Case-control study of non-Hodgkin's lymphoma among women and heterosexual men in the San Francisco Bay Area, California

Obesity and Risk for Lymphoma: Possible Role of Leptin

Obesity, which is considered a pandemic due to its high prevalence, is a risk factor for many types of cancers, including lymphoma, through a variety of mechanisms by promoting an inflammatory state. Specifically, over the last few decades, obesity has been suggested not only to increase the risk of lymphoma but also to be associated with poor clinical outcomes and worse responses to different treatments for those diseases. Within the extensive range of proinflammatory mediators that adipose tissue releases, leptin has been demonstrated to be a key adipokine due to its pleotropic effects in many physiological systems and diseases. In this sense, different studies have analyzed leptin levels and leptin/leptin receptor expressions as a probable bridge between obesity and lymphomas. Since both obesity and lymphomas are prevalent pathophysiological conditions worldwide and their incidences have increased over the last few years, here we review the possible role of leptin as a promising proinflammatory mediator promoting lymphomas.

Vaccination History and Risk of Lymphoma and Its Major Subtypes

BACKGROUND

Vaccinations have been hypothesized to play a role in lymphoma etiology, but there are few studies, mixed results, and limited data on lymphoma subtypes. Herein, we investigate the association of vaccinations with risk of major lymphoma subtypes.

METHODS

We studied 2,461 lymphoma cases and 2,253 controls enrolled from 2002 to 2014. Participants self-reported history of vaccinations against hepatitis A, hepatitis B, yellow fever, and influenza. Polytomous logistic regression was used to estimate OR and 95% confidence intervals (CI), adjusting for potential confounders.

RESULTS

After multivariable adjustment, vaccination against influenza was inversely associated with lymphoma (OR = 0.82; 95% CI, 0.66-1.02), which was stronger for last vaccination 1+ years before enrollment (OR = 0.71; 95% CI, 0.56-0.91) and for >5 influenza vaccinations (OR = 0.56; 95% CI, 0.46-0.68). Ever vaccination against hepatitis A (OR = 0.81; 95% CI, 0.66-1.00) but not hepatitis B (OR = 0.97; 95% CI, 0.81-1.18) was associated with lymphoma risk, although more recent vaccinations were inversely associated with lymphoma risk for both hepatitis A (<6 years before enrollment, OR = 0.56; 95% CI, 0.40-0.77) and hepatitis B (<9 years before enrollment, OR = 0.72; 95% CI, 0.55-0.93). Ever vaccination against yellow fever was inversely associated with risk (OR = 0.73; 95% CI, 0.55-0.96), and this did not vary by time since last vaccination. Although there was no overall statistical evidence for heterogeneity of vaccination history by lymphoma subtype, the only statistically significant inverse associations were observed for influenza and yellow fever vaccinations with diffuse large B-cell and follicular lymphoma.

CONCLUSIONS

Selected vaccinations were inversely associated with lymphoma risk, with time since last vaccination relevant for some of these vaccines.

IMPACT

Vaccinations against hepatitis A, hepatitis B, yellow fever, and influenza are unlikely to increase lymphoma risk.

Nonmedical Cannabis Use: Patterns and Correlates of Use, Exposure, and Harm, and Cancer Risk

Cannabis has certain health benefits, but some people may experience harms from use. Co-use of tobacco and cannabis is common. Smoke from cannabis contains many of the same carcinogens and toxicants as the smoke from tobacco, raising concerns that cannabis smoking may be a risk factor for cancer. With growing access to and acceptance of medical and nonmedical cannabis, there is an urgent need to understand the risks and benefits of the current modes of cannabis use and how cannabis may be associated with cancer risk. This monograph summarizes a session from a National Cancer Institute Symposium on nonmedical cannabis use and cancer risk. We had 3 objectives: describe the relation between nonmedical cannabis use and cancer risk, delineate patterns and correlates of cannabis co-use with tobacco, and document potentially harmful inhalational exposure resulting from smoked and vaped cannabis. Methodological limitations in the literature and future research recommendations are provided.

Pros and Cons of the Cannabinoid System in Cancer: Focus on Hematological Malignancies

The endocannabinoid system (ECS) is a composite cell-signaling system that allows endogenous cannabinoid ligands to control cell functions through the interaction with cannabinoid receptors. Modifications of the ECS might contribute to the pathogenesis of different diseases, including cancers. However, the use of these compounds as antitumor agents remains debatable. Pre-clinical experimental studies have shown that cannabinoids (CBs) might be effective for the treatment of hematological malignancies, such as leukemia and lymphoma. Specifically, CBs may activate programmed cell death mechanisms, thus blocking cancer cell growth, and may modulate both autophagy and angiogenesis. Therefore, CBs may have significant anti-tumor effects in hematologic diseases and may synergistically act with chemotherapeutic agents, possibly also reducing chemoresistance. Moreover, targeting ECS might be considered as a novel approach for the management of graft versus host disease, thus reducing some symptoms such as anorexia, cachexia, fatigue, anxiety, depression, and neuropathic pain. The aim of the present review is to collect the state of the art of CBs effects on hematological tumors, thus focusing on the essential topics that might be useful before moving into the clinical practice.

N-vinyl compounds: studies on metabolism, genotoxicity, carcinogenicity

Several N-vinyl compounds are produced in high volumes and are widely employed in the production of copolymers and polymers used in chemical, pharmaceutical, cosmetic and food industry. Hence, information on their genotoxicity and carcinogenicity is requisite. This review presents hitherto available information on the carcinogenicity and genotoxicity of N-vinyl compounds as well as their metabolism potentially generating genotoxic and carcinogenic derivatives. The genotoxicity and carcinogenicity of the investigated N-vinyl compounds vary widely from no observed carcinogenicity tested in lifetime bioassays in two rodent species (up to very high doses) to carcinogenicity in rats at very low doses in the absence of apparent genotoxicity. Despite of the presence of the vinyl group potentially metabolized to an epoxide followed by covalent binding to DNA, genotoxicity was observed for only one of the considered N-vinyl compounds, N-vinyl carbazole. Carcinogenicity was investigated only for two, of which one, N-vinyl pyrrolidone was carcinogenic (but not genotoxic) and ranitidine was neither carcinogenic nor genotoxic. As far as investigated, neither a metabolically formed epoxide nor a therefrom derived diol has been reported for any of the considered N-vinyl compounds. It is concluded that the information collected in this review will further the understanding of the carcinogenic potentials of N-vinyl compounds and may eventually allow approaching their prediction and prevention. A suggestion how to prevent genotoxicity in designing of N-vinyl compounds is presented. However, the available information is scarce and further research especially on the metabolism of N-vinyl compounds is highly desirable.

