Adjuvant therapy for colorectal cancer

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Abstract
In spite of the improvements in surgical techniques and intensive care therapy, no appreciable improvement in the prognosis for patients with colorectal cancer has been made in recent years. Several types of adjuvant treatment, including radiotherapy, chemotherapy, and immunotherapy, have therefore been proposed and used in clinical trials, mainly in the United States and western Europe. The results obtained by the Gastrointestinal Group of the European Organization for Research and Treatment of Cancer (EORTC), using preoperative radiation therapy with 3450 rads, are reported here; this therapy results in a reduction in the number of local recurrences and also appears to prolong the five-year survival period, although a longer follow-up is required to confirm this. According to the Gastrointestinal Tumor Study Group (GITSG), postoperative radiation therapy with chemotherapy seems to prolong the tumor-free interval in stages B2 and C when compared to surgery alone. Nonspecific immunotherapy does not appear to improve surgical results either in terms of local recurrences or survival. Some clinical trials suggest that systemic polychemotherapy benefit subgroups of patients with colorectal cancer. Toxicity is still very high, however; 5-FU is the more active and safe single agent but, due to the low response rate, it appears essential to identify new, more active drugs. Particular attention has been focused recently on prophylactic infusion chemotherapy of the liver, and clinical trials are now being made by several groups, including the EORTC. Preliminary results seem to show a reduced incidence of liver metastases in patients infused with 5-FU after radical surgery. Adjuvant therapy in colorectal cancer patients undergoing radical surgery has so far given encouraging results. Future results are awaited with optimism, but they must be achieved through prospective clinical trials conducted by well-organized cooperative groups.