Table 3. The EGFR mutation types in plasma and cerebrospinal fluid among patients with CNS metastasis.
| Characteristics | Plasma | Cerebrospinal fluid | |||||
|---|---|---|---|---|---|---|---|
| L858R | 19del | T790M | L858R | 19del | T790M | ||
| Brain metastases | |||||||
| EGFR-TKI naïve | 7/10 (70.0%) | 11/14 (78.6%) | 1/1 (100.0%) | 1/10 (10.0%) | 4/14 (28.6%) | 0/1 (00.0%) | |
| EGFR-TKI treateda | 7/15 (46.7%) | 10/15 (66.7%) | 4/7 (57.1%) | 4/15 (26.7%) | 7/15 (46.7%) | 0/7 (00.0%) | |
| Total | 14/25 (56.0%) | 21/29 (72.4%) | 5/8 (62.5%) | 5/25 (20.0%) | 11/29 (37.9%) | 0/8 (00.0%) | |
| Leptomeningeal metastases | |||||||
| EGFR-TKI naïveb | 0/3 (00.0%) | 1/3 (33.3%) | 0 | 3/3 (100.0%) | 3/3 (100.0%) | 0 | |
| EGFR-TKI treated | 5/14 (35.7.0%) | 4/7 (57.1%) | 4/9 (44.4%) | 11/14 (78.6%) | 6/7 (85.7%) | 4/9 (44.4%) | |
| Total | 5/17 (29.4%) | 5/10 (50.0%) | 4/9 (44.4%) | 14/17 (82.4%) | 9/10 (90.0%) | 4/9 (44.4%) | |
a, 1 patient had both L858R and 19del EGFR mutation; b, 1 patient had both L858R and 19del EGFR mutation. TKI, tyrosine kinase inhibitors; CNS, central nervous system.