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1.
BMC Cancer ; 23(1): 1084, 2023 Nov 09.
Article in English | MEDLINE | ID: mdl-37946198

ABSTRACT

BACKGROUND: Survival following melanoma and chronic lymphocytic leukemia (CLL) have both been individually associated with previous history of non-melanoma skin cancers (specifically keratinocyte carcinomas [KC]). Furthermore, melanoma and CLL have been reported to occur within the same patients. The survival experience of patients with both cancers is understudied, and the role of history of KC is unknown. Additional research is needed to tease apart the independent associations between KC and CLL survival, KC and melanoma survival, and the co-occurrence of all three cancers. METHODS: A retrospective cohort study was conducted among patients who were diagnosed with melanoma and/or CLL at a comprehensive cancer center between 2008 and 2020. Multivariable Cox regression models were used to examine the association between history of KC and survival following melanoma and/or CLL with careful consideration of calendar year of diagnosis, treatment regimens and other risk factors. A nested case-control study comparing patients with both CLL and melanoma to those with only CLL or only melanoma was conducted to compare blood parameters across the three groups. RESULTS: A time-dependent association was observed between history of KC and favorable melanoma survival within 4 years following diagnosis and poorer survival post 7 years after melanoma diagnosis. History of KC was not significantly associated with survival following the diagnosis of CLL, after adjustment for clinical factors including historical/concurrent melanoma. Patients with co-occurring melanoma and CLL tended to be diagnosed with melanoma first and had elevated blood parameters including white blood cell and lymphocyte counts as compared with patients who were diagnosed with only melanoma. CONCLUSIONS: History of KC was an independent predictor of survival following melanoma but not of CLL. Additional studies are needed to determine if blood parameters obtained at the time of melanoma diagnosis could be used as a cost-effective way to identify those at high risk of asymptomatic CLL for the promotion of earlier CLL diagnosis.


Subject(s)
Carcinoma , Leukemia, Lymphocytic, Chronic, B-Cell , Melanoma , Skin Neoplasms , Humans , Leukemia, Lymphocytic, Chronic, B-Cell/complications , Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology , Leukemia, Lymphocytic, Chronic, B-Cell/pathology , Skin Neoplasms/epidemiology , Retrospective Studies , Case-Control Studies , Melanoma/complications , Melanoma/epidemiology , Carcinoma/pathology , Keratinocytes/pathology
2.
Blood ; 136(17): 1946-1955, 2020 10 22.
Article in English | MEDLINE | ID: mdl-32518952

ABSTRACT

The ALLIANCE A041202 trial found that continuously administered ibrutinib in the first-line setting significantly prolonged progression-free survival compared with a fixed-duration treatment of rituximab and bendamustine in older adults with chronic lymphocytic leukemia (CLL). In this study, we created a Markov model to assess the cost-effectiveness of ibrutinib in the first-line setting, compared with a strategy of using ibrutinib in the third-line after failure of time-limited bendamustine and venetoclax-based regimens. We estimated transition probabilities from randomized trials using parametric survival modeling. Lifetime direct health care costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratios (ICERs) were calculated from a US payer perspective. First-line ibrutinib was associated with an improvement of 0.26 QALYs and 0.40 life-years compared with using ibrutinib in the third-line setting. However, using ibrutinib in the first-line led to significantly higher health care costs (incremental cost of $612 700), resulting in an ICER of $2 350 041 per QALY. The monthly cost of ibrutinib would need to be decreased by 72% for first-line ibrutinib therapy to be cost-effective at a willingness-to-pay threshold of $150 000 per QALY. In a scenario analysis where ibrutinib was used in the second-line in the delayed ibrutinib arm, first-line ibrutinib had an incremental cost of $478 823, an incremental effectiveness of 0.05 QALYs, and an ICER of $9 810 360 per QALY when compared with second-line use. These data suggest that first-line ibrutinib for unselected older adults with CLL is unlikely to be cost-effective under current pricing. Delaying ibrutinib for most patients with CLL until later lines of therapy may be a reasonable strategy to limit health care costs without compromising clinical outcomes.


