ADJUVANT THERAPY FOR COLORECTAL-CANCER - PRESENT AND FUTURE PERSPECTIVES

In recent years, adjuvant therapy for colorectal cancer has advanced c onsiderably. This article reviews these advances and provides an updat e of the most recent and ongoing trials. In 1990, adjuvant therapy bec ame the ''standard of care'' for patients with Stage III colon cancer (Dukes C) in the United States. Recent clinical trial data indicate th at adjuvant treatment may also be effective in patients with Stage II (Dukes B-2) colon cancer. The combination of 5-fluorouracil plus leuco vorin may slightly improve survival (5-10 percent) compared with the s tandard 5-fluorouracil plus levamisole combination. The three-drug reg imen (5-fluorouracil plus levamisole plus leucovorin) is more toxic, w ith no superior effect on survival. Intraportal chemotherapy, although it may significantly improve patient survival, does not decrease the frequency of liver metastases. However, it is still a promising form o f adjuvant therapy owing to its short treatment period and relatively equivalent effects in survival compared with that of systemic therapy. For patients with Stage II or Stage III rectal cancer, postoperative systemic 5-fluorouracil plus radiation therapy plus protracted venous 5-fluorouracil infusion is the most effective postoperative adjuvant r egimen. However, results from several studies show that preoperative r adiation alone or chemoradiation for advanced local rectal cancers mig ht also be effective while also improving resectability, decreasing mo rbidity, and increasing the chance that a sphincter-sparing procedure may be performed. The role of leucovorin in rectal cancer remains to b e determined. Immune therapies with agents such as interferon-alpha-2a , monoclonal antibody 17-1A, and autologous tumor vaccines are being a ssessed and could further improve survival.