Paracetamol Intake and Hematologic Malignancies: A Meta-Analysis of Observational Studies

Hematologic malignancies cause more than half a million deaths every year worldwide. Analgesics were suggested as chemopreventive agents for several cancers but so far, results from individual studies about the relationship between paracetamol (acetaminophen) use and hematologic malignancies are conflicting. Therefore, we decided to perform a systematic review and meta-analysis. We retrieved studies published in any language by systematically searching Medline, Embase, Conference Proceedings Citation Index, Open Access Theses and Dissertations, and the five regional bibliographic databases of the World Health Organization until December 2020. Pooled odds ratios (OR) and their 95% confidence intervals (CI) were calculated according to the inverse of their variances. We performed separate analyses by histologic type. We also evaluated publication bias and assessed quality. A total of 17 study units met our inclusion criteria. The results show an association of hematologic malignancies with any paracetamol intake (OR 1.49, 95% CI 1.23-1.80) and with high paracetamol intake (OR 1.77, 95% CI 1.45-2.16). By subtype, risk was higher for multiple myeloma (OR 2.13, 95% CI 1.54-2.94) for any use and OR 3.16, 95% CI 1.96-5.10 for high intake, while risk was lower and non-significant for non-Hodgkin lymphoma. This meta-analysis provides evidence that paracetamol intake may be associated with hematologic malignancies and suggests that a dose-response effect is plausible. These results are unlikely to be due to publication bias or low quality of studies. Future research should focus on assessing the dose-response relationship.

Scoping Review and Meta-Analysis Suggests that Cannabis Use May Reduce Cancer Risk in the United States

Introduction: Cannabis smoke contains carcinogens similar to tobacco, in addition to compounds with antitumor activity. Cannabis use reduces the risk of obesity and cannabinoids inhibit chronic inflammation, known causes of cancer. The net effect of Cannabis use on cancer risk is not known. Objective: To examine the association between Cannabis use and cancer risk in the United States. Methods: Identify and analyze published data on cancer risk in Cannabis users. Results: A total of 55 data points, consisting of risk ratios of cancer in Cannabis users and nonusers, were identified from 34 studies. Of these, 5 did not contain data essential for inclusion in the meta-analysis. The remaining data showed a nonsignificant trend to an association with reduced risk (relative risk [RR]=0.90, p>0.06, N=50) although heterogeneity is high (I²=72.4%). Removal of data with high risk of selection bias (defined as those from North Africa and those that failed to adjust for tobacco) and data with high risk of performance bias (defined as those with fewer than 20 cases or controls among Cannabis users) resulted in an RR <1.0 (RR=0.86, p<0.017, N=24) and large effect size (Hedges g=0.66), but did not decrease heterogeneity (I²=74.9). Of all cancer sites, only testicular cancer showed an RR value >1, although this was not significant and had a negligible effect size (RR=1.12, p=0.3, Hedges g=0.02). Following removal of testicular cancers the remaining data showed a decrease in risk (RR=0.87, p<0.025, N=41). Cancers of the head and neck showed a negative association with cancer risk (RR=0.83, p<0.05), with a large effect size (Hedges g=0.55), but high heterogeneity (I²=79.2%). RR did not reach statistical significance in the remaining cancer site categories (lung, testicular, obesity-associated, other). The data are consistent with a negative association between Cannabis use and nontesticular cancer, but there is low confidence in this result due to high heterogeneity and a paucity of data for many cancer types.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Association Between Marijuana Use and Risk of Cancer: A Systematic Review and Meta-analysis

Importance

Marijuana use is common and growing in the United States amid a trend toward legalization. Exposure to tobacco smoke is a well-described preventable cause of many cancers; the association of marijuana use with the development of cancer is not clear.

Objective

To assess the association of marijuana use with cancer development.

Data Sources

A search of PubMed, Embase, PsycINFO, MEDLINE, and the Cochrane Library was conducted on June 11, 2018, and updated on April 30, 2019. A systematic review and meta-analysis of studies published from January 1, 1973, to April 30, 2019, and references of included studies were performed, with data analyzed from January 2 through October 4, 2019.

Study Selection

English-language studies involving adult marijuana users and reporting cancer development. The search strategy contained the following 2 concepts linked together with the AND operator: marijuana OR marihuana OR tetrahydrocannabinol OR cannabinoid OR cannabis; AND cancer OR malignancy OR carcinoma OR tumor OR neoplasm.

Data Extraction and Synthesis

Two reviewers independently reviewed titles, abstracts, and full-text articles; 3 reviewers independently assessed study characteristics and graded evidence strength by consensus.

Main Outcomes and Measures

Rates of cancer in marijuana users, with ever use defined as at least 1 joint-year exposure (equivalent to 1 joint per day for 1 year), compared with nonusers. Meta-analysis was conducted if there were at least 2 studies of the same design addressing the same cancer without high risk of bias when heterogeneity was low to moderate for the following 4 cancers: lung, head and neck squamous cell carcinoma, oral squamous cell carcinoma, and testicular germ cell tumor (TGCT), with comparisons expressed as odds ratios (ORs) with 95% CIs.

Results

Twenty-five English-language studies (19 case-control, 5 cohort, and 1 cross-sectional) were included; few studies (n = 2) were at low risk of bias. In pooled analysis of case-control studies, ever use of marijuana was not associated with head and neck squamous cell carcinoma or oral cancer. In pooled analysis of 3 case-control studies, more than 10 years of marijuana use (joint-years not reported) was associated with TGCT (OR, 1.36; 95% CI, 1.03-1.81; P = .03; I2 = 0%) and nonseminoma TGCT (OR, 1.85; 95% CI, 1.10-3.11; P = .04; I2 = 0%). Evaluations of ever use generally found no association with cancers, but exposure levels were low and poorly defined. Findings for lung cancer were mixed, confounded by few marijuana-only smokers, poor exposure assessment, and inadequate adjustment; meta-analysis was not performed for several outcomes.

Conclusions and Relevance

Low-strength evidence suggests that smoking marijuana is associated with developing TGCT; its association with other cancers and the consequences of higher levels of use are unclear. Long-term studies in marijuana-only smokers would improve understanding of marijuana's association with lung, oral, and other cancers.

Trial Registration

PROSPERO identifier: CRD42018102457.

Allergic conditions are not associated with the risk of non-Hodgkin's lymphoma or Hodgkin's lymphoma: a systematic review and meta-analysis

We aimed to systematically evaluate the association between allergic conditions and the risk of Hodgkin’s lymphoma (HL) and non-HL (NHL). Systematic literature searches in PubMed and Embase were conducted up to October 2015 to identify eligible studies. Either a fixed-effects model or a random-effects model was adopted to estimate overall odds ratios (ORs) according to heterogeneity across studies. Subgroup and publication bias analyses were applied. A total of 24 case–control studies and 13 cohort studies (conducted from 1987 to 2015) were included in the analysis of the risk of NHL. History of any allergic condition was inversely associated with the risk of NHL in case–control studies (OR =0.83, 95% CI 0.76–0.91), while the reduction in the risk of NHL was not observed in cohort studies (OR =1.18, 95% CI 0.98–1.42). Significant association with the risk of NHL was found for asthma, hay fever, food allergy, allergic rhinitis, and hives. In the pooled analysis of the risk of HL, 12 studies (two were cohort studies) were included. The pooled OR was 0.96 (95% CI 0.84–1.09) for case–control studies and 1.46 (95% CI 0.63–3.38) for cohort studies. For specific allergic condition, we observed a reduced risk of HL in individuals with hay fever and food allergy. In conclusion, history of any allergic condition was not significantly associated with the risk of NHL or HL. Several specific allergic conditions, including asthma, hay fever, food allergy, and allergic rhinitis, might be associated with a reduced risk of NHL, while individuals with hay fever or food allergy may have a reduced risk of HL.

