Study cohort characteristics according to ePD-L1 (n=313)
| Preoperative ePD-L1 | Postoperative ePD-L1 | ePD-L1 change | |||||||
| <17.10 pg/mL | ≥17.10 pg/mL | P Value | <8.75 pg/mL | ≥8.75 pg/mL | P Value | <6.93 pg/mL | ≥6.93 pg/mL | P value | |
| No | 156 | 157 | – | 156 | 157 | – | 156 | 157 | – |
| Sex (male, %) | 113 (72.4) | 106 (67.5) | 0.344 | 115 (73.7) | 104 (66.2) | 0.150 | 109 (69.9) | 110 (70.1) | 0.971 |
| Median age (Q1, Q3), year | 59 (54, 67) | 58 (53, 67) | 0.620 | 58 (53, 66) | 59 (54, 67) | 0.330 | 59 (54, 67) | 58 (53, 66) | 0.363 |
| Median BMI (Q1, Q3), kg/cm2 | 22.8 (20.2, 25.4) | 22.8 (20.7, 24.8) | 0.901 | 23.1 (20.1, 26.2) | 22.5 (20.7, 24.6) | 0.177 | 23.0 (20.7, 26.5) | 22.6 (20.1, 24.6) | 0.392 |
| Undifferentiated type (n, %) | 57 (36.5) | 72 (45.9) | 0.094 | 58 (37.2) | 71 (45.2) | 0.149 | 53 (34.0) | 76 (48.4) | 0.009 |
| Borrmann typing (III and IV, %) | 86 (55.1) | 113 (72.0) | 0.002 | 92 (59.0) | 107 (68.2) | 0.092 | 95 (60.9) | 104 (66.2) | 0.327 |
| T stage (T3–T4, %) | 70 (44.9) | 122 (77.7) | <0.001 | 80 (51.3) | 112 (71.3) | <0.001 | 83 (53.2) | 109 (69.4) | 0.003 |
| T1 | 60 (38.5) | 20 (12.7) | 54 (34.6) | 26 (16.6) | 51 (32.7) | 29 (18.5) | |||
| T2 | 26 (16.7) | 15 (9.6) | 22 (14.1) | 19 (12.1) | 22 (14.1) | 19 (12.1) | |||
| T3 | 61 (39.1) | 70 (44.6) | 62 (39.7) | 69 (43.9) | 64 (41.0) | 67 (42.7) | |||
| T4 | 9 (5.8) | 52 (33.1) | 18 (11.5) | 43 (27.4) | 19 (12.2) | 42 (26.8) | |||
| N stage (N1–N3, %) | 62 (39.7) | 92 (58.6) | 0.001 | 64 (41.0) | 90 (57.3) | 0.004 | 66 (42.3) | 88 (56.1) | 0.015 |
| N0 | 94 (60.3) | 27 (39.7) | 92 (59.0) | 67 (42.7) | 90 (57.7) | 69 (43.9) | |||
| N1 | 27 (17.3) | 11 (16.2) | 27 (17.3) | 27 (17.2) | 23 (14.7) | 31 (19.7) | |||
| N2 | 18 (11.5) | 7 (10.3) | 14 (9.0) | 19 (12.1) | 15 (9.6) | 18 (11.5) | |||
| N3 | 17 (10.9) | 23 (33.8) | 23 (14.7) | 44 (28.0) | 28 (17.9) | 39 (24.8) | |||
| M stage (M1, %) | 14 (9.0) | 19 (12.1) | 0.369 | 8 (5.1) | 25 (15.9) | 0.002 | 21 (13.5) | 12 (7.6) | 0.095 |
| TNM stage (stage 3–4, %) | 37 (23.7) | 82 (52.2) | <0.001 | 40 (25.6) | 79 (50.3) | <0.001 | 52 (33.3) | 67 (42.7) | 0.089 |
| 1 | 61 (39.1) | 24 (15.3) | 60 (38.5) | 25 (15.9) | 51 (32.7) | 34 (21.7) | |||
| 2 | 58 (37.2) | 51 (32.5) | 56 (35.9) | 53 (33.8) | 53 (34.0) | 56 (35.7) | |||
| 3 | 25 (16.0) | 67 (42.7) | 34 (21.8) | 58 (36.9) | 35 (22.4) | 57 (36.3) | |||
| 4 | 12 (7.7) | 15 (9.6) | 6 (3.8) | 21 (13.4) | 17 (10.9) | 10 (6.4) | |||
| Concomitant disease (n, %) | 62 (39.7) | 60 (38.2) | 0.783 | 61 (39.1) | 61 (38.9) | 0.964 | 68 (43.6) | 54 (34.4) | 0.096 |
| Type of gastrectomy (total, %) | 71 (45.5) | 82 (52.2) | 0.236 | 73 (46.8) | 80 (50.9) | 0.463 | 66 (42.3) | 87 (55.4) | 0.020 |
| Operation time, median (Q1, Q3), min | 170 (145, 200) | 175 (150, 210) | 0.847 | 175 (155, 205) | 175 (120, 210) | 0.071 | 170 (120, 195) | 180 (155, 210) | 0.003 |
| Intraoperative blood loss, median (Q1, Q3), mL | 100 (100, 200) | 160 (100, 200) | 0.016 | 100 (100, 200) | 100 (100, 200) | 0.153 | 100 (100, 200) | 100 (100, 200) | 0.067 |
| Lymphadenectomy (≥D2, %) | 92 (59.0) | 102 (65.0) | 0.276 | 100 (64.1) | 94 (59.9) | 0.442 | 84 (53.8) | 110 (70.1) | 0.003 |
| Adjuvant chemotherapy (n, %) | 93 (59.6) | 100 (63.7) | 0.460 | 99 (63.5) | 94 (59.9) | 0.515 | 92 (59.0) | 101 (64.3) | 0.331 |
| Postoperative complications (n, %) | 15 (9.6) | 34 (21.7) | 0.003 | 20 (12.8) | 29 (18.5) | 0.170 | 14 (9.0) | 35 (22.3) | 0.001 |
Data are presented as n (%) or median (first to third quartile). Categorical data were compared by means of Fisher’s exact test, whereas continuous data were compared using Wilcoxon rank-sum test. P<0.05 was considered significant and is highlighted in bold. TNM staging was performed according to the eighth edition of the Union for International Cancer Control TNM classification. Concomitant disease refers to chronic diseases that do not meet the exclusion criteria, such as hypertension, diabetes. Gastrectomy, lymphadenectomy and adjuvant chemotherapy were carried out according to Japanese Gastric Cancer Treatment Guidelines 2018 (fifth edition). Postoperative complications were defined as intra-abdominal infectious complications of Grade II or higher according to the Clavien-Dindo classification. The cut-off values for preoperative, postoperative and change in ePD-L1 were defined according to corresponding median values. Bold values mean P＜0.05.
BMI, body mass index; ePD-L1, plasma extracellular vesicular programmed cell death ligand-1.