Trends in overweight and obesity by socioeconomic status in Year 6 school children, Australian Capital Territory, 2006-2018.

BACKGROUND: Due to the high prevalence and adverse consequences, overweight and obesity in children continues to be a major public health concern worldwide. Socioeconomic background and health-related behaviours (such as diet, physical activity and sedentary behaviors) are important factors associated with weight status in children. Using a series of height and weight assessments from the Australian Capital Territory Physical Activity and Nutrition Survey (ACTPANS), trends in prevalence of overweight and obesity by socioeconomic status were examined in ACT Year 6 school children between 2006 and 2018. METHODS: The ACTPANS has been conducted every 3 years since 2006. A total of 6729 children were surveyed. Complete data on height and weight were available for 6384 (94.9%) participants. Trends in the prevalence of overweight and obesity and associations between weight status and risk factors (such as socioeconomic status, physical activity, screen time and consumption of sugar-sweetened soft drinks (SSD)) were examined using logistic regression. RESULTS: The prevalence of overweight and obesity remained stable in girls (from 22.5% in 2006 to 21.6% in 2018) but declined in boys (from 27.8 to 17.9%). During the same period, levels of physical activity increased slightly, while screen time and the consumption of fast food and SSD decreased. Socioeconomic gradient, based on the school-level Index of Community Socio-Educational Advantage (ICSEA), was highly associated with prevalence of overweight and obesity. Since 2006, the estimated prevalence of overweight and obesity has remained high in the lowest SES groups, but a concurrent downward trend was observed in the highest SES group, leading to increasing disparity between SES groups. Children in the lowest ICSEA quintile were more likely to be overweight or obese compared to those in the moderate and highest ICSEA quintiles. Children in lower ICSEA quintiles also reported lower levels of physical activity, higher levels of screen time, and higher levels of fast food and SSD consumption compared to those in higher ICSEA quintiles. CONCLUSIONS: While recent trends in overweight and obesity in ACT children are encouraging, the prevalence remains unacceptably high, especially in those from low socioeconomic backgrounds. Additional prevention efforts are required to address the socioeconomic disparity.

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.

The role of latitude, ultraviolet radiation exposure and vitamin D in childhood asthma and hayfever: an Australian multicenter study.

Observations of increasing allergy prevalence with decreasing distance from the Equator and positive associations with ambient ultraviolet radiation have contributed to a growing interest in the possible role of vitamin D in the etiology of allergy. The aims of this study were to describe any latitudinal variation in the prevalence of childhood allergy in Australia and to evaluate, in parallel, the individual associations between ultraviolet radiation (UVR)- and vitamin D-related measures and hayfever asthma and both conditions. Participants were population-based controls who took part in a multicenter case-control study, aged 18-61 yr and resident in one of four study regions ranging in latitude from 27°S to 43°S. Data were derived from a self-administered questionnaire, interview and examination by a research officer and biologic sampling. Latitude and longitude coordinates were geocoded from participants' residential locations and climatic data were linked to postcodes of current residence. Stored serum was analyzed for 25-hydroxyvitamin D concentrations and silicone rubber casts of the skin were used as an objective measure of cumulative actinic damage. There was an inverse latitude gradient for asthma (a 9% decrease per increasing degree of latitude); however, this pattern did not persist after adjusting for average daily temperature. There was no association between any of the UVR- or vitamin D-related measures and childhood asthma, but greater time in the sun in winter between the ages 6-15 yr was associated with an increase in the odds of having hayfever [adjusted odds ratios (OR) 1.29; 95% CI 1.01-1.63]. Oral supplementation with cod liver oil in childhood increased the odds of a history of having both asthma and hayfever (2.87; 1.00-8.32). Further investigation of the possible role of early vitamin D supplementation in the development of allergy is warranted. Our results also suggest that solar exposure during childhood may be important in allergic sensitization. Plausible explanations, including biologic mechanisms, exist for both observations.

Tumor necrosis factor (TNF) and lymphotoxin-alpha (LTA) polymorphisms and risk of non-Hodgkin lymphoma in the InterLymph Consortium.

