymphoma were consistently higher when based on self-reported, compared with registry data-based, family history of any cancer or of hematopoietic cancer., Conclusions: Reliability of self-reported family history of cancer varies between case patients and control subjects. Recall bias may thus produce biased results in case-control studies of familial cancer risk.

Background: Some autoimmune and chronic inflammatory disorders are associated with increased risks of non-Hodgkin lymphoma (NHL). Because different NHL subtypes develop at different stages of lymphocyte differentiation, associations of autoimmune and inflammatory disorders with specific NHL subtypes could lead to a better understanding of lymphomagenic mechanisms., Methods: In a population-based case-control study in Denmark and Sweden, 3055 NHL patients and 3187 matched control subjects were asked about their history of autoimmune and chronic inflammatory disorders, markers of severity, and treatment. Logistic regression with adjustment for study matching factors was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for NHL overall and for NHL subtypes., Results: Risks of all NHL were increased in association with rheumatoid arthritis (OR = 1.5, 95% CI = 1.1 to 1.9), primary Sjögren syndrome (OR = 6.1, 95% CI = 1.4 to 27), systemic lupus erythematosus (OR = 4.6, 95% CI = 1.0 to 22), and celiac disease (OR = 2.1, 95% CI = 1.0 to 4.8). All of these conditions were also associated with diffuse large B-cell lymphoma, and some were associated with marginal zone, lymphoplasmacytic, or T-cell lymphoma. Ever use of nonsteroidal anti-inflammatory drugs, systemic corticosteroids, and selected immunosuppressants was associated with risk of NHL in rheumatoid arthritis patients but not in subjects without rheumatoid arthritis. Also, multivariable adjustment for treatment had little impact on risk estimates. Psoriasis, sarcoidosis, and inflammatory bowel disorders were not associated with increased risk of NHL overall or of any NHL subtype., Conclusions: Our results confirm the associations between certain autoimmune disorders and risk of NHL and suggest that the associations may not be general but rather mediated through specific NHL subtypes. These NHL subtypes develop during postantigen exposure stages of lymphocyte differentiation, consistent with a role of antigenic drive in autoimmunity-related lymphomagenesis.

Conflicting results from previous epidemiologic studies shed little light on whether medication use is associated with risk of non-Hodgkin's lymphoma (NHL). To investigate this question, the authors conducted a population-based case-control study in Denmark and Sweden from 1999 to 2002, including 3,055 incident NHL cases and 3,187 controls. Participants reported their past use of medications and history of particular medical conditions. Unconditional logistic regression was used to estimate multivariate odds ratios and 95% confidence intervals for the associations between medication use and risk of NHL; all statistical tests were two sided. Use of antibiotics more than 10 times during adulthood was positively associated with risk of NHL and most major NHL subtypes; when users were compared with nonusers, the odds ratio for NHL was 1.8 (95% confidence interval: 1.4, 2.3); p(trend) for total antibiotic use <0.001. In addition, high cumulative use of nonsteroidal anti-inflammatory drugs was marginally associated with elevated NHL risk. Other medications evaluated were not associated with risk of NHL or its most common subtypes. Findings suggest that inflammation, infections, susceptibility to infections, and/or use of antibiotics or nonsteroidal anti-inflammatory drugs to treat these conditions may increase the risk of NHL. However, most of the medications examined were not associated with NHL risk.

Background: A family history of hematopoietic malignancy is associated with an increased risk of non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL), although the magnitude of the relative risk is unclear. We estimated the association between familial hematopoietic cancer and risk of lymphoma using validated, registry-based family data, and we also investigated whether associations between some environmental exposures and risk of lymphoma vary between individuals with and without such a family history., Methods: In a population-based case-control study of malignant lymphoma, 1506 case patients and 1229 control subjects were linked to the Swedish Multi-Generation Register and then to the Swedish Cancer Register to ascertain history of cancer in first-degree relatives of patients with malignant lymphoma. Multiple logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations with the risk of lymphoma., Results: A history of hematopoietic malignancy in any first-degree relative was associated with an increased risk of all NHL (OR = 1.8, 95% CI = 1.2 to 2.5), common B-cell NHL subtypes, and HL. Relative risks were generally stronger in association with sibling hematopoietic cancer (OR for all NHL = 3.2, 95% CI = 1.3 to 7.6) than with parental hematopoietic cancer (OR = 1.6, 95% CI = 1.1 to 2.3). A family history of NHL or chronic lymphocytic leukemia (CLL) was associated with an increased risk of several NHL subtypes and HL, whereas familial multiple myeloma was associated with a higher risk of follicular lymphoma. There was no statistically significant heterogeneity in NHL risk associations with environmental factors between individuals with and without familial hematopoietic malignancy., Conclusions: The increased risk of NHL and HL among individuals with a family history of hematopoietic malignancy was approximately twofold for both lymphoma types. There was no evidence that etiologic associations varied between familial NHL and nonfamilial NHL.

