American Journal of Epidemiology Advance Access originally published online on August 31, 2005
American Journal of Epidemiology 2005 162(8):753-763; doi:10.1093/aje/kwi272
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ORIGINAL CONTRIBUTIONS |
Variation in the Seasonal Diagnosis of Acute Lymphoblastic Leukemia: Evidence from Singapore, the United States, and Sweden
1 Division of Clinical Trials and Epidemiological Sciences, National Cancer Centre, Singapore
2 Skaraborgsinstitutet, Skövde, Sweden
3 Centre for Molecular Epidemiology, National University of Singapore, Singapore
4 Medical Statistics Unit, School of Health and Related Research, University of Sheffield, Sheffield, United Kingdom
Correspondence to Fei Gao, Division of Clinical Trials and Epidemiological Sciences, National Cancer Centre, 11 Hospital Drive, Singapore 169610 (e-mail: ctegfe{at}nccs.com.sg).
This study investigated, by summing data over successive years, the evidence for the seasonal diagnosis of acute lymphoblastic leukemia. To do so, the authors estimated the dates of peak diagnosis over a range of geographic locations including Singapore (19681999), Hawaii and mainland United States (19731999), and western Sweden (19771994) at latitudes of 1.16°N to 58.24°N. In contrast to other studies, the authors used case-by-case information on dates, gender, and age rather than grouped data for analysis. The seasonal pattern was estimated by fitting a von Mises distribution to the data from each location. No seasonal pattern was found in Singapore, which is close to the equator and does not have marked climatic changes. Likewise, seasonality was not demonstrated in Hawaii or mainland United States despite a 26.18° range of latitudes. In contrast, a significant peak (early January) was observed for western Sweden that appeared strongest for males (December 22, 95% confidence interval: November 16, January 16) and those less than age 20 years (January 14, 95% confidence interval: December 8, March 27). Thus, despite a wide geographic range of localities, there is little evidence of any seasonality in the diagnosis of acute lymphoblastic leukemia in most populations studied and no strong evidence of any influence of climate (as expressed by latitude).
leukemia, lymphoblastic, acute; seasons
Abbreviations: ALL, acute lymphoblastic leukemia; SEER, Surveillance, Epidemiology, and End Results