Abstract
Background
The prognostic significance of the aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio in hepatocellular carcinoma remains uncertain. The aim of the current study was to evaluate the association between the AST/ALT ratio and prognosis in patients with hepatocellular carcinoma after hepatectomy, and to explore the role of underlying liver diseases as mediators.
Methods
This retrospective study included patients with hepatocellular carcinoma who underwent hepatectomy between January 2014 and January 2018 at two Chinese hospitals. The maximally selected rank statistic and g-computation approach were used to quantify and visualize the association between the AST/ALT ratio and overall survival or recurrence-free survival. The role of mediators (chronic hepatitis B, hepatic steatosis and liver cirrhosis) was analysed.
Results
Among the 1519 patients (mean(s.d.) age at baseline, 50.5(11.3) years), 1309 (86.2%) were male. During a median follow-up of 46.0 months, 514 (33.8%) patients died and 358 (23.6%) patients experienced recurrence. The optimal cut-off value for the AST/ALT ratio was 1.4, and the AST/ALT ratio greater than or equal to 1.4 was independently associated with a 39.0% increased risk of death and a 30.0% increased risk of recurrence (overall survival: hazard ratio (HR), 1.39; 95% c.i. 1.15 to 1.68; recurrence-free survival: HR, 1.30; 95% c.i. 1.12 to 1.52) after adjusting for confounders. Chronic hepatitis B significantly mediated the association of the ratio of AST/ALT with both overall survival and recurrence-free survival (20.3% for overall survival; 20.1% for recurrence-free survival).
Conclusion
The AST/ALT ratio greater than or equal to 1.4 was associated with shorter overall survival and recurrence-free survival in patients with hepatocellular carcinoma after hepatectomy, and chronic hepatitis B may play a role in their association.
To quantify and visualize the association between the aspartate aminotransferase/alanine aminotransferase ratio and prognosis in patients with hepatocellular carcinoma after hepatectomy, and to explore the underlying liver disease of mediators in their association. The aspartate aminotransferase/alanine aminotransferase ratio greater than or equal to 1.4 was associated with shorter overall survival and recurrence-free survival in patients with hepatocellular carcinoma after hepatectomy, and chronic hepatitis B may play a role in their association.
Introduction
Hepatocellular carcinoma (HCC) is a prevalent primary liver cancer that significantly contributes to cancer-related death worldwide1. Hepatectomy is the recommended therapeutic approach for individuals diagnosed with HCC who meet operability criteria and it has demonstrated efficacy in extending patient survival2,3. Nevertheless, the overall prognosis for HCC patients remains inadequate due to the heterogeneity of the disease and its high recurrence rate4–6. Accurate prognostic evaluation of HCC is crucial in guiding treatment decisions and predicting patient outcomes.
Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are liver enzymes that can indicate hepatocellular damage7. The AST/ALT ratio is a non-invasive biomarker of liver function damage and can be used to assess the causes of liver diseases such as hepatic fibrosis, cirrhosis and non-alcoholic fatty liver disease8,9. The prognostic significance of the AST/ALT ratio and its optimal cut-off value remain uncertain, highlighting the need for more precise estimates of its prognostic impact. Some studies found that patients with AST/ALT ratios greater than 2 had significantly lower overall survival (OS) than those with AST/ALT ratios less than or equal to 210,11. A retrospective Taiwanese multicentre study showed that HCC patients with an AST/ALT ratio of 1–2 and greater than 2 had an increased risk of death compared with those with an AST/ALT ratio less than 112. The practice of researchers dividing the AST/ALT ratio into predetermined categories presents an opportunity to form risk subgroups13,14, but it has some flaws such as the loss of pertinent information, the seemingly subjective selection of cut-off values and the doubtful homogeneity within the groups15. As such, given the lack of agreement on the ideal cut-off points, it was crucial to measure the correlation between the AST/ALT ratio and prognosis. A survival heatmap was performed in this study to directly depict the survival probability over time and as a function of a continuous covariate simultaneously16. This plot used g-computation based on a suitable time-to-event model to obtain the relevant estimates17,18.
To date, the contribution of the AST/ALT ratio to survival is still unknown and this study tried to examine the association between the AST/ALT ratio and OS or recurrence-free survival (RFS) among patients with HCC after hepatectomy. Another aim of the study included the analysis of potential mediators (chronic hepatitis B, hepatic steatosis and liver cirrhosis).
