Inhibition of growth of a murine squamous cell carcinoma by a cyclooxygenase inhibitor increases leukotriene B4 production

OBJECTIVE: To determine the role of metabolites of arachidonic acid in the growth of squamous cell carcinomas of the head and neck. DESIGN: Investigation of the effect of a cyclooxygenase inhibitor, piroxicam, on the growth of squamous cell carcinoma in a murine model. INTERVENTION: C3H/HeJ mice bearing squamous cell carcinoma (SCCVII) were treated with piroxicam (0.08 mg/d, orally) for 30 days beginning 1 day before tumor inoculation. MAIN OUTCOME MEASURES: Decrease in tumor volumes and tumor growth rates. RESULTS: Significant inhibition of tumor growth (P = .002) and final tumor weight (P = .0007) was noted in the group receiving piroxicam therapy. Prostaglandin E2 levels in the tumor tissue were unrelated to treatment or tumor size. Increased levels of leukotriene B4 were observed in the piroxicam-treated group (P = .03), and larger tumors were associated with decreased leukotriene B4 levels (P = .0001). CONCLUSIONS: Cyclooxygenase inhibitors may be effective in the treatment of some squamous cell carcinomas. The therapeutic effect of cyclooxygenase inhibitors may result from shunting into the lipoxygenase pathway of arachidonic acid metabolism.