Atopy and Specific Cancer Sites: a Review of Epidemiological Studies

Mounting evidence appears to link asthma and atopy to cancer susceptibility. This review presents and discusses published epidemiological studies on the association between site-specific cancers and atopy. PubMed was searched electronically for publications between 1995 and 2015, and cited references were researched manually. Quantitative studies relating to atopy, allergy, or asthma and cancer were identified and tabulated. Despite many exposure-related limitations, patterns in the studies were observed. Asthma, specifically, has been observed to be a risk factor for lung cancer. A protective effect of atopic diseases against pancreatic cancer has been shown consistently in case-control studies but not in cohort studies. Allergy of any type appears to be protective against glioma and adult acute lymphoblastic leukemia. Most studies on atopic diseases and non-Hodgkin lymphoma or colorectal cancer reported an inverse association. The other sites identified had varying and non-significant outcomes. Further research should be dedicated to carefully defined exposure assessments of "atopy" as well as the biological plausibility in the association between atopic diseases and cancer.

Use of acetaminophen in relation to the occurrence of cancer: a review of epidemiologic studies

Acetaminophen has several pharmacologic properties that suggest it could be carcinogenic in human beings. A number of epidemiologic studies have been conducted to examine whether use of acetaminophen actually predisposes to the occurrence of one or more forms of cancer. There are inherent limitations to many of these studies, including the inaccurate identification of users and nonusers of acetaminophen, relatively short follow-up for cancer incidence, and the potential for confounding by indication. The present manuscript reviews the results of epidemiologic studies of acetaminophen use in relation to cancer incidence published through the end of 2015. The limitations of the underlying studies notwithstanding, some interim conclusions can be reached. For all but several forms of cancer, there is no suggestion that persons who have taken acetaminophen are at altered risk, even persons who have consumed a large quantity of the drug or those who have taken it for an extended duration. While in some studies the incidence of renal cell carcinoma has been observed to be increased among acetaminophen users, several other studies have failed to observe any such association; the reason for the discrepant findings is unclear. Some of the small number of studies that have presented data on the incidence of lymphoma, leukemia, and plasma cell disorders have found the risk to be modestly higher in users than nonusers of acetaminophen, but the results of other studies of these malignancies will be needed to gauge the possible role of publication bias as the basis for the positive results.

Common immune-related exposures/conditions and risk of non-Hodgkin lymphoma: a case-control study of disease-discordant twin pairs

We evaluated the association between common immune system-altering experiences and non-Hodgkin lymphoma (NHL) risk using a case-control study of 162 like-sex twin pairs discordant for NHL, identified from the International Twin Study. Information on medical history and evidence of childhood exposure to microbes was obtained by questionnaire from 1998 to 2002. Conditional logistic regression was used to estimate odds ratios and 95% confidence intervals. Intra-twin-pair agreement between twins on individual exposures was high (76%-97%). A negative association between NHL and seasonal hay fever (odds ratio (OR) = 0.28, 95% confidence interval (CI): 0.10, 0.75) and certain allergies (OR = 0.29, 95% CI: 0.13, 0.68) was observed. The number of atopic diseases was negatively associated with NHL (P for trend = 0.0003). A history of infectious mononucleosis was negatively associated with NHL risk (OR = 0.35, 95% CI: 0.14, 0.90). NHL risk was associated with more frequent childhood exposure to microbes during early life (P for trend = 0.04). No differences in association by NHL subtype were observed, although statistical power for these comparisons was low. These observations support the hypothesis that immune-related exposures, especially atopy, are associated with decreased NHL risk. Use of the within-twin-pair study design mitigates confounding by genome, family structure, and unmeasured characteristics of early childhood factors.

Role of leptin and leptin receptors in hematological malignancies

Leptin is an adipose-derived cytokine that has an important role in bodyweight homeostasis and energy balance. There are a number of studies which have suggested that leptin and its receptors dysregulation play a critical role in the development of malignancies including hematological malignancies, mainly via activation of the JAK/STAT pathway which regulates downstream signaling pathways such as PI3K/AKT signaling and ERK1/2. In this review, current understandings of leptin/leptin receptors mediated pathogenesis in various lymphoid malignancies are described. Blocking of the leptin receptor might be a unique therapeutic approach for many hematological malignancies.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

IMPACT

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

Epidemiology and etiology of non-hodgkin lymphoma

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

Can Aspirin and Cancer Prevention be Ageless Companions?

Over the past few decades, the rate of cancer diagnosis has increased worldwide due to the increase in population and average life expectancy, and also, due to the advances in diagnostic medical technology that facilitate early cancer detection and recognition. Nonetheless, the treatment options have not been developed proportional to this increase, with a huge number of patients frequently being diagnosed with different types of fatal cancer. This has prompted different health organizations to search for novel strategies to prevent cancer, or even halt its progression. Having failed to provide optimum vascular protection benefits, especially with the introduction of relatively superior antiplatelets, such as adenosine diphosphate (ADP) receptor inhibitors; clopidogrel and ticagrelor, regular aspirin use was proposed to reduce the risk of common cancers like colorectal cancer, gastric cancer, breast cancer, lung cancer, prostate cancer and haematological malignancies, as suggested by epidemiological studies. However, it is difficult to draw any firm conclusions on such weak data, as this could raise false hopes among patients and physicians and could potentially mislead scientific research. Clearly, current evidence highlights a gap in medical research and emphasizes the need to carry out interventional studies in high risk for cancer patients using specific aspirin doses in order to validate the data. This should also shed some light on the risk-benefit profile in view of the potential for bleeding complications, especially with the higher doses.

An epidemiologic review of marijuana and cancer: an update

Marijuana use is legal in two states and additional states are considering legalization. Approximately 18 million Americans are current marijuana users. There is currently no consensus on whether marijuana use is associated with cancer risk. Our objective is to review the epidemiologic studies on this possible association. We identified 34 epidemiologic studies on upper aerodigestive tract cancers (n = 11), lung cancer (n = 6), testicular cancer (n = 3), childhood cancers (n = 6), all cancers (n = 1), anal cancer (n = 1), penile cancer (n = 1), non-Hodgkin lymphoma (n = 2), malignant primary gliomas (n = 1), bladder cancer (n = 1), and Kaposi sarcoma (n = 1). Studies on head and neck cancer reported increased and decreased risks, possibly because there is no association, or because risks differ by human papillomavirus status or geographic differences. The lung cancer studies largely appear not to support an association with marijuana use, possibly because of the smaller amounts of marijuana regularly smoked compared with tobacco. Three testicular cancer case-control studies reported increased risks with marijuana use [summary ORs, 1.56; 95% confidence interval (CI), 1.09-2.23 for higher frequency and 1.50 (95% CI, 1.08-2.09) for ≥10 years]. For other cancer sites, there is still insufficient data to make any conclusions. Considering that marijuana use may change due to legalization, well-designed studies on marijuana use and cancer are warranted.

