Predictive Value of Leukocyte- and Platelet-Derived Ratios in Rectal Adenocarcinoma

Advances in treatment of rectal cancer have improved survival, but there is variability in response to therapy. Recent data suggest the utility of the lymphocyte-to-monocyte ratio (LMR), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) in predicting survival. Our aim was to examine these ratios in rectal cancer patients and determine whether any association exists with overall survival (OS).

Using prospectively maintained institutional data, a query was completed for clinical stage II-III rectal adenocarcinoma patients treated from 2002 to 2016. We included patients who had a complete blood count collected before neoadjuvant chemoradiation (pre-CRT) and again before surgery (post-CRT). The LMR, NLR, and PLR were calculated for the pre-CRT and post-CRT time points. Potential cutpoints associated with OS differences were determined using maximally selected rank statistics. Survival curves were compared using log-rank tests and were adjusted for age and stage using Cox regression.

A total of 146 patients were included. Cutpoints were significantly associated with OS for pre-CRT ratios but not for post-CRT ratios. Within the pretreatment group, a "low" (<2.86) LMR was associated with decreased OS (log-rank P = 0.004). In the same group, a "high" (>4.47) NLR and "high" PLR (>203.6) were associated with decreased OS (log-rank P < 0.001). With covariate adjustment for age, and separately for final pathologic stage, the associations between OS and LMR, NLR, and PLR each retained statistical significance.

If obtained before the start of neoadjuvant chemoradiation, LMR, NLR, and PLR values are accurate predictors of 5-y OS in patients with locally advanced rectal adenocarcinoma.