A randomized trial comparing defined-duration with continuous irinotecan until disease progression in fluoropyrimidine and thymidylate synthase inhibitor-resistant advanced colorectal cancer.

OBJECTIVE

Irinotecan given until disease progression is an accepted standard treatment for advanced colorectal cancer (CRC) resistant to fluoropyrimidines. It is not known whether a predefined period of irinotecan treatment would result in similar duration of disease control. We performed a multicenter phase III trial to compare the two policies of defined-duration versus continuous irinotecan treatment.

METHODS

Three hundred thirty-three eligible patients with advanced CRC progressing on or within 24 weeks of completing fluoropyrimidine-based chemotherapy were prospectively registered. After receiving eight cycles of irinotecan given at 350 mg/m2 once every 3 weeks, 55 patients with responding or stable disease were randomly assigned to stop irinotecan (n = 30) or continue until disease progression (n = 25). Registered patients were not randomly assigned predominantly due to disease progression (n = 236) and intolerable toxicity (n = 38).

RESULTS

From the time of random assignment, there were no differences in failure-free survival (P = .999) or overall survival (P = .11) between the two arms. No difference was seen in mean global health status quality-of-life score between the two arms at 12 weeks after random assignment. No grade 3 diarrhea and febrile neutropenia was seen in the continue-irinotecan arm after random assignment.

CONCLUSIONS

For most patients, the decision to continue on irinotecan beyond 24 weeks is influenced by disease progression or treatment-related toxicity. However, for 17% of patients in whom this decision is clinically relevant, there seems to be little benefit from continuing irinotecan, though the drug was well tolerated without any deterioration in quality of life.