Pigmentary characteristics, sun sensitivity and non-Hodgkin lymphoma

A Population-Based Family Case-Control Study of Sun Exposure and Follicular Lymphoma Risk

BACKGROUND

Epidemiologic evidence suggests an inverse association between sun exposure and follicular lymphoma risk.

METHODS

We conducted an Australian population-based family case-control study based on 666 cases and 459 controls (288 related, 171 unrelated). Participants completed a lifetime residence and work calendar and recalled outdoor hours on weekdays, weekends, and holidays in the warmer and cooler months at ages 10, 20, 30, and 40 years, and clothing types worn in the warmer months. We used a group-based trajectory modeling approach to identify outdoor hour trajectories over time and examined associations with follicular lymphoma risk using logistic regression.

RESULTS

We observed an inverse association between follicular lymphoma risk and several measures of high lifetime sun exposure, particularly intermittent exposure (weekends, holidays). Associations included reduced risk with increasing time outdoors on holidays in the warmer months [highest category OR = 0.56; 95% confidence interval (CI), 0.42-0.76; Ptrend < 0.01], high outdoor hours on weekends in the warmer months (highest category OR = 0.71; 95% CI, 0.52-0.96), and increasing time outdoors in the warmer and cooler months combined (highest category OR = 0.66; 95% CI, 0.50-0.91; Ptrend 0.01). Risk was reduced for high outdoor hour maintainers in the warmer months across the decade years (OR = 0.71; 95% CI, 0.53-0.96).

CONCLUSIONS

High total and intermittent sun exposure, particularly in the warmer months, may be protective against the development of follicular lymphoma.

IMPACT

Although sun exposure is not recommended as a cancer control policy, confirming this association may provide insights regarding the future control of this intractable malignancy.

Occupational ultraviolet exposure and risk of non-Hodgkin's lymphomas: a meta-analysis

Non-Hodgkin lymphoma is a heterogeneous group of lympho-proliferative disorders. We performed a meta-analysis to summarize the available evidence from case-control studies and cohort study on the inconsistent association between occupational sun exposure and the risk of non-Hodgkin lymphoma. We searched PubMed, ISI web of science, the Cochrane Library, EMBASE and reference lists for relevant articles. Study specific odds ratios or relative risk and 95% confidence intervals were pooled by using fixed-effects or random-effects models. Ten case-control studies and one cohort study were included in the meta-analysis. Overall, the pooled odds ratios for occupational ultraviolet exposure and non-Hodgkin lymphoma risk was 1.15(95% confidence intervals: 0.99, 1.32; I² = 44.4%). Occupational sun exposure was positively associated with the risk of NHL 1.14 (95% confidence intervals: 1.05, 1.23; I²=25.4% p for heterogeneity =0.202) in Caucasian population. Common subtypes of non-Hodgkin lymphoma and ultraviolet exposure had the negative results. The pooled odds ratios was 1.16, (95%confidence intervals: 0.90, 1.50) for T-cell non-Hodgkin lymphoma; 0.79, (95%confidence intervals: 0.61, 1.02) for B-cell non-Hodgkin lymphoma; 1.13, (95%confidence intervals: 0.96, 1.34) for chronic lymphocytic leukemia; 1.25, (95%confidence intervals: 0.95, 1.64) for males; 1.49, (95%confidence intervals: 0.99, 2.25) for females. Data suggested that occupational ultraviolet exposure was a risk factor for non-Hodgkin lymphoma in Caucasian population. While, there had no relationship between occupational ultraviolet exposure and risk of non-Hodgkin lymphoma in general population as well as non-Hodgkin lymphoma common subtypes. Besides, gender specific occupational sun exposure also indicated no association on risk of non-Hodgkin lymphoma.

Joint occurrence of Merkel cell carcinoma and non-Hodgkin lymphomas in four Nordic countries

The objective of this study was to assess the reciprocal association between non-Hodgkin lymphoma (NHL) and Merkel cell carcinoma (MCC) using the data of four Nordic Cancer Registries. Data for this study were drawn from the Danish, Finnish, Norwegian, and Swedish cancer registries. Standardized incidence ratios (SIRs) for MCC among NHL patients, and for NHL among MCC patients, were calculated. There were 109 838 individuals with NHL and 1411 individuals with MCC, of which 28 had joint occurrence of NHL and MCC. In 18 cases, NHL was diagnosed first, and in 10 cases, MCC was diagnosed first. The SIR for MCC after NHL was 4.34 (95% confidence interval 2.57-6.85). The SIR for NHL after MCC was 3.13 (1.50-5.77). Although the absolute frequency of joint occurrence of MCC and NHL is low, individuals suffering from one of the cancer forms have an increased risk of the other.

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.

'Behind blue eyes'†: the association between eye colour and deep infiltrating endometriosis

STUDY QUESTION

Is the prevalence of blue eye colour higher in women with deep endometriosis?

SUMMARY ANSWER

Blue eye colour is more common in women with deep endometriosis when compared with both women with ovarian endometriomas and women without a history of endometriosis.

WHAT IS KNOWN ALREADY

Recent and intriguing evidence suggests that women with deep endometriosis may have particular phenotypic characteristics including a higher prevalence of a light-colour iris. Available epidemiological evidence is however weak.

STUDY DESIGN, SIZE, DURATION

Case-control study performed in a large academic department specializing in the study and treatment of endometriosis. Individual iris colour was evaluated in daylight and categorized in three grades, namely blue-grey (blue), hazel-green (green) and brown. One observer assessed iris colour. In addition, the women themselves were invited to indicate the colour of their eyes according to the same classification system. Cases with discordant eye colour determinations between the observer and the woman were excluded from the final analysis.

PARTICIPANTS MATERIALS, SETTINGS, METHODS

Two hundred and twenty-three women with deep endometriosis (cases), 247 with ovarian endometriomas and 301 without a history of endometriosis were enrolled.

