Survival of Adults with Acute Lymphoblastic Leukemia in Germany and the United States
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Survival of Adults with Acute Lymphoblastic Leukemia in Germany and the United States Dianne Pulte1,2*, Lina Jansen1, Adam Gondos1, Alexander Katalinic3, Benjamin Barnes4, Meike Ressing5, Bernd Holleczek6, Andrea Eberle7, Hermann Brenner1,8, the GEKID Cancer Survival Working Group" 1 Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2 Cardeza Foundation and Division of Hematology, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America, 3 Institute of Cancer Epidemiology, University of Lu¨beck, Lu¨beck, Germany, 4 National Center for Cancer Registry Data, Robert Koch Institute, Berlin, Germany, 5 Cancer Registry of Rhineland-Palatinate, Institute of Medical Biostatistics, Epidemiology, and Informatics, Johannes Gutenberg University Mainz, Mainz, Germany, 6 Saarland Cancer Registry, Saarbru¨cken, Germany, 7 Cancer Registry of Bremen, Leibniz Institute for Prevention Research and Epidemiology – BIPS, Bremen, Germany, 8 German Cancer Consortium (DKTK), Heidelberg, Germany Abstract Background: Adulthood acute lymphoblastic leukemia (ALL) is a rare disease. In contrast to childhood ALL, survival for adults with ALL is poor. Recently, new protocols, including use of pediatric protocols in young adults, have improved survival in clinical trials. Here, we examine population level survival in Germany and the United States (US) to gain insight into the extent to which changes in clinical trials have translated into better survival on the population level. Methods: Data were extracted from the Surveillance, Epidemiology, and End Results database in the US and 11 cancer registries in Germany. Patients age 15–69 diagnosed with ALL were included. Period analysis was used to estimate 5-year relative survival (RS). Results: Overall 5-year RS was estimated at 43.4% for Germany and 35.5% for the US (p = 0.004), with a decrease in survival with increasing age. Survival was higher in Germany than the US for men (43.6% versus 37.7%, p = 0.002) but not for women (42.4% versus 40.3%, p.0.1). Five-year RS estimates increased in Germany and the US between 2002 and 2006 by 11.8 and 7.3 percent units, respectively (p = 0.02 and 0.04, respectively). Conclusions: Survival for adults with ALL continues to be low compared with that for children, but a substantial increase in 5-year survival estimates was seen from 2002 to 2006 in both Germany and the US. The reasons for the survival differences between both countries require clarification. Citation: Pulte D, Jansen L, Gondos A, Katalinic A, Barnes B, et al. (2014) Survival of Adults with Acute Lymphoblastic Leukemia in Germany and the United States. PLoS ONE 9(1): e85554. doi:10.1371/journal.pone.0085554 Editor: Mirjam Moerbeek, Utrecht University, Netherlands Received April 19, 2013; Accepted December 4, 2013; Published January 27, 2014 Copyright: ß 2014 Pulte et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported in part by a grant from the German Cancer Aid (Deutsche Krebshilfe, no. 108257) and a visiting scientist grant from the DKFZ. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: [email protected] " Membership of the GEKID Cancer Survival Working Group is provided in the Acknowledgments. Introduction all forms of leukemia [10] due to lack of a unified, high quality population level database. Recently, a collaborative effort between Acute lymphoblastic leukemia (ALL) is a rare cancer, especially the German Cancer Research Center and population based in adults. Survival estimates for patients with ALL are high for cancer registries in Germany covering 11 federal states has allowed children, both in clinical trials [1] and population based studies for evaluation of population level survival for rare cancers in [2], but decrease rapidly with age [3,4], and adult ALL is Germany, including evaluation of age and sex specific survival frequently fatal [5,6]. Aggressive treatment of ALL has demon- [11]. strated increased survival in young and middle aged adult patients Here, we examine survival of adults diagnosed with ALL in in clinical trials [5]. However, these changes have not yet been Germany by age and gender and compare survival to that seen in confirmed on the population level. patients with ALL in the US. Because of the rarity of ALL in adults, there are relatively few population level data available concerning survival of patients with Methods ALL and most available data come from the Surveillance, Epidemiology, and End Results (SEER) database in the United