Methods
Study design and patients
This study retrospectively reviewed records of patients who underwent hepatectomy for HCC between January 2014 and January 2018 at Guangxi Medical University Cancer Hospital (Nanning, China) and the First People’s Hospital of Qinzhou (Qinzhou, China). Patients included in the study were aged 18 years or older, with a confirmed diagnosis of HCC by postoperative pathology, and had preoperative liver function graded as Child–Pugh A or Child–Pugh B19. Exclusion criteria were as follows: history of neoadjuvant therapies before surgery, previous history of other malignancies, presence of distant metastasis and incomplete clinical information. All patients with hepatitis B virus (HBV)-related HCC were treated with nucleoside analogue (NA) starting before surgery and continuing after surgery.
The study protocol was approved by the Ethics Review Committees of the Guangxi Medical University Cancer Hospital (LW2023028) and the First People’s Hospital of Qinzhou (QZDY-EC-202308001) and it conformed to the Declaration of Helsinki. Due to the retrospective nature of the study, written informed consent was not required. This study was conducted according to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines20.
Assessment of AST/ALT ratio
AST and ALT were measured in blood samples collected from patients during the second morning of their hospitalization, after an overnight fast, prior to undergoing a hepatectomy. The AST/ALT ratio was determined using maximally selected rank statistics, based on the primary outcome of OS. This model finds a threshold value for a continuous predictor variable that best discriminates between two groups or outcomes, such as time-to-event data21.
Outcomes and follow-up
The primary outcome was OS, defined as the interval from the date of hepatic resection until the date of last follow-up or death. The secondary outcome was RFS, defined as the interval from the date of hepatic resection to the date of tumour recurrence, death or last follow-up. Follow-up visits started the first month after surgery and continued every 2 months for the first year, and then every 6 months thereafter until 31 August 2022, or until death. During these visits, data such as HCC recurrence, liver function, survival or death were collected. Follow-up was conducted via phone and through review of the hospitals’ data management system.
Statistical analysis
Covariates are described in the Supplementary method and expressed as means and s.d. if continuous data are shown. Baseline characteristics were collected according to the AST/ALT ratio and groups were compared using the χ2 test or Fisher’s exact test, as appropriate. Survival curves were generated using the Kaplan–Meier method. The OS and RFS curves were compared between groups using the log rank test.
Cox proportional hazards models were used to examine the association between groups and OS and RFS with 95% c.i. Two models were estimated: model 1 was adjusted for age and sex and model 2 for the confounders associated with the outcomes of interest or with a change of HRs of more than 1%. No major violations of the proportional hazard assumption for OS or RFS were identified.
The AST/ALT ratios were split into quartiles and then included in Cox proportional hazards models in order to search for a linear trend between the AST/ALT ratio and OS or RFS. The potential nonlinear associations were examined using a restricted cubic spline (RCS) regression model, and the RCS model was conducted with 4 knots at the 5th, 35th, 65th, 95th percentiles of the AST/ALT ratio. Subgroup analyses were performed to analyse the potential demographic and clinical characteristics associated with the AST/ALT ratio and OS or RFS. P values for interaction were evaluated using interaction terms and likelihood ratio tests. To explore whether the effect of the AST/ALT ratio on OS or RFS is proportionally mediated by the underlying liver disease, logistic regression models and parametric survival models were used for mediation analysis.
A new graphical representation was introduced, the survival heatmap16, which used the g-computation approach proposed by Robins17 to quantify and visualize the relationship between the AST/ALT ratio and OS or RFS. This estimated the required probability taking into account potential confounding variables18. The survival heatmap represented a continuous extension of the standard Kaplan–Meier plot, and visualized the survival probability as a function of time and a continuous covariate by utilizing a colour-scaled area16.
Five sensitivity analyses were conducted: the first was adjusted for all covariates (age, sex, BMI, hypertension, type 2 diabetes mellitus, hepatic steatosis, liver cirrhosis, chronic hepatitis B, tumour size, tumour number, microvascular invasion, macrovascular invasion, Child–Pugh grade, Barcelona clinic liver cancer (BCLC) stage22, α-fetoprotein, platelet count, prothrombin time, total bilirubin, albumin, prealbumin, resection and transarterial chemoembolization (TACE)); then all analyses were repeated excluding deaths occurring within the first 3 months to reduce potential reverse causation as a result of perioperative death; for the third, all analyses were performed in patients with albumin-bilirubin (ALBI) grade 1 or ALBI grade 2; the fourth used the logit of 1:1 propensity scores with a greedy algorithm and nearest neighbour approach (maximum caliper distance, 0.2), and the effect values were calculated by a cluster-robust approach after matching23; and the last one used inverse probability of treatment weighting (IPTW) with a cluster-robust approach24.
