Background: The role of carcinoembryonic antigen (CEA) change patterns in tumor response and long-term outcome is unclear. This study aimed to investigate the correlation between changes in CEA levels and tumor response as a potential prognostic model.
Methods: CEA levels were determined from baseline to progression. A χ2 test was used to assess the correlation between CEA changes and tumor response. Univariate and multivariate COX models were used to explore the correlation of CEA changes to progression-free survival (PFS) and overall survival (OS).
Results: All 114 patients were divided into five groups according to CEA change pattern (A: patients had an initial fast CEA decrease that then turned into a slow increase; B: patients had an initial slow CEA decrease that then turned to a slow increase; C: patients had a continually slow CEA increase; D: patients had a continually fast CEA increase; E: patients had an initial fast CEA decrease that then turned into a fast increase). Patients in Group A had the longest OS and PFS while Group E patients had the shortest OS. Baseline to week 12 and week 12 to week 18 change rates were consistent with tumor response and progression, respectively. An increase in CEA level by ≥2.7% from week 12 to 18 was an independent negative prognostic factor of OS.
Conclusions: CEA changes mirror the tumor response to first-line chemotherapy and are associated with prognosis. CEA monitoring may be a substitute for computed tomography during the CEA stable period of treatment.
Keywords: CEA change; Metastatic colorectal cancer; Progression; Tumor response.