title: Excess of proximal microsatellite-stable colorectal cancer in African Americans from a multiethnic study.
abstract: OBJECTIVE
  African Americans (AA) have the highest incidence of colorectal cancer compared with other U.S. populations and more proximal colorectal cancers. The objective is to elucidate the basis of these cancer disparities.
  
  
  METHODS
  Of note, 566 AA and 328 non-Hispanic White (NHW) colorectal cancers were ascertained in five Chicago hospitals. Clinical and exposure data were collected. Microsatellite instability (MSI) and BRAF (V600E) and KRAS mutations were tested. Statistical significance of categorical variables was tested by the Fisher exact test or logistic regression and age by the Mann-Whitney U test.
  
  
  RESULTS
  Over a 10-year period, the median age at diagnosis significantly decreased for both AAs (68-61; P < 0.01) and NHWs (64.5- 62; P = 0.04); more AA patients were diagnosed before age 50 than NHWs (22% vs. 15%; P = 0.01). AAs had more proximal colorectal cancer than NHWs (49.5% vs. 33.7%; P < 0.01), but overall frequencies of MSI, BRAF and KRAS mutations were not different nor were they different by location in the colon. Proximal colorectal cancers often presented with lymphocytic infiltrate (P < 0.01) and were diagnosed at older ages (P = 0.02). Smoking, drinking, and obesity were less common in this group, but results were not statistically significant.
  
  
  CONCLUSIONS
  Patients with colorectal cancer have gotten progressively younger. The excess of colorectal cancer in AAs predominantly consists of more proximal, microsatellite stable tumors, commonly presenting lymphocytic infiltrate and less often associated with toxic exposures or a higher BMI. Younger AAs had more distal colorectal cancers than older ones. These data suggest two different mechanisms driving younger age and proximal location of colorectal cancers in AAs.
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Xicola
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Molly
authors.initials: M
authors.lastname: Gagnon
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Julia R
authors.initials: JR
authors.lastname: Clark
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Timothy
authors.initials: T
authors.lastname: Carroll
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Weihua
authors.initials: W
authors.lastname: Gao
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Christian
authors.initials: C
authors.lastname: Fernandez
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Dragana
authors.initials: D
authors.lastname: Mijic
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: James B
authors.initials: JB
authors.lastname: Rawson
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Ashley
authors.initials: A
authors.lastname: Janoski
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Cenk K
authors.initials: CK
authors.lastname: Pusatcioglu
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Rajaram
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Adam B
authors.initials: AB
authors.lastname: Gluskin
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Maureen
authors.initials: M
authors.lastname: Regan
authors.affiliation: John H Stroger, Jr Hospital, Chicago, Illinois.
authors.forename: Vivek
authors.initials: V
authors.lastname: Chaudhry
authors.affiliation: John H Stroger, Jr Hospital, Chicago, Illinois.
authors.forename: Herand
authors.initials: H
authors.lastname: Abcarian
authors.affiliation: John H Stroger, Jr Hospital, Chicago, Illinois.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Blumetti
authors.affiliation: John H Stroger, Jr Hospital, Chicago, Illinois.
authors.forename: Jose
authors.initials: J
authors.lastname: Cintron
authors.affiliation: Rush University Medical Center, Chicago, Illinois.
authors.forename: Joshua
authors.initials: J
authors.lastname: Melson
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Hui
authors.initials: H
authors.lastname: Xie
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Grace
authors.initials: G
authors.lastname: Guzman
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Rajyasree
authors.initials: R
authors.lastname: Emmadi
authors.affiliation: John H Stroger, Jr Hospital, Chicago, Illinois.
authors.forename: Victoria
authors.initials: V
authors.lastname: Alagiozian-Angelova
authors.affiliation: University of Chicago, Chicago, Illinois.
authors.forename: Sonia S
authors.initials: SS
authors.lastname: Kupfer
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Carol
authors.initials: C
authors.lastname: Braunschweig
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois. xavier.llor@yale.edu naellis@email.arizona.edu.
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Ellis
authors.affiliation: University of Illinois at Chicago, Chicago, Illinois. Jesse Brown VA Medical Center, Chicago, Illinois. xavier.llor@yale.edu naellis@email.arizona.edu.
authors.forename: Xavier
authors.initials: X
authors.lastname: Llor
mesh_terms: D001741:Black or African American / Q000235:genetics; D017677:Age Distribution; D017668:Age of Onset; D000368:Aged; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000235:genetics* / Q000473:pathology; D006801:Humans; D053842:Microsatellite Instability; D008875:Middle Aged; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins / Q000235:genetics
chemical_list: C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins