title: A genome wide association study on Newfoundland colorectal cancer patients' survival outcomes.
abstract: BACKGROUND
  In this study we performed genome-wide association studies to identify candidate SNPs that may predict the risk of disease outcome in colorectal cancer.
  
  
  METHODS
  Patient cohort consisted of 505 unrelated patients with Caucasian ancestry. Germline DNA samples were genotyped using the Illumina® human Omni-1quad SNP chip. Associations of SNPs with overall and disease free survivals were examined primarily for 431 patients with microsatellite instability-low (MSI-L) or stable (MSS) colorectal tumors using Cox proportional hazards method adjusting for clinical covariates. Bootstrap method was applied for internal validation of results. As exploratory analyses, association analyses for the colon (n = 334) and rectal (n = 171) cancer patients were also performed.
  
  
  RESULTS
  As a result, there was no SNP that reached the genomewide significance levels (p < 5x10(-8)) in any of the analyses. A small number of genetic markers (n = 10) showed nominal associations (p <10(-6)) for MSS/MSI-L, colon, or rectal cancer patient groups. These markers were located in two non-coding RNA genes or intergenic regions and none were amino acid substituting polymorphisms. Bootstrap analysis for the MSS/MSI-L cohort data suggested the robustness of the observed nominal associations.
  
  
  CONCLUSIONS
  Likely due to small number of patients, our study did not identify an acceptable level of association of SNPs with outcome in MSS/MSI-L, colon, or rectal cancer patients. A number of SNPs with sub-optimal p-values were, however, identified; these loci may be promising and examined in other larger-sized patient cohorts.
authors: Department of Biostatistics, Princess Margaret Cancer Centre, Toronto, ON Canada M5G 2 M9 ; Dalla Lana School of Public Health, University of Toronto, Toronto, ON Canada M5T 3M7.
authors: Wei
authors: W
authors: Xu
authors: Department of Biostatistics, Princess Margaret Cancer Centre, Toronto, ON Canada M5G 2 M9 ; Dalla Lana School of Public Health, University of Toronto, Toronto, ON Canada M5T 3M7.
authors: Jingxiong
authors: J
authors: Xu
authors: Dalla Lana School of Public Health, University of Toronto, Toronto, ON Canada M5T 3M7.
authors: Konstantin
authors: K
authors: Shestopaloff
authors: Clinical Epidemiology Unit, Faculty of Medicine, Memorial University, St. John's, NL Canada A1B 3V6.
authors: Elizabeth
authors: E
authors: Dicks
authors: Discipline of Genetics, Faculty of Medicine, Memorial University, St. John's, NL Canada A1B 3 V6.
authors: Jane
authors: J
authors: Green
authors: Clinical Epidemiology Unit, Faculty of Medicine, Memorial University, St. John's, NL Canada A1B 3V6.
authors: Patrick
authors: P
authors: Parfrey
authors: Discipline of Genetics, Faculty of Medicine, Memorial University, St. John's, NL Canada A1B 3 V6.
authors: Roger
authors: R
authors: Green
authors: Discipline of Genetics, Faculty of Medicine, Memorial University, St. John's, NL Canada A1B 3 V6 ; Discipline of Oncology, Faculty of Medicine, Memorial University, St. John's, NL Canada A1B 3 V6.
authors: Sevtap
authors: S
authors: Savas
keywords: Clinical outcome; Colorectal cancer; Genome-wide; SNP; Survival analyses