Preoperative assessment of sarcopenia and comparisons between SG and NSG regarding baseline characteristics
Baseline characteristics of SG and NSG were summarized in Table 1. SG included significantly more patients that had a remarkably lower body mass index, which was consistent with previous studies[18, 19]. The SG included 574 patients while there were 365 patients in the NSG. SG was not significantly different from NSG in terms of most baseline characteristics except significantly lower BMI (P < 0.001), larger tumor size (P < 0.001), and and more weight loss (P = 0.029).
Table 1
Comparisons between SG and NSG regarding baseline characteristics.
Characteristics
|
No.
|
Sarcopenia
|
χ2/t
|
P
|
|
|
No(N = 365)
|
Yes(N = 574)
|
Value
|
Value
|
BMI
|
|
22.24 ± 2.98
|
21.52 ± 2.45
|
3.907
|
0.000
|
Age
|
|
57.76 ± 12.89
|
58.65 ± 12.62
|
-1.048
|
0.295
|
<60y
|
470(50.1)
|
187(51.2)
|
283(49.3)
|
0.332
|
0.564
|
≥ 60y
|
469(49.9)
|
178(48.8)
|
291(50.7)
|
|
|
Gender
|
|
|
|
0.290
|
0.590
|
Male
|
553(58.9)
|
211(57.8)
|
342(59.6)
|
|
|
Female
|
386(41.1)
|
154(42.2)
|
232(40.4)
|
|
|
Weight loss
|
|
|
|
4.747
|
0.029
|
No
|
527(56.1)
|
221(60.5)
|
306(53.3)
|
|
|
Yes
|
412(43.9)
|
144(39.5)
|
268(46.7)
|
|
|
Intestinal obstruction
|
|
|
|
0.002
|
0.963
|
No
|
870(92.7)
|
338(92.6)
|
532(92.7)
|
|
|
Yes
|
69(7.3)
|
27(7.4)
|
42(7.3)
|
|
|
Tumor size
|
|
|
|
18.851
|
0.000
|
<5cm
|
480(51.1)
|
219(60.0)
|
261(45.5)
|
|
|
≥ 5cm
|
459(48.9)
|
146(40.0)
|
313(54.5)
|
|
|
Location
|
|
|
|
1.851
|
0.604
|
Rectum
|
569(60.6)
|
230(63.0)
|
339(59.1)
|
|
|
Sigmoid colon
|
289(30.8)
|
104(28.5)
|
185(32.2)
|
|
|
Descending colon
|
60(6.4)
|
22(6.0)
|
38(6.6)
|
|
|
Splenic flexure
|
21(2.2)
|
9(2.5)
|
12(2.1)
|
|
|
Gross morphology
|
|
|
|
3.412
|
0.182
|
Massive
|
306(32.6)
|
109(29.9)
|
197(34.3)
|
|
|
Ulcerative
|
530(56.4)
|
209(57.3)
|
321(55.9)
|
|
|
Infiltrative
|
103(11.0)
|
47(12.9)
|
56(9.8)
|
|
|
Differentiation
|
|
|
|
0.970
|
0.325
|
Medium/poor
|
874(93.1)
|
336(92.1)
|
538(93.7)
|
|
|
Well
|
65(6.9)
|
29(7.9)
|
36(6.3)
|
|
|
Component
|
|
|
|
1.730
|
0.421
|
Adenocarcinoma
|
899(95.7)
|
346(94.8)
|
553(96.3)
|
|
|
Mucinous
|
32(3.4)
|
16(4.4)
|
16(2.8)
|
|
|
Siglet-ring carcinoma
|
8(0.9)
|
3(0.8)
|
5(0.9)
|
|
|
Vessel invasion
|
|
|
|
2.308
|
0.129
|
No
|
890(94.8)
|
351(96.2)
|
539(93.9)
|
|
|
Yes
|
49(5.2)
|
14(3.8)
|
35(6.1)
|
|
|
Nerve invasion
|
|
|
|
1.715
|
0.190
|
No
|
922(98.2)
|
361(98.9)
|
561(97.7)
|
|
|
Yes
|
17(1.8)
|
4(1.1)
|
13(2.3)
|
|
|
T
|
|
|
|
7.720
|
0.052
|
T1
|
37(3.9)
|
19(5.2)
|
18(3.1)
|
|
|
T2
|
160(17.0)
|
69(18.9)
|
91(15.9)
|
|
|
T3
|
372(39.6)
|
151(41.4)
|
221(38.5)
|
|
|
T4
|
370(39.4)
|
126(34.5)
|
244(42.5)
|
|
|
N
|
|
|
|
0.129
|
0.937
|
N0
|
553(58.9)
|
214(58.6)
|
339(59.1)
|
|
|
N1
|
244(26.0)
|
97(26.6)
|
147(25.6)
|
|
|
N2
|
142(15.1)
|
54(14.8)
|
88(15.3)
|
|
|
AJCC/UICC
|
|
|
|
3.063
|
0.216
|
Ⅰ
|
162(17.3)
|
72(19.7)
|
90(15.7)
|
|
|
Ⅱ
|
392(41.7)
|
143(39.2)
|
249(43.4)
|
|
|
Ⅲ
|
385(41.0)
|
150(41.1)
|
235(40.9)
|
|
|
CEA level(µg/L)
|
|
|
|
0.042
|
0.838
|
<5
|
616(65.6)
|
238(65.2)