All analyses were performed using R statistical software version 4.2.2 (R Foundation). Propensity scores were computed with the MatchIt package, and IPTW was implemented using the MatchIt and survey packages. The cluster-robust approach was performed using the lmtest and sandwich packages, the g-computation approach was carried out using the contsurvplot package and the mediation analyses were performed using the mediation package. Two-sided P < 0.05 was considered as statistically significant.
Results
Baseline characteristics
During the study interval, 1856 patients with HCC underwent curative hepatectomy at the previously mentioned hospitals. Of these, 337 were excluded because baseline or survival data were incomplete. A total of 1519 (81.8%) patients were included for analysis.
Of the 1519 patients, the mean(s.d.) age at baseline was 50.5(11.3) years; 1309 (86.2%) of the patients were male and 210 (13.8%) were female (Table 1). When the AST/ALT ratio was 1.4, it was associated with the most pronounced disparity in OS (HR = 1.812) as shown in Fig. 1 and Table S1. At baseline, 502 (33.0%) patients had an AST/ALT ratio greater than or equal to 1.4 and they were more likely older, female, without hepatic steatosis or chronic hepatitis B, with micro-/macrovascular invasion submitted to a major resection, with a C stage of BCLC or a high level of α-fetoprotein, with a larger tumour size, and a lower BMI, albumin and prealbumin levels (all P <0.001). The baseline characteristics according to quantile of AST/ALT ratio are shown in Table S2.
Table 1.
Baseline characteristics of patients*
| Characteristics | Overall (n = 1519) | AST/ALT ratio† | P | |
|---|---|---|---|---|
| <1.4 (n = 1017) | ≥1.4 (n = 502) | |||
| Age (years) | <0.001 | |||
| <60 | 1173 (77.2) | 815 (80.1) | 358 (71.3) | |
| ≥60 | 346 (22.8) | 202 (19.9) | 144 (28.7) | |
| Sex | <0.001 | |||
| Male | 1309 (86.2) | 909 (89.4) | 400 (79.7) | |
| Female | 210 (13.8) | 108 (10.6) | 102 (20.3) | |
| BMI (kg/m2) | <0.001 | |||
| <23 | 874 (57.5) | 543 (53.4) | 331 (65.9) | |
| ≥23 | 645 (42.5) | 474 (46.6) | 171 (34.1) | |
| Hypertension | 0.689 | |||
| No | 1364 (89.8) | 911 (89.6) | 453 (90.2) | |
| Yes | 155 (10.2) | 106 (10.4) | 49 (9.8) | |
| Type 2 diabetes mellitus | 0.091 | |||
| No | 1390 (91.5) | 922 (90.7) | 468 (93.2) | |
| Yes | 129 (8.5) | 95 (9.3) | 34 (6.8) | |
| Hepatic steatosis | <0.001 | |||
| No | 1180 (77.7) | 753 (74.0) | 427 (85.1) | |
| Yes | 339 (22.3) | 264 (26.0) | 75 (14.9) | |
| Liver cirrhosis | 0.289 | |||
| No | 478 (31.5) | 311 (30.6) | 167 (33.3) | |
| Yes | 1041 (68.5) | 706 (69.4) | 335 (66.7) | |
| Chronic hepatitis B | <0.001 | |||
| No | 261 (17.2) | 138 (13.6) | 123 (24.5) | |
| Yes | 1258 (82.8) | 879 (86.4) | 379 (75.5) | |
| Tumour size (cm) | <0.001 | |||
| ≤5 | 588 (38.7) | 462 (45.4) | 126 (25.1) | |
| >5 | 931 (61.3) | 555 (54.6) | 376 (74.9) | |
| Tumour number | 0.248 | |||
| Single | 1190 (78.3) | 788 (77.5) | 402 (80.1) | |
| Multiple | 329 (21.7) | 229 (22.5) | 100 (19.9) | |
| Microvascular invasion | <0.001 | |||
| No | 689 (45.4) | 504 (49.6) | 185 (36.9) | |
| Yes | 830 (54.6) | 513 (50.4) | 317 (63.1) | |
| Macrovascular invasion | <0.001 | |||
| No | 1250 (82.3) | 867 (85.3) | 383 (76.3) | |
| Yes | 269 (17.7) | 150 (14.7) | 119 (23.7) | |
| Child–Pugh grade | 0.557 | |||
| A | 1424 (93.7) | 956 (94.0) | 468 (93.2) | |
| B | 95 (6.3) | 61 (6.0) | 34 (6.8) | |
| BCLC stage | <0.001 | |||
| 0/A | 918 (60.4) | 648 (63.7) | 270 (53.8) | |
| B | 266 (17.5) | 181 (17.8) | 85 (16.9) | |
| C | 335 (22.1) | 188 (18.5) | 147 (29.3) | |
| α-fetoprotein (ng/ml) | <0.001 | |||
