Tumour markers as early predictors of response to chemotherapy in advanced colorectal carcinoma

Background: To evaluate the reliability and validity of serum carcinoembryonic antigen (CEA), tissue polypeptide-specific antigen (TPS), vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in monitoring palliative chemotherapy in advanced colorectal cancer (ACRC). Methods: Serum was prospectively collected from 87 patients with ACRC treated with first-line 5-fluorouracil and leucovorin before and 2, 4 and 10 weeks after induction. Results: Eight patients had normal baseline TPS levels, and these patients had a favourable outcome with prolonged survival and a higher rate of objective responses than patients with elevated TPS levels. At 10 weeks, all responders had a decreasing TPS value. The sensitivity for a decrease of >25% using TPS was 83% and 86% for objective and subjective responses, respectively, and the specificity was 65% and 72%, respectively. CEA had, in the same setting, a sensitivity of 45% and 46%, respectively, and the specificity was 88%. VEGF was elevated in 54% of the patients and bFGF in 15% of the patients. The VEGF values decreased during therapy in 94% of the patients, but the changes in serial VEGF values did not correlate with survival or response. Tumour markers used together did not enhance the predictive values of TPS alone. Conclusions: Repeated measurements of CEA, VEGF and bFGF in serum are of limited value in monitoring chemotherapy in ACRC. TPS seems to be of greater interest, but does not predict exactly