A comprehensive review of the literature concludes that the neutrophil-to-lymphocyte ratio (NLR) is a factor can be used to predict overall survival in patients with malignant pleural mesothelioma (MPM).
The authors, based in China, recently published their study, “Prognostic significance of neutrophil-to-lymphocyte ratio in patients with malignant pleural mesothelioma: a meta-analysis,” in the open access journal Oncotarget.
Researchers in the cancer field are increasingly noticing enhanced inflammatory responses in various cancer models. Inflammatory cells such as neutrophils, platelets, and lymphocytes that reside in the environment surrounding tumors may impact tumor development.
More importantly, several studies have shown that increased systemic inflammation is a poor predictor for overall survival (OS) in several cancer types, including gastrointestinal, pancreatic, and renal cancers.
The NLR is typically derived from blood counts and is a noninvasive measure of an inflammatory response. This simple ratio has been related to poor survival for a variety of cancers such as renal cell carcinoma, colorectal cancer, hepatocellular carcinoma, prostate cancer, and gastric cancer.
But there is some discrepancy in the literature regarding NLR’s ability to act as a prognostic biomarker for MPM. The current study pooled the results from 11 studies, totaling 1,533 patients of Asian or Caucasian descent. These studies were published between 2010 and 2016.
Results from the study show that, overall, an elevated NLR was significantly associated with a poor OS in patients with MPM. Patients with high NLR are 48 percent more likely to have a worse outcome compared to patients with a low NLR.
When stratified by different subgroups such as ethnicity or study, a significant association between NLR and OS was also observed, which indicates the robustness of this conclusion.
NLR level was also associated with histology, where patients with non-epithelioid histological subtype were 41 percent more likely to have an elevated NLR. No associations between NLR level and gender, tumor stage, or performance status (PS) score were observed.
There are several limitations to this study. First, the optimal cut-off to determine “high” versus “low” NLR is unclear. In the studies included in the current analysis, the cut-off values ranged from 3 to 5 and were based on the median value of all patients included in the particular study.
A subgroup analysis showed that NLR was able to predict overall survival when a cut-off of 3 or 5 was used, but not 4. Future studies should determine the optimal cut-off and a standard should be set in place.
Additionally, differences in baseline features included in the studies, such as histology, treatment, and follow-up period, may influence the results of the current study.
The authors conclude that “the NLR could be useful for predicting survival of patients with MPM,” but also suggest that due to the limitations discussed, “further studies were warranted to conform to the exact value of NLR in the prognosis of MPM.”