Use of non-steroidal anti-inflammatory drugs and risk of non-Hodgkin lymphoma: a systematic review and meta-analysis

Epidemiological study findings regarding the association between use of non-steroidal anti-inflammatory drugs (NSAIDs) and risk of non-Hodgkin lymphoma (NHL) have been inconsistent. We aimed to systematically review epidemiological studies of the association and calculate pooled relative risks using meta-analytic methods. We searched eight electronic literature databases and three clinical trial registers to identify all studies (including observational studies and randomized clinical trials) of the association published prior to October 2013. Identified studies were independently reviewed by two researchers. We used a random effects model to calculate pooled odds ratio (PORs). Heterogeneity amongst studies was examined using Cochran's Q and I-squared (I(2)) tests; and sources of heterogeneity were explored using subgroup and meta-regression analyses. A total of 17 studies (12 case-control studies and five cohort studies), all adult studies, were included. Use of NSAIDs was not associated with overall risk of NHL [POR = 1.05, and 95% confidence interval (95% CI) 0.90-1.22] or NHL subtypes including B-cell lymphoma, T-cell lymphoma, follicular lymphoma, diffuse large B-cell lymphoma and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Aspirin use was associated with reduced risk of CLL/SLL (POR = 0.70, 95% CI 0.54-0.91) but not with the risk of all NHLs (POR = 1.02, 95% CI 0.89-1.17). Use of non-aspirin NSAIDs was associated with increased risk of NHL (POR = 1.41, 95% CI 1.01-1.97) amongst females only. The epidemiologic evidence remains inconclusive. Effects of NSAIDs may differ by drug type, NHL subtype, and sex and more studies taking into consideration these differences are needed.

Allergy and risk of hematologic malignancies: associations and mechanisms

Increasing evidence indicates that a dysregulated immune system, as the one found in allergic disorders, can affect survival of tumor cells. A possible association between allergies and risk of hematologic malignancies has been examined in several epidemiological studies; however, results were not always consistent. The aim of this review is to report the preclinical and clinical data, which support a correlation between allergy and hematologic neoplasms. Immune system modulation could represent a powerful tool in the prevention and treatment of hematologic malignancies.

Medical consequences of marijuana use: a review of current literature

With the advent of legalization of marijuana for medicinal and recreational purposes, and the increase use of marijuana, healthcare providers will be increasingly confronted with marijuana users as patients in clinical environments. While there is vast literature regarding the societal and mental health harms associated with marijuana use, there is a paucity of reviews of the potential consequences of marijuana use on physical health or medical conditions. We examine the recent literature on the physical harms associated with illicit and legal marijuana administration. We surveyed the peer-reviewed medical literature from 1998 to 2013 of studies assessing the association of marijuana use and physical diseases. We conclude that healthcare providers should be cognizant that the existing literature suggests that marijuana use can cause physical harm. However, evidence is needed, and further research should be considered, to prove causal associations of marijuana with many physical health conditions.

Polymorphisms in DNA repair pathway genes, body mass index, and risk of non-Hodgkin lymphoma

We conducted a population-based case-control study in Connecticut women to test the hypothesis that genetic variations in DNA repair pathway genes may modify the relationship between body mass index (BMI) and risk of non-Hodgkin lymphoma (NHL). Compared to those with BMI <25, women with BMI ≥25 had significantly increased risk of NHL among women who carried BRCA1 (rs799917) CT/TT, ERCC2 (rs13181) AA, XRCC1 (rs1799782) CC, and WRN (rs1801195) GG genotypes, but no increase in NHL risk among women who carried BRCA1 CC, ERCC2 AC/CC, XRCC1 CT/TT, and WRN GT/TT genotypes. A significant interaction with BMI was only observed for WRN (rs1801195; P = 0.004) for T-cell lymphoma and ERCC2 (rs13181; P = 0.002) for diffuse large B-cell lymphoma. The results suggest that common genetic variation in DNA repair pathway genes may modify the association between BMI and NHL risk.

Occupational exposure to immunologically active agents and risk for lymphoma: the European Epilymph case-control study

OBJECTIVES

Allergies and asthma may be protective for the development of lymphoma. We evaluated whether occupational allergens that provoke immune reactivity and asthma through an IgE-mediated pathway are protective for lymphoma.

METHODS

The Epilymph study includes histologically or cytologically confirmed Hodgkin, B-cell, and T-cell lymphoma cases from six European countries (Spain, France, Germany, Italy, Ireland, and Czech Republic) recruited in 1998-2004. Controls were frequency matched to cases by age, gender, and study centre. Lifetime occupational exposure to seven high molecular weight (HMW) agents was evaluated through an asthma-specific job-exposure matrix. 2205 lymphoma cases and 2296 controls with complete occupational history could be included in the analysis. Associations between HMW exposures and lymphoma were evaluated using pooled unconditional logistic regression analyses.

RESULTS

Individuals exposed to HMW agents had a non-statistically significant decreased risk of any lymphoma (OR, 0.88: 95% CI, 0.74-1.05) and of B-cell lymphoma (OR, 0.91; 95% CI, 0.76-1.09), and a significantly decreased risk for Hodgkin lymphoma (OR, 0.62; 95% CI, 0.40-0.98). A decrease in risk for lymphoma was found for exposure to latex (OR, 0.74; 95% CI, 0.55-0.99).

CONCLUSIONS

Further epidemiologic and mechanistic research is needed to confirm that occupational exposure to HMW agents predisposing to asthma can reduce the risk of lymphoma.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Exploring risk factors for follicular lymphoma

Follicular lymphoma (FL) is an indolent malignancy of germinal center B cells with varied incidence across racial groups and geographic regions. Improvements in the classification of non-Hodgkin lymphoma subtypes provide an opportunity to explore associations between environmental exposures and FL incidence. Our paper found that aspects of Western lifestyle including sedentary lifestyle, obesity, and diets high in meat and milk are associated with an increased risk of FL. Diets rich in fruits and vegetables, polyunsaturated fatty acids, vitamin D, and certain antioxidants are inversely associated with FL risk. A medical history of Sjogren's syndrome, influenza vaccination, and heart disease may be associated with FL incidence. Associations between FL and exposure to pesticides, industrial solvents, hair dyes, and alcohol/tobacco were inconsistent. Genetic risk factors include variants at the 6p21.32 region of the MHC II locus, polymorphisms of the DNA repair gene XRCC3, and UV exposure in individuals with certain polymorphisms of the vitamin D receptor. Increasing our understanding of risk factors for FL must involve integrating epidemiological studies of genetics and exposures to allow for the examination of risk factors and interactions between genes and environment.

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

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

Perinatal and family risk factors for non-Hodgkin lymphoma in early life: a Swedish national cohort study

BACKGROUND

The incidence of non-Hodgkin lymphoma (NHL) in early life has increased in recent decades, but the relevant risk factors remain largely unknown. We examined perinatal and family risk factors for NHL in childhood through young adulthood.

METHODS

We conducted a national cohort study of 3 571 574 individuals born in Sweden in 1973-2008 who were followed for incidence of NHL through 2009 (ages 0-37 years). Detailed information on perinatal and family characteristics and NHL diagnoses were obtained from national birth and cancer registries. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between perinatal and family variables and NHL; P values are from two-sided tests.

RESULTS

There were 936 NHL case patients identified in 66.3 million person-years of follow-up. Independent risk factors for NHL included family history of NHL in either a sibling (adjusted HR = 9.84; 95% CI = 2.46 to 39.41; P = .001) or parent (adjusted HR = 2.36; 95% CI = 1.27 to 4.38; P = .007); high fetal growth (for ≥ 2 SDs relative to 0 to <1 SD from the mean: adjusted HR = 1.64; 95% CI = 1.19 to 2.25; P = .002); older maternal age (adjusted HR for each 5-year increment = 1.11; 95% CI = 1.04 to 1.19; P (trend) = .004); low birth order (adjusted HR for each increment of one birth = 0.91; 95% CI = 0.84 to 0.99; P (trend) = .02); and male sex (adjusted HR = 1.58; 95% CI = 1.38 to 1.80; P < .001). Male sex was associated with onset of NHL before 15 years of age but not with later-onset NHL, whereas the other risk factors did not vary by age at diagnosis. No association was found between gestational age at birth, twinning, paternal age, or parental education and NHL.

