A total of 429 patients were finally enrolled in our study, including 148 patients in the high-risk group and 281 patients in the low-risk group. The median age of patients was 56 years (range 51–62), and the median body mass index was 26.0 kg/m2 (range 23.5–28.3). There were 384 (89.5%) patients diagnosed with endometrial adenocarcinoma. In total, 140 patients (32.6%) underwent SLN dissection only, while 289 patients (67.4%) underwent pelvic lymph node dissection with or without para-aortic lymph node dissection. ICG was used in 31.0% (133/429) patients, CNP was used in 48.0% (206/429) patients and the combination of ICG and CNP was used in 21.0% (90/429) patients. Tracers showed no significant differences between the high-risk and low-risk groups (p = 0.866). The clinicopathologic characteristics are presented in Table 1.
Table 1
The clinicopathologic characteristics of EC patients.
Clinicopathologic characteristics | High risk (%) (n = 148) | Low risk (%) (n = 281) | Total (%) (n = 429) |
Age (years) | 59 (55–66) | 55 (49–60) | 56 (51–62) |
Body mass index (kg/m2) | 25.4 (23.2–27.9) | 26.2 (23.8–28.8) | 26.0 (23.5–28.3) |
Histology | | | |
Endometrial adenocarcinoma | 103 (69.6) | 281 (100.0) | 384 (89.5) |
Serous adenocarcinoma | 23 (15.5) | 0 (0.0) | 23 (5.4) |
Clear cell adenocarcinoma | 8 (5.4) | 0 (0.0) | 8 (1.9) |
Others | 14 (9.5) | 0 (0.0) | 14 (3.3) |
Stage (FIGO 2009) | | | |
I | 104 (70.3) | 263 (93.6) | 367 (85.7) |
II | 12 (8.1) | 8 (2.8) | 20 (4.7) |
III | 28 (18.9) | 10 (3.6) | 38 (8.8) |
IV | 4 (2.7) | 0 (0.0) | 4 (0.9) |
Lymph node assessment | | | |
SLNDa only | 16 (10.8) | 124 (44.1) | 140 (32.6) |
SLND + PLNDb ± PALNDc | 132 (89.2) | 157 (55.9) | 289 (67.4) |
Tracers used | | | |
ICGd | 46 (31.1) | 87 (31.0) | 133 (31.0) |
CNPe | 73 (49.3) | 133 (47.3) | 206 (48.0) |
ICG and CNP | 29 (19.6) | 61 (21.7) | 90 (21.0) |
SLN metastasis | 9 (6.0) | 3 (1.1) | 12 (2.8) |
Total lymph node metastasis | 19 (12.8) | 3 (1.1) | 22 (5.1) |
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SLND, sentinel lymph node dissection.
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PLND, pelvic lymph node dissection.
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PALND, para-aortic lymph node dissection.
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ICG, indocyanine green。
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CNP, carbon nanoparticles.
The unilateral and bilateral detection rates of SLN were 86.5% (317/429) and 55.9% (240/429), respectively. The detection rate was remarkably lower in the high-risk group than in the low-risk group (unilateral detection rate: high-risk vs. low-risk: 81.1% vs 88.9%, p = 0.018; bilateral detection rate: high-risk vs. low-risk: 43.9% vs. 62.3%, p < 0.001). There was no significant difference in unilateral and bilateral detection rates between the groups when the combination of ICG and CNP was used (unilateral detection rate: high-risk vs. low-risk: 96.6% vs. 93.4%, p = 0.547; bilateral detection rate: high-risk vs. low-risk: 55.2% vs. 72.1%, p = 0.111). The detection rates of SLN in EC are presented in Table 2. The overall sensitivity and negative predictive value were 54.5% and 97.2%, respectively. The sensitivity and negative predictive value in the high-risk group were 47.4% and 91.0%, respectively. The sensitivity and negative predictive value in the low-risk group were 100.0% and 100.0%, respectively (Table S1).
Table 2
The overall and bilateral detection between two groups of EC patients.
| Total (%) | High risk (%) | Low risk (%) | p -valuea |
unilateral detection | 371/429 (86.5) | 120/148 (81.1) | 251/281 (89.3) | 0.018* |
Bilateral detection | 240/429 (55.9) | 65/148 (43.9) | 175 (62.3) | < 0.001* |
ICG unilateral detection | 122/133(91.7) | 40/46(87.0) | 82/87(94.3) | 0.146 |
ICG bilateral detection | 78/133(58.6) | 20/46(43.5) | 58/87(66.7) | 0.01* |
CNP unilateral detection | 164/206(76.9) | 52/73(71.2) | 112/133(84.2) | 0.027* |
CNP bilateral detection | 102/206(49.5) | 29/73(39.7) | 73/133(54.9) | 0.037* |
combined unilateral detection | 85/90(94.4) | 28/29(96.6) | 57/61(93.4) | 0.547 |
combined bilateral detection | 60/90(66.7) | 16/29(55.2) | 44/61(72.1) | 0.111 |
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P-value between high risk and low risk group.