Data Sources States (US) [2–4,6,7] and cancer registries from Nordic countries A detailed description of the cancer registries from which data [8,9]. In the past, estimates of population level survival for patients were obtained has been published previously [11]. Briefly, data with leukemia in Germany have been limited to aggregate data for extracted from cancer registries throughout Germany covering 11 PLOS ONE | www.plosone.org 1 January 2014 | Volume 9 | Issue 1 | e85554 ALL Survival in Germany and the US federal states, representing a total base population of 33 million single age groups, using model-based period analysis [19]. people, were included (Table 1). Patients age 15 or older with a Additionally, model-based period analysis was employed to primary diagnosis of ALL (ICD-10 code C91.0) in 1997–2006 and estimate most recent changes in 5-year relative survival within with mortality follow up through December, 2006 were included. the 2002–2006 period. Cancer topography, morphology, and behavior were originally Because the number of cases reported to cancer registries by coded in accordance with the International Classification of death certificate only (DCO) in the German database was still Disease for Oncology (ICD-O)-3 guidelines and later converted high, the impact of the exclusion of DCO cases in the computation into ICD-10 using ‘IARCcrgTools’ [12]. Patients with both B-cell of the survival estimates was estimated by providing plausibility and T-cell acute lymphoblastic leukemia are covered under this ranges for survival estimates. The plausibility range is derived by diagnostic code in ICD-10. For some registries, data were computing relative survival once after exclusion of DCO cases available starting from later years only. Cases both with and (upper limit of the estimate) and once by multiplying the relative without preceding cancers were included. Because there were data survival estimate obtained after exclusion of DCO cases by one quality issues for patients age 70+ in some of the German minus the percentage of DCO cases (lower limit). The latter registries, only data for patients age 15–69 were included. In order estimate was suggested by Berrino et al. [20] to account for the to compare population level survival for ALL in Germany with overoptimistic estimate of relative survival after exclusion of DCO survival in the United States (US), data from the Surveillance, cases. Brenner and Holleczek [21] have shown that these two Epidemiology, and End Results (SEER13) database were analyzed estimates provide a plausibility range for true survival, as the [13]. The same inclusion criteria as for patients from the German former estimate is expected to overestimate true survival, and the cancer registries were applied for the same time period. The latter estimate is expected to underestimate true survival under SEER13 database includes data from 13 regional cancer centers in plausible assumptions. the US, covering a population of about 39 million people. Centers Relative survival was calculated as the ratio of actual survival to are chosen for inclusion based on their high quality and expected survival. Expected survival was estimated according to epidemiologically interesting population groups. The SEER the Ederer II method [22] using national life tables stratified by population is considered to be similar to the general US age, sex, and calendar year obtained from German Federal population with respect to most sociodemographic characteristics Statistical Office. Relative survival estimates for the US patients [13], although it may be more affluent than average and may have were calculated using US sex, age, calendar year, and race specific slightly higher than average survival for some cancers [14]. life tables published by the Center for Disease Control (CDC) [23]. All calculations were carried out using SAS software (version Ethics 9.2), using macros developed for standard and modeled period The data contained in the databases under study is stripped of analysis [19,24]. all sensitive identifying information prior to being made available to researchers. Thus, no additional specific informed consent was Results required for analysis of the anonymised data in this project. Written consent was neither possible nor desirable as it would Overall, 1295 patients age 15–69 were identified in the German represent a link to individual patients and thus constitute a risk of database. After exclusion of DCO cases (9.3%), 1175 cases disclosure that would not otherwise exist. remained for analysis. Median age at diagnosis was 39 years