Patient characteristics
In total, 187 patients with HCC were initially identified by chart review, of which 50 patients were excluded due to ineligibility or loss to follow-up after RT (Fig. 2). The remaining 137 patients were included in the final analysis. The comparison of patients’ clinicopathological features according to sarcopenia status before SBRT is listed in Table 1. Overall, 67 (49%) patients had sarcopenia, and 70 (51%) patients did not have sarcopenia. Patients with sarcopenia were more likely to be males or have a larger tumor size, lower serum albumin level, and lower body mass index.
Table 1
Patient characteristics according to the presence of pre-SBRT sarcopenia
|
No. (%)
|
|
|
|
Variable
|
Overall
|
Sarcopenia
|
Non-sarcopenia
|
P-value
|
Age, year
|
|
|
|
|
Mean (SD)*
|
65(11.7)
|
67.2 (13.2)
|
62.6 (13.5)
|
0.24
|
≤ 60
|
52 (38.0)
|
23 (44.2)
|
29 (55.8)
|
0.39
|
> 60
|
85 (62.0)
|
44 (51.8)
|
41 (48.2)
|
|
Sex
|
|
|
|
< 0.001
|
Male
|
106 (77.8)
|
63 (59.4)
|
43 (40.6)
|
|
Female
|
31 (22.2)
|
4 (12.9)
|
27 (87.1)
|
|
Liver disease
|
|
|
|
0.80
|
HBV
|
71 (51.8)
|
37 (52.1)
|
34 (47.9)
|
|
HCV
|
36 (26.3)
|
16 (44.4)
|
20 (55.6)
|
|
HBV and HCV
|
8 (5.8)
|
3 (37.5)
|
5 (62.5)
|
|
Non-virus
|
22 (16.1)
|
11 (50.0)
|
11 (50.0)
|
|
ECOG
|
|
|
|
0.27
|
0–1
|
119 (86.9)
|
56 (47.1)
|
63 (52.9)
|
|
2
|
18 (13.1)
|
11 (61.1)
|
7 (38.9)
|
|
AFP, ng/ml
|
|
|
|
0.17
|
≤200
|
79 (57.7)
|
40 (50.6)
|
39 (49.4)
|
|
> 200
|
51 (37.2)
|
26 (51.0)
|
25 (49.0)
|
|
missing
|
7 (5.1)
|
1 (14.3)
|
6 (85.7)
|
|
ALBI score
|
|
|
|
0.51
|
Mean (SD)*
|
-2.42 (0.57)
|
-2.39 (0.55)
|
-2.45 (0.60)
|
|
Albumin
|
|
|
|
0.05
|
Mean (SD)*
|
3.70 (0.56)
|
3.66 (0.56)
|
3.74 (0.56)
|
|
NLR
|
|
|
|
0.45
|
≤2.5
|
57 (41.6)
|
25 (43.9)
|
32 (56.1)
|
|
>2.5
|
62 (45.3)
|
34 (54.8)
|
28 (45.2)
|
|
Missing
|
18 (13.1)
|
8 (44.4)
|
10 (55.6)
|
|
Prior treatment
|
|
|
|
0.12
|
Yes
|
85 (62)
|
46 (54.1)
|
39 (45.9)
|
|
No
|
52 (38)
|
21 (40.4)
|
31 (59.6)
|
|
No. of tumor
|
|
|
|
0.69
|
Multiple
|
78 (56.9)
|
37 (47.4)
|
41 (52.6)
|
|
Single
|
59 (43.1)
|
30 (50.8)
|
29 (49.2)
|
|
Tumor size, cm
|
|
|
|
0.05
|
≤5
|
67 (48.9)
|
27 (40.3)
|
40 (59.7)
|
|
> 5
|
70 (51.1)
|
40 (57.1)
|
30 (42.9)
|
|
Macrovascular invasion
|
|
|
|
> .99
|
Yes
|
47 (34.3)
|
23 (48.9)
|
24 (51.1)
|
|
No
|
90 (65.7)
|
44 (48.9)
|
46 (51.1)
|
|
Extrahepatic metastasis
|
|
|
|
0.93
|
Yes
|
27 (19.7)
|
13 (48.1)
|
14 (51.9)
|
|
No
|
110 (80.3)
|
54 (49.1)
|
56 (50.9)
|
|
BMI
|
|
|
|
< 0.001
|
Mean (SD)*
|
24.7 (4.1)
|
23.2 (3.2)
|
26.1 (4.5)
|
|
SMI
|
|
|
|
< 0.001
|
Mean (SD)*
|
44.9 (8.8)
|
40.8 (5.5)
|
48.8 (9.5)
|
|
BED, Gy
|
|
|
|
0.30
|
Mean (SD)*
|
87.4 (21.9)
|
85.4 (23.5)
|
89.4 (20.1)
|
|
Abbreviations: SBRT= stereotactic body radiotherapy; HBV = hepatitis B virus; HCV= hepatitis C virus; ECOG = Eastern Cooperative Oncology Group; AFP = alpha fetal protein; ALBI= albumin-bilirubin; NLR= neutrophil lymphocyte ratio; BMI= body mass index; SMI= skeletal muscle index; BED = biological effective dose; SD = standard deviation. *t-test
The intraclass correlation coefficients for SMI (pre-SBRT: 0.99; post-SBRT: 0.99) reflect the high consistency of measurements between the two observers. The median interval between pre- and post-SBRT CT scans was 3 (interquartile range, 2.1–3.7) months. For 90 days, patients with sarcopenia had a mean SMI loss of 1.9, with a relative loss of 4.5%, while patients without sarcopenia had a mean SMI loss of 1.3, with a relative loss of 2.2%.
