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J Cancer. 2011 Apr 1;2:177-85.

Mature Results of a Prospective Randomized Trial Comparing 5-Flourouracil with Leucovorin to 5-Flourouracil with Levamisole as Adjuvant Therapy of Stage II and III Colorectal Cancer- The Israel Cooperative Oncology Group (ICOG) Study.

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1. Department of Oncology, Tel Aviv-Souraski Medical Center, Tel Aviv, Israel.



Survival benefit with adjuvant therapy was shown in patients with Stage III colorectal cancer (CRC). This study evaluates long-term (10-year) outcome in patients with CRC randomly assigned to adjuvant 5-Fluorouracil/Leucovorin (5FU+LV) or 5-FU/Levamisole (5FU+LEV).


Between 1990 and 1995, 398 patients with curatively resected Stage II-III CRC were randomly assigned to adjuvant 5FU+LV or 5FU+LEV for 12 months.


No difference was evident in 10-year relapse-free or overall survival between study groups. Grade III toxicity was similar between groups; however, neurotoxicity was significantly greater with 5FU+LEV (p=0.02) and gastrointestinal toxicity with 5FU+LV (p=0.03). Female patients treated with 5FU+LEV had improved overall survival.


Adjuvant treatment of CRC is still based on leucovorin modulated fluorouracil. The long-term follow-up results of this trial indicate that the adjuvant treatment of Stage II-III CRC with 5FU+LV or 5FU+LEV is equally effective. The finding of improved survival in female subjects treated with 5FU+LEV warrants further study to determine if Levamisole is a better modulator of 5-FU than Leucovorin in this patient subset.


5-fluorouracil; adjuvant chemotherapy; colorectal cancer; leucovorin; levamisole; survival


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