It has been thought that there is a strong relationship between inflammation and carcinogenesis so that the development of cancer occurs with chronic inflammation in many organs. An in-depth understanding of the mechanism by which inflammation can lead to carcinogenesis may enable the development of drugs targeted at important molecules, providing a powerful tool for preventing cancer development. In this review, we focused on a signal transduction system, the nuclear factor-kappaB (NF-κB) pathway, which is thought to play a role in the process leading from inflammation to carcinogenesis, and may thus serve as a candidate for targeted intervention. (Cancer Sci 2008; 99: 836–842)