Insecticide use and risk of non-Hodgkin lymphoma subtypes: A subset meta-analysis of the North American Pooled Project.

Insecticide use has been linked to increased risk of non-Hodgkin lymphoma (NHL), however, findings of epidemiologic studies have been inconsistent, particularly for NHL subtypes. We analyzed 1690 NHL cases and 5131 controls in the North American Pooled Project (NAPP) to investigate self-reported insecticide use and risk of NHL overall and by subtypes: follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL) and small lymphocytic lymphoma (SLL). Odds ratios (OR) and 95% confidence intervals for each insecticide were estimated using logistic regression. Subtype-specific associations were evaluated using ASSET (Association analysis for SubSETs). Increased risks of multiple NHL subtypes were observed for lindane (OR = 1.60, 1.20-2.10: FL, DLCBL, SLL), chlordane (OR = 1.59, 1.17-2.16: FL, SLL) and DDT (OR = 1.36, 1.06-1.73: DLBCL, SLL). Positive trends were observed, within the subsets with identified associations, for increasing categories of exposure duration for lindane (Ptrend = 1.7 × 10-4 ), chlordane (Ptrend = 1.0 × 10-3 ) and DDT (Ptrend = 4.2 × 10-3 ), however, the exposure-response relationship was nonlinear. Ever use of pyrethrum was associated with an increased risk of FL (OR = 3.65, 1.45-9.15), and the relationship with duration of use appeared monotonic (OR for >10 years: OR = 5.38, 1.75-16.53; Ptrend = 3.6 × 10-3 ). Our analysis identified several novel associations between insecticide use and specific NHL subtypes, suggesting possible etiologic heterogeneity in the context of pesticide exposure.

Risk of non-Hodgkin lymphoma associated with germline variation in genes that regulate the cell cycle, apoptosis, and lymphocyte development.

Chromosomal translocations are the hallmark genetic aberration in non-Hodgkin lymphoma (NHL), with specific translocations often selectively associated with specific NHL subtypes. Because many NHL-associated translocations involve cell cycle, apoptosis, and lymphocyte development regulatory genes, we evaluated NHL risk associated with common genetic variation in 20 candidate genes in these pathways. Genotyping of 203 tag single nucleotide polymorphisms (SNP) was conducted in 1,946 NHL cases and 1,808 controls pooled from 3 independent population-based case-control studies. We used logistic regression to compute odds ratios (OR) and 95% confidence intervals (CI) for NHL and four major NHL subtypes in relation to tag SNP genotypes and haplotypes. We observed the most striking associations for tag SNPs in the proapoptotic gene BCL2L11 (BIM) and BCL7A, which is involved in a rare NHL-associated translocation. Variants in BCL2L11 were strongly related to follicular lymphoma only, particularly rs3789068 (OR(AG), 1.41; 95% CI, 1.10-1.81; OR(GG), 1.65; 95% CI, 1.25-2.19; P(trend) = 0.0004). Variants in BCL7A were strongly related to diffuse large B-cell lymphoma only, particularly rs1880030 (OR(AG), 1.34; 95% CI, 1.08-1.68; OR(AA), 1.60; 95% CI, 1.22-2.08; P(trend) = 0.0004). The associations for both variants were similar in all three studies and supported by haplotype analyses. We also observed notable associations for variants in BCL6, CCND1, and MYC. Our results support the role of common genetic variation in cell cycle, apoptosis, and lymphocyte development regulatory genes in lymphomagenesis, and suggest that effects may vary by NHL subtype. Replication of our findings and further study to identify functional SNPs are warranted.

Etiologic heterogeneity among non-Hodgkin lymphoma subtypes.

Understanding patterns of etiologic commonality and heterogeneity for non-Hodgkin lymphomas may illuminate lymphomagenesis. We present the first systematic comparison of risks by lymphoma subtype for a broad range of putative risk factors in a population-based case-control study, including diffuse large B-cell (DLBCL; N = 416), follicular (N = 318), and marginal zone lymphomas (N = 106), and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL; N = 133). We required at least 2 of 3 analyses to support differences in risk: (1) polytomous logistic regression, (2) homogeneity tests, or (3) dichotomous logistic regression, analyzing all 7 possible pairwise comparisons among the subtypes, corresponding to various groupings by clinical behavior, genetic features, and differentiation. Late birth order and high body mass index (>/= 35) kg/m(2)) increased risk for DLBCL alone. Autoimmune conditions increased risk for marginal zone lymphoma alone. The tumor necrosis factor G-308A polymorphism (rs1800629) increased risks for both DLBCL and marginal zone lymphoma. Exposure to certain dietary heterocyclic amines from meat consumption increased risk for CLL/SLL alone. We observed no significant risk factors for follicular lymphoma alone. These data clearly support both etiologic commonality and heterogeneity for lymphoma subtypes, suggesting that immune dysfunction is of greater etiologic importance for DLBCL and marginal zone lymphoma than for CLL/SLL and follicular lymphoma.

Common variants in genes that mediate immunity and risk of multiple myeloma.

Multiple myeloma (MM) is a B-cell malignancy characterized by aberrant immune function. Using genomic DNA extracted from 127 MM cases aged 21-84 years and 545 population-based controls, we examined the risk of MM associated with 82 common variants in 45 genes that mediate immunity among women of European American descent. Genotyping was determined using validated and optimized TaqMan assays. We estimated haplotype frequencies from unphased genotype data for 20 of these genes using the expectation-maximization progressive insertion algorithm. Compared with controls, MM risk was positively associated with homozygotes of single loci, IL4R (-28120T, rs2107356) and FCGR2A (-120G, rs1801274) (OR = 1.91, 95% CI 1.08-3.38 and 1.95, 95% CI 1.06-3.60, respectively). For genes in which linkage disequilibrium was observed between multiple loci, MM risk was positively associated with the haplotype block covering part of the LTA*TNF complex (LTA -82C/-90G *TNF -1036C/-487G/-417G, OR = 1.63, 95% CI 1.02-2.16) compared with the most frequently occurring haplotype observed among controls (LTA -82A/-90A *TNF -1036C/-487G/-417G). Our findings provide preliminary evidence that common genetic variants in specific immune-mediated pathways could influence the risk of MM.