| <400 | 921 (60.6) | 662 (65.1) | 259 (51.6) | |
| ≥400 | 598 (39.4) | 355 (34.9) | 243 (48.4) | |
| Platelet count (×109/l) | 0.521 | |||
| <100 | 103 (6.8) | 66 (6.5) | 37 (7.4) | |
| ≥100 | 1416 (93.2) | 951 (93.5) | 465 (92.6) | |
| Prothrombin time (s) | 0.996 | |||
| ≤13 | 920 (60.6) | 616 (60.6) | 304 (60.6) | |
| >13 | 599 (39.4) | 401 (39.4) | 198 (39.4) | |
| Total bilirubin (μmol/l) | 0.071 | |||
| ≤21 | 1283 (84.5) | 871 (85.6) | 412 (82.1) | |
| >21 | 236 (15.5) | 146 (14.4) | 90 (17.9) | |
| Albumin (g/l) | <0.001 | |||
| ≤35 | 276 (18.2) | 160 (15.7) | 116 (23.1) | |
| >35 | 1243 (81.8) | 857 (84.3) | 386 (76.9) | |
| Prealbumin (g/l) | <0.001 | |||
| ≤160 | 580 (38.2) | 330 (32.4) | 250 (49.8) | |
| >160 | 939 (61.8) | 687 (67.6) | 252 (50.2) | |
| Resection | <0.001 | |||
| Minor | 1035 (68.1) | 737 (72.5) | 298 (59.4) | |
| Major | 484 (31.9) | 280 (27.5) | 204 (40.6) | |
| TACE | 0.920 | |||
| No | 729 (48.0) | 489 (48.1) | 240 (47.8) | |
| Yes | 790 (52.0) | 528 (51.9) | 262 (52.2) | |
*Values are n (%), unless otherwise specified. †Optimal cut-point for the AST/ALT ratio was calculated by using maximally selected log rank statistic. ALT, alanine aminotransferase; AST, aspartate aminotransferase; BCLC, Barcelona clinic liver cancer; TACE, transarterial chemoembolization.
Fig. 1.
Kaplan–Meier curves for survival in patients with hepatocellular carcinoma stratified by the cut-point of the AST/ALT ratio
Graphs show the Kaplan–Meier estimates for overall survival a and recurrence-free survival b; vertical lines indicate censored data. Optimal cut-point for the AST/ALT ratio is 1.4 calculated by maximally selected log rank statistic. ALT, alanine aminotransferase; AST, aspartate aminotransferase.
Survival analyses
During a median follow-up of 46.0 months (range: 1.0–87.0 months), 514 (33.8%) patients died, and 358 (23.6%) patients exhibited recurrence. The median OS was not achieved, but the 1-, 3- and 5-year OS rates were 87.9%, 68.7% and 59.9% (Fig. 2a); the median RFS was 20.0 months (95% c.i. 17.0 to 23.0 months), and the 1-, 3- and 5-year RFS rates were 58.3%, 39.3% and 31.1% (Fig. 2b). The patients with an AST/ALT ratio greater than or equal to 1.4 had worse OS (Fig. 1a) and RFS (Fig. 1b) than those with an AST/ALT ratio less than 1.4 (all log rank P < 0.001). When analysing the AST/ALT ratio as quartiles, it was also found that the higher quartiles had worse OS and RFS (all P <0.001; Fig. S3).
Fig. 2.
Adjusted HRs of survival events risk and survival probability, according to the AST/ALT ratio
Graphs show HRs for overall survival a and recurrence-free survival b according to the AST/ALT ratio. Data were fitted by a restricted cubic spline Cox proportional hazards regression model, and conducted with 4 knots at the 5th, 35th, 65th, 95th percentiles of the AST/ALT ratio (reference is the 5th percentile). Solid lines indicate HRs, and shadow shape indicates 95% c.i. Overall survival probability c and recurrence-free survival probability d at different points in months as a function of the AST/ALT ratio are shown using the g-computation approach. For overall survival, models were adjusted for sex, BMI, tumour size, microvascular invasion, prealbumin, chronic hepatitis B, microvascular invasion, BCLC stage, and resection; for recurrence-free survival, models were adjusted for gender, tumour size, microvascular invasion, chronic hepatitis B, hepatic steatosis, microvascular invasion, prealbumin, BCLC stage, resection, and transarterial chemoembolization. HRs, hazard ratios; c.i., confidence intervals; BCLC, Barcelona clinic liver cancer; ALT, alanine aminotransferase; AST, aspartate aminotransferase.
