Chemotherapy-induced carcinoembryonic antigen surge in patients with metastatic colorectal cancer

Objectives: To investigate the incidence of carcinoembryonic antigen (CEA) surge in patients with metastatic colorectal cancer (MCRC) and its implications on clinical outcome. Methods: A retrospective chart review of patients with MCRC treated with chemotherapy at Roswell Park Cancer Institute from January 2000 to May 2004 was conducted. A CEA surge was defined as an increase of >20% from baseline followed by a >20% drop in one or more subsequent CEA levels compared to baseline. The incidence of CEA surge and its association with clinical outcome was investigated. Results: Eighty-nine patients were evaluable for CEA surge. A CEA surge was documented in 10 patients. The CEA surge lasted <4 months in all 10 patients and was associated with a clinical benefit. No significant correlation was noted between CEA surge and site of primary tumor, site of metastatic disease, or tumor differentiation. Conclusions: CEA surges can be observed in patients receiving chemotherapy for MCRC and are often associated with a clinical benefit. None of the CEA surges satisfied the American Society of Clinical Oncology definition of CEA progression. A rise in CEA after initiation of chemotherapy, unless lasting >4 months, cannot be used as an indicator of progressive disease.