MAIN RESULTS AND THE ROLE OF CHANCE

After exclusion of 52 discordant cases, the proportions of brown, blue and green eye colours were, respectively, 61, 30 and 9% in the deep endometriosis group, 74, 16 and 10% in the endometrioma group and 75, 15 and 10% in the non-endometriosis group. Women in the deep endometriosis group had a statistically significant excess of blue eyes and a reduced proportion of brown eyes compared with the two control groups (P = 0.002 and P < 0.001, respectively). The proportion of blue eyes was almost identical in the ovarian endometrioma group and the non-endometriosis group, and that of green eyes was substantially similar in all study groups. The OR (95% CI) of having blue eyes in women with deep endometriosis compared with women with ovarian endometriosis and with those without endometriosis was, respectively, 2.2 (1.4-3.6) and 2.5 (1.6-3.9).

LIMITATIONS, REASON FOR CAUTION

We cannot exclude that some women without a previous diagnosis of endometriosis indeed had the disease. However, this would have led to a reduction of the observed difference in proportion of blue eyes, thus to a potential underestimation of the real strength of the association. Moreover, under-ascertainment is possible with regard to peritoneal disease, but unlikely with deep endometriotic lesions and ovarian endometriomas.

WIDER IMPLICATIONS OF THE FINDINGS

There are two possible explanations for our findings. Both may have intriguing implications for future research on endometriosis. Firstly, genes involved in the control of iris colour transmission may lie in a region with a strong pattern of linkage disequilibrium with genes involved in the invasiveness of endometriosis. Alternatively, blue eye colour could be considered an indicator of a photo-sensitive phenotype resulting in limited exposure to sunlight and UVB radiation. Limited sunlight exposure is associated with reduced circulating 25-hydroxyvitamin D3, an element that has recently been linked to endometriosis development.

Sex- and subtype-specific analysis of H2AFX polymorphisms in non-Hodgkin lymphoma

H2AFX encodes a histone variant involved in signaling sites of DNA damage and recruiting repair factors. Genetic variants in H2AFX may influence risk of non-Hodgkin lymphoma (NHL), a heterogeneous group of lymphoid tumors that are characterized by chromosomal translocations. We previously reported that rs2509049, a common variant in the promoter of H2AFX, was associated with risk for NHL in the British Columbia population. Here we report results for 13 single nucleotide polymorphisms (SNPs) in 100 Kb surrounding H2AFX in an expanded collection of 568 NHL cases and 547 controls. After correction for multiple testing, significant associations were present for mantle cell lymphoma (p=0.007 for rs604714) and all B-cell lymphomas (p=0.046 for rs2509049). Strong linkage disequilibrium in the 5 Kb upstream of H2AFX limited the ability to determine which specific SNP (rs2509049, rs7759, rs8551, rs643788, rs604714, or rs603826), if any, was responsible. There was a significant interaction between sex and rs2509049 in the all B-cell lymphomas group (p=0.002); a sex-stratified analysis revealed that the association was confined to females (p=0.001). Neither the overall nor the female-specific association with rs2509049 was replicated in any of four independent NHL sample sets. Meta-analysis of all five study populations (3,882 B-cell NHL cases and 3,718 controls) supported a weak association with B-cell lymphoma (OR=0.92, 95% CI=0.86-0.99, p=0.034), although this association was not significant after exclusion of the British Columbia data. Further research into the potential sex-specificity of the H2AFX-NHL association may identify a subset of NHL cases that are influenced by genotype at this locus.

Sun exposure may increase risk of prostate cancer in the high UV environment of New South Wales, Australia: a case-control study

Ultraviolet (UV) radiation in sunlight may influence risk of prostate cancer. In New South Wales (NSW), Australia, we examined the relationship between sun exposure at 30 and 50 years of age and risk of prostate cancer in a case-control study combining the NSW prostate cancer care and outcome study (cases) and the NSW non-Hodgkin's lymphoma study (controls). Prostate cancer risk increased with increasing estimated sun exposure (adjusted OR for highest vs. lowest quartiles of average weekly sun exposure in the warmer months 2.07 95% CI: 1.36-3.15) and this increase was most evident with weekend sun exposure (adjusted OR=5.55, 95% CI: 2.94-10.48). High sun sensitivity was also positively associated with risk for prostate cancer (adjusted OR=1.63, 95% CI: 1.09-2.44). The apparent effects of weekly sun exposure did not vary by disease aggressiveness. Our results suggest that increasing sun exposure in mid-adult years increases prostate cancer risk in a high ambient solar UV environment. Given that previous studies, conducted mainly in low solar UV environments, have generally found evidence of a negative association, our findings suggest there may be a U-shaped relationship between solar UV exposure and prostate cancer. Further studies are needed to test the hypothesis that high solar UV exposure is a risk factor for prostate cancer and to explore possible mechanisms for such an association.

Sunlight exposure, vitamin D, and risk of non-Hodgkin lymphoma in the Nurses' Health Study

PURPOSE

Case-control studies suggest increased sun exposure reduces non-Hodgkin lymphoma (NHL) risk. Evidence from prospective cohort studies, however, is limited and inconsistent. We evaluated the association between ambient ultraviolet radiation (UV) exposure and NHL in a nationwide cohort of women, the Nurses' Health Study (NHS).

METHODS

Between 1976 and 2006, we identified 1064 incident NHL cases among 115,482 women in the prospective NHS. Exposures assessed included average annual UV-B flux based on residence at various times during life, vitamin D intake, and predicted plasma 25-hydroxyvitamin D levels. We estimated incidence rate ratios (RRs) and 95% confidence intervals (CIs) for risk of all NHL and histologic subtypes using Cox proportional hazards models.

RESULTS

NHL risk was increased for women residing in areas of high ambient UV radiation (UV-B flux >113 R-B count × 10(-4)) compared to those with lower exposure (<113), with positive linear trends at all time points. The multivariable-adjusted RR for high UV area at age 15 was 1.21 (95% CI: 1.00, 1.47; p-trend < 0.01). There was no evidence of statistical heterogeneity by subtype, although power was limited for subtype analyses. We observed no association between vitamin D measures and risk of NHL overall or by subtype.

CONCLUSIONS

Our findings do not support the hypothesis of a protective effect of UV radiation exposure on NHL risk. We found no association between vitamin D and NHL risk.