Subject(s)
Adenine/analogs & derivatives , Chemotherapy, Adjuvant , Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy , Neoadjuvant Therapy , Piperidines/economics , Piperidines/therapeutic use , Adenine/economics , Adenine/therapeutic use , Aged , Chemotherapy, Adjuvant/economics , Chemotherapy, Adjuvant/statistics & numerical data , Cost-Benefit Analysis , Drug Costs/statistics & numerical data , Female , Humans , Leukemia, Lymphocytic, Chronic, B-Cell/economics , Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology , Male , Markov Chains , Models, Economic , Neoadjuvant Therapy/economics , Neoadjuvant Therapy/statistics & numerical data , Palliative Care/economics , Palliative Care/statistics & numerical data , Quality-Adjusted Life Years , Salvage Therapy/economics , Salvage Therapy/statistics & numerical data , United States/epidemiology
3.
Expert Opin Pharmacother ; 21(11): 1299-1309, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32292084

ABSTRACT

INTRODUCTION: Duvelisib, a first in class, oral, dual PI3 k-delta/gamma inhibitor recently received FDA approval for previously treated CLL (chronic lymphocytic leukemia)/SLL (small lymphocytic lymphoma) and follicular lymphoma. Data coming from the phase III 'DUO' trial, in fact, showed a superior progression-free survival (PFS) in CLL patients treated with duvelisib compared to ofatumumab. AREAS COVERED: This review provides analysis of the mechanism of action of duvelisib and includes the rationale for the use of double inhibition. The authors also give their clinical experience with duvelisib. Overall, despite the high efficacy of the drug, some concern remains on duvelisib-related adverse events leading to treatment interruption in a significant proportion of patients. EXPERT OPINION: Considering the unmet need of salvage therapies in patients failing BTK and/or Bcl2 inhibitors, treatment with duvelisib represents a new valid option in the CLL therapeutic armamentarium. Therefore, the correct management of adverse events with early treatment suspension, dose reductions and prompt supportive treatment could help to manage treatment, thus improving patient outcome. Finally, the association of duvelisib with other targeted therapies, such as ibrutinib or venetoclax, could allow clinicians to capitalize on the synergistic activity of these agents.


Subject(s)
Antineoplastic Agents/therapeutic use , Isoquinolines/therapeutic use , Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy , Purines/therapeutic use , Administration, Oral , Antineoplastic Agents/administration & dosage , Antineoplastic Agents/adverse effects , Antineoplastic Agents/pharmacokinetics , Class Ia Phosphatidylinositol 3-Kinase/metabolism , Class Ib Phosphatidylinositol 3-Kinase/metabolism , Clinical Trials as Topic , Drug Evaluation, Preclinical , Humans , Isoquinolines/administration & dosage , Isoquinolines/adverse effects , Isoquinolines/pharmacokinetics , Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology , Progression-Free Survival , Purines/administration & dosage , Purines/adverse effects , Purines/pharmacokinetics , Salvage Therapy
4.
Cancer J ; 25(6): 418-427, 2019.
Article in English | MEDLINE | ID: mdl-31764123

ABSTRACT

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia and is clinically heterogeneous. Integration of oral targeted therapies (OTTs) in the management of CLL has fundamentally altered CLL treatment pathways and improved outcomes for patients with CLL.We review the cost-effectiveness of OTTs in the treatment of CLL. We used MeSH (Medical Subject Heading) terms and keywords to search the National Library of Medicine online MEDLINE database (PubMed) for articles related to cost-effectiveness of OTTs in CLL care.Oral targeted therapies add considerable expense to the treatment of CLL for patients and the health care system. Cost-effectiveness analyses of OTTs are not uniform in their conclusions and depend on patient groups selected for analysis. Given the substantial increase in expense associated with integration of OTTs in CLL treatment, cost reduction methods are needed to ensure equitable access to novel therapies for all patients with CLL.


