Non-Hodgkin's lymphoma in homosexual men in the San Francisco Bay Area: occupational, chemical, and environmental exposures

An evidence-based analysis of epidemiologic associations between lymphatic and hematopoietic cancers and occupational exposure to gasoline

The presence of benzene in motor gasoline has been a health concern for potential increased risk of acute myelogenous leukemia and perhaps other lymphatic/hematopoietic cancers for approximately 40 years. Because of the widespread and increasing use of gasoline by consumers and the high exposure potential of occupational cohorts, a thorough understanding of this issue is important. The current study utilizes an evidence-based approach to examine whether or not the available epidemiologic studies demonstrate a strong and consistent association between occupational exposure to gasoline and lymphatic/hematopoietic cancers. Among 67 epidemiologic studies initially identified, 54 were ranked according to specific criteria relating to the relevance and robustness of each study for answering the research question. The 30 highest-ranked studies were sorted into three tiers of evidence and were analyzed for strength, specificity, consistency, temporality, dose-response trends and coherence. Meta statistics were also calculated for each general and specific lymphatic/hematopoietic cancer category with adequate data. The evidence-based analysis did not confirm any strong and consistent association between occupational exposure to gasoline and lymphatic/hematopoietic cancers based on the epidemiologic studies available to date. These epidemiologic findings, combined with the evidence showing relatively low occupational benzene vapor exposures associated with gasoline formulations during the last three decades, suggest that current motor gasoline formulations are not associated with increased lymphatic/hematopoietic cancer risks related to benzene.

Exposure to animals and increased risk of marginal zone B-cell lymphomas of the ocular adnexae

BACKGROUND

Ocular adnexal marginal zone B-cell lymphoma (OAMZL) has been associated with Chlamydophila psittaci, an infection that may be transmitted by carrier animals. However, it is still unclear whether exposure to animals affects the risk of OAMZL in comparison with other lymphoma histotypes. We therefore investigated the role of professional and/or domestic exposures to animals in the occurrence of OAMZL, as compared with other types of lymphoma.

METHODS

A hospital-based case-control study was carried out on 43 consecutive OAMZL patients (cases) and 87 consecutive patients with nodal non-Hodgkin's lymphomas (NHLs; controls). Multiple logistic regression (MLR) odds ratios (ORs), and 95% confidence intervals (CIs) were used to estimate the association between exposures to animals and OAMZL risk.

RESULTS

A higher proportion of cases reported a lifetime exposure to household animals (79.1% vs 64.4% among controls), with a non-statistical significant MLR-OR of 2.18 (95% CI: 0.85-5.62). The OAMZL cases more frequently reported a history of occupation in breeding and/or slaughtering than controls (34.9% vs 6.9%), with an overall increased risk of 7.69 (95%CI: 2.65-22.34).

CONCLUSION

These results indicate that, compared with nodal NHLs, the risk of OAMZL is markedly increased by contact with animals, particularly by occupational exposures.

Occupational exposure to gasoline and the risk of non-Hodgkin lymphoma: a review and meta-analysis of the literature

AIMS

Gasoline comprises over 500 chemicals, including the known or suspected carcinogens benzene, 1,3-butadiene, ethylbenzene and methyl tert-butyl ether (MTBE). To assess whether work in the production, distribution and use of gasoline is associated with non-Hodgkin lymphoma (NHL), we reviewed the published literature on this topic.

METHOD

English-language peer-reviewed articles were identified by keyword searches of bibliographic databases. Twenty-two cohorts and thirteen case-control studies examined the risk of NHL among persons employed in the downstream petroleum industry.

RESULT

No positive associations were found with the exception of one study. The pooled risk estimate from a random-effects meta-analysis was 1.02 (95% confidence interval (CI) 0.94-1.12). Although there were no estimates available, exposure is likely to have varied by occupation, location and time period; there was no evidence however that risk estimates varied by any of these factors. NHL is a heterogeneous disease, yet no data were reported for NHL subtypes.

CONCLUSION

In summary, there is no suggestion across an extensive literature that exposure to gasoline at the levels workers' experience in an occupational setting increases the risk of 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.