GWAS of follicular lymphoma reveals allelic heterogeneity at 6p21.32 and suggests shared genetic susceptibility with diffuse large B-cell lymphoma

Non-Hodgkin lymphoma (NHL) represents a diverse group of hematological malignancies, of which follicular lymphoma (FL) is a prevalent subtype. A previous genome-wide association study has established a marker, rs10484561 in the human leukocyte antigen (HLA) class II region on 6p21.32 associated with increased FL risk. Here, in a three-stage genome-wide association study, starting with a genome-wide scan of 379 FL cases and 791 controls followed by validation in 1,049 cases and 5,790 controls, we identified a second independent FL-associated locus on 6p21.32, rs2647012 (OR(combined)  = 0.64, P(combined)  = 2 × 10(-21)) located 962 bp away from rs10484561 (r(2)<0.1 in controls). After mutual adjustment, the associations at the two SNPs remained genome-wide significant (rs2647012:OR(adjusted)  = 0.70, P(adjusted)  =  4 × 10(-12); rs10484561:OR(adjusted)  = 1.64, P(adjusted)  = 5 × 10(-15)). Haplotype and coalescence analyses indicated that rs2647012 arose on an evolutionarily distinct haplotype from that of rs10484561 and tags a novel allele with an opposite (protective) effect on FL risk. Moreover, in a follow-up analysis of the top 6 FL-associated SNPs in 4,449 cases of other NHL subtypes, rs10484561 was associated with risk of diffuse large B-cell lymphoma (OR(combined)  = 1.36, P(combined)  =  1.4 × 10(-7)). Our results reveal the presence of allelic heterogeneity within the HLA class II region influencing FL susceptibility and indicate a possible shared genetic etiology with diffuse large B-cell lymphoma. These findings suggest that the HLA class II region plays a complex yet important role in NHL.

Multiple indicators of ambient and personal ultraviolet radiation exposure and risk of non-Hodgkin lymphoma (United States)

Recent epidemiologic studies have suggested that ultraviolet radiation (UV) may protect against non-Hodgkin lymphoma (NHL), but few, if any, have assessed multiple indicators of ambient and personal UV exposure. Using the US Radiologic Technologists study, we examined the association between NHL and self-reported time outdoors in summer, as well as average year-round and seasonal ambient exposures based on satellite estimates for different age periods, and sun susceptibility in participants who had responded to two questionnaires (1994-1998, 2003-2005) and who were cancer-free as of the earlier questionnaire. Using unconditional logistic regression, we estimated the odds ratio (OR) and 95% confidence intervals for 64,103 participants with 137 NHL cases. Self-reported time outdoors in summer was unrelated to risk. Lower risk was somewhat related to higher average year-round and winter ambient exposure for the period closest in time, and prior to, diagnosis (ages 20-39). Relative to 1.0 for the lowest quartile of average year-round ambient UV, the estimated OR for successively higher quartiles was 0.68 (0.42-1.10); 0.82 (0.52-1.29); and 0.64 (0.40-1.03), p-trend=0.06), for this age period. The lower NHL risk associated with higher year-round average and winter ambient UV provides modest additional support for a protective relationship between UV and NHL.

Melanocortin 1 receptor (MC1R), pigmentary characteristics and sun exposure: findings from a case-control study of diffuse large B-cell and follicular lymphoma

The relationship between skin cancer and non-Hodgkin lymphoma (NHL) suggests common genetic, host or environmental causes. Ultraviolet radiation (UVR), pigmentary characteristics have been linked with both malignancies, and for skin cancer, the melanocortin 1 receptor (MC1R) which influences pigmentation has also been implicated. This paper reports on the relationship between MC1R, skin, hair and eye colour, time spent outdoors, and diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). Persons carrying MC1R homozygote variant alleles at R151C, R160W, D294H and D84E were more likely to have fair skin, red hair and to spend less time outdoors than those who did not. The variant allele at V92M was associated with FL (odds ratio (OR)=1.61, 95% confidence interval (CI) 1.08-2.39) and the r:wild type genotype with DLBCL (OR=0.58, 95% CI 0.38-0.89). Interactions between MC1R genotypes and skin colour influenced DLBCL risk; the RR genotype increased risk in individuals with medium or dark skin, based on 5 cases and no controls, but decreased risk among those of fair skin. On the whole, DLBCL and FL risk were not related to genetic variation in MC1R, pigmentation or time spent outdoors.

Vitamin D and non-Hodgkin lymphoma risk in adults: a review

Animal and human studies support a protective effect of vitamin D sufficiency related to malignancy by uncovering paracrine and autocrine effects of extra-renal 25-hydroxyvitamin D (25(OH)D) activation including regulation of cell cycle proliferation, apoptosis induction, and increased cell differentiation signaling. Recent epidemiologic studies demonstrate a reduction in non-Hodgkin lymphoma (NHL) risk with increased sunlight exposure. As sunlight is a major vitamin D source, it has been suggested that vitamin D status may mediate this observed association. This review provides a comprehensive discussion of the current epidemiologic evidence with regard to the investigation of an association between vitamin D status and NHL risk.

Common gene variants in the tumor necrosis factor (TNF) and TNF receptor superfamilies and NF-kB transcription factors and non-Hodgkin lymphoma risk

BACKGROUND

A promoter polymorphism in the pro-inflammatory cytokine tumor necrosis factor (TNF) (TNF G-308A) is associated with increased non-Hodgkin lymphoma (NHL) risk. The protein product, TNF-alpha, activates the nuclear factor kappa beta (NF-kappaB) transcription factor, and is critical for inflammatory and apoptotic responses in cancer progression. We hypothesized that the TNF and NF-kappaB pathways are important for NHL and that gene variations across the pathways may alter NHL risk.

