Gliomas are a class of primary brain tumors that arise from glial cells and generally have a poor prognosis. ¹ The malignancy of these tumors is classified into four grades, with grade four being the most malignant. High-grade gliomas (grades 3 and 4) are characterized by high mitotic activity, angiogenesis, as well as a predisposition to central necrosis, peripheral edema, rapid disease evolution, and mean survival between 12 and 17 months. ^{1 – 3} Of these high-grade gliomas, the most common in adults are glioblastoma (grade 4), anaplastic astrocytoma, and anaplastic oligodendroglioma (both grade 3). ⁴ The most common complication of high-grade gliomas is venous thromboembolism (VTE), with an incidence of approximately 30%, ⁵ with approximately 50% of patients with glioblastoma having background activation of the coagulation system. ⁶ Furthermore, VTE tends to occur early in the disease course ⁵ and it seems that gliomas have relatively strong tendencies among neoplasms to cause coagulation dysfunction, when compared to other brain neoplasms. ^{7 , 8}

VTE is a common complication found in many cancers that can be triggered directly by the tumor, such as overexpression of tissue factor (TF), or indirectly through host secretion of cytokines or physical alteration of blood vessels. ^{9 , 10} It is well established that gliomas tend to overproduce active TF as a result of genetic mutations, activation of oncogenes or loss of suppressor genes such as p53 and PTEN. ^{9 , 11 – 14} This increased TF production is important in creating the host's pro-coagulant state, as TF initiates thrombin formation, a key step in thrombus formation via the extrinsic clotting pathway, which then results in reduced prothrombin time (PT). ⁶ Glioblastomas have also been shown to secrete thrombin, ¹⁵ which induces edema and leukocyte recruitment, ¹⁶ which results in a poor prognosis. ^{17 , 18} Tumor growth can also damage normal tissue, generate hypoxia and inflammation, and promote angiogenesis. ^{7 , 19} These secondary effects cause the release of procoagulant factors into the blood, such as VEGR, resulting in systemic activation of coagulation. ²⁰ It has also been suggested that disregulation of coagulation may stimulate tumor growth and metastasis. ^{7 , 13 , 19}

From this information, it is likely that understanding the clotting profiles of presurgical patients would be helpful in informing treatment with anticoagulants or determining prognosis based on coagulation profile. However, the judicious use of anticoagulants is important to not increase the risk of spontaneous intracerebral hemorrhage.

Due to the aggressive nature of high-grade glioma and the risk of VTE, we set out to evaluate how the coagulation profile of these patients differs from other patients with brain cancer using a clinical study with a control group.

The sample consisted of 21 patients with high-grade glioma (cases) and 42 patients with meningiomas (controls) that met acceptance criteria. Patients with meningiomas were chosen as the control group as these tumors are benign, allowing for a close comparison of patients that had similar conditions – with the only difference being malignancy. All patients came from the Peruvian regions of La Libertad, Ancash, and Cajamarca. The demographic characteristics of both groups are summarized in Table 1. Ages were similar, but the gender ratio was reversed between cases and controls. ECOG scores were also distributed differently between cases and controls. Furthermore, both groups had high proportions of diabetes (14%) and high blood pressure (29%).

Table 2 records the proportions of cases and controls with presurgical abnormal blood count and coagulation results. High proportions of abnormal results were found for aPTT, INR, lymphocytes, and neutrophiles.

Multivariate analysis showed that PT (aOR = 1.45; 95% CI = 1.13 – 2.28; p = 0.01), PC (aOR = 1.43; 95% CI = 1.06 – 2.25; p = 0.01) and ECOG 2 or 3 (aOR = 14.78; 95% CI = 3.71 – 58.86; p = 0.01) were associated with said high-grade glioma ( Table 3). An odds ratio (OR) in this case presents the odds of a case developing the abnormality vs the controls. Other components of the blood profile did not show significant differences between groups.

Because PT, PC, and ECOG score were initially measured as numerical variables and later dichotomized into normal and abnormal or high and low, further statistical analysis can be completed on these variables preserving their measured values. Regarding PT, values between 10 and 15 seconds were considered normal. The three cases outside of this range had PT of 16.44, 15.19, and 18.00 s, all above the normal range. A Welch’s t-test did not find a significant difference between cases ( M = 12.8, SD = 2.02) and controls ( M = 12.5, SD = .92, t(61) = .693, p = 0.529). A total of four glioma patients had abnormal PC, 1 had elevated PC (453 × 10 ⁹/L), while the other 3 had decreased PC (135, 118 and 135 × 10 ⁹/L). A Welch’s t-test using the measured PC for all participants did not find a statistically significant difference between cases ( M = 273, SD = 98.0) and controls ( M = 264, SD = 61.1, t(61) = .345, p = .732). Numerical ECOG score did show a statistically significant difference between controls ( M = 1.14, SD = .354) and cases ( M = 1.81, SD = .601, t(61) = -4.69, p < .001), with glioma cases having significantly higher ECOG scores.

