Aspirin appropriately acetylated platelet cyclooxygenase (COX)-1 but left persistently high systemic thromboxane(TX)A2 and prostaglandin (PG)E2 biosynthesis (assessed by measuring their primary urinary metabolites, i.e., 11-dehydro-TXB2 and PGEM) associated with the incomplete acetylation of COX-1 in colorectal mucosa and adenomas. The gene discussed is PTGS1; the disease is adenoma.