Table 2 shows the associations between the AST/ALT ratio and OS or RFS. After adjusting for potential confounders (in model 2), the AST/ALT ratio greater than or equal to 1.4 at baseline was independently associated with a 39.0% increased risk of death and a 30.0% increased risk of recurrence (OS: HR, 1.39; 95% c.i. 1.15 to 1.68; RFS: HR, 1.30; 95% c.i. 1.12 to 1.52). Similar results were found when modelling the AST/ALT ratio as quartiles (Table 2). After adjusting for confounders, by comparing quantile 4 with quantile 1, the adjusted HRs were 1.51 (95% c.i. 1.16 to 1.98) for OS, 1.44 (95% c.i. 1.16 to 1.79) for RFS (all P < 0.001). A linear and positive association between the AST/ALT ratio and risk of death (Fig. 2a) or recurrence (Fig. 2b) using RCS regression was also found (for nonlinearity, P = 0.103 for OS, P = 0.781 for RFS).
Table 2.
Association of AST/ALT ratio with overall survival and recurrence-free survival
| Outcome | No. of events/total | Model 1* | Model 2† | ||
|---|---|---|---|---|---|
| HR (95% c.i.) | P | HR (95% c.i.) | P | ||
| Overall survival | |||||
| AST/ALT ratio, cut-point§ | |||||
| <1.4 | 293/1017 | Reference | Reference | ||
| ≥1.4 | 221/502 | 1.88 (1.58,2.25) | <0.001 | 1.39 (1.15,1.68) | 0.001 |
| AST/ALT ratio, quantile¶ | |||||
| Quantile 1 | 94/380 | Reference | Reference | ||
| Quantile 2 | 114/380 | 1.25 (0.95,1.64) | 0.115 | 1.10 (0.84,1.45) | 0.486 |
| Quantile 3 | 138/379 | 1.76 (1.35,2.29) | <0.001 | 1.31 (1.00,1.71) | 0.048 |
| Quantile 4 | 168/380 | 2.33 (1.80,3.01) | <0.001 | 1.51 (1.16,1.98) | 0.003 |
| P for trend‡ | <0.001 | 0.001 | |||
| Recurrence-free survival | |||||
| AST/ALT ratio, cut-point§ | |||||
| <1.4 | 496/1017 | Reference | Reference | ||
| ≥1.4 | 301/502 | 1.62 (1.40,1.88) | <0.001 | 1.30 (1.12,1.52) | 0.001 |
| AST/ALT ratio, quantile¶ | |||||
| Quantile 1 | 167/380 | Reference | Reference | ||
| Quantile 2 | 193/380 | 1.24 (1.00,1.52) | 0.046 | 1.16 (0.94,1.43) | 0.171 |
| Quantile 3 | 212/379 | 1.56 (1.27,1.92) | <0.001 | 1.25 (1.02,1.54) | 0.035 |
| Quantile 4 | 225/380 | 1.94 (1.58,2.38) | <0.001 | 1.44 (1.16,1.79) | 0.001 |
| P for trend‡ | <0.001 | 0.001 | |||
*Adjusted for age, sex. †Adjusted for sex, BMI, tumour size, microvascular invasion, prealbumin, chronic hepatitis B, microvascular invasion, BCLC stage, resection for OS; and adjusted for sex, tumour size, microvascular invasion, chronic hepatitis B, hepatic steatosis, microvascular invasion, prealbumin, BCLC stage, resection, TACE for RFS. ‡Tests for linear trend were done by modelling the median value of each quantile to test ordered relations across quantiles of the AST/ALT ratio. §Optimal cut-point for the AST/ALT ratio was calculated by using maximally selected log rank statistic. ¶The quartiles of AST/ALT are 0.09 for the minimum, 0.87 for 25%, 1.13 for the median, 1.55 for 75% and 9.25 for the maximum. ALT, alanine aminotransferase; AST, aspartate aminotransferase; HR, hazard ratio; BCLC, Barcelona clinic liver cancer.
Subgroup analyses
Table 3 shows the association between the AST/ALT ratio and OS or RFS stratified by potential risk factors. The association with OS was more pronounced among patients without macrovascular invasion (P = 0.016 for interaction) and among patients submitted to minor resection (P = 0.007 for interaction).
Table 3.