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.

Non-Hodgkin lymphoma in women: reproductive factors and exogenous hormone use

Few studies of reproductive hormone exposures and non-Hodgkin lymphoma (NHL) have examined NHL subtypes. Associations between reproductive hormonal factors and risk of all NHL and of two predominant subtypes, diffuse large-cell lymphoma (DLCL) (n = 233) and follicular lymphoma (n = 173), were investigated among women (n = 581) in a large, population-based, case-control study (1,591 cases, 2,515 controls). Controls (n = 836) identified by random digit dialing were frequency matched by age and county to incident NHL cases ascertained in the San Francisco Bay Area of California in 1988-1993. Adjusted unconditional logistic regression was used to obtain odds ratios. More than four pregnancies indicated a possible lower risk of all NHL (odds ratio (OR) = 0.81, 95% confidence interval (CI): 0.55, 1.2; p-trend = 0.06) and of DLCL (OR = 0.53, 95% CI: 0.31, 0.90; p-trend = 0.01). Exclusive use of menopausal hormone therapy for > or =5 years was associated with a reduced risk of all NHL (OR = 0.68, 95% CI: 0.48, 0.98) and of DLCL (OR = 0.50, 95% CI: 0.30, 0.85). Oral contraceptive use indicated a lower risk of all NHL (OR = 0.68, 95% CI: 0.49, 0.94), and perhaps DLCL (OR = 0.79, 95% CI: 0.51, 1.2), and of follicular lymphoma (OR = 0.75, 95% CI: 0.46, 1.2). Results suggest that endogenous and exogenous reproductive hormones confer different risks by NHL subtype and are associated with a reduced risk of DLCL in women.

The non-Hodgkin lymphomas: a review of the epidemiologic literature

The non-Hodgkin lymphomas (NHL) are a heterogeneous group of B-cell and T-cell neoplasms that arise primarily in the lymph nodes. NHL incidence rates in the US doubled between about 1970 and 1990, and stabilized during the 1990s. NHL accounts for approximately 3.4% of cancer deaths in the US. Although some of the observed patterns in NHL have been related to HIV/AIDS, these conditions cannot fully explain the magnitude of the changes; neither do changes in classification systems nor improved diagnostic capabilities. Studies of occupational and environmental exposures (e.g., pesticides, solvents) have produced no consistent pattern of significant positive associations. Inverse associations with ultraviolet radiation exposure and alcohol and fish intake, and positive associations with meat and saturated fat intake have been reported in several studies; additional studies are needed to confirm or refute these associations. Family history of NHL or other hematolympho-proliferative cancers and personal history of several autoimmune disorders are associated with increased risk of NHL, but are not likely to account for a large proportion of cases. HIV and other infectious agents, such as human herpesvirus 8 and Epstein-Barr, appear to be associated with differing types of NHL, such as some B-cell lymphomas. Future epidemiologic studies should evaluate associations by NHL type, enhance exposure information collected, and elucidate factors that may identify susceptible (or resistant) subpopulations because of genetic, immunologic or other characteristics. The extent to which the etiology of NHL types may differ is important to resolve in ongoing and future studies.

Residential history, family characteristics and non-Hodgkin lymphoma, a population-based case-control study in the San Francisco Bay Area

