- Baseline characteristics of patients included in the analysis before and after propensity score matching (PSM).
| Characteristic | Before PSM | After PSM | ||||
|---|---|---|---|---|---|---|
| RT±CT (n,%) | CT (n,%) | P-value | RT±CT (n,%) | CT (n,%) | P-value | |
| Total | n=157 | n=332 | n=157 | n=157 | ||
| Age | ||||||
| <65 | 87 (55.4) | 221 (66.6) | 0.017 | 87 (55.4) | 87 (55.4) | 1.0 |
| ≥65 | 70 (44.6) | 111 (33.4) | 70 (44.6) | 70 (44.6) | ||
| Gender | ||||||
| Male | 133 (84.7) | 299 (90.1) | 0.085 | 133 (84.7) | 141 (89.8) | 0.176 |
| Female | 24 (15.3) | 33 (9.9) | 24 (15.3) | 16 (10.2) | ||
| Race | ||||||
| White | 142 (90.4) | 313 (94.3) | 0.12 | 142 (90.4) | 146 (93.0) | 0.413 |
| Black and others | 15 (9.6) | 19 (5.7) | 15 (9.6) | 11 (7.0) | ||
| Tumor histology | ||||||
| AC | 124 (79.0) | 294 (88.6) | 0.005 | 124 (79.0) | 125 (79.6) | 0.889 |
| SCC and others | 33 (21.0) | 38 (11.4) | 33 (21.0) | 32 (20.4) | ||
| Histological grade | ||||||
| Well | 5 (3.2) | 18 (5.4) | 0.179 | 5 (3.2) | 8 (5.1) | 0.400 |
| Moderate | 59 (37.6) | 115 (34.6) | 59 (37.6) | 47 (34.6) | ||
| Poor/undifferentiated | 70 (44.6) | 168 (50.6) | 70 (44.6) | 81 (52.9) | ||
| Unknown | 23 (14.6) | 31 (9.3) | 23 (14.6) | 21 (7.4) | ||
| Tumor location | ||||||
| middle | 16 (10.2) | 12(4.8) | 0.081 | 16 (10.2) | 11 (7.0) | 0.569 |
| lower | 130 (82.8) | 292(88.0) | 130 (82.8) | 133 (84.7) | ||
| others | 11 (7.0) | 24(7.2) | 11 (7.0) | 13 (8.3) | ||
| AJCC 8th Tumor, Node, Metastasis stage* | ||||||
| yp I/II | 24 (15.3) | 27 (8.1) | 0.064 | 24 (15.3) | 25 (15.9) | 0.811 |
| yp III | 19 (12.1) | 35 (10.5) | 19 (12.1) | 21 (13.4) | ||
| yp IVA | 4 (2.5) | 17 (5.1) | 4 (2.5) | 10 (6.4) | ||
| cI/II | 25 (15.9) | 35 (10.5) | 25 (15.9) | 27 (17.2) | ||
| cIII | 56 (35.7) | 124 (37.3) | 56 (35.7) | 48 (30.6) | ||
| cIVA | 4 (2.5) | 16 (4.8) | 4 (2.5) | 5 (3.2) | ||
| I/II (unknown) | 7 (4.5) | 15 (4.5) | 7 (4.5) | 8(5.1) | ||
| III (unknown) | 16 (10.2) | 54 (16.3) | 16 (10.2) | 11 (7.0) | ||
| IVA (unknown) | 2 (1.3) | 9 (2.7) | 2 (1.3) | 2 (1.3) | ||
| AJCC 8th T stage* | ||||||
| ypT1-2 | 16 (10.2) | 12 (3.6) | 0.003 | 16 (10.2) | 11 (7.0) | 0.351 |
| ypT3-4 | 31(19.7) | 67 (20.2) | 31 (19.7) | 45 (28.7) | ||
| cT1-2 | 24 (15.3) | 29 (8.7) | 24 (15.3) | 16 (10.2) | ||
| cT3-4 | 61 (38.9) | 146 (44.0) | 61 (38.9) | 64 (40.8) | ||
| T1-2 (unknown) | 10 (6.4) | 19 (5.7) | 10 (6.4) | 9 (5.7) | ||
| T3-4 (unknown) | 15 (9.6) | 59 (17.8) | 15 (9.6) | 12 (7.6) | ||
| AJCC 8th ypN stage | 0.011 | 0.721 | ||||
| ypN0 | 68 (43.3) | 109 (32.8) | 68 (43.3) | 66 (42.0) | ||
| ypN1 | 38 (24.2) | 106 (31.9) | 38 (24.2) | 42 (26.8) | ||
| ypN2 | 20 (12.7) | 60 (18.1) | 20 (12.7) | 22 (14.0) | ||
| ypN3 | 9 (5.7) | 31 (9.3) | 9 (5.7) | 12 (7.6) | ||
| Unknown | 22 (14.0) | 26 (7.8) | 22 (14.0) | 15 (9.6) | ||
| Number of nodes removed | ||||||
| <15 | 74 (47.1) | 149 (44.9) | 0.071 | 74 (47.1) | 68 (43.3) | 0.241 |
| ≥15 | 69 (43.9) | 169 (50.9) | 69 (43.9) | 81 (51.6) | ||
| Unknown | 14 (8.9) | 14 (4.2) | 14 (8.9) | 8 (5.1) | ||
| LNR (positive lymph node ratio) | ||||||
| ≤0.1 | 89 (56.7) | 173 (52.1) | 0.008 | 89 (56.7) | 90 (57.3) | 0.358 |
| >0.1 | 43 (27.4) | 130 (39.2) | 43 (27.4) | 50 (31.8) | ||
| Unknown | 25 (15.9) | 29 (8.7) | 25 (15.9) | 17 (10.8) | ||
| Tumor size | ||||||
| <50mm | 76 (48.4) | 137 (41.4) | 0.271 | 76 (48.4) | 67 (42.7) | 0.419 |
| ≥50mm | 49 (31.2) | 126 (38.0) | 49 (31.2) | 60 (38.2) | ||
| Unknown | 32 (20.4) | 69 (20.8) | 32 (20.4) | 30 (19.1) | ||
AC: Adenocarcinoma, SCC: Squamous cell carcinoma, AJCC: American Joint Committee on Cancer, RT±CT: radiotherapy with or without chemotherapy
↵* The staging provided in the database was further subdivided into yp and c stages based on the “CS Lymph Nodes Eval (2004-2015)” field extracted from the SEER data. 2018-2019 was not marked with a staging type and was defined as unknown.