title: A compendium of genome-wide associations for cancer: critical synopsis and reappraisal.
abstract: Since 2007, genome-wide association (GWA) studies have identified numerous well-supported, novel genetic risk loci for common cancers; however, there are concerns that this technology is reaching its limits. We provide an overview of GWA-identified genetic associations with solid tumors. We simulated the distribution of population risk alleles for colorectal, prostate, testicular, and thyroid cancers based on genetic variants identified in GWA studies. We also evaluated whether statistical power to detect typical genetic effects could be improved with studies performing GWA analyses of all available samples rather than multistage designs. Fifty-six eligible articles yielded 92 eligible associations between cancer phenotypes and genetic variants with a median per-allele odds ratio (OR) of 1.22 (interquartile range = 1.15-1.36). Half of the associations pertained to prostate, colorectal, or breast cancer. Individuals at the upper quartile of simulated risk had only 2.1- to 4.2-fold higher relative risk than those in the lower quartile. Comprehensive evaluation of currently available samples with GWA platforms would yield few additional variants with per-allele OR = 1.4, but many more variants with OR = 1.2 could be detected; statistical power to detect weak associations (OR = 1.07) would still be negligible. The GWA approach is effective in identifying common genetic variants with moderate effect; however, identifying loci with very small effects and rare variants will require major new efforts. At present, the utility of GWA-identified risk loci in risk stratification for cancer is limited.
authors.affiliation: Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina 45110, Greece. jioannid@cc.uoi.gr
authors.forename: John P A
authors.initials: JP
authors.lastname: Ioannidis
authors.forename: Peter
authors.initials: P
authors.lastname: Castaldi
authors.forename: Evangelos
authors.initials: E
authors.lastname: Evangelou
mesh_terms: D056808:Biostatistics; D001943:Breast Neoplasms / Q000235:genetics; D015179:Colorectal Neoplasms / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D015894:Genome, Human; D055106:Genome-Wide Association Study; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000235:genetics*; D016017:Odds Ratio; D020641:Polymorphism, Single Nucleotide; D011471:Prostatic Neoplasms / Q000235:genetics; D018570:Risk Assessment; D012307:Risk Factors; D013736:Testicular Neoplasms / Q000235:genetics; D013964:Thyroid Neoplasms / Q000235:genetics; D044465:White People / Q000235:genetics