title: Investigation of spatio-temporal cancer clusters using residential histories in a case-control study of non-Hodgkin lymphoma in the United States.
abstract: BACKGROUND
  Non-Hodgkin lymphoma (NHL) is an enigmatic disease with few known risk factors. Spatio-temporal epidemiologic analyses have the potential to reveal patterns that may give clues to new risk factors worthy of investigation. We sought to investigate clusters of NHL through space and time based on life course residential histories.
  
  
  METHODS
  We used residential histories from a population-based NHL case-control study of 1300 cases and 1044 controls with recruitment centers in Iowa, Detroit, Seattle, and Los Angeles, and diagnosed in 1998-2000. Novel methods for cluster detection allowing for residential mobility, called Q-statistics, were used to quantify nearest neighbor relationships through space and time over the life course to identify cancer clusters. Analyses were performed on all cases together and on two subgroups of NHL: Diffuse large B-cell lymphoma and follicular lymphoma. These more homogenous subgroups of cases might have a more common etiology that could potentially be detected in cluster analysis. Based on simulation studies designed to help account for multiple testing across space and through time, we required at least four significant cases nearby one another to declare a region a potential cluster, along with confirmatory analyses using spatial-only scanning windows (SaTScan).
  
  
  RESULTS
  Evidence of a small cluster in southeastern Oakland County, MI was suggested using residences 10-18 years prior to diagnosis, and confirmed by SaTScan in a time-slice analysis 20 years prior to diagnosis, when all cases were included in the analysis. Consistent evidence of clusters was not seen in the two histologic subgroups.
  
  
  CONCLUSIONS
  Suggestive evidence of a small space-time cluster in southeastern Oakland County, MI was detected in this NHL case-control study in the USA.
authors.affiliation: Danish Cancer Society Research Center, Copenhagen, Denmark. rikke@nordsborg.dk.
authors.forename: Rikke Baastrup
authors.initials: RB
authors.lastname: Nordsborg
authors.affiliation: Department of Preventive Medicine, Stony Brook University, Stony Brook, NY, USA.|Department of Health Science, Brigham Young University, Provo, UT, USA.
authors.forename: Chantel D
authors.initials: CD
authors.lastname: Sloan
authors.affiliation: Department of Applied Mathematics, Stony Brook University, Stony Brook, NY, USA.
authors.forename: Haseeb
authors.initials: H
authors.lastname: Shahid
authors.affiliation: BioMedware, Inc, Ann Arbor, MI, USA.|State University of New York at Buffalo, Buffalo, NY, USA.
authors.forename: Geoffrey M
authors.initials: GM
authors.lastname: Jacquez
authors.affiliation: Department of Environmental & Occupational Health, Drexel University School of Public Health, Philadelphia, PA, USA.
authors.forename: Anneclaire J
authors.initials: AJ
authors.lastname: De Roos
authors.affiliation: Mayo Clinic College of Medicine, Rochester, MN, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Cerhan
authors.affiliation: Department of Preventive Medicine and Pathology, and Norris Comprehensive Cancer Center, USC Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
authors.forename: Wendy
authors.initials: W
authors.lastname: Cozen
authors.affiliation: Department of Family Medicine and Public Health Sciences, Wayne State University, Detroit, MI, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Severson
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD, USA.
authors.forename: Mary H
authors.initials: MH
authors.lastname: Ward
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD, USA.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Morton
authors.affiliation: Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: Ole
authors.initials: O
authors.lastname: Raaschou-Nielsen
authors.affiliation: Department of Preventive Medicine, Stony Brook University, Stony Brook, NY, USA.|Program in Public Health, Stony Brook University, Stony Brook, NY, USA.
authors.forename: Jaymie R
authors.initials: JR
authors.lastname: Meliker
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D016000:Cluster Analysis; D005260:Female; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D012111:Residence Characteristics; D012307:Risk Factors; D062211:Spatio-Temporal Analysis; D014481:United States / Q000453:epidemiology