Irinotecan is a camptothecin analog which exerts its cytotoxic effects by forming a covalent complex with topoisomerase I and DNA, resulting in inhibition of DNA re-ligation, accumulation of DNA double strand breaks and apoptotic cell death (1). Irinotecan is FDA approved for use in the front-line and second-line treatment of colorectal cancer. It has also demonstrated activity in a variety of other non-hematologic tumors. The recently updated ASCO antiemetic guidelines characterize irinotecan as having moderate emetic risk. (2). However, the emetogenic potential of this agent has been poorly characterized and there are no published prospective trials with emesis as a primary-end point. In addition there is a complete paucity of information on the potential of irinotecan to induce emesis beyond the first day after chemotherapy, so-called delayed emesis. Best characterized following cisplatin, delayed emesis is also associated with a number of other chemotherapy agents that similar to irinotecan appear to be moderately emetogenic such as carboplatin, cyclophosphamide and doxorubicin. Antiemetic prophylaxis for delayed emesis following irinotecan is not routinely prescribed at the present time. Prospectively obtained information on the potential of irinotecan to cause delayed emesis would be helpful in guiding appropriate antiemetic practice.
