Adjuvant chemotherapy in colorectal cancer with high-dose leucovorin and fluorouracil: impact on disease-free survival and overall survival.

Abstract

The rationale for using adjuvant chemotherapy in colorectal cancer is to achieve better disease control and thus reduce the high rates of tumor recurrence and mortality in patients who undergo curative surgery. The current literature, including relevant abstracts, on clinical trials of fluorouracil (5-FU) in combination with high-dose leucovorin as adjuvant chemotherapy for colorectal cancer is reviewed. The intent is not to present new data, but to present the reader with a broad perspective and larger patient experience on which to base well-reasoned treatment decisions. Published clinical trials and abstracts presented at the 1996 American Society of Clinical Oncology (ASCO) meeting that assessed 5-FU in combination with high-dose leucovorin as adjuvant chemotherapy for colorectal cancer were surveyed. End points of interest were disease-free survival (DFS), overall survival, and toxicity. In randomized trials that used high-dose leucovorin at doses that ranged from daily-times-five 200 mg/m2 to weekly 500 mg/m2 in combination with 5-FU, significant improvements in both DFS and overall survival were observed over surgery alone (control). In patients treated with high-dose leucovorin/5-FU, DFS rates ranged from 71% to 77% compared with control (58% to 64%). A similar trend was seen in overall survival, with a range of 75% to 84% compared with control (63% to 77%). Toxicities observed for high-dose leucovorin administered on a weekly or daily-times-five schedule were diarrhea, stomatitis, myelosuppression, and nausea. Overall, the results of these randomized trials support the use of high-dose leucovorin/5-FU as adjuvant therapy for colorectal cancer. Longer follow-up studies are needed to compare the benefits of these different regimens in terms of survival and to characterize adverse effects, especially those that may not be immediately evident. Adjuvant therapy with high-dose leucovorin/5-FU is an effective regimen that is well tolerated by many patients with colorectal cancer.