3.1 Patient Characteristics
We identified 173 patients with LM evaluated at our center between June 2011 and June 2021 (Table 1). median age at LM diagnosis was 59 years (range, 32-84). Ever-smokers accounted for 49.1% of the patients (n = 85). There was a preponderance of adenocarcinoma. A prominent majority (107, 61.8%) of patients had targetable mutations identified from primary or metastatic malignant pathology specimens: there were 95 cases with EGFR mutations, eight with ALK rearrangement and four with ROS proto-oncogene 1(ROS-1). 58.4% (101/173) received targeted therapy before they were diagnosed as LM. Most patients (127/173; 73.4%) had brain metastasis (BM) before or simultaneously with LM diagnosis. Before LM diagnosis, 48 patients had history of brain radiotherapy (BRT) (27.7%). The median time from NSCLC diagnosis to LM diagnosis was 11.1 months (range: 0-23.9). The ECOG PS was 0–2 for 67.1% of patients. Regarding treatments modalities for LM, 23 (13.3%) patients received supportive care alone after they were diagnosed as LM, 102 (59.0%) patients received TKI therapy, there were 22.5% (23/102) received first/second generation TKI therapy, and 77.5% (79/102) received third generation TKI therapy, 22 (12.7%) patients received whole brain radiotherapy, 51 (29.5%) patients received chemotherapy, and 40 (23.1%) patients received intrathecal chemotherapy (ITC).
Table 1 Patient Characteristics
Characteristics
|
group
|
N=173 (n, %)
|
Median age, years (range)
|
|
59 (32-84)
|
Sex (%)
|
male
|
95 (54.9)
|
|
female
|
78 (45.1)
|
Age1 (%)
|
<60
|
87 (50.3)
|
|
≥60
|
86 (49.7)
|
Smoking status (%)
|
Never
|
88 (50.9)
|
|
Former
|
85 (49.1)
|
Pulmonary lesion (%)
|
Unknown
|
5 ( 2.9)
|
|
Left
|
81 (46.8)
|
|
Right
|
87 (50.3)
|
Histological type (%)
|
LUAD
|
145 (83.8)
|
|
Non-LUAD
|
28 (16.2)
|
Targetable mutations (%)
|
No
|
66 (38.2)
|
|
Yes
|
107 (61.8)
|
Specific mutation (%)
|
EGFR
|
95 (88.8)
|
|
ALK
|
8 ( 7.5)
|
|
ROS-1
|
4 ( 3.7)
|
Initial diagnosis with BM (%)
|
No
|
93 (53.8)
|
|
Yes
|
80 (46.2)
|
Initial diagnosis with LM (%)
|
No
|
119 (68.8)
|
|
Yes
|
54 (31.2)
|
TKI therapy before LM (%)
|
No
|
72 (41.6)
|
|
Yes
|
101 (58.4)
|
BRT before LM (%)
|
No
|
125 (72.3)
|
|
Yes
|
48 (27.7)
|
CNS symptoms (%)
|
No
|
20 (11.6)
|
|
Yes
|
153 (88.4)
|
ECOG PS (%)
|
≤2
|
116 (67.1)
|
|
>2
|
57 (32.9)
|
LM and BM (%)
|
No
|
46 (26.6)
|
|
Yes
|
127 (73.4)
|
LM Treat (%)
|
No
|
23 (13.3)
|
|
Yes
|
150 (86.7)
|
WBRT (%)
|
No
|
151 (87.3)
|
|
Yes
|
22 (12.7)
|
LM Chemotherapy therapy (%)
|
No
|
122 (70.5)
|
|
Yes
|
51 (29.5)
|
ITC (%)
|
No
|
133 (76.9)
|
|
Yes
|
40 (23.1)
|
LM_ TKI therapy (%)
|
No
|
71 (41.0)
|
|
Yes
|
102 (59.0)
|
TKI therapy _drugs (%)
|
1/2 generation
|
23 (22.5)
|
|
3 generation
|
79 (77.5)
|
Death (%)
|
Yes
|
134 (77.5)
|
|
Lost follow-up
|
5 ( 2.9)
|
|
No
|
34 (19.6)
|
Notes: LUAD, lung adenocarcinoma; BM, brain metastasis; LM, leptomeningeal metastasis; TKI, tyrosine kinase inhibitor; BRT, brain radiotherapy; CNS, central nervous system; ECOG PS: Eastern Cooperative Oncology Group Performance Status; WBRT, whole brain radiotherapy; ITC, Intrathecal chemotherapy.
3.2 Radiographic Burden of Disease
There are 136 patients in the “LM MRI+” cohort, A prominent majority (103, 75.7%) of patients were linear leptomeningeal disease (Table2), Cerebrum and cerebellum were the most vulnerable sites involvement of LM (Fig. 1). MRI site extent of radiographic involvement at LC-LM diagnosis ranged from 0 to 4 sites involved (Table2); median was 1 site and mean were 1.21 sites. In the “LM MRI+” cohort (n = 136), MRI site extent of radiographic involvement 3-4 sites was significantly shorter than that those who involved 1-2 sites (3.77 vs 10.07months; HR: 1.84; 95% CI: 1.02–3.31; P = 0.034; Fig. 2), but there was no association between number of sites involved and overall survival (HR: 1.13; 95% CI: 0.94–1.35; P = 0.208). There was no association between anatomic location of LM and survival.