Survival
With a median follow-up of 14.1 months in the entire cohort and 32.7 months in those alive, 102 deaths were observed at the time of the analysis. Thirteen patients with sarcopenia were alive, with a median survival of 16.1 months, while 22 patients without sarcopenia were alive, with a median survival of 24.0 months. The 1- and 2- year OS in patients with sarcopenia were 60.2% and 44%, respectively, compared with 64.7% and 51.8% in patients without sarcopenia (p = 0.04) (Fig. 3a). The median survival was 6.3 months and 31.4 months in patients with and without SMI loss ≥ 7%, respectively. The 1- and 2- year OS in patients with SMI loss ≥ 7% were 31.9% and 20.3%, respectively, compared with 74.9% and 59.3% in patients without SMI loss ≥ 7% (p = < 0.001) (Fig. 3b).
Prognostic factors
On univariate analysis, independent survival predictors were the presence of pre-SBRT sarcopenia, SMI loss, biological effective dose, ECOG, presence of extrahepatic metastasis, neutrophil-to-lymphocyte ratio (NLR), albumin-bilirubin score, tumor size, multiple tumors, and macrovascular invasion. On multivariate analysis, independent survival predictors were SMI loss, presence of extrahepatic metastasis, NLR, and multiple tumors, in which there was only a statistically significant trend for the presence of pre-SBRT sarcopenia and tumor size (Table 2).
Table 2
Uni- and multi-variate analysis for overall survival
|
Univariate
|
Multivariate
|
Variable
|
HR (95% CI)
|
p
|
HR (95% CI)
|
p
|
Pre-SBRT sarcopenia
|
1.50 (1.01–2.22)
|
0.04
|
1.61 (0.99–2.61)
|
0.05
|
SMI loss ≥ 7%
|
3.24 (2.11–4.99)
|
< 0.001
|
1.96 (1.15–3.33)
|
0.01
|
Age > 60
|
1.20 (0.80–1.79)
|
0.39
|
|
|
Sex male vs. female
|
0.94 (0.59–1.49)
|
0.76
|
|
|
ECOG ≥ 2
|
3.38 (1.90–5.99)
|
< 0.001
|
1.59 (0.80–3.15)
|
0.19
|
AFP ≥ 200 ng/ml
|
1.45 (0.97–2.18)
|
0.07
|
1.44 (0.87–2.39)
|
0.16
|
ALBI (per 0.01-unit increase)
|
1.005 (1.002–1.009)
|
0.003
|
0.999 (0.995–1.004)
|
0.77
|
NLR ≥ 2.5
|
2.27 (1.47–3.49)
|
< 0.001
|
1.79 (1.07-3.00)
|
0.03
|
Prior Treatment
|
1.00 (0.67–1.50)
|
1.00
|
|
|
Multiple tumors
|
2.19 (1.46–3.30)
|
< 0.001
|
2.19 (1.30–3.71)
|
0.003
|
Tumor size ≥ 5 cm
|
2.12 (1.42–3.16)
|
< 0.001
|
1.57 (0.95–2.59)
|
0.08
|
Macrovascular invasion
|
1.92 (1.27–2.92)
|
0.002
|
1.26 (0.76–2.07)
|
0.37
|
Extrahepatic metastasis
|
6.65 (3.90-11.32)
|
< 0.001
|
3.47 (1.79–6.73)
|
< 0.001
|
BED (per 1Gy increase)
|
0.985 (0.976–0.995)
|
0.003
|
0.998 (0.985–1.010)
|
0.69
|
Abbreviations: SBRT= stereotactic body radiotherapy; SMI= skeletal muscle index; ECOG = Eastern Cooperative Oncology Group; AFP = alpha fetal protein; ALBI= albumin-bilirubin; NLR= neutrophil lymphocyte ratio; BED = biological effective dose; HR = hazard ratio; CI = confidence interval.
To clarify the prognostic significance of SMI loss, separate Cox models were performed according to the absence and presence of pre-SBRT sarcopenia. Multivariate analysis showed that SMI loss ≥ 7% remained an independent survival predictor in patients with sarcopenia rather than in patients without sarcopenia (Table 3). The results were similar regardless of the different definitions applied (eTables 1–6 in the Supplement).