CONCLUSION

In this large national cohort study, family history of NHL, high fetal growth, older maternal age, low birth order, and male sex were independent risk factors for NHL in early life.

Allergy-associated symptoms in relation to childhood non-Hodgkin's as contrasted to Hodgkin's lymphomas: a case-control study in Greece and meta-analysis

An increase of the prevalence of childhood allergic diseases and the incidence of childhood Hodgkin's (HL) and non-Hodgkin's lymphoma (NHL) were reported in the late 20th century. Among adults, several studies point to an inverse association with lymphoma; it remains to be confirmed whether allergy is also related to childhood lymphomas and whether the association, if any, is of an aetiologic nature. Between 1996 and 2008, 277 children (aged 0-14 years) with HL (N = 111) or NHL (N = 166) were enrolled in Nationwide Registry for Childhood Hematological Malignancies (NARECHEM), a Greek hospital-based-registry of childhood hematological malignancies. Hospital controls were individually matched to cases on age and sex. Multivariate conditional logistic regression was used to estimate odds ratios (ORs) with 95%confidence intervals (CIs) for associations of allergic diseases and other covariates with childhood HL or NHL risk. Subsequently, we combined our results with those of a French case-control study in a meta-analysis amounting to a total of 330 NHL cases/1478 controls and 239 HL cases/959 controls. After controlling for sociodemographic, perinatal and environmental factors, childhood NHL was less prevalent among children with allergy-associated symptoms overall (OR:0.50, 95%CI:0.27-0.92) or a history of asthma (OR:0.43, 95%CI:0.21-0.88). By contrast, allergy did not seem to be associated with childhood HL risk, although statistical power was limited. Fewer seaside holidays and higher birth weight were also associated with increased childhood NHL risk. The combined OR of the two studies for the association of asthma with NHL risk was: 0.52, 95%CI:0.32-0.84, whereas for HL: 0.86, 95%CI:0.51-1.45. Allergy seems to be strongly and inversely associated with childhood NHL. It remains to be elucidated in future investigations comprising larger populations, focusing on specific disease subtypes and employing more pertinent study-designs, whether this association is genuinely protective.

Anthropometric factors, physical activity, and risk of non-Hodgkin's lymphoma in the Women's Health Initiative

BACKGROUND

Incidence rates of non-Hodgkin's lymphoma (NHL) increased substantially in the United States and worldwide during the latter part of the 20th century, but little is known about its etiology. Obesity is associated with impaired immune function through which it may influence the risk of NHL; other factors reflecting energy homeostasis (height, abdominal adiposity, and physical activity) may also be involved.

METHODS

We examined the association of anthropometric factors and physical activity with risk of NHL and its major subtypes in a large cohort of women aged 50-79 years old who were enrolled at 40 clinical centers in the United States between 1993 and 1998. Over a mean follow-up period of 11 years, 1123 cases of NHL were identified among 158,975 women. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

Height at baseline was positively associated with risk of all NHL and with that of diffuse large B-cell lymphoma (HRs(q4vs.q1) 1.19, 95% CI 1.00-1.43 and 1.43, 95% CI 1.01-2.03, respectively). Measures of obesity and abdominal adiposity at baseline were not associated with risk. Hazard ratios for NHL were increased for women in the highest quartile of weight and body mass index at age 18 (HRs(q4vs.q1) 1.29, 95% CI 1.01-1.65 and 1.27, 95% CI 1.01-1.59, respectively). Some measures of recreational physical activity were modestly associated with increased risk of NHL overall, but there were no clear associations with specific subtypes.

CONCLUSION

Our findings regarding anthropometric measures are consistent with those of several previous reports, suggesting that early life influences on growth and immune function may influence the risk of NHL later in life.

Long-term use of acetaminophen, aspirin, and other nonsteroidal anti-inflammatory drugs and risk of hematologic malignancies: results from the prospective Vitamins and Lifestyle (VITAL) study

PURPOSE

Among previous studies examining the associations of over-the-counter analgesics or nonsteroidal anti-inflammatory drugs (NSAIDs) and incident hematologic malignancies, results were inconsistent for NSAIDs but suggested an increased risk with acetaminophen (paracetamol). Herein, we used a large prospective cohort study to examine these associations.

PATIENTS AND METHODS

In total, 64,839 men and women age 50 to 76 years were recruited from 2000 to 2002 to the Vitamins and Lifestyle (VITAL) study. Incident hematologic malignancies (n = 577) were identified through December 2008 by linkage to the Surveillance, Epidemiology and End Results cancer registry. Hazard ratios (HRs) associated with use of analgesics for total incident hematologic malignancies and cancer subcategories were estimated by Cox proportional hazards models. Models were adjusted for age, sex, race/ethnicity, education, smoking, self-rated health, arthritis, chronic musculoskeletal pain, migraines, headaches, fatigue, and family history of leukemia/lymphoma.

RESULTS

After adjustment, there was an increased risk of incident hematologic malignancies associated with high use (≥ 4 days/week for ≥ 4 years) of acetaminophen (HR, 1.84; 95% CI, 1.35 to 2.50 for high use; P trend = .004). This association was seen for myeloid neoplasms (HR, 2.26; 95% CI, 1.24 to 4.12), non-Hodgkin's lymphomas (HR, 1.81; 95% CI, 1.12 to 2.93), and plasma cell disorders (HR, 2.42; 95% CI, 1.08 to 5.41), but not chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL; HR, 0.84; 95% CI, 0.31 to 2.28). By comparison, there was no association with risk of incident hematologic malignancies for increasing use of aspirin, nonaspirin NSAIDs, or ibuprofen.

CONCLUSION

High use of acetaminophen was associated with an almost two-fold increased risk of incident hematologic malignancies other than CLL/SLL. Neither aspirin nor nonaspirin NSAIDs are likely useful for prevention of hematologic malignancies.

A functional TNFRSF5 polymorphism and risk of non-Hodgkin lymphoma, a pooled analysis

Interaction between CD40 and its ligand, CD154, has a key function in immune regulation. Recent experimental data support a role of deregulated CD40 signalling in lymphomagenesis. Data from earlier studies that are part of this pooling study implicate a functional polymorphism (-1C>T, rs1883832) in the TNFRSF5 gene encoding CD40 in the etiology of follicular lymphoma. Here, the association of this variant with non-Hodgkin lymphoma (NHL) risk was replicated in a European multicenter study of 855 NHL cases and 1,206 controls. In the combined analysis of 2,617 cases and 3,605 controls, carrying the TT genotype was associated with an increased risk for all NHL (OR = 1.4; p for linear trend = 0.00009), diffuse large B-cell lymphoma (OR = 1.6; p for linear trend = 0.002) and follicular lymphoma (OR = 1.6; p for linear trend = 0.001). These data suggest a possible role of this functional polymorphism in lymphomas originating within the germinal center.