Subject(s)
Cost-Benefit Analysis , Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy , Molecular Targeted Therapy , Clinical Decision-Making , Combined Modality Therapy , Critical Pathways , Disease Management , Disease Susceptibility , Humans , Leukemia, Lymphocytic, Chronic, B-Cell/diagnosis , Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology , Leukemia, Lymphocytic, Chronic, B-Cell/etiology , Molecular Targeted Therapy/economics , Molecular Targeted Therapy/methods , Practice Guidelines as Topic , Treatment Outcome
5.
Leuk Lymphoma ; 55(4): 841-7, 2014 Apr.
Article in English | MEDLINE | ID: mdl-23829282

ABSTRACT

Complementary and alternative medicine (CAM) is common in patients with cancer and its use is steadily increasing over time. We performed a multicenter survey in which the use of CAM in 442 Italian patients with chronic lymphocytic leukemia (CLL), the commonest form of leukemia in Western countries, was assessed. Data were collected by means of a face-to-face standardized questionnaire with several items. Mean age was 69 years; 258 patients (58%) were male and 184 (42%) female. Seventy-three patients (16.5%) were found to be CAM users. The most common CAM therapies were green tea, aloe formulations and high dose vitamins. Predictors of CAM use were female gender, younger age, higher education level, internet availability and newspaper reading. The reasons for CAM popularity among these patients are complex. Given the number of patients combining therapy with CAM and its possible drug interactions, doctor interest as well as patient education about CAM should be improved.


Subject(s)
Complementary Therapies , Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology , Leukemia, Lymphocytic, Chronic, B-Cell/therapy , Adult , Aged , Aged, 80 and over , Female , Geography , Health Care Surveys , Humans , Italy/epidemiology , Leukemia, Lymphocytic, Chronic, B-Cell/diagnosis , Male , Middle Aged , Neoplasm Staging , Risk Factors , Surveys and Questionnaires
6.
J Natl Cancer Inst ; 104(22): 1724-37, 2012 Nov 21.
Article in English | MEDLINE | ID: mdl-23111193

ABSTRACT

BACKGROUND: Benzene at high concentrations is known to cause acute myeloid leukemia (AML), but its relationship with other lymphohematopoietic (LH) cancers remains uncertain, particularly at low concentrations. In this pooled analysis, we examined the risk of five LH cancers relative to lower levels of benzene exposure in petroleum workers. METHODS: We updated three nested case-control studies from Australia, Canada, and the United Kingdom with new incident LH cancers among petroleum distribution workers through December 31, 2006, and pooled 370 potential case subjects and 1587 matched LH cancer-free control subjects. Quantitative benzene exposure in parts per million (ppm) was blindly reconstructed using historical monitoring data, and exposure certainty was scored as high, medium, or low. Two hematopathologists assigned diagnoses and scored the certainty of diagnosis as high, medium, or low. Dose-response relationships were examined for five LH cancers, including the three most common leukemia cell-types (AML, chronic myeloid leukemia [CML], and chronic lymphoid leukemia [CLL]) and two myeloid tumors (myelodysplastic syndrome [MDS] and myeloproliferative disease [MPD]). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression, controlling for age, sex, and time period. RESULTS: Cumulative benzene exposure showed a monotonic dose-response relationship with MDS (highest vs lowest tertile, >2.93 vs ≤0.348 ppm-years, OR = 4.33, 95% CI = 1.31 to 14.3). For peak benezene exposures (>3 ppm), the risk of MDS was increased in high and medium certainty diagnoses (peak exposure vs no peak exposure, OR = 6.32, 95% CI = 1.32 to 30.2) and in workers having the highest exposure certainty (peak exposure vs no peak exposure, OR = 5.74, 95% CI = 1.05 to 31.2). There was little evidence of dose-response relationships for AML, CLL, CML, or MPD. CONCLUSIONS: Relatively low-level exposure to benzene experienced by petroleum distribution workers was associated with an increased risk of MDS, but not AML, suggesting that MDS may be the more relevant health risk for lower exposures.