Table 2 Diagnostic of LM
Characteristics
|
lever
|
N=173 (n, %)
|
Cytological examination
|
No
|
53 (30.6)
|
|
Yes
|
120 (69.4)
|
Positive cytology
|
No
|
32 (26.7)
|
|
Yes
|
88 (73.3)
|
Radiographic evidence
|
equivocal
|
37
|
|
unequivocal
|
136
|
MRI type
|
linear
|
103
|
|
nodular
|
30
|
|
linear and nodular
|
3
|
Number of MRI sites
|
1
|
79
|
|
2
|
43
|
|
3
|
11
|
|
4
|
3
|
3.3 CSF Findings
120 (69.4%) individuals had CSF cytology data available at the time of LC-LM diagnosis. Using the criterion of positive CSF cytology as cytology that conclusively revealed malignant cells or cells suspected of malignancy in a patient with acceptable clinical signs and symptoms, we found that 73.3% (88/120) of patients had positive CSF cytology. When this cohort was studied, a positive CSF cytology at the time of diagnosis was not linked to an elevated risk of mortality (p = 0.159). In 102 individuals, the CSF protein levels at the time of the LC-LM diagnosis were available; the presence of CSF proteins over the upper limit of normal was not significantly related to survival (p = 0.311). Low CSF chloride, however, was linked to a higher probability of passing away from the time of LC-LM diagnosis (HR: 2.15; 95% CI: 1.34-3.44; p = 0.002).
Cell-free DNA (cfDNA) was extracted from a subset of 19 patients who had CSF collected at time of LC-LM diagnosis. cfDNA concentration ranged from 0.720ng to 47.300ng, with a median of 4.840 ng and mean of 14.486 ng. Using the median cutpoint, there was no increased risk of death associated with the above median value of cfDNA concentration (HR: 1.43; 95% CI: 0.43-4.73; p = 0.554), due to impacted by small sample size.
3.4 Mutation Profiling of Paired CSF and Plasma
There are 22 patients those tumor tissue detected EGFR mutations underwent NGS with paired CSF and plasma. 21 (95.5%) CSF samples and 8(36.4%) plasma samples were detected drive genes, of which EGFR-sensitive mutations were detected in 9 CSF and plasma samples and 1 No EGFR-sensitive mutations were detected in both CSF and plasma samples, the concordance was 45.5%. TP53 was detected in 18 CSF and 4 plasma samples. The detection rate of CSF TP53 was higher (81.8%) than plasma (18.2%; χ²= 17.82, p<0.001), We also found that the exons where the TP53 mutation site located were different. In our study, exons 5 and 8 of the TP53 frequent mutation (Fig. 3) and related to poor prognosis. T790M mutations were detected in 3 samples, including 1 in CSF and 2 in plasma. MET amplification was detected in 5 CSF samples, and no MET amplification was detected in plasma samples. In addition, EGFR amplification (7 cases), IKZF1 (7 cases), CDKN2A/B (6 cases), RICTOR amplification (6 cases), PIK3CA mutation (4 case), MAP2K4 (4 cases), ERBB2 amplification (3 cases), CDK4 (3 cases), STK11 (3cases), RB1 (2cases), PTEN mutation (2 cases), and ATM (2 cases) and PMS2 (2 cases) were also detected in CSF.
3.5 Presence of a Targetable Mutation
107 (61.8%) patients harbored a targetable mutation, which included mutations in EGFR, ALK, and ROS-1. Those with a clinically actionable mutation were significantly longer overall survival than those without (6.30 vs 12.17 months; HR:0.63; 95% CI: 0.45-0.90; p=0.009; Fig. 4). Due to the limited number of patients with each specific targetable mutation (other than EGFR mutations, which dominated the cohort), the potential prognostic importance of each individual mutation was unable to be determined.
3.6 Survival After Diagnosis with LM
The median follow-up time was 34.1 months, the median OS of the entire cohort (173 patients) was 9.33 months (95% CI: 6.35‒12.31) with 77.5% maturity (134/173). Univariate analysis revealed that sex, smoking status, histological type, targetable mutations, TKI therapy before LM, PS, LM treat and LM TKI therapy were potential prognostic factors for LM (Table 3). Among these, targetable mutations, PS, LM treat and LM TKI therapy were independent prognostic factors for LM in the multivariate analysis (Fig. 5).
Table 3 Univariate analysis for LC-LM
Univariate analysis (N = 173)
|
Variable name
|
HR (95%CI)
|
p-value
|
Sex (male vs. female)
|
0.63 (0.45-0.89)
|
0.01*
|
age1(<60 vs ≥60)
|
1.08 (0.77-1.52)
|
0.659
|
Smoking status (never vs former)
|
1.64 (1.16-2.33)
|
0.005*
|
Histological type (non-LUAD vs LUAD)
|
0.52 (0.331-0.830)
|
0.006*
|
Targetable mutations (no vs yes)
|
0.63 (0.45-0.9)
|
0.010*
|
Initial diagnosis with BM (no vs yes)
|
1.05 (0.75-1.47)
|
0.789
|
Initial diagnosis with LM (no vs yes)
|
0.80 (0.55-1.15)
|
0.225
|
TKI therapy before LM (no vs yes)
|
0.59 (0.416-0.824)
|
0.002*
|
BRT before LM (no vs yes)
|
1.31 (0.91-1.89)
|
0.142
|
CNS symptoms (no vs yes)
|
1.33 (0.78-2.28)
|
0.299
|
ECOG PS (≤2 vs>2)
|
3.08 (2.1-4.51)
|
<0.001*
|
LM and BM (no vs yes)
|
1.5 (1-2.26)
|
0.053
|
LM Treat (no vs yes)
|
0.27 (0.17-0.43)
|
<0.001*
|
WBRT (no vs yes)
|
1.45 (0.9-2.34)
|
0.125
|
LM Chemotherapy therapy (no vs yes)
|
1.27 (0.88-1.84)
|
0.195
|
ITC (no vs yes)
|
1.04 (0.67-1.6)
|
0.865
|
LM_ TKI therapy (no vs yes)
|
0.39 (0.28-0.55)
|
<0.001*
|