Ornithine decarboxylase levels in the rectal mucosa of patients with colonic neoplasia.

Ornithine decarboxylase (ODC) activity in biopsy specimens of normal-appearing rectal mucosa was measured in 15 control patients, 5 patients with colon adenomas, and 11 patients with colon cancer. While women had significantly higher ODC activity than men, ODC activity was increased regardless of gender in the rectal mucosal biopsies of patients with benign or malignant colonic neoplasia compared with those of controls. The positive predictive value of ODC activity for remote colonic neoplasia was 61% for women and 91% for men. The results provide a rationale for long-term studies of ODC activity in rectal mucosa as a biological marker of high risk for large bowel neoplasia.