Subject(s)
Benzene/toxicity , Extraction and Processing Industry , Myelodysplastic Syndromes/epidemiology , Myelodysplastic Syndromes/etiology , Occupational Diseases/epidemiology , Occupational Diseases/etiology , Occupational Exposure/adverse effects , Petroleum , Adult , Australia/epidemiology , Canada/epidemiology , Case-Control Studies , Humans , Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology , Leukemia, Lymphocytic, Chronic, B-Cell/etiology , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/epidemiology , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/etiology , Leukemia, Myeloid, Acute/epidemiology , Leukemia, Myeloid, Acute/etiology , Logistic Models , Male , Middle Aged , Myelodysplastic Syndromes/chemically induced , Myelodysplastic Syndromes/diagnosis , Myeloproliferative Disorders/epidemiology , Myeloproliferative Disorders/etiology , Occupational Diseases/chemically induced , Odds Ratio , United Kingdom/epidemiology
7.
Blood ; 118(6): 1591-9, 2011 Aug 11.
Article in English | MEDLINE | ID: mdl-21622649

ABSTRACT

To lend clarity to inconsistent prior findings of an inverse association between ultraviolet radiation (UVR) exposure and risk of lymphoid malignancies, we examined the association of prospectively ascertained residential ambient UVR exposure with risk of non-Hodgkin lymphomas (NHLs), multiple myeloma (MM), and classical Hodgkin lymphoma in the California Teachers Study cohort. Among 121 216 eligible women, 629 were diagnosed with NHL, 119 with MM, and 38 with Hodgkin lymphoma between 1995-1996 and 2007. Cox proportional hazards regression was used to estimate incidence rate ratios (RRs) with 95% confidence intervals (CIs). Residential UVR levels within a 20-km radius were associated with reduced risk of overall NHL (RR for highest vs lowest statewide quartile of minimum UVR [≥ 5100 vs < 4915 W-h/m(2)], 0.58; 95% CI, 0.42-0.80), especially diffuse large B-cell lymphoma (RR, 0.36; 95% CI, 0.17-0.78) and chronic lymphocytic leukemia/small lymphocytic lymphoma (RR, 0.46; 95% CI, 0.21-1.01), and MM (RR for maximum UVR, 0.57; 95% CI, 0.36-0.90). These associations were not modified by skin sensitivity to sunlight, race/ethnicity, body mass index, or neighborhood socioeconomic status. Dietary vitamin D also was not associated with risk of lymphoid malignancies. These results support a protective effect of routine residential UVR exposure against lymphomagenesis through mechanisms possibly independent of vitamin D.


Subject(s)
Hodgkin Disease/epidemiology , Lymphoma, Non-Hodgkin/epidemiology , Multiple Myeloma/epidemiology , Sunlight , Ultraviolet Rays , Vitamin D/administration & dosage , Adult , Aged , Aged, 80 and over , Bone Density Conservation Agents/administration & dosage , California/epidemiology , Dietary Supplements , Faculty/statistics & numerical data , Female , Humans , Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology , Lymphoma, Large B-Cell, Diffuse/epidemiology , Middle Aged , Proportional Hazards Models , Prospective Studies , Risk Assessment/methods , Risk Assessment/statistics & numerical data , Risk Factors , Surveys and Questionnaires , Young Adult
8.
J Oncol Pharm Pract ; 17(2): 91-103, 2011 Jun.
Article in English | MEDLINE | ID: mdl-20085962

ABSTRACT

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia and has a heterogeneous clinical course. Some patients experience an indolent disease course, which does not require treatment or affect their overall quality of life. Other patients present with symptomatic advanced disease that rapidly progresses and requires therapy. For these patients, chemotherapy is the mainstay of treatment and has undergone significant evolution in the past few decades. From alkylating agents to purine analogs, response rates have greatly improved with new chemotherapy regimens. The development of chemoimmunotherapy regimens has also transformed the treatment of CLL. This article will review front-line treatment options for CLL and discuss the updated National Comprehensive Cancer Network guidelines.