Long-term use of cholesterol-lowering drugs and cancer incidence in a large United States cohort

HMG-coA reductase inhibitors, commonly known as statins, account for the great majority of cholesterol-lowering drug use. However, little is known about the association between long-term statin use and incidence of most types of cancers. We examined the association between long-term use of cholesterol-lowering drugs, predominantly statins, and the incidence of ten common cancers, as well as overall cancer incidence, among 133,255 participants (60,059 men and 73,196 women) in the Cancer Prevention Study II Nutrition Cohort during the period from 1997 to 2007. Multivariate Cox proportional hazards regression was used to estimate relative risks (RR). Current use status and duration of use were updated during follow-up using information from biennial follow-up questionnaires. Current use of cholesterol-lowering drugs for five or more years was not associated with overall cancer incidence (RR = 0.97, 95% CI = 0.92-1.03), or incidence of prostate, breast, colorectal, lung, bladder, renal cell, or pancreatic cancer but was associated with lower risk of melanoma (RR = 0.79, 95% CI = 0.66-0.96), endometrial cancer (RR = 0.65, 95% CI = 0.45-0.94), and non-Hodgkin lymphoma (NHL; RR = 0.74, 95% CI = 0.62-0.89). These results suggest that long-term use of statins is unlikely to substantially increase or decrease overall cancer risk. However, associations between long-term statin use and risk of endometrial cancer, melanoma, and NHL deserve further investigation.

Chemokine polymorphisms and lymphoma: a pooled analysis

Polymorphisms in chemokine genes have been associated with human immunodeficiency virus (HIV)-related non-Hodgkin lymphoma (NHL) but are understudied in non-HIV-related NHL. Associations of NHL and NHL subtypes with polymorphisms and haplotypes in CCR5, CCR2, CCL5, CXCL12, and CX(3)CR(1) were explored in a pooled analysis of three case-control studies (San Francisco Bay Area, California; United Kingdom; total: cases N = 1610, controls N = 1992). Adjusted unconditional logistic regression was used to estimate relative risks among HIV-negative non-Hispanic Caucasians. The CCR5 Delta32 deletion reduced the risk of NHL (odds ratio = 0.56, 95% confidence interval = 0.38-0.83) in men but not women with similar effects observed for diffuse large-cell and follicular lymphoma (FL). NHL risk also was reduced in men with the CCR2/CCR5 haplotype characterized by the CCR5 Delta32 deletion. The CCL5 -403A allele conferred reduced risks of FL and chronic lymphocytic leukemia/small lymphocytic lymphoma. Results should be interpreted conservatively. Continued investigation is warranted to confirm these findings.

Cytokine polymorphisms in Th1/Th2 pathway genes, body mass index, and risk of non-Hodgkin lymphoma

We conducted a population-based, case-control study in Connecticut women to test the hypothesis that genetic variations in Th1 and Th2 cytokine genes modify the relationship between body mass index (BMI) and risk of non-Hodgkin lymphoma (NHL). Compared with those with BMI less than 25 kg/m(2), women with BMI more than or equal to 25 kg/m(2) had 50% to 90% increased risk of NHL among women who carried IFNGR2 (rs9808753) AA, IL5 (rs2069812) CT/TT, IL7R (rs1494555) AA, and TNF (rs1799724) CC genotypes, but no increased risk among women with IFNGR2 AG/GG, IL5 CC, IL7R AG/GG, and TNF CT/TT genotypes. A significant interaction with BMI was only observed for IFNGR2 (rs9808753 P(forinteraction) = .034) and IL7R (rs1494555 P(forinteraction) = .016) for NHL overall; IL7R (rs1494555 P(forinteraction) = .016) and TNF (1799724 P(forinteraction) = .031) for B-cell lymphoma; and IL5 (rs2069812 P(forinteraction) = .034) for T-cell lymphoma. After stratification by common B-cell lymphoma subtypes, a significant interaction was observed for IFNGR2 (rs9808753 P(forinteraction) = .006), IL13 (rs20541 P(forinteraction) = .019), and IL7R (rs1494555 P(forinteraction) = .012) for marginal zone B-cell lymphoma; IL7R (rs1494555 P(forinteraction) = .017) for small lymphocytic lymphoma/chronic lymphocytic leukemia; and IL12A (rs568408 P(forinteraction) = .013) and TNF (1799724 P(forinteraction) = .04) for follicular lymphoma. The results suggest that common genetic variation in Th1/Th2 pathway genes may modify the association between BMI and NHL risk.

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

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

Solvent exposure and non-Hodgkin lymphoma: no risk in a population-based study in the San Francisco Bay Area

The literature on environmental exposures and risk of non-Hodgkin lymphoma (NHL) is inconsistent and no occupational exposures have been conclusively identified as causal factors. We used job exposure matrices to assess the association between occupational exposure to solvents in a population-based case-control study of NHL (n = 1,591 cases; n = 2,515 controls) in the San Francisco Bay Area between 1988 and 1995. Occupational histories were collected during in-person interviews and were coded according to the 1980 U.S. Department of Commerce Alphabetic Index of Industries and Occupations. Odds ratios and 95% confidence intervals were adjusted for potential confounders. Our results have provided no support for an association between NHL and occupational exposure to solvents.

Distinct patterns of HIV-1 evolution within metastatic tissues in patients with non-Hodgkins lymphoma

Despite highly active antiretroviral therapy (HAART), AIDS related lymphoma (ARL) occurs at a significantly higher rate in patients infected with the Human Immunodeficiency Virus (HIV) than in the general population. HIV-infected macrophages are a known viral reservoir and have been shown to have lymphomagenic potential in SCID mice; therefore, there is an interest in determining if a viral component to lymphomagenesis also exists. We sequenced HIV-1 envelope gp120 clones obtained post mortem from several tumor and non-tumor tissues of two patients who died with AIDS-related Non-Hodgkin's lymphoma (ARL-NH). Similar results were found in both patients: 1) high-resolution phylogenetic analysis showed a significant degree of compartmentalization between lymphoma and non-lymphoma viral sub-populations while viral sub-populations from lymph nodes appeared to be intermixed within sequences from tumor and non-tumor tissues, 2) a 100-fold increase in the effective HIV population size in tumor versus non-tumor tissues was associated with the emergence of lymphadenopathy and aggressive metastatic ARL, and 3) HIV gene flow among lymph nodes, normal and metastatic tissues was non-random. The different population dynamics between the viruses found in tumors versus the non-tumor associated viruses suggest that there is a significant relationship between HIV evolution and lymphoma pathogenesis. Moreover, the study indicates that HIV could be used as an effective marker to study the origin and dissemination of lymphomas in vivo.

Reproductive factors and non-Hodgkin lymphoma risk in the California Teachers Study

Background

Non-Hodgkin lymphoma (NHL) is a malignancy etiologically linked to immunomodulatory exposures and disorders. Endogenous female sex hormones may modify immune function and influence NHL risk. Few studies have examined associations between reproductive factors, which can serve as surrogates for such hormonal exposures, and NHL risk by subtype.