METHODOLOGY/PRINCIPAL FINDINGS

We genotyped 500 tag single nucleotide polymorphisms (SNPs) from 48 candidate gene regions (defined as 20 kb 5', 10 kb 3') in the TNF and TNF receptor superfamilies and the NF-kappaB and related transcription factors, in 1946 NHL cases and 1808 controls pooled from three independent population-based case-control studies. We obtained a gene region-level summary of association by computing the minimum p-value ("minP test"). We used logistic regression to compute odds ratios and 95% confidence intervals for NHL and four major NHL subtypes in relation to SNP genotypes and haplotypes. For NHL, the tail strength statistic supported an overall relationship between the TNF/NF-kappaB pathway and NHL (p = 0.02). We confirmed the association between TNF/LTA on chromosome 6p21.3 with NHL and found the LTA rs2844484 SNP most significantly and specifically associated with the major subtype, diffuse large B-cell lymphoma (DLBCL) (p-trend = 0.001). We also implicated for the first time, variants in NFKBIL1 on chromosome 6p21.3, associated with NHL. Other gene regions identified as statistically significantly associated with NHL included FAS, IRF4, TNFSF13B, TANK, TNFSF7 and TNFRSF13C. Accordingly, the single most significant SNPs associated with NHL were FAS rs4934436 (p-trend = 0.0024), IRF4 rs12211228 (p-trend = 0.0026), TNFSF13B rs2582869 (p-trend = 0.0055), TANK rs1921310 (p-trend = 0.0025), TNFSF7 rs16994592 (p-trend = 0.0024), and TNFRSF13C rs6002551 (p-trend = 0.0074). All associations were consistent in each study with no apparent specificity for NHL subtype.

CONCLUSIONS/SIGNIFICANCE

Our results provide consistent evidence that variation in the TNF superfamily of genes and specifically within chromosome 6p21.3 impacts lymphomagenesis. Further characterization of these susceptibility loci and identification of functional variants are warranted.

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.

A pooled investigation of Toll-like receptor gene variants and risk of non-Hodgkin lymphoma

Toll-like receptors (TLRs) may influence the development of non-Hodgkin lymphoma (NHL) given their important roles in recognizing microbial pathogens and stimulating multiple immune pathways. We conducted an investigation of TLR gene variants in a pooled analysis including three population-based case-control studies of NHL (1946 cases and 1808 controls). Thirty-six tag single-nucleotide polymorphisms (SNPs) in TLR2, TLR4 and the TLR10-TLR1-TLR6 gene cluster were genotyped. Two TLR10-TLR1-TLR6 variants in moderate linkage disequilibrium were significantly associated with NHL: rs10008492 [odds ratio for CT genotype (OR(CT)) 1.12, 95% confidence interval (CI) 0.97-1.30; OR(TT) 1.40, 95% CI 1.15-1.71; P(trend) = 0.001] and rs4833103 (OR(AC) 0.75, 95% CI 0.64-0.88; OR(AA) 0.74, 95% CI 0.62-0.90; P(trend) = 0.002; P(dominant) = 0.0002). Associations with these SNPs were consistent across all the three studies and did not appreciably differ by histologic subtype. We found little evidence of association between TLR2 variation and all NHL, although the rare variant rs3804100 was significantly associated with marginal zone lymphoma (MZL), both overall (OR(CT/CC) 1.89, 95% CI 1.27-2.81; P(dominant) = 0.002) and in two of the three studies. No associations with TLR4 variants were observed. This pooled analysis provides strong evidence that variation in the TLR10-TLR1-TLR6 region is associated with NHL risk and suggests that TLR2 variants may influence susceptibility to MZL.

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.

UV radiation exposure, skin type and lymphoid malignancies: results of a French case-control study

OBJECTIVES

Investigating the relationship between skin type, UV exposure, and lymphoid malignancies (LM).

METHODS

We conducted a hospital-based case-control study in France, including 813 incident cases of non-Hodgkin's lymphoma (NHL), Hodgkin's lymphoma (HL), lymphoproliferative syndrome (LPS) or multiple myeloma and 748 controls.

RESULTS

Positive associations between HL and blond/red hair (OR = 1.8 [0.8-3.8]), very fair/fair skin (OR = 1.6 [1.0-2.5]) were observed. High propensity to burn was associated with HL (OR = 1.5 [1.0-2.2]) and LPS (OR = 1.4 [1.0-2.1]). Poor ability to tan was significantly associated with HL (OR = 1.7 [1.0-2.8]). Having light hair with high propensity to burn was associated with NHL (OR = 1.5 [0.9-2.5]) and significantly with HL (OR = 3.4 [1.4-8.4]). Having dark hair with high propensity to burn was significantly associated with LPS (OR = 1.5 [1.0-2.2]). The associations with HL and NHL were significant for men only, with significant interactions. Outdoors activities since leaving school or in the last decade were not related to LM. Only an almost negative trend was observed. Prior exposure to artificial UV was not associated with LM.

CONCLUSION

These results suggest a positive association between the most reactive and palest skin types and NHL or HL in men and do not rule out a slight negative relationship between UV exposure and LM.

One-carbon metabolism gene polymorphisms and risk of non-Hodgkin lymphoma in Australia

Dysregulation of the one-carbon metabolic pathway, which controls nucleotide synthesis and DNA methylation, may promote lymphomagenesis. We evaluated the association between polymorphisms in one-carbon metabolism genes and risk of non-Hodgkin lymphoma (NHL) in a population-based case-control study in Australia. Cases (n = 561) and controls (n = 506) were genotyped for 14 selected single-nucleotide polymorphisms in 10 genes (CBS, FPGS, FTHFD, MTHFR, MTHFS, MTR, SHMT1, SLC19A1, TCN1, and TYMS). We also conducted a meta-analysis of all studies of Caucasian populations investigating the association between MTHFR Ex5+79C > T (a.k.a., 677C>T) and NHL risk. A global test of 13 genotypes was statistically significant for diffuse large B-cell lymphoma (DLBCL; P = 0.008), but not for follicular lymphoma (FL; P = 0.27) or all NHL (P = 0.17). The T allele at MTHFR Ex5+79 was marginally significantly associated with all NHL (OR = 1.25, 95% CI = 0.98-1.59) and DLBCL (1.36, 0.96-1.93). The T allele at TYMS Ex8+157 was associated with a reduced risk of FL (0.64, 0.46-0.91). An elevated risk of NHL was also observed among carriers of the G allele at FTHFD Ex21+31 (all NHL, 1.31, 1.02-1.69; DLBCL, 1.50, 1.05-2.14). A meta-analysis of 11 studies conducted in Caucasian populations of European origin (4,121 cases and 5,358 controls) supported an association between the MTHFR Ex5+79 T allele and increased NHL risk (additive model, P = 0.01). In conclusion, the results of this study suggest that genetic polymorphisms of one-carbon metabolism genes such as MTHFR and TYMS may influence susceptibility to NHL.

