Irinotecan in combination with radiation therapy for small-cell and non-small-cell lung cancer

Lung cancer is the leading cause of cancer-related death in the United States. There was rapidprogress in the treatment of lung cancer during past decades, but local control and survival rates are still poor. Radiation therapy has been an indispensable part of the management of lung cancer, and a recent paradigm is concurrent chemoradiation therapy. Many novel chemotherapeutic agents were recently developed to improve both local and systemic control of cancer, including camptothecin derivatives, which are topoisomerase I inhibitors. Irinotecan (CPT-H, Camptosar) is a semisynthetic water-soluble derivative of camptothecin. Irinotecan is active as a single agent against lung cancer, and is also a potent radiosensitizzing agent in human lung cancer cell lines and xenografts. There have been many phase I and II clinical trials demonstrating promising results of single-agent irinotecan and combination with concurrent therapy. This article reviews irinotecan's mechanism of action of cytotoxicity and of radiation-sensitizing effects, as well as recent clinical data regarding combining radiation therapy and irinotecan for both non-small-cell and small-cell lung cancer.