title: PIK3CA Somatic Mutation Status in Relation to Patient and Tumor Factors in Racial/Ethnic Minorities with Colorectal Cancer.
abstract: BACKGROUND
  Approximately 10% to 20% of colorectal cancers exhibit somatic mutations in the phosphoinositide-3-kinase, catalytic, alpha polypeptide gene (PIK3CA). We evaluated the relationship of PIK3CA mutation status in colorectal cancer with race/ethnicity, colorectal cancer survival, and other patient and tumor factors.
  
  
  METHODS
  This study comprised 377 racial/ethnic minorities with incident invasive colorectal cancer, enrolled in the Colon Cancer Family Registry via population-based cancer registries. Tumor specimens were tested for PIK3CA mutations in exon 9 and 20 hotspots, BRAF p.V600E mutations, and DNA mismatch repair (MMR). In logistic regression models, we evaluated the association between PIK3CA mutation status and race/ethnicity, overall, and by mutation site. Using Cox regression, we evaluated the association between PIK3CA mutation status and survival after colorectal cancer diagnosis.
  
  
  RESULTS
  PIK3CA mutations were detected in 42 cases (11%), with a similar prevalence across racial/ethnic groups. Individuals with PIK3CA-mutated colorectal cancer were significantly more likely than those with PIK3CA-wildtype disease to have proximal colon cancer, MMR-deficient tumors, and a germline MMR mutation (P ≤ 0.01). There was no evidence for an association between PIK3CA and overall survival (HR, 0.77; 95% confidence interval, 0.43-1.39).
  
  
  CONCLUSIONS
  The prevalence of PIK3CA mutation status in colorectal cancer does not differ according to race/ethnicity, but may vary according to other relevant clinicopathologic and etiologic factors, including germline MMR mutation status, tumor MMR status, and tumor site.
  
  
  CONCLUSIONS
  These findings underscore the importance of PIK3CA mutation status in colorectal cancer epidemiology and provide evidence that the prevalence of such mutations is similar across several racial/ethnic groups.
authors.affiliation: Epidemiology Department, University of Washington, Seattle, Washington. Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington. aiphipps@u.washington.edu.
authors.forename: Amanda I
authors.initials: AI
authors.lastname: Phipps
authors.affiliation: Division of Gastroenterology, University of Colorado School of Medicine, Denver, Colorado. Department of Medicine, Veterans Affairs Medical Center, Denver, Colorado.
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Ahnen
authors.affiliation: Cancer Prevention Institute of California, Fremont, California.
authors.forename: Iona
authors.initials: I
authors.lastname: Cheng
authors.affiliation: Epidemiology Department, University of Washington, Seattle, Washington. Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington.
authors.forename: Polly A
authors.initials: PA
authors.lastname: Newcomb
authors.affiliation: Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Aung Ko
authors.initials: AK
authors.lastname: Win
authors.affiliation: Epidemiology Program, University of Hawaii Cancer Center, Honolulu, Hawaii.
authors.forename: Terrilea
authors.initials: T
authors.lastname: Burnett
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics; D058534:Class I Phosphatidylinositol 3-Kinases; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000208:ethnology / Q000235:genetics*; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000235:genetics*; D005260:Female; D014943:Global Health; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D008913:Minority Groups; D009154:Mutation; D009367:Neoplasm Staging; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics* / Q000378:metabolism; D018426:SEER Program; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human