Retrospective evaluation of toxicity in three different schedules of adjuvant chemotherapy for patients with resected colorectal cancer

Adjuvant chemotherapy has been established since 1990 as standard treatment for patients with colon cancer stage III (Dukes' C). Chemotherapeutic sche mes combining 5-fluorouracil with levamisole or leucovorin have shown signi ficant advantage over surgery alone. Adjuvant trials are being currently im plemented to investigate some relevant questions, such as which is the opti mal duration of chemotherapy, as well as the possible advantage of levamiso l versus leucovorin schedules, and of high-dose versus low-dose leucovorin. While these trials are ongoing, a retrospective evaluation of the toxicity associated with the different chemotherapeutic schemes might be of help wh en choosing the most appropriate regimen for individual patients not involv ed in clinical trials. A total of 519 patients subjected to three different schedules of adjuvant chemotherapy between 1993 and 1996, were evaluated f or toxicity according to the NCI-CTC criteria. Chemotherapeutic regimens we re: 5-fluorouracil plus levamisole (5-Fu+Lev; Moertel schedule), 5-fluorour acil plus low-dose leucovorin (5-Fu+LVLD; NCCTG schedule) and 5-fluorouraci l plus high-dose leucovorin (5-Fu+LVHD; IMPACT-modified schedule). 5-Fu+LVL D is significantly more toxic than the other two regimens in terms of neutr openia, mucositis and diarrhea. Delay in chemotherapy and dose reduction of 5-fluorouracil were also more frequent in the 5-Fu+LVLD group. However, th e percentage of prematurely discontinued treatments was significantly highe r in the 5-Fu+Lev group. Information on toxicity of adjuvant chemotherapy f or colon cancer may help medical oncologists to choose the most appropriate regimen for individual patients not involved in clinical trials.