Table 3
Multivariate analysis for overall survival according to the presence of pre-SBRT sarcopenia
|
Sarcopenia
|
Nonsarcopenia
|
Variable
|
HR (95% CI)
|
p
|
HR (95% CI)
|
p
|
SMI loss ≥ 7%
|
3.06 (1.22–7.63)
|
0.02
|
1.73 (0.72–4.13)
|
0.22
|
ECOG ≥ 2
|
1.39 (0.48–4.04)
|
0.55
|
3.58 (1.16–11.01)
|
0.03
|
Extrahepatic metastasis
|
2.42 (0.73–8.02)
|
0.15
|
3.36 (1.36–8.31)
|
0.009
|
AFP ≥ 200 ng/ml
|
3.30 (1.51–7.20)
|
0.003
|
0.90 (0.37–2.18)
|
0.81
|
ALBI (per 0.01-unit increase)
|
1.000 (0.990–1.006)
|
0.93
|
0.998 (0.991–1.005)
|
0.52
|
NLR ≥ 2.5
|
3.61 (1.60–8.14)
|
0.002
|
1.50 (0.68–3.29)
|
0.31
|
Multiple tumors
|
3.66 (1.47–9.13)
|
0.005
|
2.44 (1.08–5.54)
|
0.03
|
Tumor size ≥ 5 cm
|
0.87 (0.41–1.86)
|
0.72
|
2.40 (1.16–4.97)
|
0.02
|
Macrovascular invasion
|
1.93 (0.88–4.20)
|
0.10
|
1.05 (0.46–2.36)
|
0.92
|
Extrahepatic metastasis
|
2.42 (0.73–8.02)
|
0.15
|
3.36 (1.36–8.31)
|
0.009
|
BED (per 1Gy increase)
|
1.002 (0.984–1.020)
|
0.83
|
0.990 (0.972–1.007)
|
0.25
|
Abbreviations: SBRT= stereotactic body radiotherapy; SMI= skeletal muscle index; ECOG = Eastern Cooperative Oncology Group; AFP = alpha fetal protein; ALBI= albumin-bilirubin; NLR= neutrophil lymphocyte ratio; BED = biological effective dose; HR = hazard ratio; CI = confidence interval.
Logistic regression demonstrated that patients who were female, older, or had pre-SBRT non-sarcopenia, higher NLR, and larger tumors were more likely to develop SMI loss ≥ 7% after SBRT (Table 4).
Table 4
Factors associated with the occurrence of SMI loss
Variable
|
OR (95%CI)
|
P-value
|
Pre-SBRT sarcopenia
|
0.24 (0.06–0.94)
|
0.04
|
BMI ≥ 24
|
0.48 (0.15–1.53)
|
0.21
|
Age (per 1-unit increase)
|
1.06 (1.01–1.12)
|
0.03
|
Sex female
|
26.70 (3.37-211.37)
|
0.002
|
ECOG ≥ 2
|
1.90 (0.42–8.63)
|
0.40
|
AFP ≥ 200 ng/ml
|
3.40 (0.90-12.88)
|
0.07
|
ALBI (per 0.01-unit increase)
|
1.020 (0.986–1.054)
|
0.25
|
Albumin (per 0.1-unit increase)
|
1.08 (0.76–1.52)
|
0.68
|
NLR (per 0.1-unit increase)
|
1.03 (1.00-1.05)
|
0.02
|
Child-Pugh A
|
3.43 (0.45–26.49)
|
0.24
|
Prior Treatment
|
0.98 (0.32–3.02)
|
0.98
|
Multiple tumors
|
3.43 (0.99–11.90)
|
0.05
|
Tumor size ≥ 5 cm
|
6.32 (1.61–24.88)
|
0.008
|
Extrahepatic metastasis
|
0.87 (0.20–3.85)
|
0.86
|
Macrovascular invasion
|
1.80 (0.54–6.04)
|
0.34
|
BED (per 1Gy increase)
|
0.999 (0.972–1.027)
|
0.96
|
Abbreviations: SMI= skeletal muscle index; SBRT= stereotactic body radiotherapy; BMI= body mass index; ECOG = Eastern Cooperative Oncology Group; AFP = alpha fetal protein; ALBI= albumin-bilirubin; NLR= neutrophil lymphocyte ratio; BED = biological effective dose; OR = odds ratio; CI = confidence interval.
Toxicity
One patient without adequate follow-up was excluded from the toxicity analysis. Thirteen patients had missing values for the post-SBRT CP score. For patients with evaluable data, pre-SBRT sarcopenia was not correlated with the incidence of CP score increase by ≥ 2 within 3 months, in the absence of disease progression (15.9% and 12.8% in patients with and without pre-SBRT sarcopenia, respectively; p = 0.67). However, more patients with SMI loss ≥ 7% experienced an increase in CP score by ≥ 2 compared to their counterparts (38.1% and 7.1% in patients with and without SMI loss ≥ 7%, respectively; p = 0.001).