Time and spatial trends in lymphoid leukemia and lymphoma incidence and survival among children and adolescents in Manitoba, Canada: 1984-2013

PLOS ONE, Dec 2019

Objectives To test for time and spatial trends in lymphoid malignancies, including lymphoid leukemia (LL), Hodgkin lymphoma (HL), and non-Hodgkin lymphoma (NHL), in children and adolescents in the province of Manitoba, Canada. Methods Incident cases diagnosed between 1984 and 2013 were identified from the Manitoba Cancer Registry. We assessed time trends in age-standardized incidence rates using joinpoint regression and in 5-year relative survival using Poisson regression model. Kulldorff's scan method was used to assess spatial variation and clustering. Results Age-standardized incidence rates (per million person-years) in males and females were 34.0 (95% confidence interval [CI] 28.9–39.1) and 26.2 (95% CI 21.5–30.7) for LL, 10.5 (95% CI 7.7–13.3) and 12.5 (95% CI 9.4–15.7) for HL, 12.5 (95% CI 9.3–15.4) and 7.7 (95% CI 5.2–10.2) for NHL (except for Burkitt lymphomas), and 3.2 (95% CI 1.6–4.7) and 1.5 (95% CI 0.4–2.5) for Burkitt lymphomas. Age- and sex- standardized LL incidence rate increased 1.4% (95% CI 0.3%-2.5%) per year, while the changes for HL and NHL incidence rates were not statistically significant. There were geographic differences in age-standardized incidence rates for LL, HL, and NHL and spatial clusters were detected in southern part of the province. Five-year relative survival has improved over time and there was no difference between rural and urban areas. Conclusions Lymphoid leukemia incidence rate increased over time and varied by geographic area. Further research should examine the factors contributing to these trends.

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Time and spatial trends in lymphoid leukemia and lymphoma incidence and survival among children and adolescents in Manitoba, Canada: 1984-2013

April Time and spatial trends in lymphoid leukemia and lymphoma incidence and survival among children and adolescents in Manitoba, Canada: 1984-2013 Xibiao Ye 0 2 3 4 Mahmoud Torabi 0 2 3 4 Lisa M. Lix 0 2 3 4 Salaheddin M. Mahmud 0 2 3 4 0 Funding: This research was funded by the Manitoba Medical Service Foundation ( 1 317309). The funders had no role in study design , data 2 Data Availability Statement: Data are available from the Manitoba Centre for Health Policy for researchers who meet the criteria for access to confidential data. Data access requests can be sent to 3 Department of Community Health Sciences, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba , Winnipeg, Manitoba , Canada , 2 George & Fay Yee Centre for Healthcare Innovation, University of Manitoba , Winnipeg, Manitoba , Canada 4 Editor: Ji-Hyun Lee, UNM Cancer Center , UNITED STATES To test for time and spatial trends in lymphoid malignancies, including lymphoid leukemia (LL), Hodgkin lymphoma (HL), and non-Hodgkin lymphoma (NHL), in children and adolescents in the province of Manitoba, Canada. Objectives Methods Results Incident cases diagnosed between 1984 and 2013 were identified from the Manitoba Cancer Registry. We assessed time trends in age-standardized incidence rates using joinpoint regression and in 5-year relative survival using Poisson regression model. Kulldorff's scan method was used to assess spatial variation and clustering. Age-standardized incidence rates (per million person-years) in males and females were 34.0 (95% confidence interval [CI] 28.9±39.1) and 26.2 (95% CI 21.5±30.7) for LL, 10.5 (95% CI 7.7±13.3) and 12.5 (95% CI 9.4±15.7) for HL, 12.5 (95% CI 9.3±15.4) and 7.7 (95% CI 5.2±10.2) for NHL (except for Burkitt lymphomas), and 3.2 (95% CI 1.6±4.7) and 1.5 (95% CI 0.4±2.5) for Burkitt lymphomas. Age- and sex- standardized LL incidence rate increased 1.4% (95% CI 0.3%-2.5%) per year, while the changes for HL and NHL incidence rates were not statistically significant. There were geographic differences in age-standardized incidence rates for LL, HL, and NHL and spatial clusters were detected in southern part of the province. Five-year relative survival has improved over time and there was no difference between rural and urban areas. Conclusions Lymphoid leukemia incidence rate increased over time and varied by geographic area. Further research should examine the factors contributing to these trends. collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: SMM has received unrestricted research grants from GlaxoSmithKline, Sanofi Pasteur and Pfizer for unrelated studies. There are no patents, products in development or marketed products to declare. This does not alter our adherence to all the PLOS ONE policies on sharing data and materials. The data that support the findings of this study are available from the Manitoba Centre for Health Policy but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors upon reasonable request and with permission of the Manitoba Centre for Health Policy. Abbreviations: 95% CI, 95% confidence interval; APC, annual percentage change; BL, Burkitt lymphomas; HL, Hodgkin lymphoma; HR, hazard ratio; ICCC-3, International Classification of Childhood Cancer, 3rd Edition; ICD, International Classification of Diseases; LL, lymphoid leukemia; NHL, non-Hodgkin lymphoma; RS, relative survival. Introduction Hematological malignancies as a group are the most common cancer in children (under age of 15 years) and adolescents (15±19 years) and account for 40% of total cancer cases in this population [1]. Acute lymphoid leukemia (ALL) is the most common hematological malignancy, followed by Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) [1]. Little is known about the etiology of the cancers and there are only a few established risk factors, including high-level ionizing radiation [ 2 ], certain chemotherapeutic agents [ 3 ] (e.g., diethylstilbestrol [ 4 ]), certain genetic disorders (e.g., Down syndrome [ 5 ]), and congenital immunodeficiency diseases [1]. Analyzing time and spatial trends of cancer incidence may provide useful information to generate new hypotheses for etiological research. Despite extensive research on time trends in hematological malignancy incidence in adults, few studies have been conducted in children and adolescents. A recent international comparative analysis showed differences in temporal trends in leukemia and lymphoma incidence rates in children by country [ 6 ]. Data have also shown geographical variations in incidence among children and adolescents at the country level [7±11], but less is known about the variation within smaller areas (e.g., provinces or regions). Short-term and long-term survival of hematological malignancy patients (...truncated)


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Xibiao Ye, Mahmoud Torabi, Lisa M. Lix, Salaheddin M. Mahmud. Time and spatial trends in lymphoid leukemia and lymphoma incidence and survival among children and adolescents in Manitoba, Canada: 1984-2013, PLOS ONE, 2017, Volume 12, Issue 4, DOI: 10.1371/journal.pone.0175701