Atopy, exposure to pesticides and risk of non-Hodgkin lymphoma

Pesticide exposure has been associated with non-Hodgkin lymphoma (NHL) risk in a number of studies, and two recent studies suggest that the increased risk may be confined to those with a history of asthma. We examined the interaction between occupational pesticide exposure and atopy on risk of NHL in an Australian population-based case-control study. Incident cases (n = 694) were diagnosed in New South Wales or the Australian Capital Territory between 2000 and 2001 and controls (n = 694) were randomly selected from electoral rolls and frequency-matched to cases by age, sex and state of residence. Occupational pesticide exposure was determined by an expert occupational hygienist's assessment of job-specific questionnaires administered by telephone. History of atopy (asthma, hay fever, eczema and food allergy) was self-reported. Logistic regression models included the three matching variables, ethnicity and sun exposure. The OR for NHL with substantial pesticide exposure and any history of asthma was 3.07 (95% CI 0.55-17.10) and with substantial pesticide exposure and no asthma history it was 4.23 (95% CI 1.76-10.16). The p-value for interaction was 0.29. A similar pattern of risk was observed for each of the pesticide subtypes; for asthma at various times of life; for hay fever, eczema, food allergy and any atopy, in men only and for follicular lymphomas only. Although this study had limited power, the findings do not suggest modification of the association between pesticide exposure and NHL risk by asthma or atopic disease more generally.

Occupational exposure to ionizing and non-ionizing radiation and risk of non-Hodgkin lymphoma

OBJECTIVE

To investigate the association between occupational exposure to ionizing, ultraviolet (UV), radiofrequency (RF) and extremely low frequency (ELF) radiation and risk of developing non-Hodgkin lymphoma (NHL) in a population-based case-control study.

METHODS

The study population consisted of 694 NHL cases, first diagnosed between 1 January 2000 and 31 August 2001, and 694 controls from two regions in Australia, matched by age, sex and region of residence. A detailed occupation history was first obtained using a lifetime calendar and a telephone interview. Exposure to radiation was then assessed using a Finnish job-exposure matrix (FINJEM). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated from logistic regression models that included the matching variables as covariates.

RESULTS

For ionizing radiation, the ORs were close to unity. For UV and ELF radiation, the highest exposed group of workers had ORs of 1.32 (95% CI=0.96-1.81) and 1.25 (95% CI=0.91-1.72), respectively. For UV radiation there was a positive dose-response when exposure was lagged by 5 and 10 years (P for trend 0.04 for both lag periods). Workers in the upper tertile of exposure for RF radiation had an OR of 3.15 (95% CI=0.63-15.87), but the estimate was based on very small numbers.

CONCLUSIONS

Our results do not provide support for an association between NHL and occupational exposure to ionizing or ELF radiation. For UV radiation, our findings are consistent with a weak positive association. Further investigation focusing on UV and RF radiation and NHL is required.

Sun exposure and non-Hodgkin lymphoma

It was initially hypothesized that sun exposure might cause non-Hodgkin lymphoma (NHL) on the following grounds: its incidence was increasing in parallel with that of cutaneous melanoma; its risk was increased in those with a history of melanoma or other skin cancer; sun exposure causes immune suppression; and immunosuppression for other reasons is associated with an increased risk of NHL. The association of NHL with prior skin cancer has been found consistently in subsequent studies, but results of ecological analyses have only partially supported this hypothesis. Contrary to it, three recent studies of NHL in individuals found that risk decreased, generally by 25% to 40%, across categories of increasing total or recreational, but not occupational, sun exposure. One study, thus far reported only in abstract, showed the opposite. Production of vitamin D from sun exposure offers a plausible mechanism for protection against NHL by sun exposure. A recent study has found a reduced risk of NHL in people with a high dietary intake of vitamin D. Results of additional studies in individuals and a planned original-data meta-analysis of case-control studies should help to resolve the present conflicting results on sun exposure and NHL.

Polymorphisms in immune function genes and risk of non-Hodgkin lymphoma: findings from the New South Wales non-Hodgkin Lymphoma Study

Recent findings suggest that genetic polymorphisms in TNF and IL10 are associated with an increased risk of non-Hodgkin lymphoma (NHL), particularly for diffuse large B-cell lymphoma (DLBCL). To further investigate the contribution of common genetic variation in key cytokine and innate immunity genes to the etiology of NHL, we genotyped participants in a case-control study of NHL conducted in Australia (545 cases, 498 controls). We investigated 36 single nucleotide polymorphisms in IL10, TNF and 21 other immune function genes. We observed an elevated risk of DLBCL with the IL10 -3575T>A polymorphism [TA genotype: odds ratio (OR)=1.32, 95% confidence interval (CI)=0.86-2.02; AA, OR=1.84, 95% CI=1.10-3.08; trend test, P=0.02]. Our most noteworthy TNF finding was an association between -857C>T and a decreased risk of NHL (CT or TT, OR=0.59, 95% CI=0.42-0.84, P=0.003) and particularly follicular lymphoma (OR=0.40, 95% CI=0.23-0.68, P=0.0009). Additionally, TNF -863C>A was associated with an elevated risk of DLBCL (CA, OR=1.45, 95% CI=0.95-2.21; AA, OR=2.06, 95% CI=0.88-4.83; trend test, P=0.02). Our findings offer further evidence that variation in the IL10 and TNF loci influences NHL risk. Additional studies are needed to clarify the genetic and biologic basis for these relationships.

