Table 2.
Demographic data of the patients and lesions
| ER + SS (n = 162) | Surgery (n = 392) | P Value | |
| Sex | |||
| Male | 95 | 221 | 0.62b |
| Female | 67 | 171 | |
| Age, yr (mean ± SD) | 62.3 ± 10.5 | 63.1 ± 11.0 | 0.41d |
| Lesion size | |||
| Endoscopically estimated | 29.1 ± 20.7 | 24.0 ± 12.9 | <0.01d |
| Histologically evaluated | 27.5 ± 20.0 | 22.3 ± 15.2 | <0.01d |
| Macroscopic feature | <0.01b | ||
| Ip/Isp/Is/Is + IIa | 85 (52.5%) | 134 (34.2%) | |
| IIa/IIc/IIa + IIc/Is + IIc | 77 (47.5%) | 258 (65.8%) | |
| Location of the lesion | 0.47b | ||
| Proximal colon (C-T) | 56 (34.6%) | 123 (31.4%) | |
| Distal colon (D-Rs) | 60 (37.0%) | 137 (34.9%) | |
| Rectum (Ra-Rb) | 46 (28.4%) | 132 (33.7%) | |
| Mean period to surgery [mo] | 2.4 ± 1.5 | 0.8 ± 1.0 | <0.01d |
| Lymphatic invasion | <0.01b | ||
| (+) | 51 (30.9%) | 77 (19.6%) | |
| (−) | 111 (69.1%) | 31 (80.4%) | |
| Venous invasion | 0.02b | ||
| (+) | 35 (21.6%) | 125 (31.9%) | |
| (−) | 127 (78.4%) | 267 (68.1%) | |
| Predominant histology | <0.01b | ||
| Well-differentiated tubular adenocarcinoma | 149 (92.0%) | 300 (76.5%) | |
| Moderately differentiated tubular adenocarcinoma | 12 (7.4%) | 83 (21.1%) | |
| Poorly differentiated tubular adenocarcinoma | 0 | 3 (0.8%) | |
| Mucinous | 1 (0.6%) | 2 (0.5%) | |
| Papillary adenocarcinoma | 0 | 4 (1.0%) | |
| Risk factor of LNMa | 0.31b | ||
| (+) | 20 (12.4%) | 61 (15.7%) | |
| (−)/unknown | 142 (87.6%) | 327 (84.3%) | |
| Depth of invasion | <0.01b | ||
| pT1a | 27 (16.7%) | 12 (3.1%) | |
| pT1b | 135 (83.3%) | 380 (96.9%) | |
| Recurrence | 0.79c | ||
| (+) | 4 (2.5%) | 13 (3.3%) | |
| (−) | 158 (97.5%) | 379 (96.7%) |
A higher number of patients were diagnosed with T1a, and most lesions were histologically diagnosed as well-differentiated adenocarcinoma in the secondary surgery group.
ER, endoscopic resection; LNM, lymph node metastasis; SS, secondary surgery.
a
Risk factors of LNM included histological findings of the poorly differentiated component, mucinous adenocarcinoma component, signet ring cell component, budding grade 2 or 3, pT1a: pathologically evaluated submucosal invasion <1,000 μm, pT1b: pathologically evaluated submucosal invasion ≥1,000 μm.
b
The chi-square test.
c
The Fisher exact test.
d
The Student t test.