A population-based, case-control study (N = 1,593 cases, N = 2,515 controls) was conducted in the San Francisco Bay Area, California, to determine risk factors for non-Hodgkin lymphoma (NHL). This report examines residential characteristics, number of siblings, childhood infections, and allergic rhinitis to evaluate the association between NHL and the hygiene hypothesis. Adjusted unconditional logistic regression analyses included HIV-negative participants (N = 1,304 cases, N = 2,402 controls) ages 21 to 74 years, who completed in-person interviews. At childhood ages, odds ratios (OR) for NHL decreased with increasing number of household rooms (age 8 years, P(trend) = 0.08; age 15 years, P(trend) < 0.0001) and increased with more crowded living conditions (quartiles of no. people/no. rooms; age 8 years, P(trend) < 0.0001; age 15 years, P(trend) = 0.0004), whereas at older ages a greater number of people in the household and greater number of household rooms were positively associated with NHL. ORs increased with increasing number of siblings (P(trend) = 0.0003) and increasing birth order (P(trend) = 0.01). Participants with five or more younger siblings had a 50% increased OR for NHL. ORs for NHL decreased with an increasing number of different infections during childhood (age 8 years, P(trend) < 0.0001; age 15 years, P(trend) = 0.0003) and with history of allergic rhinitis (P < 0.0001). Our results are somewhat consistent with the hygiene hypothesis that less crowding and better sanitation results in fewer infections early in life and an increased incidence of immune-related conditions later in life. The role of the complex relationship between residential history, family characteristics, childhood infections, and immune function in the development of NHL warrants further investigation in pooled analyses.

Changes in Cancer Registry Coding for Lymphoma Subtypes: Reliability Over Time and Relevance for Surveillance and Study

Because lymphoma comprises numerous histologic subtypes, understanding the reasons for ongoing increases in its incidence requires surveillance and etiologic study of these subtypes. However, this research has been hindered by many coexisting classification schemes. The Revised European American classification of Lymphoid Neoplasms (REAL)/WHO system developed in 1994 and now used in clinical settings was not incorporated into the International Classification of Diseases-Oncology (ICD-O), used by cancer registries, until the release of the third edition (ICD-O-3) in 2001. Studies including patients diagnosed before 2001 may have codes from earlier ICD-O versions that must be converted to ICD-O-3 and have higher proportions of unclassified (e.g., lymphoma and not otherwise specified) cases. To better understand (a) the agreement of computer-converted ICD-O-3 codes to ICD-O-3 codes generated directly from diagnostic pathology reports and (b) the reproducibility of unclassified status, we reviewed a population-based series of diagnostic pathology reports for lymphoma patients diagnosed before (1988-1994; n = 1,493) and after (1998-2000; n = 1,527) the REAL/WHO scheme was introduced. Overall, computer- and coder-assigned ICD-O-3 codes agreed for 77% of patients in both groups and improved slightly (82%) when codes were grouped. The most common lymphoma subtypes, diffuse large B cell and follicular, had relatively good reliability (84-89%) throughout the study period. T-cell and natural killer cell lymphomas had worse agreement than B-cell lymphomas, even when grouped. Many (42-43%) lymphomas reported as unclassifiable could be assigned a subtype upon pathology report review. These findings suggest that the study of lymphoma subtypes could be improved by (a) use of more standardized terminology in pathology reports, (b) grouping individual ICD-O-3 codes to reduce misclassification bias, and (c) routine secondary editing of unclassified lymphomas by central cancer registries.

The epidemiology of non-Hodgkin lymphoma

Non-Hodgkin lymphoma (NHL) includes a group of more than 20 different malignant lymphoproliferative diseases that originate from lymphocytes. Rates of NHL have increased dramatically over the past few decades, although the rate of increase has recently slowed. It is now the sixth most common cancer in Australia. Globally, it is somewhat more common in men than in women, and rates are highest in North America and Australia. The causes of the increase in NHL rates are largely unknown. The best described risk factor for NHL is immune deficiency; rates of NHL are greatly increased, with relative risks of 10-100 or more, in people with immune deficiency associated with immune suppressive therapy after transplantation, HIV/AIDS, and congenital conditions. In addition, some NHL subtypes are associated with specific infections. These include immune-deficiency-associated central nervous system NHL (Epstein-Barr virus); gastric mucosa-associated lymphoid tissue NHL (Helicobacter pylori); adult T-cell leukemia/lymphoma (human T-lymphotrophic virus type 1) and body cavity-based lymphoma (human herpesvirus 8). However, these specific infections account for a very small proportion of total NHL incidence. In addition to immune deficiency and infection, other immune-related conditions are increasingly being recognised as related to NHL risk. Specific autoimmune conditions, including rheumatoid arthritis, systemic lupus erythema, Sjogren's syndrome, psoriasis and coeliac disease are associated with moderately increased risk of NHL. On the other hand, allergic and atopic conditions and their correlates such as early birth order, appear to be associated with a decreased risk of NHL.A variety of other exposures are less strongly related to NHL risk. These include occupational exposures, including some pesticides, herbicides, and solvents. Recently, two studies have reported that sun exposure is associated with a decreased risk of NHL. Smoking appears to be weakly positively associated with risk of follicular NHL, and alcohol intake is associated with a decreased risk of NHL. The pooled analysis of several case-control studies of NHL risk that are currently in the field promises to help clarify which of these risk factors are real, and will contribute to the elucidation of the mechanisms of how disorders of the immune system, and other factors, are related to NHL risk.

