Abstract 1265P
Background
The main purpose is to select a more effective method for the diagnosis of leptomeningeal metastases (LM) by comparing various detection methods. The secondary purpose is to identify specific mutation patterns of genes in cerebrospinal fluid (CSF) with LM and to explore the value of CSF tumor markers and circulating tumor DNA (ctDNA) testing in guiding clinical treatment.
Methods
The levels of tumor markers in serum and CSF of patients with LM were detected by chemiluminescence. The ctDNA of CSF supernatant and plasma were detected by the next-generation sequencing technology.
Results
The results showed that the positive rate of CSF cytology was 30.7% (12/39), and the positive rate of MRI was 58.9% (23/39). The sensitivity of CEA (75.8%, 25/33) in CSF was better than that of NSE (51.7%, 15/29) and CFRA-211 (33.3%, 9/27). The positive rate of ctDNA in CSF supernatant was significantly higher than that in plasma (92.3% VS 41%, P<0.05). The positive rate of CSF tumor markers combined with CSF-ctDNA was 100%, which was higher than the traditional methods (66.7% ) including cytology and magnetic resonance. The positive rates of cytology (42.1%), MRI (68.4%) and CSF-ctDNA (100%) were all increased when tumor markers in CSF were higher than those in serum. The positive rate of CSF-ctDNA was higher in LM patients with hydrocephalus (P<0.05). More gene mutations were detected in CSF than in plasma, and 111 mutations were unique in cerebrospinal fluid. There were more copy number variation (CNV) mutations in CSF and plasma after multiple TKIs compared to patients who received a single TKI (P<0.05).
Conclusions
The positive rates of CSF tumor markers combined with CSF-ctDNA were higher than those of traditional diagnostic methods including cytology and imaging. CSF-ctDNA testing reveals a unique mutation profile in CSF for patients with LM. Dynamic detection of CSF tumor markers and ctDNA can better predict the efficacy and guide drug use.
Clinical trial identification
NCT03029065.
Editorial acknowledgement
Not applicable.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.