The UPP was identified mostly (353/371, 95.1%) in EC patients with successful SLN mapping, and the bilateral UPP was detected in 55.8% (207/371) of these patients. In the high-risk group, the unilateral and bilateral detection rates of UPP were 93.3% (112/120) and 51.7% (62/120), respectively (Fig. 1). In the low-risk group, the unilateral and bilateral detection rates of UPP were 96.0% (241/251) and 57.8% (145/251), respectively. The detection rate of UPP was similar in high- and low-risk groups (p = 0.261). The LPP was found in only 57 patients (57/371, 15.4%). The detection rate of LPP was significantly lower in the high-risk group than in the low-risk group (10.0% vs 17.9%, p = 0.048). Isolated LPP was rarely detected in EC patients (5/371, 1.3%), and there was no difference in this regard between the two groups (high-risk group vs. low-risk group: 0.8% vs. 1.6%, p = 0.910). The lymphatic drainage pathways in the two groups of EC patients are shown in Table 3.
Table 3
Lymphatic drainage pathway between two groups of EC patients.
| Total (%) (n = 371) | High risk (%) (n = 120) | Low risk (%) (n = 251) | p -valuea |
UPPa unilateral | 353 (95.1) | 112 (93.3) | 241 (96.0) | 0.261 |
LPPb unilateral | 57 (15.4) | 12 (10.0) | 45 (17.9) | 0.048* |
UPP bilateral | 207 (55.8) | 62 (51.7) | 145 (57.8) | 0.268 |
LPP bilateral | 4 (1.1) | 0 (0.0) | 4 (1.6) | 0.394 |
UPP only | 301 (81.1) | 101 (84.2) | 200 (79.7) | 0.302 |
LPP only | 5 (1.3) | 1 (0.8) | 4 (1.6) | 0.910 |
UPP and LPP | 52 (14.0) | 11 (9.2) | 41 (16.3) | 0.063 |
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UPP, upper paracervical pathway.
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LPP, lower paracervical pathway.
About 1801 SLNs were dissected from 371 EC patients, including 520 SLNs in the high-risk group and 1281 SLNs in the low-risk group. External iliac SLNs (46.6% in total; high-risk group vs. low-risk group: 44.0% vs 47.6%, p = 0.167) and obturator SLNs (37.8% in total; high-risk group vs. low-risk group: 40.0% vs. 36.9%, p = 0.223) were the most common SLNs. Common iliac SLNs were significantly more common in the high-risk group than in the low-risk group (7.5% vs. 5.1%, p = 0.045), while internal iliac SLNs were significantly less common in the high-risk group than in the low-risk group (1.9% vs. 6.9%, p < 0.001). Interestingly, SLNs in the para-aortic or precaval area were more common in the high-risk group, compared with the low-risk group (2.9% vs. 0.9%, p = 0.001). The distribution of SLNs in the two groups of EC patients is shown in Table S2 and Fig. 2.
We found that lymphatic metastasis mostly affected external iliac (18/103, 18.5%) and obturator (34/103, 33.0%) lymph nodes. Internal iliac metastatic lymph nodes were significantly less common in the high-risk group than in the low-risk group (1.1% vs. 27.3%, p = 0.001), while para-aortic or precaval metastatic lymph nodes were more common in the high-risk group (32.6% vs 9.1%, p = 0.208). The distribution of metastatic lymph nodes in the high- and low-risk patients is shown in Table 4.
Table 4
The distribution of metastatic lymph nodes between high and low risk patients.
Lymphatic area | Total (%) (MLNs = 103) | High risk (%) (MLNs = 92) | Low risk (%) (MLNs = 11) |
External iliac | 18 (18.5) | 15(16.3) | 3 (27.3) |
Obturator fossa | 34 (33.0) | 30 (32.6) | 4 (36.4) |
Deep inguinal | 1 (1.0) | 1 (1.1) | 0 (0.0) |
Parametrial | 2 (1.9) | 2 (2.2) | 0 (0.0) |
Internal iliac | 4 (3.9) | 1 (1.1) | 3 (27.3) |
Presacral | 7 (6.8) | 7 (7.6) | 0 (0.0) |
Common iliac | 6 (5.8) | 6 (6.5) | 0 (0.0) |
Para-aortic or precaval | 31 (30.1) | 30 (32.6) | 1 (9.1) |