Correlation of epidermal growth factor receptor (EGFR) T790M mutation status in plasma with demographics and clinical features of patients treated at the University Health Network (UHN)
| Characteristic | All patients (n=107) |
EGFR T790M positive (n=34) |
EGFR T790M negative or inconclusive (n=73) | P value |
| Age, N | 103 | 32 | 71 | 0.36 |
| Mean, years (SD) | 65.6 (12.9) | 67.5 (12) | 64.8 (13.3) | |
| Median, years (min, max) | 64 (31, 99) | 71 (43, 86) | 63 (31, 99) | |
| Sex, N | 106 | 33 | 73 | 0.83 |
| Male, N (%) | 66 (62) | 20 (61) | 46 (63) | |
| Female, N (%) | 40 (38) | 13 (39) | 27 (37) | |
| Smoking status, N | 104 | 33 | 71 | 0.82 |
| Never, N (%) | 27 (26) | 9 (27) | 18 (25) | |
| Former, N (%) | 77 (74) | 24 (73) | 53 (75) | |
| Number of metastatic sites, N | 105 | 32 | 73 | 0.16 |
| Mean, N (SD) | 3.4 (1.6) | 3.7 (1.1) | 3.3 (1.7) | |
| Median, N (min, max) | 3 (0, 9) | 3.5 (2, 7) | 3 (0, 9) | |
| Metastases, N | 104 | 32 | 72 | |
| CNS, N (%) | 51 (49) | 14 (44) | 37 (51) | 0.53 |
| Bone, N (%) | 57 (55) | 21 (66) | 36 (50) | 0.2 |
| Liver, N (%) | 19 (18) | 7 (22) | 12 (17) | 0.59 |
| Lymph node, N (%) | 62 (60) | 21 (66) | 41 (57) | 0.52 |
| Adrenal, N (%) | 12 (12) | 3 (9) | 9 (13) | 0.75 |
| None (disease in lung only), N (%) | 9 (9) | 0 (0) | 9 (13) | 0.05 |
| Size of large tumour, N | 80 | 28 | 52 | 0.4 |
| Mean, mm (SD) | 2.9 (2.7) | 3.4 (3.6) | 2.7 (2) | |
| Median, mm (range) | 2.2 (0.3, 19) | 2.7 (0.3, 19) | 2.2 (0.4, 10.8) | |
| Prior TKI treatment, N | 104 | 33 | 71 | 0.84 |
| First-generation (gefitinib, erlotinib), N (%) | 95 (91) | 31 (94) | 64 (90) | |
| Second-generation (afatinib), N (%) | 9 (9) | 2 (6) | 7 (10) | |
| TKI treatment duration, N | 93 | 33 | 70 | 0.74 |
| Mean, days (SD) | 527.2 (418.4) | 471.7 (220.4) | 553.4 (483.9) | |
| Median, days (min, max) | 422 (28, 2149) | 458 (162, 1205) | 406 (28, 2149) | |
| LDH levels, N | 93 | 29 | 64 | 0.83 |
| ≤220 U/L, N (%) | 47 (51) | 14 (48) | 33 (52) | |
| >220 U/L, N (%) | 46 (49) | 15 (52) | 31 (48) | |
| EGFR sensitising mutation, N | 83 | 29 | 55 | 0.32 |
| L858R, N (%) | 35 (42) | 11 (38) | 24 (44) | |
| Exon 19 deletion, N (%) | 44 (53) | 18 (62) | 26 (48) | |
| Other (G719S/C/A, L861Q, N771delinsHV), N (%) | 4 (5) | 0 (0) | 4 (7) |
CNS, central nervous system ; LDH, lactate dehydrogenase; TKI, tyrosine kinase inhibitor.