Association between the AST/ALT ratio and survival events risk stratified by different factors
| Subgroup | Overall survival* | Recurrence-free survival† | ||
|---|---|---|---|---|
| HR (95% c.i.) | P for interaction | HR (95% c.i.) | P for interaction | |
| Sex | 0.471 | 0.099 | ||
| Male | 1.43 (1.17,1.75) | 1.38 (1.17,1.63) | ||
| Female | 1.14 (0.65,2.00) | 0.78 (0.49,1.25) | ||
| BMI (kg/m2) | 0.136 | 0.292 | ||
| <23 | 1.25 (0.99,1.59) | 1.28 (1.05,1.56) | ||
| ≥23 | 1.72 (1.25,2.36) | 1.40 (1.09,1.79) | ||
| Tumour size (cm) | 0.573 | 0.861 | ||
| ≤5 | 1.36 (0.89,2.09) | 1.30 (0.94,1.79) | ||
| >5 | 1.39 (1.12,1.71) | 1.30 (1.09,1.55) | ||
| Macrovascular invasion | 0.016 | 0.096 | ||
| No | 1.61 (1.29,2.01) | 1.42 (1.19,1.70) | ||
| Yes | 1.12 (0.79,1.59) | 1.20 (0.87,1.65) | ||
| Chronic hepatitis B | 0.659 | 0.767 | ||
| No | 1.50 (0.88,2.55) | 1.50 (0.99,2.27) | ||
| Yes | 1.39 (1.13,1.70) | 1.28 (1.08,1.51) | ||
| Hepatic steatosis | 0.095 | 0.074 | ||
| No | 1.30 (1.06,1.60) | 1.23 (1.04,1.46) | ||
| Yes | 1.94 (1.22,3.10) | 1.88 (1.27,2.77) | ||
| Microvascular invasion | 0.238 | 0.701 | ||
| No | 1.53 (1.08,2.17) | 1.35 (1.03,1.77) | ||
| Yes | 1.34 (1.08,1.68) | 1.27 (1.05,1.53) | ||
| Prealbumin (g/l) | 0.391 | 0.306 | ||
| ≤160 | 1.37 (1.06,1.79) | 1.50 (1.19,1.88) | ||
| >160 | 1.40 (1.07,1.83) | 1.16 (0.94,1.44) | ||
| BCLC stage | 0.377 | 0.259 | ||
| 0/A | 1.48 (1.11,1.96) | 1.41 (1.13,1.76) | ||
| B | 1.75 (1.16,2.65) | 1.53 (1.07,2.20) | ||
| C | 1.32 (0.95,1.82) | 1.22 (0.92,1.63) | ||
| Resection | 0.007 | 0.566 | ||
| Minor | 1.81 (1.40,2.33) | 1.42 (1.16,1.73) | ||
| Major | 1.11 (0.84,1.47) | 1.28 (1.01,1.64) | ||
| TACE | 0.264 | 0.052 | ||
| No | 1.40 (1.02,1.92) | 1.41 (1.08,1.82) | ||
| Yes | 1.43 (1.13,1.82) | 1.27 (1.05,1.55) | ||
*Adjusted for sex, BMI, tumour size, microvascular invasion, prealbumin, chronic hepatitis B, microvascular invasion, BCLC stage and resection. †Adjusted for sex, tumour size, microvascular invasion, chronic hepatitis B, hepatic steatosis, microvascular invasion, prealbumin, BCLC stage, resection and TACE. ALT, alanine aminotransferase; AST, aspartate aminotransferase; HR, hazard ratio; TACE, transarterial chemoembolization; BCLC, Barcelona clinic liver cancer.
Mediation analyses
It was observed that chronic hepatitis B significantly mediated the association between the AST/ALT ratio and both OS and RFS (proportion of 20.3% and 20.1% respectively, all P < 0.05). In contrast, liver cirrhosis and hepatic steatosis were not found to act as mediators in the association between these variables (Table 4).
Table 4.
Mediation analysis of chronic hepatitis B, hepatic steatosis, and liver cirrhosis in the association of the AST/ALT ratio and overall survival, recurrence-free survival*
| Pathways | Total effect | Proportion mediated | P value for mediated |
|---|---|---|---|
| Chronic hepatitis B | |||
| AST/ALT ratio → chronic hepatitis B → OS | −37.6 | 20.3% | 0.006 |
| AST/ALT ratio → chronic hepatitis B → RFS | −14.2 | 20.1% | 0.008 |
| Hepatic steatosis | |||
| AST/ALT ratio → hepatic steatosis → OS | −38.5 | 0.3% | 0.920 |
| AST/ALT ratio → hepatic steatosis → RFS | −14.8 | 5.0% | 0.180 |
| Liver cirrhosis | |||
| AST/ALT ratio → liver cirrhosis → OS | −38.0 | 0.04% | 0.890 |
| AST/ALT ratio → liver cirrhosis → RFS | −14.7 | 0.06% | 0.852 |
*Logistic regression models and parametric survival models were used for mediation analysis. All models were adjusted for sex, BMI, tumour size, microvascular invasion, prealbumin, microvascular invasion, BCLC stage, resection for OS. Adjusted for sex, tumour size, microvascular invasion, microvascular invasion, prealbumin, BCLC stage, resection, TACE for RFS. ALT, alanine aminotransferase; AST, aspartate aminotransferase; OS, overall survival; RFS, recurrence-free survival; BCLC, Barcelona clinic liver cancer; TACE, transarterial chemoembolization.