Methodology/Principal Findings

Women in the California Teachers Study cohort provided detailed data in 1995–1996 on reproductive history. Follow-up through 2007 identified 574 women with incident B-cell NHL. Hazard rate ratios (RR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards models to assess associations between reproductive factors and all B-cell NHL combined, diffuse large B-cell lymphomas, follicular lymphomas, and B-cell chronic lymphocytic leukemias/small lymphocytic lymphomas. Pregnancy was marginally associated with lower risk of B-cell NHL (RR = 0.84, 95% CI = 0.68–1.04). Much of the reduction in risk was observed after one full-term pregnancy relative to nulligravid women (RR = 0.75, 95% CI = 0.54–1.06; P for trend <0.01), particularly for diffuse large B-cell lymphomas (P for trend = 0.13), but not among women who had only incomplete pregnancies. Age at first full-term pregnancy was marginally inversely associated with B-cell NHL risk overall (P for trend = 0.08) and for diffuse large B-cell lymphomas (P for trend = 0.056). Breast feeding was not associated with B-cell NHL risk overall or by subtype.

Conclusions

Full-term pregnancy and early age at first full-term pregnancy account for most of the observed reduction in B-cell NHL risk associated with gravidity. Pregnancy-related hormonal exposures, including prolonged and high-level exposure to progesterone during a full-term pregnancy may inhibit development of B-cell NHL.

Occupational exposure to high molecular weight allergens and lymphoma risk among Italian adults

OBJECTIVES

Exposure to high molecular weight (HMW) allergens that provoke immune reactivity through an IgE-mediated pathway has been associated with a decreased risk of B-cell lymphoma. The present analysis was conducted to assess the associations between occupational exposure to specific HMW allergens and the risk of B-cell, T-cell, and Hodgkin's lymphomas.

METHODS

We analyzed data from 2,290 incident lymphoma cases and 1,771 population-based controls enrolled in a multicenter study of hematolymphopoietic malignancies conducted in Italy between 1991 and 1993. All cases were histologically or cytologically confirmed. Controls were frequency-matched to cases based on age, sex, and study center. An industrial hygienist evaluated HMW occupational exposure classifications after an asthma-specific job exposure matrix was applied to participants' job histories. Unconditional logistic regression was used to assess associations between occupational exposures that occurred > or = 10 years before the date of lymphoma diagnosis and B-cell, T-cell, and Hodgkin's lymphomas.

RESULTS

Ten percent of cases and 11% of controls were occupationally exposed to HMW allergens. Exposed individuals had a decreased risk for all lymphomas combined (odds ratio, 0.78; 95% confidence interval, 0.63-0.97), particularly for B-cell lymphomas (odds ratio, 0.75; 95% confidence interval, 0.59-0.94). The decreased risks for all lymphomas were also observed when HMW allergen exposure was limited to animal and latex allergens.

CONCLUSIONS

These findings support the hypothesis that occupational exposure to immunologically active HMW allergens is inversely associated with the risk for lymphoma. The effect of exposure to specific allergens warrants further assessment.

Atopic disease and risk of non-Hodgkin lymphoma: an InterLymph pooled analysis

We performed a pooled analysis of data on atopic disease and risk of non-Hodgkin lymphoma (NHL) from 13 case-control studies, including 13,535 NHL cases and 16,388 controls. Self-reported atopic diseases diagnosed 2 years or more before NHL diagnosis (cases) or interview (controls) were analyzed. Pooled odds ratios (OR) and 95% confidence intervals (95% CI) were computed in two-stage random-effects or joint fixed-effects models, and adjusted for age, sex, and study center. When modeled individually, lifetime history of asthma, hay fever, specific allergy (excluding hay fever, asthma, and eczema), and food allergy were associated with a significant reduction in NHL risk, and there was no association for eczema. When each atopic condition was included in the same model, reduced NHL risk was only associated with a history of allergy (OR, 0.80; 95% CI, 0.68-0.94) and reduced B-cell NHL risk was associated with history of hay fever (OR, 0.85; 95% CI, 0.77-0.95) and allergy (OR, 0.84; 95% CI, 0.76-0.93). Significant reductions in B-cell NHL risk were also observed in individuals who were likely to be truly or highly atopic-those with hay fever, allergy, or asthma and at least one other atopic condition over their lifetime. The inverse associations were consistent for the diffuse large B-cell and follicular subtypes. Eczema was positively associated with lymphomas of the skin; misdiagnosis of lymphoma as eczema is likely, but progression of eczema to cutaneous lymphoma cannot be excluded. This pooled study shows evidence of a modest but consistent reduction in the risk of B-cell NHL associated with atopy.

Body mass index, height, and risk of lymphatic malignancies: a prospective cohort study

The association among body mass index (BMI), height, and the risk of lymphatic malignancies was investigated in the Netherlands Cohort Study. The participants (n = 120,852), Dutch men and women aged 55-69 years, completed a self-administered questionnaire at baseline in 1986. After 13.3 years of follow-up, data on 1,042 lymphatic malignancy cases (including diffuse large-cell lymphoma, chronic lymphocytic leukemia, multiple myeloma, and other subtypes) and 4,588 subcohort members were available. Incidence rate ratios were estimated by using Cox regression models. BMI at baseline and BMI change since the age of 20 years were not associated with lymphatic malignancy risk. However, the rate ratio of lymphatic malignancies per 4-unit increase in BMI at 20 years of age was 1.13 (95% confidence interval (CI): 1.01, 1.25). The rate ratio of lymphatic malignancies per 5-cm increase in height was 1.08 (95% CI: 1.02, 1.15). For diffuse large-cell lymphoma, follicular lymphoma, and chronic lymphocytic leukemia, the relative risks were 1.19 (95% CI: 1.07, 1.33), 1.15 (95% CI: 0.95, 1.40), and 1.09 (95% CI: 0.95, 1.26), respectively, for each 5-cm increase in height. The positive associations among BMI at 20 years of age, height, and the risk of lymphatic malignancies suggest that exposures during early life play a role in the etiology of lymphatic malignancies.

Vaccination history and risk of non-Hodgkin lymphoma: a population-based, case-control study

OBJECTIVE

As factors that alter the immune system have been implicated in non-Hodgkin lymphoma (NHL) etiology, it is of interest to explore the association between vaccination and risk of NHL. Results of few epidemiologic studies conducted thus far are inconsistent, and only one has examined the association by histologic subtype.

SUBJECTS

A population-based, case-control study of 387 patients with NHL and 535 controls conducted in Nebraska between 1999 and 2002.

METHODS

Information on vaccination for tetanus, polio, influenza, smallpox, and tuberculosis, as well as important environmental factors, was collected by telephone interview. Risk was estimated by odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for confounders.

RESULTS

We found that NHL risk was inversely associated with ever receiving a polio (OR = 0.59, CI = 0.40-0.87) or smallpox (OR = 0.71, CI = 0.51-0.98) vaccination, and positively associated with influenza vaccination (OR = 1.53, CI = 1.14-2.06). No significant association was found for tetanus or tuberculosis vaccination. The patterns of association were similar between men and women. Analysis by histologic subtypes showed that polio vaccination was associated with a lower risk of follicular (OR = 0.54, CI = 0.31-0.92) and chronic lymphocytic leukemia/small lymphocytic lymphomas (OR = 0.29, CI = 0.12-0.69) and smallpox vaccination was associated with a lower risk of marginal zone lymphoma (OR = 0.41, CI = 0.19-0.88). In contrast, ever receiving an influenza vaccination was associated with a higher risk of follicular (OR = 1.98, CI = 1.23-3.18) and diffuse large B cell lymphomas (OR = 1.88, CI = 1.13-3.12).

