Depth of invasion parallels increased cyclooxygenase-2 levels in patients with gastric carcinoma

BACKGROUND: Nonsteroidal anti-inflammatory drugs may reduce the incidence of intestinal carcinoma, presumably through inhibition of cyclooxygenase-2 (COX-2). The authors correlated tumor expression of COX-2 with clinicopathologic features in tissues from patients with gastric carcinoma. METHODS: Thirty-three surgical specimens, including carcinomas and corresponding noncancerous mucosa, were sampled. Reverse transcription-polymerase chain reaction analysis was performed concomitantly for COX-1 and COX-2. A COX-2 index was determined from the band density ratio of COX-2 to constitutively expressed COX-1. Immunohistochemical staining with COX-2 antibody and routine histologic assessment were performed in the same specimens. RESULTS: The COX-2 index in gastric carcinoma was significantly higher than in normal mucosa (3.4 +/- 0.7 vs. 2.2 +/- 0.7; P < 0.05). COX-2 indices were significantly higher in gastric carcinoma tissues with deep invasion; indices for pT1, pT2, pT3, and pT4 carcinomas were 0.8 +/- 0.3, 2.8 +/- 0.5, 4.3 +/- 1.0, and 8.8 +/- 5.5, respectively (P < 0.05). Immunohistochemistry demonstrated COX-2 protein diffusely in the cytoplasm of tumor cells but not in surrounding stroma or in noncancerous mucosa. CONCLUSIONS: COX-2 mRNA expression in gastric carcinoma tissue is correlated closely with depth of invasion, indicating that COX-2 is involved in the growth of gastric carcinoma.