The platelets-neutrophils to lymphocytes ratio: a new prognostic marker in metastatic colorectal cancer.

BACKGROUND

The cancer micro-environment is recognized as having an increasing importance in cancer progression. Immune cells originating from the peripheral blood are important elements of this environment. Thrombocytosis, neutrophilia and lymphocytopenia have been found to be negative prognostic indicators in many cancers. This study aims to evaluate the potential of the use of a novel hematological marker, the platelet-neutrophil to lymphocyte ratio (PNLR) as a practical, reliable, and inexpensive prognostic tool in metastatic colorectal adenocarcinomas.

METHODS

Charts from 305 patients with colorectal cancer were retrospectively reviewed. Of these, 152 had metastatic disease with complete follow-up data on progression and survival. Data were extracted and stratified by a PNLR cut-off point of 2,000. Baseline parameters of the two groups were evaluated and compared with the χ test. Univariate and multivariate Cox proportional-hazards regression analyses were performed on variables of interest.

RESULTS

A total of 102 (67.1%) patients had a PNLR of less than 2,000 while the index for 50 (32.9%) patients was 2,000 or higher. Patients with a PNLR above 2,000 had a shorter median progression-free survival (PFS) [6.5 13.3 months; hazard ratio (HR), 2.05; 95% CI, 1.32-3.19, P=0.001] than in patients with a PNLR below the threshold. Similar results were observed for median overall survival (OS) (9.6 21.8 months; HR, 2.33; 95% CI, 1.44-3.79, P=0.001). PNLR had a higher predictive HR than Eastern Cooperative Oncology Group (ECOG) performance status (PS).

CONCLUSIONS

In this retrospective analysis of metastatic colorectal cancer patients, PNLR had prognostic value for both OS and PFS. While other variables held significance for poorer prognosis, PNLR had the highest HR and the highest significance in multivariate analysis for both PFS and OS. Thus, it represents a powerful and objective prognostic tool in the evaluation of metastatic colorectal cancer patients that is readily available and does not require any additional expenses.