Subject(s)
Antineoplastic Agents/therapeutic use , Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy , Adult , Age Factors , Aged , Antibodies, Monoclonal/adverse effects , Antibodies, Monoclonal/therapeutic use , Antimetabolites, Antineoplastic/adverse effects , Antimetabolites, Antineoplastic/therapeutic use , Antineoplastic Agents/adverse effects , Antineoplastic Agents, Alkylating/adverse effects , Antineoplastic Agents, Alkylating/therapeutic use , Humans , Leukemia, Lymphocytic, Chronic, B-Cell/diagnosis , Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology , Neoplasm Staging , Practice Guidelines as Topic , Prognosis
9.
Clin J Oncol Nurs ; 12(3): 417-23, 2008 Jun.
Article in English | MEDLINE | ID: mdl-18515240

ABSTRACT

Chronic lymphocytic leukemia (CLL) is the most commonly diagnosed form of leukemia in the Western world, accounting for approximately 20%-30% of all cases of leukemia. Despite recent medical and scientific advances, the literature on the subjective experience and nursing care of patients diagnosed with CLL remains scarce and sporadic. This article provides a brief overview on the pathophysiology, clinical characteristics, and treatment options of CLL with focus placed on implications for nursing care. Fatigue, the most common symptom reported by patients, and infection, the leading cause of disease-related deaths, also will be addressed. Emerging data examining quality of life and the incidence of anxiety and depression in this patient population will be reviewed, and strategies aimed at addressing the educational needs of patients and family members will be discussed.


Subject(s)
Leukemia, Lymphocytic, Chronic, B-Cell/diagnosis , Leukemia, Lymphocytic, Chronic, B-Cell/therapy , Oncology Nursing/organization & administration , Anxiety/etiology , Depression/etiology , Fatigue/etiology , Health Services Needs and Demand , Holistic Health , Humans , Incidence , Infections/etiology , Leukemia, Lymphocytic, Chronic, B-Cell/complications , Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology , Leukemia, Lymphocytic, Chronic, B-Cell/psychology , Neoplasm Staging , Nurse's Role , Nursing Assessment , Patient Care Planning , Patient Education as Topic , Prognosis , Quality of Life/psychology , Risk Factors , Social Support , Survival Rate
10.
J Toxicol Environ Health A ; 66(7): 581-97, 2003 Apr 11.
Article in English | MEDLINE | ID: mdl-12751389

ABSTRACT

Among numerous studies of occupational groups with varied chemical exposures (e.g., farmers, petroleum workers, and rubber workers), some have reported excess risk for non-Hodgkin's lymphoma (NHL), multiple myeloma, and other cancers of the B-lymphocyte cell line. While not conclusive, these studies raise questions about the effects of chemical exposures on the lymphocytic versus myeloid cell lines. Almost 70 occupational cohort studies were identified that addressed B-cell cancer risks in 9 major industrial categories, in order to look for common patterns across industries. This effort was substantially limited by the inconsistent nature of lymphohematopoietic (LH) classification schemes across studies and over time, and the relative paucity of B-cell-specific results in studies for any given industry. Taking these limitations into consideration, a descriptive, graphical analysis suggested a pattern of B-cell cancer elevations in the rubber and "general chemical" industries, but no consistent patterns in petroleum production/distribution or petrochemical production. The limited data sources, which lack detail about differences in hazard and exposure for different types of products/chemicals, did not allow a comprehensive look at possible common exposures associated with B-cell cancer elevations across industries. This study suggests that evaluation of possible associations between specific chemical exposures and B-cell malignancies would require additional studies with clear and common definitions of B-cell outcomes. The article concludes by giving an example of a possible common framework for categorizing NHL, the diseases for which most classification issues arise.


