Non-invasive X-ray micro-computed tomographic evaluation of indomethacin on urethane-induced lung carcinogenesis in mice.

Lung cancer is the leading cause of cancer-related death worldwide. We previously reported that respiration-gated X-ray micro-computed tomography (micro-CT) is a useful tool for analyzing lung tumor development in animal models. Lung tumors were induced by a single intraperitoneal injection (250 mg/kg) of urethane in male A/J mice, followed by indomethacin treatment at 5 ppm in the diet. The mice were scanned by micro-CT every 4 weeks from 10 to 26 weeks after urethane administration. Total incidence and multiplicity of lung tumors were not significantly reduced by indomethacin treatment, as compared with untreated mice. However, the incidence of adenocarcinoma tended to be reduced by indomethacin treatment. Moreover, the size of lung tumors, especially adenomas, was suppressed by indomethacin treatment. Micro-CT analysis revealed that indomethacin effectively suppressed tumor development after urethane treatment for 10 weeks. These findings indicate that indomethacin suppresses lung carcinogenesis in mice and micro-CT is a useful non-invasive imaging approach for evaluating the characteristics and suppression of lung tumors in mice treated with cancer chemopreventive agents.