Immunocytochemical detection of ornithine decarboxylase (ODC) in paraffin-embedded tissues as a possible prognostic indicator for oral lesions.

Intracellular levels of ornithine decarboxylase (ODC) are raised following mitogenic stimulus and in neoplasia. Because lesions of the oral cavity are often difficult to assess histologically, we have determined the value of immunocytochemical detection of ODC as a prognostic indicator in 74 routinely fixed and paraffin-embedded oral biopsies using peroxidase-antiperoxidase and immunogold-silver staining. The latter proved more sensitive, yielding positive reactions in 32 of 43 oral carcinomas (11/14 well differentiated, 16/21 moderately differentiated and 3/5 poorly differentiated) and 7/11 potentially malignant lesions, compared with 19/45 carcinomas and 1/15 potentially malignant lesions, by peroxidase anti-peroxidase. Hyperplastic lesions (n = 7) and normal non-keratinized buccal mucosa (n = 7) were all negative. Follow-up was possible in 13 of the carcinoma patients. Of 7 positive ODC reactions but clinically node-free at biopsy, 2 died and 2 had recurrences within 3 years, whereas all of 6 with no immunoreactivity were symptom-free after 3-5 years. Immunostaining for ODC may be helpful for the prognostic assessment of routinely processed oral lesions and in choosing treatment.