g-computation analysis
Figures 2c,d and 3 show the OS and RFS probabilities over different time intervals (in months), calculated using g-computation. The results indicate a clear inverse relationship between higher AST/ALT ratios and reduced OS and PFS rates at 12, 24, 36, 48 and 60 months after adjusting for confounding factors. A dose-response effect was also evident. The survival heatmaps (Fig. 3a,b) provide detailed results of the probability plots. The interactive survival 3D surface visualizations in Fig. S4 offer additional insights into the survival outcomes associated with different AST/ALT ratios.
Fig. 3.
Visualizing the effect of the AST/ALT ratio on survival outcome using the g-computation approach
Survival heatmaps for the effect of the AST/ALT ratio on overall survival a and recurrence-free survival b. Models were fitted using a Cox proportional hazards regression model and the g-computation approach, for OS, models adjusted for sex, BMI, tumour size, microvascular invasion, prealbumin, chronic hepatitis B, microvascular invasion, BCLC stage, and resection; for recurrence-free survival, models adjusted for sex, tumour size, microvascular invasion, chronic hepatitis B, hepatic steatosis, microvascular invasion, prealbumin, BCLC stage, resection, and TACE. ALT, alanine aminotransferase; AST, aspartate aminotransferase; BCLC, Barcelona clinic liver cancer; TACE, transarterial chemoembolization.
Sensitivity analysis
The results did not significantly change after adjusting for all covariates (Table S3). Similar results were found when excluded patients died in the first 3 months (Table S4) and in patients with ALBI grade 1 or ALBI grade 2 (Table S5). The results remained robust when using propensity matching or IPTW (Tables S6–S8).
Discussion
This study shows that an AST/ALT ratio greater than or equal to 1.4 at baseline was independently associated with a 39.0% higher risk of death and a 30.0% higher risk of recurrence. The indirect effects of the mediators revealed that chronic hepatitis B accounted for a substantial proportion of the association between the AST/ALT ratio and both OS and RFS, at 20.3% and 20.1% respectively. These findings suggest that when using the AST/ALT ratio as a prognostic marker, it was important to consider the hepatitis status of patients.
Increasing evidence suggests that a higher AST/ALT ratio is associated with an increased risk of death and recurrence. Notably, Mo et al.25 demonstrated that the AST/ALT ratio served as an autonomous prognostic indicator for OS in patients with hepatitis B virus-associated HCC undergoing hepatectomy. Similarly, von Felden et al.10 posited that the AST/ALT ratio was predictive of unfavourable outcomes in HCC. Furthermore, a Taiwanese multicentre study revealed that HCC patients with a higher AST/ALT ratio exhibited a higher risk of death12. In the current study, the optimal cut-off value for the AST/ALT ratio was 1.4 at baseline using maximally selected rank statistics. Patients with AST/ALT ratios greater than or equal to 1.4 presented with larger tumours, vascular involvement and elevated alpha fetoprotein (AFP) levels, contributing to the association between higher ratios and poorer survival outcomes. Such patients likely represented a distinct subgroup with severe liver disease, including inflammation and fibrosis, affecting their overall health. Consequently, closer monitoring, both before and after surgery, is vital to manage potential complications and optimize their condition for surgery. Careful perioperative management is crucial in patients with a high AST/ALT ratio undergoing major resections.
Although the association between the AST/ALT ratio and prognosis has been examined in several studies, the exact cut-off value of the AST/ALT ratio to predict the prognosis of HCC patients is still not clear. Liu et al. used the receiver operating characteristic (ROC) curve to establish an AST/ALT ratio cut-off of 1.2 in HCC patients receiving TACE. Those with ratios over 1.2 had markedly lower 1-, 3- and 5-year survival rates compared with those with ratios at or below 1.226. Mo et al. proposed a cut-off greater than or equal to 1.1 calculated via RCS regression for hepatitis B virus-related HCC patients25. Clinical practice also indicated that some studies suggested a cut-off of 210,11. Determining the optimal cut-off value in the prognostic assessment of HCC is challenging due to the heterogeneity of the study population, methods and samples. The correlation between the AST/ALT ratio and HCC prognosis provides a way to improve patient care. It could aid treatment decisions by stratifying risk, enabling aggressive therapies for high-risk individuals, and long-term prognosis assessment, guiding surveillance frequency for the early detection of disease recurrence.