Polymorphisms in ghrelin and neuropeptide Y genes are associated with non-Hodgkin lymphoma

We previously reported a positive association among body mass index, single nucleotide polymorphisms (SNP) in the leptin and leptin receptor genes that are involved in body weight regulation, and non-Hodgkin lymphoma (NHL). Polymorphisms in the ghrelin (GHRL) and neuropeptide Y (NPY) genes were examined in the same population-based case-control study of NHL to further explore the role of genes involved in energy homeostasis and obesity in susceptibility to NHL. Ghrelin is an orexigenic hormone that induces NPY release and inhibits proinflammatory cytokines via its antagonistic relationship with leptin. NPY is a potent appetite stimulator controlled by ghrelin and leptin and also acts as a mediator of immune function. DNA from 458 cases and 812 controls was genotyped. Among genotyped GHRL SNPs, the variant allele for GHRL -4427G>A was inversely associated with all NHL [odds ratios (OR), 0.78; 95% confidence interval (95% CI), 0.59-1.0] and more specifically with diffuse large cell lymphoma (DLCL; homozygous variant: OR, 0.31; 95% CI, 0.13-0.74). Another SNP, GHRL 5179A>G, decreased the risk of DLCL (homozygous variant: OR, 0.35; 95% CI, 0.10-1.2). NPY -485T>C, 1258G>A, and 5671C>T were in total linkage disequilibrium (D' = 0.99) and the homozygous variants were associated with an increased risk of NHL in NPY SNPs -485T>C (OR, 1.7; 95% CI, 1.1-2.5), 1258G>A (OR, 1.7; 95% CI, 1.1-2.5), and 5671C>T (OR, 1.9; 95% CI, 1.3-2.8). When stratified by subtype, the variant allele for NPY 1128T>C was positively associated with follicular lymphoma (OR, 2.3; 95% CI, 1.1-4.9) as were homozygous variants for NPY SNPs -485T>C (OR, 2.4; 95% CI, 1.3-4.4), 1258G>A (OR, 2.0; 95% CI, 1.1-3.5), and 5671C>T (OR, 1.8; 95% CI, 1.1-3.0). These results add further support for the hypothesis that SNPs in energy-regulating genes affect risk of NHL.

Tobacco use and non-Hodgkin lymphoma: results from a population-based case-control study in the San Francisco Bay Area, California

OBJECTIVE

Investigate the association between tobacco use and non-Hodgkin lymphoma (NHL).

METHODS

Tobacco-use data were collected during in-person interviews in a population-based case-control study of NHL (N=1593 patients, N=2515 controls) conducted in the San Francisco Bay Area between 1988 and 1995. Odds ratios (ORs) for HIV-negative participants were obtained from adjusted unconditional logistic regression models stratified by sex.

RESULTS

NHL was not associated with overall tobacco use, intensity or duration of cigarette smoking in women or men. However, ORs were increased for NHL among men who used any non-cigarette tobacco alone (OR=1.7), non-cigarette tobacco and cigarettes (OR=1.4), multiple types of non-cigarette tobacco alone (OR=2.1) and smokeless tobacco alone (OR=4.0). In analyses stratified by sex and age, ORs for NHL associated with cigarette smoking in general were above unity among those aged > or =60 years. ORs for follicular lymphoma were increased in men who used cigarettes and other tobacco, cigars alone and smokeless tobacco alone. Diffuse large-cell lymphoma in men was associated with use of cigarettes and other tobacco, and multiple types of non-cigarette tobacco.

