Definition of AAR
To exclude collinearity, correlation analysis was performed between serum log2-transformed AST and ALB. As shown in Fig. 1A, the R2 value was − 0.22 (95% CI: -0.28, -0.16), suggesting that both variables independently reflect the status of the underlying liver disease. AAR was calculated as the ratio of preoperative serum AST to serum ALB. Of the 991 patients enrolled in this study, we used X-tile plots to generate two optimal cut-off values, namely, 0.7 and 1.6, which categorises resection HCC patients into three strata with a highly different probability of RFS: low-risk (AAR < 0.7, n = 323), intermediate-risk (AAR 0.7–1.6, n = 514), and high-risk (AAR > 1.6, n = 154) (Fig. 1B-D). With AAR < 0.7 category as the reference, the hazard ratios (HRs) for AAR 0.7–1.6 and AAR > 1.6 categories were 1.833 (95% CI: 1.358–2.476) and 3.688 (95% CI: 2.624–5.183), respectively.
Relationship of AAR with clinicopathologic parameters
Table 1shows all patient demographics and clinical characteristics. There were 830 (83.8%) male patients. The majority of patients (942, 95.1%) had a history of HBV infection, and 821 patients (82.8%) had liver cirrhosis.
Table 1
|
all
|
Low-risk group
|
Intermediate-risk group
|
High-risk group
|
p value
|
Variables
|
n = 991
|
n = 323
|
n = 514
|
n = 154
|
|
Age (> 60 y)
|
231 (23.3)
|
71 (22.0)
|
124 (24.1)
|
36 (23.4)
|
0.775
|
Gender (male, %)
|
830 (83.8)
|
273 (84.5)
|
429 (83.5)
|
128 (83.1)
|
0.897
|
Diabetes
|
131 (13.2)
|
51 (15.8)
|
59 (11.5)
|
21 (13.6)
|
0.198
|
HBsAg
|
942 (95.1)
|
300 (92.9)
|
492 (95.7)
|
150 (97.4)
|
0.063
|
HBeAg
|
218 (22.0)
|
42 (13.0)
|
135 (26.3)
|
41 (26.6)
|
< 0.001
|
HBV-DNA (> 103IU/mL)
|
575 (58.0)
|
130 (40.2)
|
324 (63.0)
|
121 (78.6)
|
< 0.001
|
Cirrhosis
|
821 (82.8)
|
263 (81.4)
|
432 (84.0)
|
126 (81.8)
|
0.578
|
Tumor size (cm)
|
4.5 [3.0, 7.5]
|
4.0 [2.8, 5.5]
|
5.0 [3.0, 7.5]
|
8.1 [4.6, 12.0]
|
< 0.001
|
Multiple tumors
|
89 (9.0)
|
25 (7.7)
|
52 (10.1)
|
12 (7.8)
|
0.430
|
MVI
|
227 (22.9)
|
43 (13.3)
|
133 (25.9)
|
51 (33.1)
|
< 0.001
|
Capsular invasion
|
436 (44.0)
|
136 (42.1)
|
228 (44.4)
|
72 (46.8)
|
0.615
|
Satellite lesion
|
102 (10.3)
|
26 (8.0)
|
60 (11.7)
|
16 (10.4)
|
0.244
|
Tumor differentiation
|
|
|
|
|
0.704
|
well
|
14 (1.4)
|
5 (1.5)
|
6 (1.2)
|
3 (1.9)
|
|
moderate
|
534 (53.9)
|
183 (56.7)
|
271 (52.7)
|
80 (51.9)
|
|
poorly
|
443 (44.7)
|
135 (41.8)
|
237 (46.1)
|
71 (46.1)
|
|
AFP (> 400ng/mL)
|
376 (37.9)
|
103 (31.9)
|
197 (38.3)
|
76 (49.4)
|
0.001
|
INR
|
1.04 [1.00, 1.10]
|
1.03 [0.98, 1.08]
|
1.04 [1.00, 1.10]
|
1.07 [1.01, 1.14]
|
< 0.001
|
PLR (> 103.5)
|
382 (38.5)
|
114 (35.3)
|
183 (35.6)
|
85 (55.2)
|
< 0.001
|
NLR (> 2.6)
|
327 (33.0)
|
91 (28.2)
|
167 (32.5)
|
69 (44.8)
|
0.001
|
ALT (> 40IU/L)
|
403 (40.7)
|
38 (11.8)
|
239 (46.5)
|
126 (81.8)
|
< 0.001
|
TBIL (> 17.1µmol/L)
|
40 (4.0)
|
8 (2.5)
|
14 (2.7)
|
18 (11.7)
|
< 0.001
|
CREA (µmol/L)
|
69.0 [60.0, 80.0]
|
72.0 [63.0, 82.0]
|
69.0 [60.0, 80.3]
|
65.0 [57.5, 74.8]
|
< 0.001
|
MVI, microvascular invasion; AFP, α-fetoprotein; PLR, platelet-to-lymphocyte ratio; NLR, neutrophil-to-lymphocyte ratio; ALT, alanine aminotransferase; TBIL, total bilirubin; CREA, creatinine |
Patients in the high AAR group were more likely to have HBeAg-positivity (p < 0.001), positive HBV-DNA (p < 0.001), larger tumour size (p < 0.001), higher incidence of MVI (p < 0.001), and AFP > 400 ng/mL (p = 0.001) than those in the low AAR group. Patients in the high AAR group also had significantly higher PLR (p < 0.001) and higher NLR (p = 0.001) than those in the low AAR group. Regarding other liver function parameters, patients in the high AAR group had significantly higher ALT (> 40 IU/L, p < 0.001), higher TBIL (> 17.1 µmol/L, p < 0.001), and lower creatine level (p < 0.001) than those in the low AAR group. Generally, with a high AAR, the tumour was more advanced and systemic inflammation was higher.
