The impact of carcinoembryonic antigen flare in patients with advanced colorectal cancer receiving first-line chemotherapy

Background: Carcinoembryonic antigen (CEA) flare may have a favourable response to chemotherapy, but its impact on survival is unknown. This study aimed to evaluate the incidence of CEA flare and its impact on objective response rate (ORR), progression-free survival (PFS) and overall survival (OS). Patients and methods: Patients with histologically proven advanced colorectal cancer undergoing first-line chemotherapy with three or more serial CEA measurements (one at baseline and two or more during treatment) were included. Patients were grouped according to CEA kinetic as flare (F), decreasing CEA, normal baseline CEA, stable CEA and increasing CEA (I). Results: From January 2000 to February 2008, 837 patients were screened of whom 670 were eligible. CEA flare occurred in 78 (11.6%) patients. On multivariate analysis, compared with patients with increasing CEA, patients with CEA flare had a significantly better ORR [I versus F: 11% versus 73%; risk ratio (RR): 27.96; 95% confidence interval (CI): 9.55–81.88; P < 0.001], PFS (median 3.1 versus 8.3 months; RR: 0.38; 95% CI: 0.26–0.56; P < 0.001) and OS (median 10.9 versus 17.7 months; RR: 0.53; 95% CI: 0.34–0.82; P < 0.001). Conclusions: Compared with patients with rising CEA, flare was an independent favourable predictive and prognostic factor for tumour response and survival.