The prognostic value of serum CA 19-9 in patients with metastatic colorectal cancer.

Abstract

e15131 Background: CEA is regarded as the marker of choice for monitoring patients with colorectal cancer (CRC), but the value of using CA19-9 is insufficient. The prognostic value of serum CA19-9 in combination with CEA was evaluated in patients with metastatic CRC (mCRC) before first (1) and third line therapy (3LT). Methods: From April 2004 to May 2015, pretreatment serum samples were collected from 160 and 255 patients with mCRC before 1LT and 3LT, respectively. Median age was 64 [range 33-87] and male/female ratio 243(59%)/172(41%). Serum CA19-9 was determined by routine chemiluminescent immunometric assay (normal range 0-37 KU/l). Progression-free survival (PFS) and overall (OS) crude, adjusted hazard ratios (HR) and corresponding 95% confidence intervals (CIs) were estimated using Cox regression analysis. CA19-9 and CEA were included as log2-transformed continuous variables and adjustment included mutually between CA19-9 and CEA in addition to primary tumor location, sex and age. Results: In 3LT median pretreatment CEA levels were higher than in 1LT (59 µg/l [IQR 14-288] vs. 23[6-153] P < 0.01) while CA19-9 values were similar (112 KU/l [23-626] vs. 98[19-390]). In patients treated with 3LT univariate analysis showed that high levels of CA19-9 and CEA were associated with short PFS (CA19-9: HR = 1.06, 95% CI 1.02-1.10, P < 0.01; CEA: HR = 1.05, 1.00-1.09, P = 0.04). In 1LT neither CA19-9 nor CEA were significantly associated with PFS. In a multivariate analysis, none of the biomarkers were significantly associated with PFS. In patients treated with 3LT univariate analysis showed that high levels of CA 19-9 and CEA were associated with short OS (CA19-9: HR = 1.11, 1.07-1.16, P < 0.01; CEA: HR = 1.1, 1.06-1.16, P < 0.01). In patients treated with 1LT high levels of CA-19-9 but not CEA was significantly associated with a shorter OS (HR = 1.07, 1.00-1.14, P = 0.04). In 3LT multivariate analyses showed that high levels of CA19-9 and CEA were the only factors associated with a shorter OS (CA19-9: HR = 1.08, 1.03-1.13, P < 0.01; CEA: HR = 1.07, 1.01-1.14, P < 0.01), while there was no significant association to OS in 1LT. Conclusions: Serum CA19-9 may be a valuable prognostic biomarker in combination with CEA in mCRC patients receiving third line therapy.