BACKGROUND
Multiple classes of molecular biomarkers have been studied as potential predictors for rectal cancer (RC) response. Carcinoembryonic antigen (CEA) is the most widely used blood-based marker of RC and has proven to be an effective predictive marker. Cancer antigen 19-9 (CA19-9) is another tumor biomarker used for RC diagnosis and postoperative monitoring, as well as monitoring of the therapeutic effect. Using a panel of tumor markers for RC outcome prediction is a practical approach.
AIM
To assess the predictive effect of pre-neoadjuvant chemoradiotherapy (NCRT) CEA and CA19-9 levels on the prognosis of stage II/III RC patients.
METHODS
CEA and CA19-9 levels were evaluated 1 wk before NCRT. According to the receiver operating characteristic curve analysis, the optimal cut-off point of CEA and CA19-9 levels for the prognosis were 3.55 and 19.01, respectively. The novel serum tumor biomarker (NSTB) scores were as follows: score 0: Pre-NCRT CEA < 3.55 and CA19-9 < 19.01; score 2: Pre-NCRT CEA > 3.55 and CA19-9 > 19.01; score 1: Other situations. Pathological information was recorded according to histopathological reports after the operation.
RESULTS
In the univariate analysis, pre-NCRT CEA < 3.55 [
P
= 0.025 for overall survival (OS),
P
= 0.019 for disease-free survival (DFS)], pre-NCRT CA19-9 < 19.01 (
P
= 0.014 for OS,
P
= 0.009 for DFS), a lower NSTB score (0-1
vs
2,
P
= 0.009 for OS,
P
= 0.005 for DFS) could predict a better prognosis. However, in the multivariate analysis, only a lower NSTB score (0-1
vs
2; for OS, HR = 0.485, 95%CI: 0.251-0.940,
P
= 0.032; for DFS, HR = 0.453, 95%CI: 0.234-0.877,
P
= 0.019) and higher pathological grade, node and metastasis stage (0-I
vs
II-III; for OS, HR = 0.363, 95%CI: 0.158-0.837,
P
= 0.017; for DFS, HR = 0.342, 95%CI: 0.149-0.786,
P
= 0.012) were independent predictive factors.
CONCLUSION
The combination of post-NCRT CEA and CA19-9 was a predictive factor for clinical stage II/III RC patients receiving NCRT, and the combined index had a stronger predictive effect.