In an International Lymphoma Epidemiology Consortium pooled analysis, polymorphisms in 2 immune-system-related genes, tumor necrosis factor (TNF) and interleukin-10 (IL10), were associated with non-Hodgkin lymphoma (NHL) risk. Here, 8,847 participants were added to previous data (patients diagnosed from 1989 to 2005 in 14 case-control studies; 7,999 cases, 8,452 controls) for testing of polymorphisms in the TNF -308G>A (rs1800629), lymphotoxin-alpha (LTA) 252A>G (rs909253), IL10 -3575T>A (rs1800890, rs1800896), and nucleotide-binding oligomerization domain containing 2 (NOD2) 3020insC (rs2066847) genes. Odds ratios were estimated for non-Hispanic whites and several ethnic subgroups using 2-sided tests. Consistent with previous findings, odds ratios were increased for "new" participant TNF -308A carriers (NHL: per-allele odds ratio (OR(allelic)) = 1.10, P(trend) = 0.001; diffuse large B-cell lymphoma (DLBCL): OR(allelic) = 1.23, P(trend) = 0.004). In the combined population, odds ratios were increased for TNF -308A carriers (NHL: OR(allelic) = 1.13, P(trend) = 0.0001; DLBCL: OR(allelic) = 1.25, P(trend) = 3.7 x 10(-6); marginal zone lymphoma: OR(allelic) = 1.35, P(trend) = 0.004) and LTA 252G carriers (DLBCL: OR(allelic) = 1.12, P(trend) = 0.006; mycosis fungoides: OR(allelic) = 1.44, P(trend) = 0.015). The LTA 252A>G/TNF -308G>A haplotype containing the LTA/TNF variant alleles was strongly associated with DLBCL (P = 2.9 x 10(-8)). Results suggested associations between IL10 -3575T>A and DLBCL (P(trend) = 0.02) and IL10 -1082A>G and mantle cell lymphoma (P(trend) = 0.04). These findings strengthen previous results for DLBCL and the LTA 252A>G/TNF -308A locus and provide robust evidence that these TNF/LTA gene variants, or others in linkage disequilibrium, are involved in NHL etiology.

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.

Eczema, birth order, and infection.

The association between infections occurring in the first 2 years of life and development of eczema was investigated in 1,782 control children from a national population-based case-control study in the United Kingdom conducted over the period 1991-1996. Dates of eczema and infectious diagnoses were ascertained from contemporaneously collected primary care records. Children diagnosed with eczema before the age of 2 years had more prior clinically diagnosed infections recorded than did children without eczema (rate ratio = 1.26, 95% confidence interval (CI): 1.18, 1.36). The difference in infection rates between children with and without eczema was apparent from birth and throughout the first 2 years of life. As expected, compared with children of second or higher birth order, those firstborn were at increased risk of eczema (p = 0.020); however, the relation between eczema and prior infection was evident only among children of second or higher birth order and not among firstborn children (rate ratio = 1.45, 95% CI: 1.32, 1.59, and rate ratio = 1.08, 95% CI: 0.98, 1.20, respectively). The authors' results are consistent with the notion that the association between birth order and eczema is unlikely to be attributable to variations in early infectious exposure.

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.

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.

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.

Medical history, lifestyle, family history, and occupational risk factors for peripheral T-cell lymphomas: the InterLymph Non-Hodgkin Lymphoma Subtypes Project.

BACKGROUND: Accounting for 10%-15% of all non-Hodgkin lymphomas in Western populations, peripheral T-cell lymphomas (PTCL) are the most common T-cell lymphoma but little is known about their etiology. Our aim was to identify etiologic risk factors for PTCL overall, and for specific PTCL subtypes, by analyzing data from 15 epidemiologic studies participating in the InterLymph Consortium. METHODS: A pooled analysis of individual-level data for 584 histologically confirmed PTCL cases and 15912 controls from 15 case-control studies conducted in Europe, North America, and Australia was undertaken. Data collected from questionnaires were harmonized to permit evaluation of a broad range of potential risk factors. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression. RESULTS: Risk factors associated with increased overall PTCL risk with a P value less than .05 included: a family history of hematologic malignancies (OR = 1.92, 95% CI = 1.30 to 2.84); celiac disease (OR = 17.8, 95% CI = 8.61 to 36.79); eczema (OR = 1.41, 95% CI = 1.07 to 1.85); psoriasis (OR = 1.97, 95% CI = 1.17 to 3.32); smoking 40 or more years (OR = 1.92, 95% CI = 1.41 to 2.62); and employment as a textile worker (ever) (OR = 1.58, 95% CI = 1.05 to 2.38) and electrical fitter (ever) (OR = 2.89, 95% CI = 1.41 to 5.95). Exposures associated with reduced overall PTCL risk included a personal history of allergies (OR = 0.69, 95% CI = 0.54 to 0.87), alcohol consumption (ever) (OR = 0.64, 95% CI = 0.49 to 0.82), and having ever lived or worked on a farm (OR = 0.72, 95% CI = 0.55% to 0.95%). We also observed the well-established risk elevation for enteropathy-type PTCL among those with celiac disease in our data. Conclusions Our pooled analyses identified a number of new potential risk factors for PTCL and require further validation in independent series.

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

BACKGROUND: Little is known about the etiology of hairy cell leukemia (HCL), a rare B-cell lymphoproliferative disorder with marked male predominance. Our aim was to identify key risk factors for HCL. METHODS: A pooled analysis of individual-level data for 154 histologically confirmed HCL cases and 8834 controls from five case-control studies, conducted in Europe and Australia, was undertaken. Age-, race and/or ethnicity-, sex-, and study-adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression. RESULTS: The usual patterns for age and sex in HCL were observed, with a median age of 55 years and sex ratio of 3.7 males to females. Cigarette smoking was inversely associated with HCL (OR = 0.51, 95% CI = 0.37 to 0.71) with dose-response relationships observed for duration, frequency, and lifetime cigarette smoking (P(trend) < .001). In contrast, occupation as a farmer was positively associated with HCL (OR = 2.34, 95% CI = 1.36 to 4.01), with a dose-response relationship observed for duration (OR = 1.82, 95% CI = 0.85 to 3.88 for ≤ 10 years vs never; and OR = 2.98, 95% CI = 1.50 to 5.93 for >10 years vs never; P(trend) = .025). Adult height was also positively associated with HCL (OR = 2.69, 95% CI = 1.39 to 5.29 for upper vs lower quartile of height). The observed associations remained consistent in multivariate analysis. CONCLUSIONS: Our observations of an increased risk of HCL from farming exposures and decreased risk from smoking exposures, independent of one another, support a multifactorial origin and an etiological specificity of HCL compared with other non-Hodgkin lymphoma subtypes. The positive association with height is a novel finding that needs replication.

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.

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.

Pigmentary characteristics, sun sensitivity and non-Hodgkin lymphoma.

We report on pigmentary characteristics, sun sensitivity and some other possible risk factors for non-Hodgkin lymphoma (NHL) in people 20-74 years of age. A statewide case-control study was conducted in New South Wales, Australia, with population-based sampling of cases (n = 704) and controls (n = 694). Risk of NHL was increased in subjects with hazel eyes (OR = 1.48; 95% CI = 1.07-2.04), very fair skin (OR = 1.44; 95% CI = 1.01-2.07) and poor ability to tan (OR = 1.70; 95% CI = 1.06-2.71). Risk with mild facial freckling as a child (OR = 0.77; 95% CI = 0.59-0.99) was reduced relative to that with no or moderate to severe freckling. Smokers were not at increased risk of NHL. A past history of treatment for skin cancer was associated with a slight nonsignificant increase in risk. Previous radiotherapy and chemotherapy were associated with 1.5- to 2-fold increases in risk but with wide confidence intervals. These results provide weak support for the possibility that sun sensitivity or perhaps sun exposure increases risk of NHL.

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.