Prognostic and predictive value of CA19-9 in metastatic colorectal cancer.

Abstract

354 Background: CA19-9 has been approved by FDA as a tumor marker in pancreatic cancer. The prognostic and predictive value of CA19-9 in metastatic colorectal cancer (mCRC) is still unclear. Moreover, CA19-9, a sialyl Lewis A antigen, acts as an adhesion factor of cells lining the blood vessels, but the association between the CA19-9 value and the effect of bevacizumab (BV) has not been reported. Methods: We conducted a retrospective review of 239 patients undergoing first-line chemotherapy by oxaliplatin-based regimens at a single institution from April 2005 to December 2009. The relationship between the CA19-9 value at baseline and the various clinicopathological factors and survival data was analyzed. Results: Median age was 62 years (range 23–83 years). 133 patients had a baseline CA19-9 value above the normal upper limit (>50 U/ml, high group), 86 had ULN (<50 U/ml, normal group), and 20 had below measurement sensitivity (example of Lewis antigen negativity, low group). The rate of KRAS MT and BRAF MT was high in the CA19-9 high group (KRAS MT 41.0%/BRAF MT 10.7%) as compared with the CA19-9 normal group (KRAS MT 22.7%/BRAF MT 0%). The high CA19-9 value in all the cases was a poor prognostic factor compared with the normal value (HR: 1.61, 95% CI: 1.28–2.04, p < 0.001). In multivariate analysis, the high CA19-9 value was an independent prognostic factor (HR:1.45, 95% CI: 1.10–1.91, p = 0.0082). Moreover, in the CEA normal group (<5 ng/ml), the high CA19-9 value was a poor prognostic factor as compared with the normal CA19-9 value (HR: 1.90, 95% CI: 1.00–3.62, p = 0.049). In the CA19-9 normal group, the median survival time (MST) with BV was longer than that without BV (53.2 vs 28.4 months, HR: 0.47, 95% CI: 0.30–0.93, p = 0.030). Furthermore, in the CA19-9 high group, MST with BV was longer than that without BV (20.6 vs 16.6 months, HR: 0.65, 95% CI: 0.44–0.97, p = 0.033). Conclusions: The CA19-9 value before chemotherapy in mCRC is an independent prognostic factor and intercorrelated with KRAS/BRAF MT. Bevacizumab exhibits clinical activity in mCRC patients, regardless of CA19-9 value.