CONCLUSION

Our data do not support an association between overall tobacco use and all NHL in women or men. Further analyses are warranted in larger studies to evaluate non-cigarette tobacco use, tobacco-related biologic markers and genetic factors in the development of NHL.

Body Mass Index, Leptin and Leptin Receptor Polymorphisms, and Non-Hodgkin Lymphoma

In a population-based case-control study, obesity was associated with elevated odds ratios (ORs) for non-Hodgkin lymphoma (NHL), and the two major subtypes, diffuse large cell (DLCL) and follicular lymphoma (FL). Those who were obese (body mass index ≥ 30) were up to three times more likely to develop NHL or its major subtypes than persons with body mass index of 20 to &lt;25. Obesity-related genetic factors including common polymorphisms in the leptin gene (LEP A19G and G-2548A) and its receptor (LEPR Q223R) were investigated in DNA available for 376 patients and 805 controls. Leptin is an adipocyte-derived hormone that regulates food intake and modulates immune and inflammatory responses through its receptor. Among those with the LEP 19G allele, an increased risk estimate was found for all NHL [OR = 1.6, confidence interval (CI) 1.1–2.3], DLCL (OR = 1.6, CI 0.86–3.0), and FL lymphoma (OR = 1.9, CI 0.98–3.6). Gene-gene interaction existed between the −G2548A and LEPR Q223R polymorphisms. Specifically, among those with LEPR 223RR, the risk estimate for NHL was increased in LEP −2548GA (OR = 1.7, CI 0.88–3.1) and LEP −2548AA (OR = 2.3,CI 1.1–4.6) relative to LEP −2548GG genotypes. These results suggest that genetic interactions between leptin and its receptor may promote immune dysfunction associated with obesity and NHL and that the emerging obesity epidemic is consistent with the increasing incidence of NHL in developed countries.

Expert Review of Non-Hodgkin's Lymphomas in a Population-Based Cancer Registry: Reliability of Diagnosis and Subtype Classifications

Incidence rates of non-Hodgkin's lymphomas (NHLs) have nearly doubled in recent decades. Understanding the reasons behind these trends will require detailed surveillance and epidemiological study of NHL subtypes in large populations, using cancer registry or other multicenter data. However, little is known regarding the reliability of NHL diagnosis and subtype classification in such data, despite implications for the accuracy of incidence statistics and studies. Expert pathological re-review was completed for 1526 NHL patients who were reported to the Greater Bay Area Cancer Registry and who participated in a large population-based case-control study. Agreement of registry diagnosis with expert diagnosis and with International Classification of Diseases for Oncology-2 (Working Formulation) subtype classifications was measured with positive predictive values and kappa statistics. Agreement of registry and expert diagnoses was high (98%). Thirty patients were found on review not to have NHL; most of these had leukemia. For subtypes, agreement of registry and expert classification was more moderate (59%). Agreement varied substantially by subtype from 5% to 100% and was 77% for the most common subtype, diffuse large cell lymphoma. Seventy-seven percent of 128 registry-unclassified lymphomas were assigned a subtype on re-review. Our analyses suggest excellent diagnostic reliability but poorer subtype reliability of NHL in cancer registry data information that is critical to the interpretation of lymphoma time trends. Thus, overall NHL incidence and survival statistics from the early 1990s are probably accurate, but subtype-specific statistics could be substantially biased, especially because of high (15-20%) proportions of unclassified lymphomas.

Human Immunodeficiency Virus Hematology

The advent of potent antiretroviral therapy has altered the expected natural history of human immunodeficiency virus (HIV) infection and of many previously associated opportunistic complications, including malignancies. At the same time, HIV suppression hasn’t affected all of these complications equally and the longer expected survival of infected patients may allow the development of newer complications. Additionally, the use of potent antiretroviral combination therapy may itself lead to hematological toxicities. Together these changes affect the consultation role of the hematology-oncology specialist in comprehensive HIV care and demand ongoing education.