The effects on human health from stratospheric ozone depletion and its interactions with climate change

Ozone depletion leads to an increase in the ultraviolet-B (UV-B) component (280-315 nm) of solar ultraviolet radiation (UVR) reaching the surface of the Earth with important consequences for human health. Solar UVR has many harmful and some beneficial effects on individuals and, in this review, information mainly published since the previous report in 2003 (F. R. de Gruijl, J. Longstreth, M. Norval, A. P. Cullen, H. Slaper, M. L. Kripke, Y. Takizawa and J. C. van der Leun, Photochem. Photobiol. Sci., 2003, 2, pp. 16-28) is discussed. The eye is exposed directly to sunlight and this can result in acute or long-term damage. Studying how UV-B interacts with the surface and internal structures of the eye has led to a further understanding of the location and pathogenesis of a number of ocular diseases, including pterygium and cataract. The skin is also exposed directly to solar UVR, and the development of skin cancer is the main adverse health outcome of excessive UVR exposure. Skin cancer is the most common form of malignancy amongst fair-skinned people, and its incidence has increased markedly in recent decades. Projections consistently indicate a further doubling in the next ten years. It is recognised that genetic factors in addition to those controlling pigment variation can modulate the response of an individual to UVR. Several of the genetic factors affecting susceptibility to the development of squamous cell carcinoma, basal cell carcinoma and melanoma have been identified. Exposure to solar UVR down-regulates immune responses, in the skin and systemically, by a combination of mechanisms including the generation of particularly potent subsets of T regulatory cells. Such immunosuppression is known to be a crucial factor in the generation of skin cancers. Apart from a detrimental effect on infections caused by some members of the herpesvirus and papillomavirus families, the impact of UV-induced immunosuppression on other microbial diseases and vaccination efficacy is not clear. One important beneficial effect of solar UV-B is its contribution to the cutaneous synthesis of vitamin D, recognised to be a crucial hormone for bone health and for other aspects of general health. There is accumulating evidence that UVR exposure, either directly or via stimulation of vitamin D production, has protective effects on the development of some autoimmune diseases, including multiple sclerosis and type 1 diabetes. Adequate vitamin D may also be protective for the development of several internal cancers and infections. Difficulties associated with balancing the positive effects of vitamin D with the negative effects of too much exposure to solar UV-B are considered. Various strategies that can be adopted by the individual to protect against excessive exposure of the eye or the skin to sunlight are suggested. Finally, possible interactions between ozone depletion and climate warming are outlined briefly, as well as how these might influence human behaviour with regard to sun exposure.

Personal sun exposure and risk of non Hodgkin lymphoma: A pooled analysis from the Interlymph Consortium

In 2004-2007 4 independent case-control studies reported evidence that sun exposure might protect against NHL; a fifth, in women only, found increased risks of NHL associated with a range of sun exposure measurements. These 5 studies are the first to examine the association between personal sun exposure and NHL. We report here on the relationship between sun exposure and NHL in a pooled analysis of 10 studies participating in the International Lymphoma Epidemiology Consortium (InterLymph), including the 5 published studies. Ten case-control studies covering 8,243 cases and 9,697 controls in the USA, Europe and Australia contributed original data for participants of European origin to the pooled analysis. Four kinds of measures of self-reported personal sun exposure were assessed at interview. A two-stage estimation method was used in which study-specific odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for potential confounders including smoking and alcohol use, were obtained from unconditional logistic regression models and combined in random-effects models to obtain the pooled estimates. Risk of NHL fell significantly with the composite measure of increasing recreational sun exposure, pooled OR = 0.76 (95% CI 0.63-0.91) for the highest exposure category (p for trend 0.01). A downtrend in risk with increasing total sun exposure was not statistically significant. The protective effect of recreational sun exposure was statistically significant at 18-40 years of age and in the 10 years before diagnosis, and for B cell, but not T cell, lymphomas. Increased recreational sun exposure may protect against NHL.

Specific infections, infection-related behavior, and risk of non-Hodgkin lymphoma in adults

Infections were examined as possible risk factors for non-Hodgkin lymphoma in a population-based case-control study in New South Wales and the Australian Capital Territory, Australia. Incident cases (n = 694) had no history of HIV infection or transplantation. Controls (n = 694) were randomly selected from electoral rolls and frequency matched to cases by age, sex, and area of residence. A postal questionnaire and telephone interview measured history of specific infections, occupational exposures, and behavioral and other risk factors for infection. Blood samples were tested for antibodies to human T-lymphotrophic virus type I and hepatitis C virus. Logistic regression models included the three matching variables and ethnicity. There was no association between risk of non-Hodgkin lymphoma and any of the variables analyzed, including sexually transmitted infections, sexual behavior, blood transfusions, influenza, acne, and either occupational or domestic exposure to zoonotic infections. Non-Hodgkin lymphoma risk was nonsignificantly elevated (odds ratio, 2.99; 95% confidence interval, 0.78-11.51) for those with a history of injecting drug use. Three cases and two controls (odds ratio, 1.32; 95% confidence interval, 0.22-7.98) tested positive to hepatitis C virus infection and none tested positive to human T-lymphotrophic virus type I/II infection. This study provides consistent evidence that sexually transmitted infections and zoonoses are not risk factors for non-Hodgkin lymphoma.

Ultraviolet radiation, dietary vitamin D, and risk of non-Hodgkin lymphoma (United States)

OBJECTIVE

Because of conflicting findings about the relationship between ultraviolet (UV) radiation and the risk of non-Hodgkin lymphoma (NHL), we evaluated the risk of several indicators related to UV, including two not previously studied: dietary vitamin D, and ambient UV levels by residential location.

METHODS

As part of a case-control study conducted in four Surveillance, Epidemiology, and End Results (SEER) registries, we collected UV information from a self-administered questionnaire and computer-assisted personal interview with 551 NHL cases and 462 controls. We estimated the relative risk (RR) and 95% confidence intervals (CI) from unconditional logistic regression models.

RESULTS

Eye color, a marker of host susceptibility to UV, showed a decreasing risk gradient for lightest eyes (0.47) compared to darkest. Relative risks were in the range of 0.73-0.78 for participants reporting more hours in the mid-day summer sun. Use of sunlamps or tanning booths was associated with decreased risk (RR = 0.88), as was estimated overall ambient UV (RR = 0.76 per 50 RB-units) overall. Vitamin D intake from diet and supplements was not related to risk. Results were thus consistent for the various indicators, although some estimated risks were not statistically significant. Effects were generally similar for diffuse large B-cell (DLBCL) and follicular lymphomas.

CONCLUSION

These data suggest a slight protective effect of sunlight against NHL, and they agree with geographic patterns of NHL incidence observed in the US.