|
378(65.9)
|
|
|
≥ 5
|
323(34.4)
|
127(34.8)
|
196(34.1)
|
|
|
CA199
|
|
|
|
0.002
|
0.962
|
<37
|
811(86.4)
|
315(86.3)
|
496(86.4)
|
|
|
≥ 37
|
128(13.6)
|
50(13.7)
|
78(13.6)
|
|
|
Chemotherapy
|
|
|
|
0.283
|
0.595
|
No
|
476(50.7)
|
189(51.8)
|
287(50.0)
|
|
|
Yes
|
463(49.3)
|
176(48.2)
|
287(50.0)
|
|
|
Intraoperative and postoperative outcomes of SG and NSG
Subsequently we compared SG and NSG regarding intraoperative and postoperative outcomes, results of which demonstrated that SG had a longer hospital stay after surgery (P = 0.040), more intraoperative blood transfusion (P = 0.035), and a higher incidence of anastomotic fistula (P = 0.027), incision infection (P = 0.037) and hypoalbuminemia (P = 0.022) (Table 2).
Table 2
Comparisons between SG and NSG regarding intraoperative and postoperative outcomes
Characteristics
|
No.
|
Sarcopenia
|
χ2/t
|
P
|
|
|
No(N = 365)
|
Yes(N = 574)
|
Value
|
Value
|
Operation time
|
|
218.27 ± 85.16
|
220.36 ± 86.73
|
-0.363
|
0.717
|
Hospitalization after surgery
|
|
10.95 ± 7.18
|
12.00 ± 8.36
|
-2.061
|
0.040
|
Intraoperative
blood transfusion
|
|
|
|
|
|
No
|
828(88.2)
|
332(91.0)
|
496(86.4)
|
4.427
|
0.035
|
Yes
|
111(11.8)
|
33(9.0)
|
78(13.6)
|
|
|
Abdominal infection
|
|
|
|
1.277
|
0.258
|
No
|
914(97.3)
|
358(98.1)
|
556(96.9)
|
|
|
Yes
|
25(2.7)
|
7(1.9)
|
18(3.1)
|
|
|
Pulmonary infection
|
|
|
|
0.197
|
0.657
|
No
|
924(98.4)
|
360(98.6)
|
564(98.3)
|
|
|
Yes
|
15(1.6)
|
5(1.4)
|
10(1.7)
|
|
|
Urinary infection
|
|
|
|
0.634
|
0.426
|
No
|
925(98.5)
|
361(98.9)
|
564(98.3)
|
|
|
Yes
|
14(1.5)
|
4(1.1)
|
10(1.7)
|
|
|
Urinary retention
|
|
|
|
3.060
|
0.080
|
No
|
926(98.6)
|
363(99.5)
|
563(98.1)
|
|
|
Yes
|
13(1.4)
|
2(0.5)
|
11(1.9)
|
|
|
Ureter injury
|
|
|
|
0.753
|
0.385
|
No
|
934(99.5)
|
364(99.7)
|
570(99.3)
|
|
|
Yes
|
5(0.5)
|
1(0.3)
|
4(0.7)
|
|
|
Incision infection
|
|
|
|
4.348
|
0.037
|
No
|
920(98.0)
|
362(99.2)
|
558(97.2)
|
|
|
Yes
|
19(2.0)
|
3(0.8)
|
16(2.8)
|
|
|
Abdominal hemorrhage
|
|
|
|
3.579
|
0.059
|
No
|
934(99.5)
|
361(98.9)
|
573(99.8)
|
|
|
Yes
|
5(0.5)
|
4(1.1)
|
1(0.2)
|
|
|
Postoperative intestinal obstruction
|
|
|
|
0.240
|
0.624
|
No
|
921(98.1)
|
357(97.8)
|
564(98.3)
|
|
|
Yes
|
18(1.9)
|
8(2.2)
|
10(1.7)
|
|
|
DVT
|
|
|
|
0.047
|
0.828
|
No
|
932(99.3)
|
362(99.2)
|
570(99.3)
|
|
|
Yes
|
7(0.7)
|
3(0.8)
|
4(0.7)
|
|
|
Anastomotic fistula
|
|
|
|
4.915
|
0.027
|
No
|
889(94.7)
|
353(96.7)
|
536(93.4)
|
|
|
Yes
|
50(5.3)
|
12(3.3)
|
38(6.6)
|
|
|
Hypoalbuminemia
|
|
|
|
5.216
|
0.022
|
No
|
814(86.7)
|
328(89.9)
|
486(84.7)
|
|
|
Yes
|
125(13.3)
|
37(10.1)
|
88(15.3)
|
|
|
Survival Analysis
The Kaplan-Meier method was used to calculate OS and RFS. The overall five-year OS rates and five-year RFS rates were 75.8% and 72.2%, respectively. The five-year OS rate of SG was 73.6% while that for NSG was 79.4%. The five-year RFS rate of SG was 70.2% while that for NSG was 75.3%. Survival curves were plotted by Kaplan-Meier analysis, revealing that SG was associated with significantly worse OS (P = 0.016) (Fig. 2A) and RFS (P = 0.036) (Fig. 2B).
