DEVELOPMENTS AND CURRENT STATUS OF ADJUVA NT CHEMO AND RADIOTHERAPY FOR COLORECTAL-CANCER

A review is given of the historical and current concepts of adjuvant c hemo-and radiotherapy of colorectal cancer. Early studies analyzing th e use of single drug regimens were followed by a second study generati on investigating adjuvant chemotherapeutic combinations. 5-FU proved t o be the most efficient single drug investigated and 5-FU/MeCCNU/vincr istin the most efficient chemotherapeutic combination, but no signific ant improvement in 5-year survival rates was achieved. Clear progress was noted with the introduction of levamisol (LEV) for modulation of 5 -FU. A 33% improval in the 5-year survival rate in patients with stage III colon carcinoma was documented. It was therefore recommended (NIH consensus conference 1990) that all patients with stage III colon car cinoma be treated with this regimen unless admitted to other trials of adjuvant therapy. Preoperative radiotherapy with a dosage of 35-45 Gy can lead to downstaging of rectal cancer. Nevertheless, significant i mprovement in patient survival has not been proved convincingly using either isolated pre- or postoperative adjuvant radiotherapy. However, combined radiochemotherapy has been shown to improve both patient surv ival and local tumor control compared to surgical resection alone. It is therefore recommended that all stage II and III rectal cancer patie nts be treated with adjuvant combined radiochemotherapy. 5-FU/MeCCNU i s currently expected to be the most efficient chemotherapy in combinat ion with radiotherapy. Early data point out that MeCCNU could possibly be omitted. Intraoperative radiotherapy (IORT) allows further dosage oscalation in order to improve local tumor control without affecting r adiosensitive structures. Available data are still sparse and mostly b ased on the treatment of advanced carcinoma. A general validation of I ORT is not yet possible, but current data are promising.