Etiology and Pathogenesis > Invasion

Meeting Abstract

Cyclooxygenase-2 (COX-2) expression in human macroadenomas: a potential target for therapy

Courtnay W Bloomer, Lawrence Kenyon, Elizabeth Hammond, David W Andrews, Walter J Curran, Adam P Dicker

Jefferson Medical College, Philadelphia, PA; LDS Hospital, Salt Lake City, UT

Background: Currently, few molecular markers for pituitary macroadenomas have been identified that may serve as potential therapeutic targets. COX-2 is up regulated in many epithelial tumors but no published reports exist about expression of COX-2 in pituitary macroadenomas. This study sought to evaluate whether COX-2 expression is up regulated in pituitary macroadenomas and is associated with particular hormonal expression. Methods: Thirty-five specimens of pituitary macroadenoma were evaluated. The H&E slides were reviewed, and the representative paraffin blocks containing the index case were chosen and immunohistochemically stained for COX-2 expression (Dako). Two reviewers reviewed stained slides and an immunohistochemical score (IHS) was calculated and analyzed. We considered the expression of COX-2 as an ordinal categorical variable, and the presence/absence of each hormone as a categorical variable. We summarized the data in an r-x-c contingency table, where r represents COX-2 expression (0, 1, 2, 3) and c is the indicator of presence of hormone (0=No, 1=Yes). We tested for association of COX-2 expression with each of the hormones using two-sided Fisher's exact test at the 95% confidence level. We also dichotomized COX-2 expression as (0,1) versus (2,3) and examined the association with presence of hormone as previously described. Results: All specimens (100%) overexpressed COX-2. The association between COX-2 expression and Thyroid Stimulating Hormone (TSH) is highly statistically significant. If COX-2 expression is evaluated as 0,1,2,3, p-value = 0.023 by the Fisher's exact test. If COX-2 staining is expressed as 0,1 versus 2,3, the p-value = 0.0096. All of the samples with 2,3 for COX-2 were positive for TSH. Conclusion: The association of COX-2 and in pituitary macroadenomas represents a novel finding. The expression of COX-2 in TSH-secreting pituitary macroadenomas may represent an opportunity for adjunct therapy in these benign but clinically significant tumors. Future clinical studies are planned to determine whether therapeutic intervention with selective COX-2 inhibitors will benefit patients.

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