Subject(s)
Hazardous Substances/toxicity , Leukemia, Lymphocytic, Chronic, B-Cell/chemically induced , Lymphoma, B-Cell/chemically induced , Multiple Myeloma/chemically induced , Occupational Diseases/chemically induced , Occupational Exposure/adverse effects , Butadienes/toxicity , Case-Control Studies , Cohort Studies , Humans , Leukemia, Lymphocytic, Chronic, B-Cell/classification , Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology , Lymphoma, B-Cell/classification , Lymphoma, B-Cell/epidemiology , Multiple Myeloma/classification , Multiple Myeloma/epidemiology , Occupational Diseases/classification , Occupational Diseases/epidemiology , Occupations/statistics & numerical data , Petroleum/toxicity , Population Surveillance , Risk Factors , Rubber/toxicity , Styrene/toxicity
11.
Occup Environ Med ; 57(9): 605-14, 2000 Sep.
Article in English | MEDLINE | ID: mdl-10935941

ABSTRACT

OBJECTIVES: In response to a previous finding of increased mortality from lymphohaematopoietic (LH) malignancies, this study examines incidence of LH malignancy in a petrochemical industry cohort. Emphasis is on chronic lymphocytic leukaemia (CLL) and on comparisons by period of first employment. METHOD: The study cohort consists of 8942 employees who were active in the period 1970-92 and alive on 31 December 1982. Record linkage with the Louisiana tumour registry (LTR) provided information on cancer for cases occurring between 1983 and 1994. Standardised incidence ratios (SIR), with the south Louisiana population as a comparison, were computed for all cancers, all LH malignancies and specific LH subtypes. Analyses were conducted for sex and race categories, and by period of first employment, job type, duration of employment, and latency. RESULTS: 672 Cases of cancer were identified, including 59 LH malignancies. Women (n=1169) had an overall cancer SIR below unity and four LH malignancies versus 2.28 expected. Among the 7773 men, those first employed before 1950 had no overall cancer excess, a significant 1.4-fold increase in overall LH malignancies (43 observed versus 30.78 expected), and four CLL cases versus 3.27 expected. Findings for men first employed after 1950 are based on fewer cases, but there was no indication of excesses of overall cancer or LH malignancy. Numbers were too small in the group first employed after 1950 for meaningful analysis of LH malignancy subtypes such as CLL (one case). CONCLUSION: These findings do not suggest a continuing excess of CLL but do suggest a small increase in incidence of overall LH malignancy for workers first employed before 1950. This may reflect associations with earlier workplace conditions, although work related patterns are mixed. Interpretation is limited by the diverse group of diseases within LH malignancies, and the lack of control for non-work factors other than sex, age, race, and period of diagnosis. This study has a major advantage of more complete and reliable cancer ascertainment compared with the mortality investigation, and shows the feasibility and benefits of using cancer registry incidence data in an occupational cohort study.


Subject(s)
Hematologic Neoplasms/epidemiology , Occupational Diseases/epidemiology , Petroleum , Adult , Aged , Chemical Industry , Cohort Studies , Female , Follow-Up Studies , Hematologic Neoplasms/chemically induced , Humans , Incidence , Leukemia, Lymphocytic, Chronic, B-Cell/chemically induced , Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology , Louisiana/epidemiology , Male , Middle Aged , Occupational Diseases/chemically induced , Occupational Exposure/adverse effects , Time Factors
12.
Occup Environ Med ; 54(3): 152-66, 1997 Mar.
Article in English | MEDLINE | ID: mdl-9155776

