Table 1. Patient demographic and clinical characteristics of matched samples.
| Variables | Chemotherapy (n=273) | ICI (n=273) | P value |
|---|---|---|---|
| Age (years) at diagnosis, mean ± SD | 71.25±4.56 | 72.11±5.03 | 0.03 |
| Sex, n (%) | 0.79 | ||
| Male | 129 (47.25) | 133 (48.72) | |
| Female | 144 (52.75) | 140 (51.28) | |
| Race, n (%) | 0.20 | ||
| White | >234† (–†) | 236 (86.45) | |
| Black | 28 (10.26) | 20 (7.33) | |
| Other | <11† (–†) | 17 (6.23) | |
| Ethnicity, n (%) | 0.02 | ||
| Non-Hispanic | 254 (93.04) | <262† (–†) | |
| Hispanic | 19 (6.96) | <11† (–†) | |
| Marital status at diagnosis, n (%) | 0.60 | ||
| Non-married | 114 (41.76) | 109 (39.93) | |
| Married | 159 (58.24) | 164 (60.07) | |
| Census tract poverty indicator level, n (%) | 0.25 | ||
| 0–<5% | 57 (20.88) | 72 (26.37) | |
| 5–<10% | 71 (26.01) | 78 (28.57) | |
| 10–<20% | 72 (26.37) | 63 (23.08) | |
| 20–100% | 47 (17.22) | 33 (12.09) | |
| Unknown | 26 (9.52) | 27 (9.89) | |
| Rurality, n (%) | 0.06 | ||
| Metropolitan | 220 (80.59) | 236 (86.45) | |
| Non-metropolitan | 53 (19.41) | 37 (13.55) | |
| Index year, n (%) | – | ||
| 2010 | 27 (9.89) | – | |
| 2011 | 54 (19.78) | – | |
| 2012 | 70 (25.64) | – | |
| 2013 | 53 (19.41) | – | |
| 2014 | 69 (25.27) | – | |
| 2015 | – | 24 (8.79) | |
| 2016 | – | 117 (42.86) | |
| 2017 | – | 82 (30.04) | |
| 2018–2019 | – | 50 (18.31) | |
| Lung metastasis at diagnosis, n (%) | 0.55 | ||
| No | 207 (75.82) | 200 (73.26) | |
| Yes | 66 (24.18) | 73 (26.74) | |
| Bone metastasis at diagnosis, n (%) | 0.11 | ||
| No | 197 (72.16) | 181 (66.30) | |
| Yes | 76 (27.84) | 92 (33.70) | |
| Liver metastasis at diagnosis, n (%) | 0.003 | ||
| No | 242 (88.64) | 218 (79.85) | |
| Yes | 31 (11.36) | 55 (20.15) | |
| Charlson comorbidity index, n (%) | 0.94 | ||
| 0 | 162 (59.34) | 160 (58.61) | |
| 1 | 65 (23.81) | 69 (25.27) | |
| ≥2 | 46 (16.85) | 44 (16.12) | |
| ECOG performance status proxy, n (%) | 0.50 | ||
| ECOG PS 0–2 | >262† (–†) | 261 (95.60) | |
| ECOG PS 3–4 | <11† (–†) | 12 (4.40) | |
| Cranial radiation before index treatment, n (%) | 0.63 | ||
| No | 106 (38.83) | 108 (39.56) | |
| Yes | 167 (61.17) | 165 (60.44) | |
| Neurosurgical resection within 1 year from diagnosis, n (%) | 0.91 | ||
| No | 224 (82.05) | 223 (81.68) | |
| Yes | 49 (17.95) | 50 (18.32) | |
| NSCLC histology, n (%) | 0.009 | ||
| Adenocarcinoma | 171 (62.64) | 173 (63.37) | |
| Squamous cell carcinoma | 25 (9.16) | 46 (16.85) | |
| Other | 77 (28.21) | 54 (19.78) | |
| Tumor size at diagnosis, n (%) | 0.97 | ||
| <30 mm | 66 (24.18) | 62 (22.71) | |
| 30 to <50 mm | 79 (28.94) | 77 (28.21) | |
| 50 to <70 mm | 59 (21.61) | 57 (20.88) | |
| ≥70 mm | 37 (13.55) | 41 (15.02) | |
| Missing/unknown | 32 (11.72) | 36 (13.19) | |
| Primary tumor grade, n (%) | 0.27 | ||
| Grade I/Grade II (well differentiated/moderately differentiated) | 41 (15.02) | 31 (11.36) | |
| Grade III/Grade IV (poorly differentiated/undifferentiated; anaplastic) | 87 (31.87) | 80 (29.30) | |
| Cell type not determined | 145 (53.11) | 162 (59.34) | |
| Primary tumor laterality, n (%) | 0.32 | ||
| Bilateral involvement/midline/one side/lateral origin unknown | 14 (5.11) | <11† (–†) | |
| Right: origin of primary | 153 (55.84) | >151† (–†) | |
| Left: origin of primary | 106 (38.83) | 111 (40.66) | |
| Agents used as first-line chemotherapy treatment, n (%) | – | ||
| Platinum only | 24 (8.79) | >10† (–†) | |
| Pemetrexed only | 17 (6.23) | <11† (–†) | |
| Platinum + taxane | 105 (38.46) | 83 (30.40) | |
| Platinum + pemetrexed | 102 (37.36) | 149 (54.58) | |
| Other combinations | 25 (9.16) | 20 (7.33) | |
| Agents used as subsequent chemotherapy treatment (second line), n (%) | N=273 | N=14‡ | – |
| Taxane only | 111 (40.66) | <11† (–†) | |
| Gemcitabine only | 48 (17.58) | <11† (–†) | |
| Pemetrexed only | 84 (30.77) | <11† (–†) | |
| Other combinations | 30 (10.99) | <11† (–†) | |
| Agents used as second-line ICI, n (%) | N=259 | – | |
| Pembrolizumab | – | 57 (22.01) | |
| Nivolumab | – | 189 (72.97) | |
| Atezolizumab | – | 13 (5.02) | |
| Agents used as third-line ICI, n (%) | N=14 | – | |
| Pembrolizumab/atezolizumab | – | <11† (–†) | |
| Nivolumab | – | >4† (–†) |
All P values significant at α ≤0.05. †, according to the SEER-Medicare data use agreement, cell counts and percentages in this row are masked/concealed due to a cell having a case count of <11; ‡, this number represents the 14 third-line ICI patients that received previous second-line chemotherapy treatment. ICI, immune checkpoint inhibitor; SD, standard deviation; ECOG, Eastern Cooperative Oncology Group; PS, performance status; NSCLC, non-small cell lung cancer; SEER, Surveillance, Epidemiology, and End Results.