Background: Epidemiologic evidence of an association between tobacco smoking and non-Hodgkin's lymphoma has been conflicting. This may reflect that non-Hodgkin's lymphoma comprises several distinct disease entities with different etiologies, as some studies have indicated an association between smoking and follicular lymphoma., Objective: To investigate the association between cigarette smoking and non-Hodgkin's lymphoma risk, overall and by subtype., Methods: As part of a nationwide Danish-Swedish population-based case-control study, we interviewed 3,055 incident non-Hodgkin's lymphoma patients and 3,187 population controls. All lymphomas were uniformly classified according to the WHO classification. We used unconditional logistic regression to estimate adjusted odds ratios (OR) and 95% confidence intervals (95% CI) for the association between cigarette smoking and risk of non-Hodgkin's lymphoma., Results: Cigarette smoking was not associated with the risk of non-Hodgkin's lymphoma overall (OR, 0.97; 95% CI, 0.87-1.08) nor with the major subgroups such as diffuse large B-cell lymphoma (OR, 0.94; 95% CI, 0.79-1.10), chronic lymphocytic leukemia (OR, 0.86; 95% CI, 0.72-1.02), or follicular lymphoma (OR, 1.03; 95% CI, 0.85-1.24). Female smokers were at a marginally increased risk of follicular lymphoma (OR, 1.41; 95% CI, 1.04-1.92). Men who had ever smoked had a significantly increased risk of T-cell lymphoma (OR, 1.67; 95% CI, 1.11-2.51). No dose-response association with cigarette smoking could be established for any lymphoma subgroup., Conclusion: We found little evidence of an association between cigarette smoking and non-Hodgkin's lymphoma risk overall. Although increased risks of follicular lymphoma in female smokers and of T-cell lymphoma in male smokers were suggested, no dose-response relationship was observed, leaving limited support for causality.

Background: The incidence of malignant lymphomas has been increasing rapidly, but the causes of these malignancies remain poorly understood. One hypothesis holds that exposure to ultraviolet (UV) radiation increases lymphoma risk. We tested this hypothesis in a population-based case-control study in Denmark and Sweden., Methods: A total of 3740 patients diagnosed between October 1, 1999, and August 30, 2002, with incident malignant lymphomas, including non-Hodgkin lymphoma, chronic lymphocytic leukemia, and Hodgkin lymphoma, and 3187 population controls provided detailed information on history of UV exposure and skin cancer and information on other possible risk factors for lymphomas. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated by logistic regression. Statistical tests were two-sided., Results: Multivariable-adjusted analyses revealed consistent, statistically significant negative associations between various measures of UV light exposure and risk of non-Hodgkin lymphoma. A high frequency of sun bathing and sunburns at age 20 years and 5-10 years before the interview and sun vacations abroad were associated with 30%-40% reduced risks of non-Hodgkin lymphoma (e.g., for sunbathing four times a week or more at age 20 versus never sunbathing, OR = 0.7, 95% CI = 0.6 to 0.9; for two or more sunburns a year at age 20 versus no sunburns, OR = 0.6, 95% CI = 0.5 to 0.8). These inverse associations increased in strength with increasing levels of exposure (all P(trend)< or =.01). Similar, albeit weaker, associations were observed for Hodgkin lymphoma. There were no clear differences among non-Hodgkin lymphoma subtypes, although associations were stronger for B-cell than for T-cell lymphomas. A history of skin cancer was associated with a doubling in risks of both non-Hodgkin and Hodgkin lymphoma., Conclusions: A history of high UV exposure was associated with reduced risk of non-Hodgkin lymphoma. The positive association between skin cancer and malignant lymphomas is, therefore, unlikely to be mediated by UV exposure.

Background: The incidence of non-Hodgkin lymphoma and prevalence of obesity are increasing globally. A suggested positive association between obesity and risk of non-Hodgkin lymphoma has prompted us to investigate the relationship between body mass index (BMI) and risk of malignant lymphoma subtypes in a population-based case-control study., Methods: Telephone interviews were conducted with 3055 case patients with non-Hodgkin lymphoma and 618 case patients with Hodgkin lymphoma diagnosed between October 1, 1999, and August 30, 2002, and 3187 population-based control subjects. The interviews assessed current height, normal adult weight, and other possible risk factors. Multivariable odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for risk of lymphoma were estimated by unconditional logistic regression. All statistical tests were two-sided., Results: BMI was not associated with risk of overall non-Hodgkin lymphoma or of Hodgkin lymphoma (for example, comparing the highly obese group [BMI > or =35.0 kg/m2] with the normal-weight group [BMI = 18.5-24.9 kg/m2], OR for risk of non-Hodgkin lymphoma = 0.9, 95% CI = 0.6 to 1.3; P(trend) across all categories of BMI = .27). BMI was also not associated with risk of any non-Hodgkin lymphoma subtype evaluated, although there was some evidence of a positive association with risk of diffuse large B-cell lymphoma (for example, comparing the highly obese group with the normal-weight group, OR for diffuse large B-cell lymphoma = 1.5, 95% CI = 0.9 to 2.4; P(trend) =.05)., Conclusions: Excess weight does not appear to be associated with an increased risk of malignant lymphoma in general, or with a risk of most major lymphoma subtypes. Hence, the growing incidence of obesity is unlikely to be an important contributor to the increasing incidence of non-Hodgkin lymphoma worldwide.