Occupational exposure to ultraviolet radiation and risk of non-Hodgkin lymphoma

Individuals diagnosed with skin cancer have elevated risk of non-Hodgkin lymphoma, and those with non-Hodgkin lymphoma have excess rates of various types of skin cancers. Sunshine and other sources of ultraviolet radiation are major risk factors for skin cancer, and hence a potential common link between skin cancer and non-Hodgkin lymphoma. We analyzed the relationship between occupational exposure to ultraviolet radiation and the risk for non-Hodgkin lymphoma using data from a case-control study conducted in Northern Italy between 1985 and 1997. Cases were 446 patients with histologically confirmed incident non-Hodgkin lymphoma, and controls were 1295 patients admitted to hospital for acute non-neoplastic, non-immunological conditions. The multivariate odds ratios were computed after allowance for age, sex, area of residence, education and smoking. The odds ratio for patients reporting ever ultraviolet exposure at work was 1.01 (95% confidence interval 0.72-1.43) and 1.03 (95% confidence interval 0.72-1.49) for exposure longer than 10 years. The odds ratio was 1.09 for manual workers and 0.79 for farmers exposed to ultraviolet radiation, compared with those with other occupations not exposed to ultraviolet radiation. Our study found no association between occupational exposure to ultraviolet radiation and the risk of non-Hodgkin lymphoma.

Occupational exposure to power frequency magnetic fields and risk of non-Hodgkin lymphoma

OBJECTIVES

To investigate the risk of non-Hodgkin lymphoma (NHL) using a job-exposure matrix (JEM) to assess exposure to occupational magnetic fields at the power frequencies of 50/60 Hz.

METHODS

The study population consisted of 694 cases of NHL, first diagnosed between 1 January 2000 and 31 August 2001, and 694 controls from two regions in Australia, matched by age, sex and region of residence. A detailed occupational history was given by each subject. Exposure to power frequency magnetic fields was estimated using a population-based JEM which was specifically developed in the United States to assess occupational magnetic field exposure. The cumulative exposure distribution was divided into quartiles and adjusted odds ratios were calculated using the lowest quartile as the referent group.

RESULTS

For the total work history, the odds ratio (OR) for workers in the upper quartile of exposure was 1.48 (95% CI 1.02 to 2.16) compared to the referent (p value for trend was 0.006). When the exposure was lagged by 5 years the OR was 1.59 (95% CI 1.07 to 2.36) (p value for trend was 0.003). Adjusting for other occupational exposures did not significantly alter the results.

CONCLUSIONS

These findings provide weak support for the hypothesis that occupational exposure to 50/60 Hz magnetic fields increases the risk of NHL.

WHO non-Hodgkin's lymphoma classification by criterion-based report review followed by targeted pathology review: an effective strategy for epidemiology studies

In a previous criterion-based pathology report review of 717 cases of non-Hodgkin's lymphoma in an Australian population-based epidemiologic study, a WHO category could be assigned in 91% of cases, but confidence in this classification was high in only 57.5%. Given this lack of confidence, a pathology review was done in a subset of 315 cases, with the aims of assigning a WHO classification category and the corresponding International Classification of Diseases for Oncology, Third Edition code in all cases previously unclassified or classified with low confidence and testing the accuracy of report review in assigning a confident WHO classification. After pathology review, 10 cases were ineligible (not non-Hodgkin's lymphoma, 3.2%) and 99% (301 of 305) of the remainder were assigned a WHO classification, with high confidence in 87% (261 of 301). There was 78% overall agreement between the WHO classification assigned by report review and pathology review, with 92% agreement when there was high confidence in the report review classification and 69% agreement when there was low confidence. Eighteen percent of follicular lymphomas and 23% of diffuse large B-cell lymphomas were reclassified. The pathology review increased the accuracy of WHO classification by an estimated 12.5% in the 694 cases who were still eligible in the study. Although a potential error rate of 7.5% remained, reviewing more cases, or not reviewing any cases classified with high confidence, would have produced only a small change in accuracy. Criterion-based pathology report review of all cases followed by selective pathology review in cases classified with low confidence is recommended as a cost-saving and accurate strategy for pathology review in large epidemiologic studies.

Occupational exposure to pesticides and risk of non-Hodgkin's lymphoma

Pesticide exposure may be a risk factor for non-Hodgkin's lymphoma, but it is not certain which types of pesticides are involved. A population-based case-control study was undertaken in 2000-2001 using detailed methods of assessing occupational pesticide exposure. Cases with incident non-Hodgkin's lymphoma in two Australian states (n = 694) and controls (n = 694) were chosen from Australian electoral rolls. Logistic regression was used to estimate the risks of non-Hodgkin's lymphoma associated with exposure to subgroups of pesticides after adjustment for age, sex, ethnic origin, and residence. Approximately 10% of cases and controls had incurred pesticide exposure. Substantial exposure to any pesticide was associated with a trebling of the risk of non-Hodgkin's lymphoma (odds ratio = 3.09, 95% confidence interval: 1.42, 6.70). Subjects with substantial exposure to organochlorines, organophosphates, and "other pesticides" (all other pesticides excluding herbicides) and herbicides other than phenoxy herbicides had similarly increased risks, although the increase was statistically significant only for "other pesticides." None of the exposure metrics (probability, level, frequency, duration, or years of exposure) were associated with non-Hodgkin's lymphoma. Analyses of the major World Health Organization subtypes of non-Hodgkin's lymphoma suggested a stronger effect for follicular lymphoma. These increases in risk of non-Hodgkin's lymphoma with substantial occupational pesticide exposure are consistent with previous work.

Cigarette smoking and risk of non-Hodgkin's lymphoma--a population-based case-control study

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.

Risk of non-Hodgkin lymphoma associated with occupational exposure to solvents, metals, organic dusts and PCBs (Australia)

OBJECTIVE

Several studies have suggested that there is an occupational component to the causation of non-Hodgkin lymphoma (NHL). We aimed to use accurate means to assess occupational exposures to solvents, metals, organic dusts and polychlorinated biphenyls (PCBs) in a case-control study.

METHODS

Cases were incident NHLs during 2000 and 2001 in two regions of Australia. Controls were randomly selected from the electoral roll and frequency matched to cases by age, sex and region. A detailed occupational history was taken from each subject. For jobs with likely exposure to the chemicals of interest, additional questions were asked by telephone interview using modified job specific modules. An expert allocated exposures using the information in the job histories and the interviews. Odds ratios were calculated for each exposure adjusting for age, sex, region and ethnic origin.