In order to further evaluate the impacts of sarcopenia on OS and RFS, we then accomplished Cox regression analysis to demonstrate whether sarcopenia would independently OS and RFS. Initially, univariate Cox regression analysis was performed to identify factors significantly associated with OS, demonstrating that age (P = 0.003, HR = 1.448, 95%CI: 1.131–1.854), tumor location (P = 0.003, HR = 0.745, 95%CI: 0.611–0.907), differentiation (P = 0.006, HR = 0.345, 95%CI: 0.163–0.732), histological component (P < 0.001, HR = 2.504, 95%CI: 1.778–3.526), depth of invasion (P < 0.001, HR = 1.681, 95%CI: 1.412–2.001), lymph node metastasis (P < 0.001, HR = 2.087, 95%CI: 1.799–2.422), TNM stage (P < 0.001, HR = 2.269, 95%CI: 1.856–2.774), vessel invasion (P < 0.001, HR = 3.137, 95%CI: 2.117–4.648), nerve invasion (P < 0.001, HR = 4.311, 95%CI: 2.465–7.540), adjuvant chemotherapy (P = 0.006, HR = 0.708, 95%CI: 0.553–0.906), CEA (P < 0.001, HR = 1.598, 95%CI: 1.249–2.044), CA199 (P < 0.001, HR = 2.024, 95%CI: 1.505–2.722) and sarcopenia (P = 0.017, HR = 1.379, 95%CI: 1.060–1.794) were significantly associated with OS (Table 3). Then these variables significantly associated with OS proven by univariate Cox regression analysis were included in multivariate Cox regression analysis to identify independent predictive factors for OS, demonstrating that age (P < 0.001, HR = 1.622, 95%CI: 1.258–2.091), tumor location (P = 0.001, HR = 0.714, 95%CI: 0.585–0.871), histological component (P = 0.001, HR = 1.799, 95%CI: 1.263–2.561), depth of invasion (P = 0.012, HR = 1.309, 95%CI: 1.062–1.614), lymph node metastasis (P = 0.001, HR = 1.620, 95%CI: 1.231–2.131), nerve invasion (P = 0.044, HR = 1.840, 95%CI: 1.017–3.332), CA199 (P = 0.029, HR = 1.423, 95%CI: 1.037–1.952) and sarcopenia (P = 0.0211, HR = 1.367, 95%CI: 1.049–1.782) were independent predictive factors for OS (Table 3).
Table 3
Cox regression analysis performed to verify independent predictive factors for overall survival.
