Cerebrospinal fluid cell-free tumor DNA-based cancer molecular profiling vs. cytology examination: A comparison in cancer detection sensitivity.

Abstract

e15057 Background: The evaluation tools with the central nervous system (CNS) tumors includes magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) cytology, and brain biopsies all of which have certain limitations. Those assessments also lack the function of treatment guidance and minimal residual disease surveillance. On the hand, the innovation of mutation detection from cell-free DNA (cfDNA), specifically circulating tumor DNA (ctDNA), further provides incredible advantage in cancer diagnosis, treatment selection and disease progression surveillance. Hereby, we want to compare the sensitivity and specificity of tumor detection between cfDNA and cytology. Methods: We compared the tumor detection between CSF ctDNA-based mutation profiling and conventional CSF cytological examination in 106 cases which had both results. Results: In total 106 CSF samples from patients with clinically suspicion of leptomeningeal metastases (LM) and/or intraparenchymal metastasis, cfDNA-based testing detected previously known variants in 60 samples (56.6%), while cytological examination only picked up 28 positive cases (26.4%). Specifically, 1) 24 cases were positive by both ctDNA and cytology, 2) 36 cases were positive only by cfDNA and 3) 4 cases were positive only by cytology. Conclusions: Taken together, our results indicate a significant value of simultaneously performing ctDNA-based comprehensive cancer profiling on CSF samples to managing patients with brain tumors, especially in patients with metastatic CNS carcinomas.