In Section I, Dr. Paul Volberding reviews the biology of antiretroviral drug development and the progression in discovering new agents as the viral life cycle is further elucidated. He briefly summarizes the process of combining agents to achieve the degree of viral suppression required for long-term clinical benefit.

In Section II, Dr. Kelty Baker reviews the effects of HIV and its therapy on hematologic dyscrasia and clotting disorders. She summarizes how therapy may decrease certain previously common manifestations of HIV disease while adding new problems likely to result in referral to the hematologist. In addition, she addresses the role of secondary infections, such as parvovirus, in this spectrum of disorders.

In Section III, Dr. Alexandra Levine discusses the still challenging aspects of HIV associated non-Hodgkin’s lymphoma and the association between HIV infection and Hodgkin’s disease. She addresses current controversies in the pathogenesis of HIV related lymphomas and summarizes a number of recent trials of combination chemotherapy, with or without monoclonal antibodies, in their management. Additionally, she reviews the complex relationship of HIV disease with multicentric Castleman’s disease and recent attempts to manage this disorder.

Hematologic Aspects of HIV/AIDS

This review addresses various aspects of HIV infection pertinent to hematology, including the consequences of HIV infection on specific aspects of hematopoiesis and an update on the current biologic, epidemiologic and therapeutic aspects of AIDS-related lymphoma and Hodgkin's disease. The results of the expanding use of progenitor cell transplantation in HIV infected patients are also reviewed. In Section I, Dr. Scadden reviews the basis for HIV dysregulation of blood cell production, focusing on the role of the stem cell in HIV disease. T cell production and thymic function are discussed, with emphasis placed upon the mechanisms of immune restoration in HIV infected individuals. Results of clinical and correlative laboratory studies are presented. In Section II, Dr. Levine reviews the recent epidemiologic trends in the incidence of lymphoma, since the widespread availability of highly active anti-retroviral therapy (HAART). The biologic aspects of AIDS-lymphoma and Hodgkin's disease are discussed in terms of pathogenesis of disease. Various treatment options for these disorders and the role of concomitant anti-retroviral and chemotherapeutic intervention are addressed. Drs. Zaia and Krishnan will review the area of stem cell transplantation in patients with AIDS related lymphoma, presenting updated information on clinical results of this procedure. Additionally, they report on the use of gene therapy, with peripheral blood CD34+ cells genetically modified using a murine retrovirus, as a means to treat underlying HIV infection. Results of gene transfer experiments and subsequent gene marking in HIV infected patients are reviewed.

Blood transfusions as a risk factor for non-Hodgkin's lymphoma in the San Francisco Bay Area: a population-based study

The incidence of non-Hodgkin's lymphoma (NHL) has risen dramatically over the past 50 years. In the search for new risk factors, blood transfusions have been investigated and shown to be associated with subsequent lymphoma in some studies. The authors tested this association in a population-based, case-control study conducted between 1988 and 1995 in the San Francisco Bay Area of California. A total of 1,591 histologically confirmed adult cases of NHL were included in this study. Cases were frequency matched to 2,515 control participants by sex, county of residence, and 5-year age intervals. Multivariate logistic regression models were used to examine the impact of possible confounders. Persons who reported a history of allogeneic transfusion were not at increased risk of NHL in this population (odds ratio (OR) = 1.0, 95% confidence interval (CI): 0.84, 1.2). No significant associations were seen when lymphomas were stratified by histologic subtype, grade, or latency period. However, autologous transfusions were associated with a decreased risk (OR = 0.39, 95% CI: 0.16, 0.94). In summary, these findings are similar to those of prior negative studies and do not support some previous reports of an adverse association between blood transfusion and NHL.

Epidemiologic trends in HIV-associated lymphomas

Infection with HIV increases the risk of developing non-Hodgkin lymphoma and, to a lesser extent, Hodgkin disease. The introduction of highly active antiretroviral therapy (HAART) in 1996 changed the natural history of HIV disease, but the HIV-infected population also has changed in composition. Accordingly, the epidemiology of HIV-associated lymphomas now differs from that observed in the first 15 years of the HIV epidemic. In populations with access to HAART, reductions in lymphoma risk have been reported for NHL and suggested for Hodgkin disease, but long-term risks are as yet unknown. Lymphomas are increasingly common cancers in persons with HIV and are fatal in most patients, warranting continued attention to their incidence and etiology.

