Lack of effectiveness of combined 5- fluorouracil and methyl-CCNU therapy in advanced colorectal cancer.

Fifty-two patients with advanced colorectal cancer were treated with a combination of 5-Fluorouracil (FU) plus methyl-1,3-cis (2-chlorethyl)-1-nitrosourea (MeCCNU). The treatment schedule program consisted of 5-FU, 300 mg/m2 i.v. bolus, daily for 5 days, repeated at 5-week cycles. MeCCNU was administered at a dose of 150 mg/m2 orally on day 1 of the initial 5-day course of FU and repeated at 10-week intervals. Eighty-four percent (44/52) of the patients with advanced measurable disease developed progressive disease by 4 months or one and a half cycles of therapy. Only two patients had definite partial regression of tumor over the period of observation. The median survival of all patients measured from the onset of treatment was 9 months and is comparable to literature reports of untreated advanced colorectal cancer. This therapeutic trial of combined FU and MeCCNU, employing a dose-schedule distinct from but comparable to previous studies has failed to confirm the substantial response rate reported by other investigators and reinforces the need for exploring new drugs and combinations of drugs in advanced colorectal cancer. The use of sequential plasma CEA determinations as a primary monitor of therapy is discussed in relationship to clinical trials and guidelines for determining significant quantitative changes in plasma CEA levels are recommended.