The Prognostic Impact of Serum Bilirubin in Stage IV Colorectal Cancer Patients

Background: Bilirubin played a great role in antioxidation and anticancer and has been considered as a promising prognostic factor of non-liver disease-related death in various cancers. The aim of this study was to assess the prognostic value of pre-treatment serum bilirubin in stage IV CRC patients.

Methods: Serum bilirubin including TBIL, DBIL, and IBI which were tested at pre-treatment were investigated in 154 stage IV CRC patients in Zhongda Hospital, Nanjing, China, from July 2005 to July 2011. X-tile program was used to determine the optimal cut-off values of these three biomarkers. Kaplan-Meier analysis, univariate, and multivariate cox regression as well as time-dependent ROC curve analysis were performed to evaluate the relations between serum bilirubin and survival outcomes.

Results: We got the results that the optimal cut-off points of serum TBIL, DBIL, and IBI levels were 12.9, 6.1, and 4.8 μmol/L, respectively. Univariate analysis showed that elevated TBIL, DBIL, and CEA were significantly associated with poor 5-year OS in stage IV CRC patients. Multivariate cox analysis indicated that the high DBIL (HR=1.603, 95%CI=1.053-2.442, P<.028) and CEA (HR=1.785, 95%CI=1.123-2.837, P=.014) could be identified as independent factors for poor OS. Furthermore, time-dependent ROC curves demonstrated that high DBIL had similar prognostic efficacy as elevated CEA for poor OS (AUC=0.63 and 0.61, respectively).

Conclusions: Pre-treatment elevated TBIL and DBIL levels were associated with poor OS in stage IV CRC patients. Moreover, DBIL could be considered as an independent prognostic biomarker for OS. Furthermore, DBIL had similar prognostic efficacy as CEA for OS.