Risk factors for non-Hodgkin's lymphoma according to family history of haematolymphoproliferative malignancies

BACKGROUND

Aetiological profiles of non-Hodgkin's lymphoma (NHL) may differ depending upon whether the disease is inheritance-related or sporadic. Because familial risk (a probable surrogate of inheritance-relatedness) of NHL is influenced by haematolymphoproliferative malignancies (HLPM), we evaluated whether non-familial risk factors differ between NHL with and without a family history of HLPM, using the Selected Cancers Study data.

METHODS

Cases were 1511 men aged 31-59 and diagnosed with NHL during 1984-1988. Controls were men without NHL, frequency-matched to cases by age range and cancer registry (n = 1910). These groups were compared: cases with a family history of HLPM and without, and controls without such a family history.

RESULTS

Polytomous logistic regression analyses showed that the odds ratio (OR) estimates of homosexual behaviour were 18.2 (95% confidence interval (CI) : 4.8-69.4) and 5.6 (95% CI : 3.3-9.5) for NHL with and without a family history of HLPM, respectively. The corresponding estimates were 3.9 (95% CI : 1.7-8.9) and 2.2 (95% CI : 1.5-3.1) for history of enlarged lymph nodes. Variables only related to NHL with a family history were use of heroin (OR = 15.6, 95% CI : 3.4-70.4), exposure to a chlorinated hydrocarbon pesticide (OR = 2.3, 95% CI : 1.0-5.0), occupational exposure to plywood, fibreboard or particleboard (OR = 2.0, 95% CI : 1.2-3.4) and history of liver diseases (other than hepatitis or cirrhosis) (OR = 6.5, 95% CI : 1.2-36.2). The association between homosexual behaviour and NHL among men with a family history was stronger for those aged 31-44, especially for B-cell type of the disease.

CONCLUSIONS

This study suggests differences in the risk factor profiles between NHL with and without a family history of HLPM. The higher risks of NHL for homosexual behaviour and heroin use, surrogates of HIV infection, in men with a family history of HLPM imply that genetic susceptibility may be influential on the occurrence of HIV-related NHL.

DNA copy number alterations in HIV-positive and HIV-negative patients with diffuse large-cell lymphomas

Individuals infected with HIV are at increased risk of developing aggressive non-Hodgkin's lymphoma with a worse prognosis than those similarly afflicted without HIV infection. The underlying genetic differences in tumor behavior between these two groups are not known. We explored the hypothesis that lymphomas from HIV-positive individuals have distinct somatic genetic changes that may provide clues to the genetic basis of disease progression and outcome. Genome-wide DNA copy number alterations (CNAs) in primary tumors from 14 HIV-positive and 11 HIV-negative patients with diffuse large B-cell lymphoma (DLCL) were quantified using comparative genomic hybridization (CGH). Tumors from HIV-positive patients displayed fewer regional DNA-CNAs than those from patients who did not have HIV. When CNAs were present, they occurred at lower frequency in HIV-positive patients. Gains at chromosomes 8q and Xp were the most frequent changes in the HIV-negative group, and gains on 2p and 12q were common in the combined HIV-positive and HIV-negative groups. No alteration was specific to AIDS-related DLCL. These data suggest that fewer somatic genomic changes are needed for progression to DLCL in HIV-immunocompromised hosts, and that other factors, such as reduced immune surveillance, may contribute to neoplastic progression.

Hair-color products and risk for non-Hodgkin's lymphoma: a population-based study in the San Francisco bay area

OBJECTIVES

As part of a large, epidemiologic study of non-Hodgkin's lymphoma, this study investigated a possible association between use of hair-color products and non-Hodgkin's lymphoma.