Characteristic
|
Univariate analysis
|
Multivariate analysis
|
P
Value
|
HR(95.0% CI)
|
P
Value
|
HR(95.0% CI)
|
Gender
|
0.363
|
0.890(0.692–1.144)
|
|
|
Age
|
0.003
|
1.448(1.131–1.854)
|
0.000
|
1.622(1.258–2.091)
|
Tumor size
|
0.622
|
1.063(0.833–1.357)
|
|
|
Location
|
0.003
|
0.745(0.611–0.907)
|
0.001
|
0.714(0.585–0.871)
|
Gross morphology
|
0.396
|
1.088(0.895–1.322)
|
|
|
Differentiation
|
0.006
|
0.345(0.163–0.732)
|
|
|
Component
|
0.000
|
2.504(1.778–3.526)
|
0.001
|
1.799(1.263–2.561)
|
T
|
0.000
|
1.681(1.412–2.001)
|
0.012
|
1.309(1.062–1.614)
|
N
|
0.000
|
2.087(1.799–2.422)
|
0.001
|
1.620(1.231–2.131)
|
AJCC/UICC
|
0.000
|
2.269(1.856–2.774)
|
|
|
Vessel invasion
|
0.000
|
3.137(2.117–4.648)
|
|
|
Nerve invasion
|
0.000
|
4.311(2.465–7.540)
|
0.044
|
1.840(1.017–3.332)
|
Chemotherapy
|
0.006
|
0.708(0.553–0.906)
|
|
|
CEA
|
0.000
|
1.598(1.249–2.044)
|
|
|
CA199
|
0.000
|
2.024(1.505–2.722)
|
0.029
|
1.423(1.037–1.952)
|
Sarcopenia
|
0.017
|
1.379(1.060–1.794)
|
0.0211
|
1.367(1.049–1.782)
|
Similarly, independent predictive factors for RFS were identified by Cox regression analysis. Initially, univariate Cox regression was performed to identify variables significantly associated with RFS, revealing that age (P = 0.030, HR = 1.305, 95%CI: 1.026–1.659), tumor location (P = 0.008, HR = 0.774, 95%CI: 0.641–0.934), differentiation (P = 0.009, HR = 0.390, 95%CI: 0.193–0.787), histological component (P < 0.001, HR = 2.195, 95%CI: 1.578–3.054), depth of invasion (P < 0.001, HR = 1.542, 95%CI: 1.311–1.813), lymph node metastasis (P < 0.001, HR = 2.136, 95%CI: 1.848–2.469), TNM stage (P < 0.001, HR = 2.367, 95%CI: 1.940–2.889), vessel invasion (P < 0.001, HR = 3.041, 95%CI: 2.079–4.449), nerve invasion (P < 0.001, HR = 3.878, 95%CI: 2.219–6.778), adjuvant chemotherapy (P < 0.001, HR = 0.623, 95%CI: 0.488–0.794), CEA (P < 0.001, HR = 1.617, 95%CI: 1.271–2.056), CA199 (P < 0.001, HR = 1.960, 95%CI: 1.460–2.631) and sarcopenia (P = 0.037, HR = 1.310, 95%CI: 1.017–1.689) were significantly associated with RFS (Table 4). Then these variables significantly associated with RFS proven by univariate Cox regression analysis were included in multivariate Cox regression analysis, revealing that age (P = 0.002, HR = 1.465, 95%CI: 1.145–1.873), tumor location (P = 0.002, HR = 0.743, 95%CI: 0.615–0.897), histological component (P = 0.015, HR = 1.536, 95%CI: 1.088–2.168), lymph node metastasis (P = 0.001, HR = 1.558, 95%CI: 1.194–2.034), CEA (P = 0.023, HR = 1.339, 95%CI: 1.041–1.722), CA199 (P = 0.026, HR = 1.421, 95%CI: 1.043–1.936) and sarcopenia (P = 0.045, HR = 1.299, 95%CI: 1.006–1.677) were independent predictive factors for RFS (Table 4).
Table 4
Cox regression analysis performed to verify independent predictive factors for recurrence-free survival.
Characteristic
|
Univariate analysis
|
Multivariate analysis
|
P
Value
|
HR(95.0% CI)
|
P
Value
|
HR(95.0% CI)
|
Gender
|
0.793
|
0.968(0.759–1.234)
|
|
|
Age
|
0.030
|
1.305(1.026–1.659)
|
0.002
|
1.465(1.145–1.873)
|
Tumor size
|
0.629
|
1.061(0.835–1.346)
|
|
|
Location
|
0.008
|
0.774(0.641–0.934)
|
0.002
|
0.743(0.615–0.897)
|
Gross morphology
|
0.674
|
1.042(0.860–1.263)
|
|
|
Differentiation
|
0.009
|
0.390(0.193–0.787)
|
|
|
Component
|
0.000
|
2.195(1.578–3.054)
|
0.015
|
1.536(1.088–2.168)
|
T
|
0.000
|
1.542(1.311–1.813)
|
|
|
N
|
0.000
|
2.136(1.848–2.469)
|
0.001
|
1.558(1.194–2.034)
|
AJCC/UICC
|
0.000
|
2.367(1.940–2.889)
|
|
|
Vessel invasion
|
0.000
|
3.041(2.079–4.449)
|
|
|
Nerve invasion
|
0.000
|
3.878(2.219–6.778)
|
|
|
Chemotherapy
|
0.000
|
0.623(0.488–0.794)
|
|
|
CEA
|
0.000
|
1.617(1.271–2.056)
|
0.023
|
1.339(1.041–1.722)
|
CA199
|
0.000
|
1.960(1.460–2.631)
|
0.026
|
1.421(1.043–1.936)
|
Sarcopenia
|
0.037
|
1.310(1.017–1.689)
|
0.045
|
1.299(1.006–1.677)
|