Irinotecan is one of the newer cytostatic agents which have a clinically re
levant antineoplastic activity in colorectal cancer. As single-agent irinot
ecan induced an overall objective response rate of about 25% in chemonaive
patients and of about 13% in 5-fluorouracil (5-FU)-pretreated patients.
In the past years an increasing number of various combinations of irinoteca
n with oxaliplatin, tomudex and especially 5-FU/folinic acid (FA) were inve
stigated in phase I/II/III trials. These trials showed that these combinati
ons are active and that the toxicity profile is acceptable and manageable.
In phase II trials combinations of irinotecan plus 5-FU/FA induced overall
objective response rates of 40-70% in chemonaive patients and of 20-30% in
patients with prior 5-FU-based chemotherapies. Two large randomized trials
compared the combination of irinotecan plus either bolus 5-FU/FA or 'infusi
onal' 5-FU/FA with 5-FU/FA alone as first-line chemotherapy for metastatic
disease. These two trials consistently showed that the combination was stat
istically significantly superior to 5-FU/FA alone concerning the induction
of objective responses (39 vs. 21% and 35 vs. 21%), median time to progress
ion (7.0 vs. 4.3 months and 6.7 vs. 4.4 months), and median survival (14.8
vs. 12.6 months and 17.4 vs. 14.1 months). Quality of life analysis perform
ed in both studies did not show that adding irinotecan to 5-FU/FA had a neg
ative impact on overall quality of life parameters of the patients. Based o
n these study results, the combination of irinotecan plus 5-FU/FA has to be
considered as a new standard first-line treatment for patients with metast
atic colorectal cancer.