RESULTS

694 cases and 694 controls (70 and 45 respectively of those potentially eligible) participated. The risk of NHL was increased by about 30 for exposure to any solvent with a dose response relationship, subgroup analysis showed the finding was restricted to solvents other than benzene. Exposure to wood dust also increased the risk of NHL slightly. Exposures to other organic dusts, metals, and PCBs were not strongly related to NHL.

CONCLUSIONS

The risk of NHL appears to be increased by exposure to solvents other than benzene and possibly to wood dust.

Birth order, atopy, and risk of non-Hodgkin lymphoma

BACKGROUND

Immune deficiency is a strong risk factor for non-Hodgkin lymphoma (NHL), but whether or not other forms of immune dysregulation are associated with NHL risk is unknown. We investigated associations between atopy, which is associated with a Th2-dominant immune response, and NHL risk. Because late birth order and childhood crowding are inversely associated with atopy, we also investigated their associations with NHL risk.

METHODS

We carried out a population-based case-control study among adults aged 20-74 years in New South Wales and the Australian Capital Territory, Australia. NHL patients without clinically apparent immune deficiency (N = 704) were selected from a cancer registry, and control subjects (N = 694) were randomly selected from state electoral rolls and frequency-matched to case patients by age, sex, and area of residence. Birth order, childhood crowding, and history of atopic conditions (hay fever, asthma, eczema, and specific allergies) were assessed by questionnaire and interview. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated from logistic regression models that included the matching variables as covariates.

RESULTS

The odds ratios for developing NHL were 0.52 (95% CI = 0.32 to 0.84) for only children, 0.55 (95% CI = 0.40 to 0.75) for first-born children, 0.70 (95% CI = 0.51 to 0.96) for second-born children, and 0.81 (0.57 to 1.14) for third-born children (all compared with fourth- or later-born children) (P(trend)<.001). Indicators of crowding in later childhood, such as sharing a bed or bedroom, were not associated with NHL risk. A history of atopic conditions was associated with a reduced risk of NHL; this reduction was statistically significant for hay fever (OR = 0.65, 95% CI = 0.52 to 0.82) and food allergies (OR = 0.29, 95% CI = 0.20 to 0.42).

CONCLUSIONS

Early birth order and its immunologic consequence, a Th2-dominated immune response, as reflected by a history of atopic disease, are associated with a reduced risk of NHL.

Cigarette Smoking and Risk of Non-Hodgkin Lymphoma: A Pooled Analysis from the International Lymphoma Epidemiology Consortium (InterLymph)

BACKGROUND

The International Lymphoma Epidemiology Consortium (InterLymph) provides an opportunity to analyze the relationship between cigarette smoking and non-Hodgkin lymphoma with sufficient statistical power to consider non-Hodgkin lymphoma subtype. The results from previous studies of this relationship have been inconsistent, likely due to the small sample sizes that arose from stratification by disease subtype. To clarify the role of cigarette smoking in the etiology of non-Hodgkin lymphoma, we conducted a pooled analysis of original patient data from nine case-control studies of non-Hodgkin lymphoma conducted in the United States, Europe, and Australia.

METHODS

Original data were obtained from each study and uniformly coded. Risk estimates from fixed-effects and two-stage random-effects models were compared to determine the impact of interstudy heterogeneity. Odds ratios (OR) and 95% confidence intervals (95% CI) were derived from unconditional logistic regression models, controlling for study center, age, sex, and race.

RESULTS

In our pooled study population of 6,594 cases and 8,892 controls, smoking was associated with slightly increased risk estimates (OR, 1.07; 95% CI, 1.00-1.15). Stratification by non-Hodgkin lymphoma subtype revealed that the most consistent association between cigarette smoking and non-Hodgkin lymphoma was observed among follicular lymphomas (n = 1452). Compared with nonsmokers, current smokers had a higher OR for follicular lymphoma (1.31; 95% CI, 1.12-1.52) than former smokers (1.06; 95% CI, 0.93-1.22). Current heavy smoking (> or = 36 pack-years) was associated with a 45% increased OR for follicular lymphoma (1.45; 95% CI, 1.15-1.82) compared with nonsmokers.

CONCLUSIONS

Cigarette smoking may increase the risk of developing follicular lymphoma but does not seem to affect risk of the other non-Hodgkin lymphoma subtypes we examined. Future research is needed to determine the biological mechanism responsible for our subtype-specific results.

Sun exposure may protect against non-Hodgkin lymphoma: A case-control study

Ultraviolet radiation is a hypothesised risk factor for non-Hodgkin lymphoma (NHL) but no epidemiological study has examined this association using direct measures of sun exposure in individuals. Adults aged 20-74 years living in NSW and ACT, Australia, were the study population. Cases (704 of 829 invited to take part, 85%) were diagnosed January 2000 to August 2001. Controls (694 of 1,136 invited to take part, 61%) were randomly selected from state electoral rolls and frequency-matched to cases by age, sex and state of residence. A self-administered questionnaire and telephone interview measured outdoor hours on working and nonworking days and vacations at 10, 20, 30, 40, 50 and 60 years of age. Logistic regression models of NHL and sun exposure contained the 3 matching variables, ethnicity and sun sensitivity measures as covariates. Contrary to expectations, risk of NHL fell with increasing reported sun exposure hours. Relative to 1.0 for the lowest quarter of total sun exposure hours, the odds ratios (ORs) for successively higher quarters were 0.72 (95% CI 0.53-0.98), 0.66 (0.48-0.91) and 0.65 (0.46-0.91) (p(trend)=0.01). The association of sun exposure on nonworking days with NHL was stronger; OR for highest quarter 0.47 (0.34-0.66) (p(trend)=0.0001). Risk also fell with sun exposure on vacations; OR for highest quarter 0.60 (0.43-0.85) (p(trend)=0.003). These associations appeared strongest in women and in childhood. There was little evident trend in risk with exposure on working day. Our results provide strong statistical evidence for an inverse association between sun exposure and NHL. Increasing evidence that vitamin D may protect against cancer makes UV-mediated synthesis of vitamin D a plausible mechanism whereby sun exposure might protect against NHL.