Table 1. Baseline characteristics of the patients with stage I NSCLC according to histology.
| Characteristics | Categories | Total, n (%) | SCC, n (%) | Non-SCC, n (%) | Statistics* | P value |
|---|---|---|---|---|---|---|
| Age, years | Median (IQR) | 66 (60–72) | 67 (61–73) | 65 (57–72) | −2.390 | 0.017a |
| Gender | Men | 291 (73.9) | 177 (60.8) | 114 (39.2) | 52.173 | <0.001 |
| Women | 103 (26.1) | 20 (19.4) | 83 (80.6) | |||
| Smoking habit | Never | 99 (28.0) | 18 (18.2) | 81 (81.8) | 47.714 | <0.001 |
| Ever | 254 (72.0) | 150 (59.1) | 104 (40.9) | |||
| ECOG performance status | 0–1 | 326 (97.0) | 161 (49.4) | 165 (50.6) | 1.459 | 0.338 |
| 2 or more | 10 (3.0) | 3 (30.0) | 7 (70.0) | |||
| CCIS | 0 | 108 (35.8) | 50 (46.3) | 58 (53.7) | 2.604 | 0.272 |
| 1 | 162 (53.6) | 82 (50.6) | 80 (49.4) | |||
| 2 or more | 32 (10.6) | 20 (62.5) | 12 (37.5) | |||
| Tumor size, cm | Median (IQR) | 3 (2.3–4.2) | 3.5 (2.5–4.5) | 2.9 (2.2–4.0) | −2.784 | 0.005a |
| T stage | 1 | 147 (37.3) | 60 (40.8) | 87 (59.2) | 7.911 | 0.007 |
| 2 | 247 (62.7) | 137 (55.5) | 110 (44.5) | |||
| Lymphatic invasion | No | 274 (75.7) | 137 (50.0) | 137 (50.0) | 0.310 | 0.625 |
| Yes | 88 (24.3) | 47 (53.4) | 41 (46.6) | |||
| Vascular invasion | No | 267 (73.8) | 133 (49.8) | 134 (50.2) | 0.420 | 0.551 |
| Yes | 95 (26.2) | 51 (53.7) | 44 (46.3) | |||
| Type of surgery | Lobectomy | 324 (82.2) | 152 (46.9) | 172 (53.1) | 11.022 | 0.004 |
| Bilobectomy | 33 (8.4) | 17 (51.5) | 16 (48.5) | |||
| Pneumonectomy | 37 (9.4) | 28 (75.7) | 9 (24.3) | |||
| Adjuvant chemotherapy | No | 346 (88.0) | 174 (50.3) | 172 (49.7) | 0.030 | 0.878 |
| Yes | 47 (12.0) | 23 (48.9) | 24 (51.1) | |||
| MST | Years (95% CIs) | 9.8 (7.9–11.8) | 10.1 (7.4–12.8) | 9.1 (NA) | 0.180 | 0.671b |
| Death | No | 234 (59.4) | 118 (50.4) | 116 (49.6) | 0.042 | 0.918 |
| Yes | 160 (40.6) | 79 (49.4) | 81 (50.6) |
P values obtained by chi-square test, except: a, Mann-Whitney U test; b, log-rank test. *, the z-value was indicated for age and tumor size, and the chi-square value was indicated for other variables. SCC, squamous cell carcinoma; IQR, interquartile range; ECOG, Eastern Cooperative Oncology Group; CCIS, Charlson comorbidity index score; MST, median survival time; NA, not applicable.