Prognostic Significance of the C-Reactive Protein-to-Albumin Ratio in Patients With Metastatic Colorectal Cancer Treated With Trifluridine/Thymidine Phosphorylase Inhibitor as Later-line Chemotherapy

Background/Aim: New drugs for metastatic colorectal cancer (mCRC) have been recently developed for use in later-line chemotherapy and have contributed to further prolongation of the survival of patients. However, in later-line chemotherapy, treatment failure may lead to discontinuation of chemotherapy and the transition to best supportive care. Therefore, a biomarker able to predict the effects of later-line chemotherapy is required. The C-reactive protein-to-albumin ratio (CAR), which is an inflammatory marker, has been reported to correlate with therapeutic outcome in patients with mCRC who underwent first-line chemotherapy. However, the significance of the CAR as a marker for predicting the chemotherapeutic outcome in patients with mCRC treated with later-line chemotherapy is unknown. Patients and Methods: We retrospectively reviewed the medical records of 40 patients with mCRC who were treated with trifluridine/thymidine phosphorylase inhibitor (FTD/TPI) as a later-line chemotherapy. The CAR was calculated from the blood samples obtained within 1 week before the initiation of FTD/TPI by dividing the serum C-reactive protein level by the serum albumin level. Results: According to the receiver operating characteristic curve analysis, we set 0.122 as the CAR cut-off, and patients were classified into groups with high or low CAR. The low-CAR group had a significantly higher disease control rate than the high-CAR group. The progression-free and overall survival rates were significantly better in the low-CAR group than in the high-CAR group. A high-CAR was associated with a greater number of prior regimens, higher serum lactate dehydrogenase level and more organs with metastases, considered to be correlated with the rate of disease progression. However, no significant differences were observed in the incidence of grade 3 or more adverse events, the relative dose intensity, or the rate of discontinuing chemotherapy between the two groups. Conclusion: The CAR may be a useful indicator for predicting the chemotherapeutic outcome in patients with mCRC treated with FTD/TPI as a late-line chemotherapy. The correlation between a high-CAR and poor prognosis was presumed to be due to the rate of cancer growth and increased resistance to chemotherapy rather than an insufficient dose of the drug.