Irinotecan in preoperative combined-modality therapy for locally advanced rectal cancer.

Irinotecan (CPT-11, Camptosar) is a semisynthetic water-soluble derivative of the plant alkaloid camptothecin. This review will focus on the potential use of irinotecan in combination with fluorouracil (5-FU) in the preoperative combined-modality treatment of advanced rectal cancer. The laboratory studies that define the mechanism of fluoropyrimidine- and camptothecin-mediated radiosensitization are discussed, and the rationale for combined-modality therapy using radiation with 5-FU and irinotecan is presented.