Background: The incidence of non-Hodgkin lymphoma (NHL) has increased worldwide in recent decades. Diet could influence NHL risk by modulating the immune system, although evidence is limited. We did a population-based case-control study to determine whether differences in diet were associated with NHL risk., Methods: A total of 597 NHL cases and 467 population controls in Sweden completed a semiquantitative food frequency questionnaire evaluating their dietary habits 2 years before the interview. Unconditional logistic regression was used to estimate the odds ratios (OR) and corresponding 95% confidence intervals (95% CI) for associations between food intake and risk of NHL., Results: High consumption of dairy products and fried red meat was associated with increased risk of NHL. The OR of NHL for individuals in the highest quartile compared with the lowest quartile of dairy intake was 1.5 (95% CI, 1.1-2.2; P(trend) = 0.003). The OR for the highest versus lowest quartile of fried red meat intake was 1.5 (95% CI, 1.0-2.1; P(trend) = 0.02). In contrast, high consumption of fruits and vegetables was associated with reduced risk of NHL, particularly follicular lymphoma, among women but not men. Compared with the lowest quartile of vegetable intake, the OR of follicular lymphoma among women in the highest quartile of vegetable intake was 0.3 (95% CI, 0.1-0.7; P(trend) = 0.002)., Conclusions: The positive associations of NHL risk with dairy products and fried red meat and the inverse association with fruits and vegetables suggest that diet affects NHL risk and could explain the increase of some histopathogic subtypes.

Background: Numerous studies have reported on the association between coeliac disease and the otherwise uncommon enteropathy-type T cell lymphoma (ETTL). A systematic risk assessment of more prevalent lymphoma entities, such as B cell and non-intestinal lymphomas, in coeliac disease has not been performed., Aims: In light of the increasing number of patients diagnosed with coeliac disease and the unknown aetiology of malignant lymphomas, we aimed to estimate the distribution and risk of lymphoma subtypes in coeliac disease., Methods: We reviewed and reclassified 56 cases of incident malignant lymphomas occurring in a Swedish population based cohort of 11,650 patients hospitalised with coeliac disease. The observed numbers of lymphoma subtypes were compared with those expected in the Swedish population., Results: The majority (n=32, 57%) of lymphomas in the cohort were not intestinal T cell lymphomas. Significantly increased risks were observed for B cell non-Hodgkin lymphoma (NHL) (standardised incidence ratio (SIR) 2.2 (95% confidence interval (CI) 1.2-3.6); 11 non-intestinal and five intestinal) and for lymphomas of non-intestinal origin (SIR 3.6 (95% CI 2.3-5.2), 11 B and 14 T cell). Furthermore, 44% of patients with B cell NHL had a history of other autoimmune/inflammatory diseases. The relative risks for T cell NHL (SIR 51 (95% CI 35-68); n=37) and for primary gastrointestinal lymphomas (SIR 24 (95% CI 16-34); five B and 25 T cell) were markedly increased, as anticipated., Conclusion: Most lymphomas complicating coeliac disease are indeed related to the disease and are not of the ETTL-type. There was a remarkable aggregation of autoimmune/inflammatory disorders, female sex, coeliac disease, and B cell lymphoma.

Objective: The effect of alcohol intake on risk of NHL is unclear. We therefore conducted a population-based case-control study to examine the association between alcohol and NHL risk., Methods: 613 NHL cases and 480 population controls in Sweden reported their average consumption of beer, wine, and liquor 2 years before the study. Unconditional logistic regression was used to estimate the odds ratios (OR) and corresponding 95% confidence intervals (CI) for associations between alcohol intake and NHL risk., Results: Intake of total alcohol, beer, wine, or liquor was not associated with risk of overall NHL. There was no difference in risk of NHL among those who habitually consumed above 19.1 g of ethanol per day, compared to those who consumed on average 0-2.2 g of ethanol per day (OR = 1.2 (95% CI: 0.8, 1.7); Ptrend = 0.29). However, the association was significantly positive among males (OR = 1.8 (95% CI: 1.1, 2.9); Ptrend = 0.06). Total alcohol, beer, wine, or liquor intake was not associated with any major histopathologic subtype of NHL examined, apart from an association between high wine consumption and increased risk of chronic lymphocytic leukemia., Conclusions: Alcohol does not appear to be a major etiologic factor for overall NHL, nor its common subtypes.