The prognostic value of neutrophil-to-lymphocyte ratio in colorectal cancer: A systematic review

BACKGROUND AND OBJECTIVES: The detection of a simple and reliable prognostic biomarker for colorectal cancer (CRC) outcomes remains a significant challenge. The use of neutrophil-to-lymphocyte ratio (NLR), has been reported to predict surgical and survival outcomes. The aim of our review was to assess the predictive value of pre-operative NLR in predicting post-operative outcomes in CRC. METHODS: A systematic review of the available studies on NLR in CRC was performed. Primarily, we assessed its ability to predict survival outcomes, and highlight values that would help adjuvant therapy choices. RESULTS: 19 studies comprising 10 259 patients were included. Eleven and eight studies reported on patients with localized CRC and colorectal liver metastasis, respectively. Five-year survival for those with localized CRC was 77.2% in patients with a “low” pre-operative NLR versus 50.8% in those with a “high” pre-operative NLR value. Alternatively, for patients with colorectal liver metastasis, patients with a “high” pre-operative NLR value had a 5-year survival of 27%. CONCLUSION: Elevated pre-operative NLR>5 is associated with poorer long-term survival in both patients with localized CRC and those with liver metastasis. NLR is a useful biomarker in delineating those patients with poorer prognosis and whom may benefit from adjuvant therapies.