Acquired resistance during cancer treatment is unfortunately a frequent event. There are several reasons for this, including the ability of the ATP-binding cassette transporters (ABC transporters), which are integral membrane proteins, to export chemotherapeutic molecules from the interior of the tumor cells. One important member of this family is the protein known as Permeability Glycoprotein (P-Glycoprotein, P-gp or ABCB1). Its clinical relevance relies mainly on the fact that the inhibition of P-gp and other ABC transporters could result in the reversal of the multidrug resistance (MDR) phenotype in some patients. Recently, other roles apart from being a key player in MDR, have emerged for P-gp. Therefore, this review discusses the relationship between P-gp and MDR, in addition to the possible role of this protein as a biomarker in cancer.

This review examines the prevalence, molecular mechanisms, and clinical implications of RAS mutations in Central Nervous System (CNS) tumors, with a particular focus on glioblastoma. We summarize the current understanding of RAS-driven oncogenic pathways, their contribution to tumor progression, and potential therapeutic strategies targeting RAS and its downstream effectors. Although direct RAS mutations are rare in primary CNS tumors, alterations in RAS signaling, such as NF-1 loss and aberrant receptor tyrosine kinase activation, contribute to malignant progression. Furthermore, emerging evidence links RAS mutations to brain metastases, highlighting their significance in CNS oncology. We also discuss recent clinical trials investigating RAS-targeted therapies, including covalent inhibitors, MEK inhibitors, and novel combination approaches. Given the increasing recognition of RAS pathway alterations in CNS malignancies, further research is needed to elucidate their role in tumor biology and explore targeted therapeutic interventions.

This systematic review and meta-analysis of diagnostic test accuracy evaluated the performance of noninvasive liquid biopsy methods for diagnosis of meningioma, the most common primary intracranial neoplasm in adults. Following PRISMA-DTA guidelines, we searched three databases. Data for 2 × 2 contingency tables were extracted, methodological quality was assessed using QUADAS-2, and a bivariate meta-analysis was performed. A total of 23 studies with 27 datasets were included. Pooled sensitivity was 0.78 (95% CI: 0.71 - 0.83) and specificity was 0.82 (95% CI: 0.76 - 0.86), with an area under the curve (AUC) of 0.86. Subgroup analysis showed that seroreactivity assays had the highest accuracy (diagnostic odds ratio or DOR = 67), while emerging technologies like cfDNA methylation showed high potential but were supported by limited data. The evidence was limited by significant publication bias (Deeks' test, p < 0.001), and meta-regression revealed that studies with a lower risk of bias reported significantly lower specificity (p = 0.008). Fluid-based biomarkers show good overall accuracy for meningioma diagnosis, but the current evidence is compromised by methodological bias, suggesting that true performance is more modest than reported. Rigorous, prospective validation of promising approaches like cfDNA methylation and seroreactivity is essential to clarify their clinical utility.