ABSTRACT

OBJECTIVES: To investigate the risk of leukaemia in workers in the petroleum distribution industry who were exposed to low levels of benzene. METHODS: From the cohort of distribution workers, 91 cases were identified as having leukaemia on either a death certificate or on cancer registration. These cases were compared with controls (four per case) randomly selected from the cohort, who were from the same company as the respective case, matched for age, and alive and under follow up at the time of case occurrence. Work histories were collected for the cases and controls, together with information about the terminals at which they had worked, fuel compositions, and occupational hygiene measurements of benzene. These data were used to derive quantitative estimates of personal exposure to benzene. Odds ratios (OR) were calculated conditional on the matching, to identify those variables in the study which were associated with risk of leukaemia. Examination of the potential effects of confounding and other variables was carried out with conditional logistic regression. Analyses were carried out for all leukaemia and separately for acute lymphoblastic, chronic lymphocytic, acute myeloid and monocytic, and chronic myeloid leukaemias. RESULTS: There was no significant increase in the overall risk of all leukaemias with higher cumulative exposure to benzene or with intensity of exposure, but risk was consistently doubled in subjects employed in the industry for > 10 years. Acute lymphoblastic leukaemia tended to occur in workers employed after 1950, who started work after the age of 30, worked for a short duration, and experienced low cumulative exposure with few peaks. The ORs did not increase with increasing cumulative exposure. The risk of chronic lymphocytic leukaemia seemed to be related most closely to duration of employment and the highest risk occurred in white collar workers with long service. These workers had only background levels of benzene exposure. There was no evidence of an association of risk with any exposure variables, and no evidence of an increasing risk with increasing cumulative exposure, mean intensity, or maximum intensity of exposure. The patterns of risk for acute myeloid and monocytic leukaemia were different from those of the lymphoid subgroups, in which duration of employment was the variable most closely related to risk. Risk was increased to an OR of 2.8 (95% confidence interval (95% CI) 0.8 to 9.4) for a cumulative exposure between 4.5 and 45 ppm-years compared with < 0.45 ppm-years. For mean intensity between 0.2 and 0.4 ppm an OR of 2.8 (95% CI 0.9 to 8.5) was found compared with < 0.02 ppm. Risk did not increase with cumulative exposure, maximum intensity, or mean intensity of exposure when treated as continuous variables. Cases of acute myeloid and monocytic leukaemia were more often classified as having peaked exposures than controls, and when variables characterising peaks, particularly daily and weekly peaks, were included in the analysis these tended to dominate the other exposure variables. However, because of the small numbers it is not possible to distinguish the relative influence of peaked and unpeaked exposures on risk of acute myeloid and monocytic leukaemia. There was no evidence of an increased risk of chronic myeloid leukaemia with increases in cumulative exposure, maximum intensity, mean intensity, and duration of employment, either as continuous or categorical variables. Analyses exploring the sensitivity of the results to the source and quality of the work histories showed similar patterns in general. However, no increases in ORs for categories of cumulative exposure were found for acute myeloid and monocytic leukaemia in the data set which included work histories obtained from personnel records still in existence, although numbers were reduced. Analyses excluding the last five and 10 years of exposure showed a tendency for ORs to reduce for chronic lymphocytic leukaemia and chronic myeloid leukaemia, and to increase for acute myeloid and monocytic leukaemia. Limitations of the study include uncertainties and gaps in the information collected, and small numbers in subcategories of exposure which can lead to wide CIs around the risk estimates and poor fit of the mathematical models. CONCLUSIONS: There is no evidence in this study of an association between exposure to benzene and lymphoid leukaemia, either acute or chronic. There is some suggestion of a relation between exposure to benzene and myeloid leukaemia, in particular for acute myeloid and monocytic leukaemia. Peaked exposures seemed to be experienced for this disease. However, in view of the limitations of the study, doubt remains as to whether the risk of acute myeloid and monocytic leukaemia is increased by cumulative exposures of < 45 ppm-years. Further work is recommended to review the work histories and redefine their quality, to explore the discrepancies between results for categorical and continuous variables, and to develop ranges around the expose estimates to enable further sensitivity analyses to be carried out.


Subject(s)
Benzene/adverse effects , Leukemia/epidemiology , Occupational Diseases/epidemiology , Occupational Exposure/adverse effects , Petroleum , Case-Control Studies , Cohort Studies , Death Certificates , Humans , Leukemia/chemically induced , Leukemia, Lymphocytic, Chronic, B-Cell/chemically induced , Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology , Leukemia, Monocytic, Acute/chemically induced , Leukemia, Monocytic, Acute/epidemiology , Leukemia, Myeloid/chemically induced , Leukemia, Myeloid/epidemiology , Logistic Models , Male , Occupational Diseases/chemically induced , Occupational Exposure/analysis , Odds Ratio , Precursor Cell Lymphoblastic Leukemia-Lymphoma/chemically induced , Precursor Cell Lymphoblastic Leukemia-Lymphoma/epidemiology , Registries , Transportation , United Kingdom/epidemiology
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