Elevated Platelet to Lymphocyte Ratio Is Associated with Poor Survival Outcomes in Patients with Colorectal Cancer

Platelet to lymphocyte ratio (PLR) is a parameter reflecting inflammatory responses in patients with cancer. Several studies have investigated the prognostic value of PLR in patients with colorectal cancer (CRC); however, the results are controversial. Thus, we carried out a meta-analysis to evaluate the association between PLR and CRC prognostication. Relevant articles were retrieved through PubMed, Embase, and Web of Science, and pooled hazard ratio (HR) and 95% confidence interval (CI) were computed by using STATA V.12.0. Both the random-effects model and fixed-effects model were utilized. A total of 13 studies (14 cohorts) with 8,601 patients were included in the meta-analysis. Pooled HRs and 95% CIs demonstrated that increased PLR predicted poor overall survival (OS) (HR = 1.81, 95% CI: 1.42-2.31, p< 0.001; I-2 = 65%, Ph = 0.002), disease-free survival (DFS) (HR = 1.84, 95% CI: 1.22-2.76, p = 0.003; I-2 = 78.3%, Ph < 0.001) and recurrence-free survival (RFS) (HR = 1.84, 95% CI: 1.41-2.41, p< 0.001; I 2 = 0, Ph = 0.686), although this was not the case for cancer-specific survival (CSS) (HR = 1.75, 95% CI: 0.59-5.17, p = 0.309; I-2 = 66.2%, Ph = 0.085) or time to recurrence (TTR) (HR = 1.21 95% CI: 0.62-2.36, p = 0.573; I-2 = 58.4%, Ph = 0.121). Subgroup analysis showed that PLR enhanced the prognostic value for OS in Caucasian patients, in small sample studies and for metastatic disease; however, this was not the case with rectal cancer. Furthermore, elevated PLR predicted reduced DFS in Caucasians and not in Asians. In conclusion, our meta-analysis showed that high PLR was a significant biomarker for poor OS, DFS, and RFS in patients with CRC; however, it had no association with CSS or TTR.