Immunohistochemical detection of ornithine-decarboxylase in primary and metastatic human breast cancer specimens

Increased ornithine decarboxylase (ODC) activity in human breast cancer spe cimens has recently been shown to be an independent adverse prognostic fact or for recurrence and death. Biochemical measurement of ODC, however, is no t practical for routine clinical use. Furthermore, it does not take into ac count the heterogeneous composition of human breast cancers which contain v ariable proportions of epithelial and stromal elements. Therefore, we devel oped an immunohistochemical method for ODC determination which can be appli ed to formalin-fixed, paraffin-embedded tissue sections. We report here our results in a series of 30 human breast cancer samples. ODC expression was detected most consistently in the malignant epithelial component of the tum ors. Twenty-seven of 30 samples stained positive with intensities ranging f rom 1+ to 3+. The fraction of malignant epithelial cells expressing ODC var ied among specimens between 10 % and > 90 %. When quantitated by H-SCORE, O DC expression was significantly higher in the malignant epithelial componen t than in normal appearing epithelial cells and stroma admixed within the t umor. Normal mammary tissue adjacent to the cancer was available for analys is in six cases. ODC expression was absent in two (while both cancers were positive) but present in four to a degree which was overall comparable to t hat observed in the corresponding tumors. We believe that this technique wi ll be useful for future studies aimed at expanding our knowledge of the rol e of ODC and polyamines (PA) in breast cancer biology.