Table 4.
Predicting factors for progression-free survival (PFS) in stage IV patients receiving first-line EGFR TKIs.
| Variable | Univariate Analysis | Multivariable Analysis—Maximal Model 1 | Multivariable Analysis—Reduced Model 1 † | Multivariable Analysis—Maximal Model 2 | Multivariable Analysis—Reduced Model 2 † | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| HR (95% CI) | p Value | HR (95% CI) | p Value | HR (95% CI) | p Value | HR (95% CI) | p Value | HR (95% CI) | p Value | |
| Concordant (vs. discordant) ‡ | 6.71 (1.54–29.23) | 0.0112 | 4.70 (0.32–69.53) | 0.2604 | 5.11 (0.69–37.59) | 0.1092 | ||||
| Male (vs. female) | 1.34 (0.59–3.04) | 0.4849 | 0.85 (0.26–2.76) | 0.7890 | 1.55 (0.56–4.28) | 0.3969 | ||||
| Age ≥65 (vs. <65) | 1.22 (0.54–2.73) | 0.6337 | 2.69 (0.53–13.72) | 0.2349 | 1.81 (0.62–5.25) | 0.2752 | ||||
| ECOG ≥ 2 (vs. ≤1) | 0.75 (0.10–5.59) | 0.7783 | 1.02 (0.08–13.35) | 0.9858 | 0.98 (0.11–8.65) | 0.9826 | ||||
| T3–4 (vs. T1–2) | 2.11 (0.71–6.22) | 0.1780 | 1.11 (0.18–6.90) | 0.9086 | 0.91 (0.24–3.43) | 0.8950 | ||||
| N1–3 (vs. N0) | 8.34 (1.92–36.22) | 0.0047 | 6.42 (1.09–37.92) | 0.0401 | 7.53 (1.70–33.26) | 0.0078 | 4.35 (0.80–23.49) | 0.0879 | 8.34 (1.92–36.22) | 0.0047 |
| Number of metastatic site(s) ≥2 (vs. ≤1) | 2.46 (0.97–6.27) | 0.0585 | 3.23 (1.03–10.14) | 0.0447 | ||||||
| Metastasis to: (with vs. without) | ||||||||||
| Brain | 3.12 (1.32–7.35) | 0.0094 | 1.75 (0.43–7.08) | 0.4351 | ||||||
| Lung | 0.96 (0.42–2.19) | 0.9314 | 0.57 (0.10–3.07) | 0.5098 | ||||||
| Bone | 2.76 (1.15–6.65) | 0.0234 | 2.57 (0.84–7.92) | 0.0994 | 2.26 (0.92–5.58) | 0.0766 | ||||
| Pleural space | 1.59 (0.67–3.75) | 0.2911 | 3.09 (0.83–11.6) | 0.0938 | ||||||
| Liver | 0.77 (0.26–2.26) | 0.6308 | 0.35 (0.06–2.02) | 0.2414 | ||||||
| Pericardial space | 1.55 (0.57–4.18) | 0.3913 | 0.72 (0.14–3.63) | 0.6877 | ||||||
| Adrenal gland | 1.42 (0.42–4.82) | 0.5712 | 2.20 (0.29–16.54) | 0.4436 | ||||||
| Other site | 1.59 (0.46–5.55) | 0.4637 | 0.48 (0.06–3.68) | 0.4776 | ||||||
| TKI used: | ||||||||||
| Gefitinib | ref | ref | ref | |||||||
| Erlotinib | 1.07 (0.38–3.04) | 0.8927 | 1.54 (0.25–9.62) | 0.6413 | 0.60 (0.17–2.12) | 0.4254 | ||||
| Afatinib | 0.75 (0.23–2.48) | 0.6429 | 1.79 (0.27–11.96) | 0.5473 | 1.28 (0.30–5.43) | 0.7344 | ||||
Abbreviation: HR = hazard ratio; CI = confidence interval; EGFR = epithelial growth factor receptor; TKI = tyrosine kinase inhibitors. † Reduced multivariable models were developed with backward variable selection method, keeping only variables with p value less than 0.1, from the maximal model. ‡ Concordant vs. discordant EGFR mutation test results in tissue and liquid biopsies.