Table 2. Comparison of patients’ characteristics and the number of harvested lymph nodes among the four learning phases.
| Characteristics | Phase 1 (1st-23th) | Phase 2 (24th-45th) | Phase 3 (46th-77th) | Phase 4 (78th-100th) | P value |
|---|---|---|---|---|---|
| Age | 62.17±7.08 | 60.09±6.42 | 63.09±8.74 | 61.65±8.03 | 0.572 |
| BMI (kg/m2) | 23.19±2.90 | 22.80±2.53 | 22.88±4.81 | 23.60±3.32 | 0.872 |
| Female/male | 4/19 | 3/19 | 6/26 | 3/20 | 0.929 |
| Diabetes | 1 (4.3%) | 1 (4.5%) | 2 (6.3%) | 1 (4.3%) | 0.984 |
| Hypertension | 6 (26.1%) | 5 (22.7%) | 11 (34.4%) | 4 (17.4%) | 0.537 |
| Tumor location | 0.101 | ||||
| Upper | 5 (21.7%) | 2 (9.1%) | 6 (18.8%) | 0 (0.0%) | |
| Middle and lower | 18 (78.3%) | 20 (90.9%) | 28 (81.3%) | 23 (100.0%) | |
| Surgical approach | 0.000 | ||||
| Ivor Lewis | 0 (0.0%) | 3 (13.6%) | 14 (43.8%) | 14 (60.9%) | |
| McKeown | 23 (100%) | 19 (86.4%) | 18 (56.3%) | 9 (39.1%) | |
| Histology | 0.841 | ||||
| SCC | 21 (91.3%) | 20 (90.9%) | 27 (84.4%) | 20 (87.0%) | |
| Other | 2 (8.7%) | 2 (9.1%) | 5 (15.6%) | 3 (13.0%) | |
| RLN-LNs | 2.00±2.15 | 2.77±2.22 | 1.81±2.18 | 2.22±2.70 | 0.470 |
| Thoracic LNs | 8.22±3.24 | 13.05±5.64 | 8.66±3.61 | 10.61±5.28 | 0.001 |
| Abdomen LNs | 10.61±8.34 | 10.86±6.24 | 10.06±6.83 | 11.35±6.23 | 0.923 |
| Total LN | 18.83±9.13 | 23.91±7.10 | 18.72±8.25 | 21.96±7.85 | 0.076 |
| T stage | 0.608 | ||||
| T0-T2 | 12 (52.2%) | 9 (40.9%) | 12 (37.5%) | 12 (52.2%) | |
| T3-T4a | 11 (47.8%) | 13 (59.1%) | 20 (62.5%) | 11 (47.8%) | |
| N stage | 0.760 | ||||
| N0-N1 | 19 (82.6%) | 18 (81.8%) | 23 (71.9%) | 18 (78.3%) | |
| N2-N3 | 4 (17.4%) | 4 (18.2%) | 9 (28.1%) | 5 (21.7%) | |
| TNM Stage | 0.583 | ||||
| 0-II | 12 (52.2%) | 12 (54.5%) | 17 (53.1%) | 16 (70.0%) | |
| III-IVa | 11 (47.8%) | 10 (45.5%) | 15 (46.9%) | 7 (30.0%) |
BMI, body mass index; SCC, squamous cell carcinoma; LN, lymph node; RLN-LN, recurrent laryngeal nerve lymph node.