Predictive value of serum and tissue carcinoembryonic antigens for radiologic response and oncologic outcome of rectal cancer

Purpose: The clinical importance of tissue CEA levels for predicting tumor response to preoperative chemoradiotherapy (CRT) for rectal cancer has not been studied. Methods: Serum CEA levels and tissue CEA expressions for 117 patients who underwent preoperative CRT for rectal cancer, were prospectively collected and analyzed at a tertiary university hospital Results: The median follow-up time was 49 months (range, 3–61 months), and the 5-year disease-free survival (DFS) rate was 68.3 %. In multivariate analysis, serum CEA (log-transformed value) [odds ratio (OR) = 0.741, 95 % confidence interval (CI) 1.588–40.422, P = 0.021], tissue CEA/GAPDH ratio (OR = 3.673, 95 % CI 1.316–12.081, P = 0.019), and tumor circumferentiality (OR = 2.960, 955 CI, 1.101–8.999, P = 0.040) were the independent predictors for good tumor response to CRT. Serum CEA level was significant prognostic factor for DFS (P = 0.004) in multivariate analysis. However, tissue CEA was not associated with DFS. Conclusions: Both serum and tissue CEA were significant factors for predicting good tumor response following preoperative CRT. However, tissue CEA was not associated with the oncologic outcome. The possibility of radiologic resistance of high CEA tumors is expected to be investigated through further studies.