[Cyclooxygenase inhibitors in chemoprevention and treatment of esophageal squamous cell carcinoma].

Cyclooxygenase inhibitors (COX) are a complex group of pharmacological compounds characterized by significant efficacy in chemoprevention of epithelial origin tumors, especially colorectal ones. It was found that inducible isoform of COX - COX-2 plays an important role in cancer growth and dissemination, e.g., by increase of cellular proliferation, reduction of apoptosis, promotion of local invasiveness and angiogenesis. COX inhibitors decrease prostaglandins' synthesis, but COX-independent mechanisms of their preventive and therapeutical activity were also proven. The influence of COX inhibitors on growth of esophageal squamous cell carcinoma and its precursor lesions was not completely clear. Most studies based on human cancer cell lines revealed antiproliferative and proapoptotic ability of both nonselective (previously called non-steroidal antiinflammatory drugs--NSAIDs) and selective COX-2 inhibitors (coxibs). In in vivo studies performed on animals exposed to chemical carcinogens, the chemopreventive effect was achieved exclusively after administration of experimental selective COX-2 inhibitors, but in the only human trial, supplementation of selective COX-2 inhibitor--celecoxib turned out ineffective. However, many epidemiological data proved effect of prolonged administration of nonselective COX inhibitors, especially acetylsalicylic acid on decreased risk of esophageal squamous cell carcinoma. Few reports concerning application of selective COX-2 inhibitors in patients with invasive squamous cell carcinoma are insufficient for ultimate evaluation of this method of therapy.