Abstract
IMPORTANCE: Use of aspirin (which inhibits platelet function) after a colon cancer diagnosis is associated with improved overall survival. Identifying predictive biomarkers of this effect could individualize therapy and decrease toxic effects.
OBJECTIVE: To demonstrate that survival benefit associated with low-dose aspirin use after a diagnosis of colorectal cancer might depend on HLA class I antigen expression.
DESIGN, SETTING, AND PARTICIPANTS: A cohort study with tumor blocks from 999 patients with colon cancer (surgically resected between 2002 and 2008), analyzed for HLA class I antigen and prostaglandin endoperoxide synthase 2 (PTGS2) expression using a tissue microarray. Mutation analysis of PIK3CA was also performed. Data on aspirin use after diagnosis were obtained from a prescription database. Parametric survival models with exponential (Poisson) distribution were used to model the survival.
MAIN OUTCOMES AND MEASURES: Overall survival.
RESULTS: The overall survival benefit associated with aspirin use after a diagnosis of colon cancer had an adjusted rate ratio (RR) of 0.53 (95% CI, 0.38-0.74; P < .001) when tumors expressed HLA class I antigen compared with an RR of 1.03 (0.66-1.61; P = .91) when HLA antigen expression was lost. The benefit of aspirin was similar for tumors with strong PTGS2 expression (0.68; 0.48-0.97; P = .03), weak PTGS2 expression (0.59; 0.38-0.97; P = .02), and wild-type PIK3CA tumors (0.55; 0.40-0.75; P < .001). No association was observed with mutated PIK3CA tumors (0.73; 0.33-1.63; P = .44).
CONCLUSIONS AND RELEVANCE: Contrary to the original hypothesis, aspirin use after colon cancer diagnosis was associated with improved survival if tumors expressed HLA class I antigen. Increased PTGS2 expression or the presence of mutated PIK3CA did not predict benefit from aspirin. HLA class I antigen might serve as a predictive biomarker for adjuvant aspirin therapy in colon cancer.
| Original language | English |
|---|---|
| Pages (from-to) | 732-9 |
| Number of pages | 8 |
| Journal | JAMA Internal Medicine |
| Volume | 174 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 2014 |
| Externally published | Yes |
Keywords
- Aspirin
- Biomarkers, Tumor
- Cohort Studies
- Colonic Neoplasms
- Cyclooxygenase 2
- DNA Mutational Analysis
- Female
- Gene Expression
- Histocompatibility Antigens Class I
- Humans
- Immunohistochemistry
- Male
- Mutation
- Phosphatidylinositol 3-Kinases
- Polymerase Chain Reaction
- Registries
- Tissue Array Analysis
- Journal Article