Baseline characteristics of patients with N1 lymph node involvement in SEER-Medicare
| Characteristic | Lymph node ratio | p Value | ||
| ≤0.15 (N=524) | 0.16–0.50 (N=849) | ≥0.5 (N=309) | ||
| Age (years), N (%) | ||||
| ≤70 | 191 (36) | 303 (36) | 108 (35) | 0.980 |
| 71–75 | 165 (31) | 279 (32) | 103 (33) | |
| >75 | 168 (32) | 267 (31) | 98 (32) | |
| Female, N (%) | 200 (38) | 379 (45) | 171 (55) | <0.0001 |
| Race/ethnicity, N (%) | ||||
| White | 483 (92) | 744 (88) | 270 (87) | 0.061 |
| African American | 18 (3) | 35 (4) | 18 (6) | |
| Hispanic/other* | 23 (4) | 70 (8) | 21 (7) | |
| Married, N (%) | 326 (62) | 531 (63) | 179 (58) | 0.338 |
| Median income in ZIP code of residence, N (%)† | ||||
| Lowest quartile | 127 (24) | 186 (22) | 73 (23) | 0.682 |
| Second quartile | 128 (24) | 221 (26) | 69 (22) | |
| Third quartile | 126 (24) | 223 (26) | 87 (28) | |
| Highest quartile | 143 (27) | 215 (25) | 80 (26) | |
| Comorbidity score, N (%) | ||||
| ≤1 | 190 (36) | 339 (40) | 117 (38) | 0.445 |
| 1–2 | 195 (37) | 290 (34) | 120 (39) | |
| >2 | 139 (27) | 220 (26) | 72 (23) | |
| Tumour status, N (%) | ||||
| T1A | 61 (12) | 95 (11) | 28 (9) | 0.364 |
| T1B | 82 (16) | 148 (17) | 59 (19) | |
| T2A | 234 (45) | 388 (46) | 152 (49) | |
| T2B | 54 (10) | 98 (12) | 32 (10) | |
| T3 | 93 (18) | 120 (14) | 38 (12) | |
| Histology, N (%) | ||||
| Adenocarcinoma | 222 (42) | 408 (48) | 175 (57) | 0.001 |
| Squamous cell carcinoma | 219 (42) | 293 (35) | 81 (26) | |
| Large cell carcinoma | 32 (6) | 62 (7) | 17 (6) | |
| Bronchioloalveolar cell carcinoma | 29 (6) | 49 (6) | 25 (8) | |
| Other | 22 (4) | 37 (4) | 11 (4) | |
| Tumour location, N (%) | ||||
| Upper lobe | 287 (55) | 450 (53) | 149 (48) | 0.118 |
| Lower lobe | 186 (36) | 337 (40) | 128 (41) | |
| Other location | 51 (10) | 62 (7) | 32 (10) | |
| Type of surgery, N (%) | ||||
| Lobectomy | 410 (78) | 722 (85) | 281 (91) | <0.0001 |
| Pneumonectomy | 114 (22) | 127 (15) | 28 (9) | |
| Postoperative radiation therapy, N (%) | ||||
| Yes | 135 (26) | 362 (43) | 158 (51) | <0.0001 |
| No | 389 (74) | 487 (57) | 151 (49) | |
| Adjuvant chemotherapy, N (%) | ||||
| Yes | 88 (17) | 177 (21) | 69 (22) | 0.091 |
| No | 436 (83) | 672 (79) | 240 (78) | |