Ornithine decarboxylase polymorphism modification of response to aspirin treatment for colorectal adenoma prevention.
BACKGROUND
Previous research suggests that the G315A single-nucleotide polymorphism in the ornithine decarboxylase (ODC) gene may be a genetic marker for risk of colorectal neoplasia and may also modify the association of aspirin use with risk.


METHODS
We tested these hypotheses among participants in the Aspirin/Folate Polyp Prevention Study who were randomly assigned to placebo or to aspirin treatment (81 or 325 mg daily) and followed for 3 years for the occurrence of new adenomas. Genomic DNA from 973 subjects was analyzed for ODC genotype. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated to test the association between ODC genotype and adenoma occurrence and interactions with aspirin treatment. All statistical tests were two-sided.


RESULTS
Of the 973 subjects, 54% were homozygous wild-type (GG), 7% were homozygous variant (AA), and 39% were heterozygous individuals; the allele frequencies varied statistically significantly by race and ethnicity. Among these subjects, the absolute risk of any adenoma was 45% and the risk of an advanced lesion was 10%. Overall, no association was found between ODC genotype and the occurrence of new adenomas, but genotype did modify the effect of aspirin on adenoma risk. Although aspirin treatment had no protective effect among subjects with a GG genotype, among subjects with at least one A allele, it was associated with statistically significant reduced risks of any adenoma (RR = 0.77, 95% CI = 0.63 to 0.95; P = .02, P(interaction) = .04) and of advanced lesions (RR = 0.51, 95% CI = 0.29 to 0.90; P = .02, P(interaction) = .02). Among subjects with at least one A allele, 40.8% who took aspirin versus 52.9% who took placebo developed adenomas; 7.1% versus 14.0% developed advanced lesions.


CONCLUSIONS
ODC genotype may modify the response to aspirin treatment for colorectal adenoma prevention.
Barry
Elizabeth L R
EL
Department of Community and Family Medicine, Dartmouth Medical School, 46 Centerra Parkway, Ste. 300, Lebanon, NH 03766, USA. elizabeth.l.barry@dartmouth.edu
Baron
John A
JA
Bhat
Shubha
S
Grau
Maria V
MV
Burke
Carol A
CA
Sandler
Robert S
RS
Ahnen
Dennis J
DJ
Haile
Robert W
RW
O'Brien
Thomas G
TG
D000236:Adenoma / Q000201:enzymology / Q000208:ethnology / Q000235:genetics / Q000517:prevention & control*; D011125:Adenomatous Polyposis Coli / Q000188:drug therapy; D000368:Aged; D000409:Alanine; D016588:Anticarcinogenic Agents / Q000627:therapeutic use*; D001241:Aspirin / Q000627:therapeutic use*; D015179:Colorectal Neoplasms / Q000201:enzymology / Q000208:ethnology / Q000235:genetics / Q000517:prevention & control*; D005260:Female; D005492:Folic Acid / Q000627:therapeutic use*; D005765:Gastrointestinal Agents / Q000627:therapeutic use*; D005787:Gene Frequency; D005838:Genotype; D005998:Glycine; D006801:Humans; D008297:Male; D008875:Middle Aged; D009955:Ornithine Decarboxylase / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D044469:Racial Groups / Q000235:genetics; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment
D016588:Anticarcinogenic Agents; D005765:Gastrointestinal Agents; D005492:Folic Acid; D009955:Ornithine Decarboxylase; D000409:Alanine; D001241:Aspirin; D005998:Glycine