CONCLUSION

Risk of NHL is inversely associated with polio and smallpox vaccination and positively associated with influenza vaccination. These associations appear to differ by histologic subtype.

Energy balance, physical activity, and cancer risk

This chapter posits that cancer is a complex and multifactorial process as demonstrated by the expression and production of key endocrine and steroid hormones that intermesh with lifestyle factors (physical activity, body size, and diet) in combination to heighten cancer risk. Excess weight has been associated with increased mortality from all cancers combined and for cancers of several specific sites. The prevalence of obesity has reached epidemic levels in many parts of the world; more than 1 billion adults are overweight with a body mass index (BMI) exceeding 25. Overweight and obesity are clinically defined indicators of a disease process characterized by the accumulation of body fat due to an excess of energy intake (nutritional intake) relative to energy expenditure (physical activity). When energy intake exceeds energy expenditure over a prolonged period of time, the result is a positive energy balance (PEB), which leads to the development of obesity. This physical state is ideal for intervention and can be modulated by changes in energy intake, expenditure, or both. Nutritional intake is a modifiable factor in the energy balance-cancer linkage primarily tested by caloric restriction studies in animals and the effect of energy availability. Restriction of calories by 10 to 40% has been shown to decrease cell proliferation, increasing apoptosis through anti-angiogenic processes. The potent anticancer effect of caloric restriction is clear, but caloric restriction alone is not generally considered to be a feasible strategy for cancer prevention in humans. Identification and development of preventive strategies that "mimic" the anticancer effects of low energy intake are desirable. The independent effect of energy intake on cancer risk has been difficult to estimate because body size and physical activity are strong determinants of total energy expenditure. The mechanisms that account for the inhibitory effects of physical activity on the carcinogenic process are reduction in fat stores, activity related changes in sex-hormone levels, altered immune function, effects in insulin and insulin-like growth factors, reduced free radical generation, and direct effect on the tumor. Epidemiologic evidence posits that the cascade of actions linking overweight and obesity to carcinogenesis are triggered by the endocrine and metabolic system. Perturbations to these systems result in the alterations in the levels of bioavailable growth factors, steroid hormones, and inflammatory markers. Elevated serum concentrations of insulin lead to a state of hyperinsulinemia. This physiological state causes a reduction in insulin-like growth factor-binding proteins and promotes the synthesis and biological activity of insulin-like growth factor (IGF)-I, which regulates cellular growth in response to available energy and nutrients from diet and body reserves. In vitro studies have clearly established that both insulin and IGF-I act as growth factors that promote cell proliferation and inhibit apoptosis. Insulin also affects on the synthesis and biological availability of the male and female sex steroids, including androgens, progesterone, and estrogens. Experimental and clinical evidence also indicates a central role of estrogens and progesterone in regulating cellular differentiation, proliferation, and apoptosis induction. Hyperinsulinemia is also associated with alterations in molecular systems such as endogenous hormones and adipokines that regulate inflammatory responses. Obesity-related dysregulation of adipokines has the ability to contribute to tumorigenesis and tumor invasion via metastatic potential. Given the substantial level of weight gain in industrialized countries in the last two decades, there is great interest in understanding all of the mechanisms by which obesity contributes to the carcinogenic process. Continued focus must be directed to understanding the various relationships between specific nutrients and dietary components and cancer cause and prevention. A reductionist approach is not sufficient for the basic biological mechanisms underlying the effect of diet and physical activity on cancer. The joint association between energy balance and cancer risk are hypothesized to share the same underlying mechanisms, the amplification of chemical mediators that modulate cancer risk depending on the responsiveness to those hormones to the target tissue of interest. Disentangling the connection between obesity, the insulin-IGF axis, endogenous hormones, inflammatory markers, and their molecular interaction is vital.

The role of non-steroidal anti-inflammatory drugs in the risk of development and treatment of hematologic malignancies

Non-steroidal anti-inflammatory drugs (NSAIDs) comprise the group of structurally diverse but similarly acting compounds that are used for relieving signs and symptoms of inflammation, especially in treatment of rheumatic diseases. Recent reports suggested potential association between regular use of NSAIDs and the risk of development of hematological malignancies. However, the data distinctly differ depending on type of NSAID used, period of its administration and type of malignancy. Regular use of aspirin and other NSAIDs was shown to correlate with reduced risk of lymphoid malignancies. Frequent use of aspirin was found to be associated with decreased risk of acute leukemia (AL) development. In contrast, correlation between long-term acetaminophen usage and increased incidence of AL and multiple myeloma (MM) was indicated. On the other hand, NSAIDs were found to exert anti-cancer effects, inhibiting proliferation and invasive growth or inducing cell apoptosis in several tumors, including hematologic malignancies. One of those agents, non-cyclooxygenase 2-inhibiting R-enantiomer of etodolac (SDX-101), exerts cytotoxic effects against chronic lymphocytic leukemia (CLL) and MM cells, and is currently investigated in phase II clinical trial in CLL. The indole-pyran analogue of SDX-101, SDX-308 (CEP-18082), showed more potent cytotoxicity than SDX-101 against MM cells and inhibited osteoclast formation and activity of mature osteoclasts. Thus, SDX-308 may be an ideal agent for bone disease in MM and related diseases. Another analogue of SDX-101, SDX-309, showed also significant anti-tumor activity in first preclinical studies. The potential role of NSAIDs in prevention and treatment of hematologic malignancies is the subject of this review.

Domestic and farm-animal exposures and risk of non-Hodgkin's lymphoma in a population-based study in the San Francisco Bay Area

OBJECTIVE

To assess the association between animal exposures and non-Hodgkin's lymphoma (NHL).

METHODS

Exposure data were collected from 1,591 cases and 2,515 controls during in-person interviews in a population-based case-control study of NHL in the San Francisco Bay Area. Odds ratios (OR) and 95% confidence intervals (95% CI) were adjusted for potential confounders.

RESULTS

Pet owners had a reduced risk of NHL (OR, 0.71; 95% CI, 0.52-0.97) and diffuse large-cell lymphoma large cell (DLCL; OR, 0.58; 95% CI, 0.39-0.87) compared with those who never had owned a pet. Ever having owned dogs and/or cats was associated with reduced risk of all NHL (OR, 0.71; 95% CI, 0.54-0.94) and of DLCL (OR, 0.60; 95% CI, 0.42-0.86). Longer duration of cat ownership (P(trend) = 0.008), dog ownership (P(trend) = 0.04), and dog and/or cat ownership (P(trend) = 0.004) was inversely associated with risk of NHL. Ownership of pets other than cats and dogs was associated with a reduced risk of NHL (OR, 0.64; 95% CI, 0.55-0.74) and DLCL (OR, 0.58; 95% CI, 0.47-0.71). Exposure to cattle for >or=5 years was associated with an increased risk of NHL (OR, 1.6; 95% CI, 1.0-2.5) as was exposure to pigs for all NHL (OR, 1.8; 95% CI, 1.2-2.6) and for DLCL (OR, 2.0; 95% CI, 1.2-3.4).

CONCLUSIONS

The association between animal exposure and NHL warrants further investigation in pooled analyses.