Relationship of AAR with clinicopathologic parameters
We further investigated the correlation between AAR and hepatic inflammation, cirrhosis, and fibrosis-related indices (ALBI, FIB-4, and ARPI; Fig. 2). Regarding the rate of patients with hepatic inflammation grade G1 or G2, there was a decreased tendency from the low-risk group to the high-risk group. In contrast, in terms of grade G3 or G4, there was an increased tendency from the low-risk group to the high-risk group. These findings suggest that AAR is positively correlated with hepatic inflammation. However, for liver cirrhosis, the correlation between both was not obvious. The ALBI, FIB-4, and ARPI were used to assess liver fibrosis. Despite the significant relationship between the risk score and ALBI or FIB-4, the correlation coefficient R2 was much small (0.36 and 0.45, respectively). Notably, the relationship between ARPI and the risk score was significant (R2 = 0.73, p < 0.001).
RFS and OS stratified by AAR
Till the final follow-up, there were 295 deaths and 556 recurrences. Survival analysis was performed based on AAR. As expected, the score could significantly distinguish the OS of HCC patients between the subgroups (all: p < 0.001, intermediate-risk vs. low-risk: p < 0.001, high-risk vs. intermediate-risk: p < 0.001). In terms of the RFS, the risk score still performed well (all: p < 0.001, intermediate-risk vs. low-risk: p = 0.006, high-risk vs. intermediate-risk: p < 0.001). The 1-, 3-, and 5-year OS were 93.8%, 85.0%, and 75.8% for the low-risk group; 89.0%, 73.0%, and 61.6% for the intermediate-risk group; and 73.5%, 47.8%, and 43.5% for the high-risk group, respectively. The 1-, 3-, and 5-year RFS were 76.3%, 54.6%, and 41.1% for the low-risk group; 68.1%, 44.4%, and 35.5% for the intermediate-risk group; and 48.2%, 31.9%, and 22.5% for the high-risk group, respectively. With a higher score, the prognosis was worse (Fig. 3A and 3B).
As shown in Fig. 4, the multivariable analysis determined that AAR (HR: 1.434, 95% CI 1.193–1.723; p < 0.001) was an independent predictor of OS in HCC patients undergoing hepatectomy, followed by tumour size, multiple tumours, AFP > 400 ng/mL, satellite lesions, MVI, liver cirrhosis, HBeAg-positivity, and INR (all p < 0.05). Similarly, the multivariable analysis determined that AAR (HR: 1.162, 95% CI 1.020–1.323; p = 0.024) was an independent predictor of RFS in HCC patients undergoing hepatectomy, followed by tumour size, multiple tumours, satellite lesions, MVI, liver cirrhosis, and HBeAg-positivity (all p < 0.05).
External validation
As shown in Supplementary Table 1, the clinicopathological features were distributed among the three groups similar to those in the primary cohort. A high AAR was associated with advanced tumours and active HBV replication. To validate the predictive role of AAR, we included another 883 patients who underwent hepatectomy between 2010 and 2014 at West China Hospital. AAR was constructed as abovementioned. As shown in Fig. 3C and 3D, AAR could significantly distinguish the OS of HCC patients between the subgroups (all: p < 0.001, intermediate-risk vs. low-risk: p = 0.02, high-risk vs. intermediate-risk: p = 0.002). In terms of RFS, the risk score still performed well (all: p < 0.001, intermediate-risk vs. low-risk: p = 0.005, high-risk vs. intermediate-risk: p = 0.187) (Fig. 3C and 3D).