METHODS

A population-based case-control study was conducted in the San Francisco Bay area. Of 4108 participants, 2544 were questioned about use of hair-color products. Control subjects were identified by use of random-digit dialing.

RESULTS

Ever use of hair-color products was reported by 56% of case and 56% of control women and 10% of case and 9% of control men. Risks were not elevated for women for use of any hair-color products. Men who ever used semipermanent hair color had slightly elevated risks for non-Hodgkin's lymphoma, with trends associated with greater lifetime frequency of use and frequency of use per year, although individual confidence intervals overlapped unity. These elevated risks were diminished with exclusive use of semipermanent products, and confidence intervals overlapped unity.

CONCLUSIONS

Integration of our results with those from experimental animal studies and other epidemiologic studies provides little convincing evidence linking non-Hodgkin's lymphoma with normal use of hair-color products in humans.

Non-Hodgkin's lymphoma risk derived from exposure to organic solvents: a review of epidemiologic studies

The rate of non-Hodgkin's lymphomas (NHL) has increased around the world during the last decades. Apart from the role of the human immunodeficiency virus (HIV) infection in the development of NHL, exposure to chemical agents like phenoxyacetic pesticides, hair dyes, metal fumes and organic solvents are suspected to be involved. The present review evaluates the results of studies that directly or indirectly searched for an association between solvent exposure and NHL. The selected studies comprised those published from 1979 to 1997, designed to investigate risk factors for NHL, whether specifically looking for solvent exposure or for general risks in which solvent exposure could be included. In 25 of the 45 reviewed studies (55.5%), fifty-four statistically significant associations between NHL and solvent exposure related occupations or industries were reported. Statistical significance was more frequently shown in studies where solvent exposure was more accurately defined. In eighteen of such studies, 13 (72.2%) defined or suggested organic solvents as possible risk factors for NHL.

Non-Hodgkin's lymphoma in HIV-positive and HIV-negative homosexual men in the San Francisco Bay Area: allergies, prior medication use, and sexual practices

Lifestyle, sexual history, and medical history characteristics were analyzed as risk factors for non-Hodgkin's lymphoma (NHL) in a population-based case-control study of 1593 subjects with NHL and 2515 control subjects conducted in the San Francisco Bay Area between 1988 and 1995. The results for homosexual men, 312 with NHL and 420 control subjects, showed that HIV infection was associated with a 20-fold increased risk for NHL. Among HIV-positive homosexual men, after adjustment for other factors, those that were associated with a reduced risk for NHL were frequency of receptive anal intercourse between the ages of 20 and 29 (1 to 9 times: OR = 0.63; > or = 10 times: OR = 0.37; trend: p = 0.02), allergy to grass, hay, leaves, plants and pollen (OR = 0.35, CI = 0.19 to 0.64), number of bee or wasp stings (1 to 3 times: OR = 0.65; > or =4 times: OR = 0.56; trend: p = 0.07), use of Tagamet (cimetidine) for 4 consecutive weeks or longer (OR = 0.39, CI = 0.17 to 0.89), vaccination against influenza (OR = 0.41, CI = 0.23 to 0.74), and lifetime frequency of amphetamine use (1 to 19 times: OR = 0.59; > or =20 times: OR = 0.38; trend: p = 0.003). Among HIV-negative homosexual men, after adjustment for other factors, factors that were associated with NHL status were frequency of receptive anal intercourse between the ages of 20 and 29 (1 to 9 times: OR = 0.39; > or =10 times: OR = 0.20; trend: p = 0.001), nonmedication allergies (OR = 0.43, CI = 0.21 to 0.89), vaccination against poliomyelitis at <10 years (OR = 0.41, CI = 0.17 to 0.99), and having five or more siblings (OR = 3.6, CI = 1.7 to 7.7). An increased immunosuppressive effect of seminal fluid on sensitive rectal tissue and support from earlier work suggesting that HIV-related lymphomas may be outgrowths of antigen-driven B cells provide a possible mechanism for the results of this study. The role of allergic reactions in NHL is likely to be complex and may be related to B-cell differentiation. These associations may provide insight into an antigen-driven process early in lymphomagenesis.