The underlying pathophysiology mechanisms by which an elevated AST/ALT ratio is associated with poor prognosis in patients remains unclear. One potential mechanism is related to cancer-related metabolic disorders27–29. In HCC, altered cellular metabolism is a hallmark of the disease, and this may contribute to the observed changes in AST and ALT levels. AST is present in both the cytoplasm and mitochondria of hepatocytes, while ALT is predominantly localized in the cytoplasm. The mitochondria play a key role in adenosine 5′-triphosphate (ATP) production through oxidative phosphorylation, but in the tumour microenvironment, ATP is generated via glycolysis. This shift in energy production may lead to changes in AST and ALT levels and ultimately contribute to the poor prognosis in HCC patients.
Limitations of the current study include its retrospective nature; its single-centre design which potentially introduced retrospective bias, although sensitivity analysis supported the association; and thyroid and muscular disorders as well as haemolysis could lead to increased serum AST levels30. Further research needs to consider these factors. Some confounding factors of the association of the AST/ALT ratio with OS and RFS, such as adjuvant therapy and other surgical factors (for example, nodal or margin status) were not adjusted in this study. The overrepresentation of male patients, although in alignment with prior research31–33, potentially constrained the generalizability, but subgroup analyses yielded consistent findings.
The study did not consider time-varying exposures, which may introduce residual confounding. This study found that the AST/ALT ratio has emerged as a promising prognostic factor for HCC. An elevated AST/ALT ratio is significantly associated with poor outcomes in HCC patients, and the association is mediated by chronic hepatitis B. Monitoring the AST/ALT ratio may help in the early identification of individuals at high risk of HCC.
Supplementary Material
Acknowledgements
R-R.H. and L-X.P. contributed equally to this work.
Contributor Information
Rong-Rui Huo, Hepatobiliary Surgery Department, Guangxi Medical University Cancer Hospital, Nanning, China.
Li-Xin Pan, Hepatobiliary Surgery Department, Guangxi Medical University Cancer Hospital, Nanning, China.
Pei-Sheng Wu, Hepatobiliary Surgery Department, The First People’s Hospital of Qinzhou, Qinzhou, China.
Xiu-Mei Liang, Hepatobiliary Surgery Department, Guangxi Medical University Cancer Hospital, Nanning, China.
Xue-Mei You, Hepatobiliary Surgery Department, Guangxi Medical University Cancer Hospital, Nanning, China; Key Laboratory of Early Prevention and Treatment for Regional High Frequency Tumour (Guangxi Medical University), Ministry of Education, Nanning, China; Guangxi Key Laboratory of Early Prevention and Treatment for Regional High Frequency Tumour (Guangxi Medical University), Nanning, China.
Liang Ma, Hepatobiliary Surgery Department, Guangxi Medical University Cancer Hospital, Nanning, China.
Jian-Hong Zhong, Hepatobiliary Surgery Department, Guangxi Medical University Cancer Hospital, Nanning, China; Key Laboratory of Early Prevention and Treatment for Regional High Frequency Tumour (Guangxi Medical University), Ministry of Education, Nanning, China; Guangxi Key Laboratory of Early Prevention and Treatment for Regional High Frequency Tumour (Guangxi Medical University), Nanning, China.
Funding
This work was supported by the Specific Research Project of Guangxi for Research Bases and Talents (GuiKe AD22035057), the National Natural Science Foundation of China (82060510 and 82260569), and the Key Laboratory of Early Prevention and Treatment for Regional High Frequency Tumor (Guangxi Medical University), Ministry of Education (GKE-ZZ202217, GKE-ZZ202311).
Disclosure
The authors declare no conflict of interest.
Supplementary material
Supplementary material is available at BJS Open online.
Data availability
Data available on request due to privacy/ethical restrictions.
Author contributions
Jian-Hong Zhong (conceived the study), all authors (participated in the acquisition of the data), Xiu-Mei Liang, and Pei-Sheng Wu (performed follow-up data), Rong-Rui Huo and Jian-Hong Zhong (analysed data), Rong-Rui Huo and Jian-Hong Zhong (drafted and revised the manuscript) and all authors (read and approved the final version of the manuscript).
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
Data available on request due to privacy/ethical restrictions.