We observe that PT was lengthened in the cases compared to the controls. This result is not consistent with two published studies using 58 cases and 22 meningioma controls ⁶ and 172 cases and 47 healthy controls. ²² The PT test evaluates the extrinsic coagulation pathway, which is initiated at the site of injury in response to the release of TF, which is often overexpressed in tumor cells. Another parameter calculated from PT that evaluates the extrinsic coagulation pathway is INR. The difference in INR between cases and controls came close to ( p = 0.08), but did not reach statistical significance. Numerical measurements of INR of cases ( M = 1.07, SD = .194) and controls ( M = 1.04, SD = 0.073) did not reach statistical significance either according to Welch’s t-test (t(61) = .706, p = .488). This result contrasts with another study comparing patients with healthy controls that found a statistically significant difference in these parameters. ²³ Although our results paint a different picture – one of longer coagualtion times, it would still be reasonable to affirm that glioma patients have a more altered extrinsic clotting pathway compared to other patients with benign brain tumors and even more so when considering healthy controls.

The aPTT test is mainly used to evaluate the intrinsic coagulation pathway. In this study, no statistical significance was found between aPTT and the presence of glioma, with proportions of altered aPTT equal between cases and controls ( Tables 2 and 3). This result differs from the findings of a study in which aPTT was shown to be significantly reduced in glioma cases, suggesting a hypercoagulable state. ⁶ Considering the numerical values for aPTT, there was a decreased aPTT among cases ( M = 26.4, SD = 4.59) versus controls ( M = 27.4, SD = 3.56), but this difference was still not statistically significant according to Welch’s t-test (t(61) = -.833 p = .411).

Potential reasons for these different observations in coagulation are confounding variables and comorbididities. The three patients with increased PT may have suffered from liver abnormalities, vitamin K deficiency, or overweight, which were not considered in the study. Removing these three patients from the dataset did result in decreased average PT among cases ( M = 12.2, SD = 1.32) versus controls ( M = 12.5, SD = .92), but this difference was still not statistically significant according to Welch’s t-test (t(58) = -.954 p = .349).

Blood count can be used to assess general condition, detect disease-related complications, and, in some cases, predict survival in patients with high-grade glioma. In this study, alterations were observed in PC, leukocytes, erythrocytes, hemoglobin, and hematocrit; however, no significant association with high-grade glioma was found in the multivariate analysis, except for PC ( Table 3). Navone et al. observed a significant increase in leukocyte count in glioblastoma patients compared to meningioma patients (p < 0.001), while hemoglobin did not show significant differences between the two study groups. ⁶ On the other hand, Kim et al. assessed the clinical importance of lymphopenia in patients with glioblastoma and reported that 42.0% (92 patients) showed decreased levels of lymphocytes, concluding that lymphopenia is a frequent event during progression and disease treatment. ²⁴ In turn, Serban et al., when studying the preoperative immunoinflammatory status of patients with glioblastoma, found elevated leukocyte counts, suggesting that this could predict reduced overall survival. ²⁵

Although nearly all blood count parameters were not shown to be different in this study, abnormal PC was significantly associated with high-grade glioma – no members of the control group had abnormal PC, while 4 patients in the case group had abnormal PC – one higher than the reference range, and three lower ( Tables 2 and 3). However, using numerical values for PC, a statistically significant difference between cases and controls was not found. This result can be compared to previous investigations ^{6 , 22} in which no statistically significant differences were found in PC between cases and controls ( p > 0.05). However, abnormal PC was statistically favored in the cases. Small study size as well as differences in the timing of blood sample collection may explain the differences in these results with other studies.

Finally, multivariate analysis also identified that a preoperative ECOG score of 2 or 3 was significantly associated with high-grade glioma. However, no studies have been found to determine whether the ECOG value is related to glioma, so more research would be needed to determine the relationship between the two. However, in cancer patients, an ECOG 3-4 is associated with a higher risk of in-hospital mortality. ^{26 , 27}

Published results may imply judicious use of anticoagulant medication among glioblastoma patients, ^{11 , 19 , 20 , 28} but other research suggests a higher risk of heammorage, ²⁹ or there is no effect in patient outcome. ^{5 , 30} Of the two blood factors associated here, platelet count has been used as a predictor of VTE ³¹ and decreased PT has been associated with decreased survival. ⁶ Our results show that there may be some patients with prolonged coagulation, which underlines the importance of testing patients before including anticoagulant therapy.

Therefore, it is still unclear whether using anticoagulant treatment is helpful in improving any aspect of glioma treatment, but the evidence somewhat leans toward use of well-tolerated drugs. Additional research on which patients would benefit from anticoagulant prophylaxis would be welcome. Given that alterations in coagulation also play a role in tumor development and metastasis, ⁷ it would also be useful to analyze whether anticoagulation therapy can inhibit tumor growth or metastasis.

This study presented certain limitations, such as limited sample size and scope since patients were not subjected to additional tests. Additionally, it was not determined when the parameters of the coagulation profile were altered, so the study could not determine when a blood analysis would produce meaningful results. For example, corticosteriod treatment can alter coagulation profile in patients with glioma. ³² In addition, cancer treatments such as sugery and chemotherapy can also alter coagulation. ¹³ Another study limitation was that the study group was compared to only one control group, that is, patients with meningioma. Meningioma patients also have alterations to coagulation profile, but to a somewhat lesser degree. ⁷ If this is the case, this study may underestimate the magnitude of changes between healthy individuals and those with gliomas.

Taken together, it appears that high-grade glioma patients have altered blood coagulation to a greater degree than patients with benign brain tumors and are more likely to be diagnosed when the disease interferes more strongly with their self-care and work activities. Furthermore, this paper has shown, for the first time, that glioma patients may also have reduced coagulation. This suggests a more careful treatment of coagulation among these patients.

NJQP: Investigation, Writing – Original Draft

APGR: Supervision, Project administration

LJFR: Conceptualization, Writing – Review & Editing