Cut-off values of preoperative inflammatory parameters for overall survival
By X-tile software, we established the optimal cut-off values for NLR (NLR=2.29), LMR (LMR=4.81), PLR (PLR=112.11) and dNLR (dNLR=1.66). Then we identified the cut-off values from the minimum P value according to the OS (Figure 1). Patients were then divided into different subgroups by the established cut-off values.
Patient characteristics
We enrolled 214 patients in our cohort, of which there were 130 males (60.7%) and 84 females (30.9%). The median age of the cohort at diagnosis was 41 years (range: 5-79 years), and 168 patients (78.5%) were above 50 years old. 162 patients underwent total resections (75.7%), and 52 patients had subtotal resections (24.3%). In the cohort, there were 132 patients being diagnosed with WHO grade II (61.7%) and the other 82 WHO grade III (38.3%), including 65 diffuse astrocytomas (WHO grade II), 21 oligodendrogliomas (WHO grade II), 46 oligoastrocytomas (WHO grade II), 65 anaplastic astrocytomas (WHO grade III), 5 anaplastic oligodendrogliomas (WHO grade III) and 12 anaplastic oligoastrocytomas (WHO grade III). All the patients accepted some form of radiotherapy and/or chemotherapy after the operation.
IDH mutations were detected in 168 (78.5%) cases. TERT promoter mutations were detected in 79 (36.9%) cases. Among the 168 IDH mutant cases, there were 159 cases harboring IDH1 mutations and 9 cases harboring IDH2 mutations. Chromosome 1p/19q codeletion was found in 57(26.6%) glioma tissues.
A total of 144 patients (67.3%) were divided into NLR low (≤2.29) group, 113 patients (52.8%) were divided into LMR low (≤4.81) group, 134 patients (62.6%) were divided into PLR low (≤112.11) group and 139 (65.0%) patients were divided into dNLR low (≤1.66) group. (Table 1)
Associations between preoperative inflammatory parameters and other clinical variables
We also examined whether or not certain baseline variables were associated with NLR, LMR, PLR and dNLR level. We found that the PLR level was correlated with gender (p<0.001). What’s more, 1p19q codeletion represented a low level of NLR (p=0.045). No other significant associations were found between inflammatory parameters and clinical variables. (Table 2)
Correlations between preoperative NLR, LMR, PLR and dNLR
Correlations between these parameters were assessed using Spearman analysis. Significant correlations were found between all of these inflammatory parameters. (Table S2)
Prognostic values of preoperative inflammatory parameters for WHO grade II and III diffuse gliomas
During the follow-up period, the median OS of these 214 cases was 5.9 years, and the median PFS was 4.7 years. The relationships between NLR, LMR, PLR, dNLR levels and survival outcomes for WHO grade II and III diffuse gliomas were presented in Figure 2. NLR>2.29 (p=0.006), LMR≤4.81 (p=0.047) and dNLR>1.66 (p=0.002) was associated with poor OS. No significance was found between different PLR level and OS of the cohort. What’s more, these inflammatory variables also showed no association with PFS. So higher NLR, higher dNLR and lower LMR foreboded a worse prognosis of WHO grade II and III diffuse gliomas (Figure 2).
Then we performed univariate and multivariate analysis of preoperative inflammatory variables for OS of WHO grade II and III diffuse gliomas. Univariate analysis for OS demonstrated that age >50 years (p=0.012), glioma WHO grade III (p<0.001), IDH wild type (p<0.001), 1p19q intact (p=0.006), NLR>2.29 (p=0.004), LMR≤4.81 (p=0.036) and dNLR>1.66 (p=0.002) were associated with poor OS. On multivariate analysis for OS, glioma WHO grade III (p<0.001), IDH wild type (p=0.006), 1p19q intact (p=0.048) and NLR>2.29 (p=0.011) remained serving as independent prognostic indicators for poor outcome (Table 3). Moreover, univariate Cox regression showed no correlations between these preoperative inflammatory variables and PFS (Table S3).
Prognostic roles of preoperative inflammatory variables for prognosis in IDH mutant or wild-type, TERT promotor mutant or wild-type and 1p19q intact or codeletion subgroups of WHO II and III diffuse gliomas.
Then we divided the cohort into IDH mutant or wild-type subgroups, TERT promotor mutant or wild-type subgroups and 1p19q intact or codeletion subgroups, respectively.
As for IDH mutant or wild-type subgroups, univariate analysis showed prognostic significances of NLR >2.29 (p=0.016) and dNLR>1.66 (p=0.022) on OS in IDH mutant subgroup (n=168). Subsequent multivariate analysis indicated that only WHO grade III (p = 0.002) and TERT promotor mutation (p = 0.006) were independent prognostic factors for OS in IDH mutant WHO grade II and III diffuse gliomas. (Figure 3A-3B, Table 3) No significant associations were obtained between these preoperative inflammatory indicators and PFS. (Figure 3A-3B) Data indicated no correlations between these preoperative inflammatory indicators and prognosis of IDH wild-type subgroup of WHO II and III diffuse gliomas (data not shown).
In TERT promotor mutation subgroup (n=79), univariate analysis showed prognostic significances of NLR >2.29 (p=0.049) and LMR>2.29 (p=0.035) on OS, but subsequent multivariate analysis demonstrated that only age>50 (p=0.003), WHO grade III (p = 0.007) and IDH mutation (p <0.001) were independent prognostic factors for OS. No significant associations were obtained between these preoperative inflammatory indicators and PFS. (Figure 3C-3D, Table 4) In TERT promotor wild type subgroup (n=135), univariate analysis showed prognostic significance of dNLR >1.66 (p=0.018) on OS, and subsequent multivariate analysis demonstrated that WHO grade (p = 0.001) and dNLR >1.66 (p=0.024) were independent prognostic factors for OS. No significant associations were observed between these preoperative inflammatory indicators and PFS. (Figure 3E, Table 4)
In 1p19q intact subgroup (n=157), univariate analysis showed prognostic significance of NLR >2.29 (p=0.009) and dNLR >1.66 (p=0.005) on OS, NLR >2.29 (p=0.004) and dNLR >1.66 (p=0.001) on PFS. Subsequent multivariate analysis demonstrated that age>50 (p=0.010), WHO grade III (p = 0.001), IDH mutation (p =0.050) and dNLR >1.66 (p=0.005) were independent prognostic factors for OS, WHO grade III (p <0.001), IDH mutation (p =0.017) and dNLR >1.66 (p=0.004) were independent prognostic factors for PFS. (Figure 3F-3G, Table 5) Data indicated no correlations between these preoperative inflammatory indicators and prognosis of 1p19q codeletion subgroup of WHO II and III diffuse gliomas.
Prognostic roles of preoperative variables for prognosis in 5 molecular subgroups of WHO II and III diffuse gliomas.
Depending on a previous study 8, we divided the cohort into five molecular groups: triple-negative, mutation in TERT only, mutation in IDH only, mutations in both IDH and TERT, and triple-positive (mutations in both IDH and TERT plus 1p/19q codeletion). In IDH mutant only subgroup (n=88), we found dNLR >1.66 to be associated with OS (p=0.037) (Figure 3H, Table S1). No other correlations were observed significantly between the other four subgroups and these preoperative inflammatory variables (data not shown).