Outcomes of Liver Resection for Metabolic Dysfunction-Associated Fatty Liver Disease or Chronic Hepatitis B-Related HCC

Aims This study aims to determine differences in severity of background liver disease at hepatocellular carcinoma (HCC) diagnosis and long-term survival outcomes among patients undergoing liver resection for HCC in the background of metabolic dysfunction-associated fatty liver disease (MAFLD) compared to chronic hepatitis B (CHB) alone or concurrent CHB (CHB/MAFLD). Methods Patient demographics and comorbidities, clinicopathologic data, perioperative and long-term outcomes among patients who underwent liver resection for HCC were reviewed. Overall and recurrence-free survival were calculated with the Kaplan-Meier method, with the values compared using the log-rank test. Results From January 2014 to December 2018, 1325 patients underwent potential curative liver resection of HCC; 67 (5.0%), 176 (13.3%), and 1082 (81.7%) patients had MAFLD alone, CHB concurrent with MAFLD, and CHB alone, respectively. At HCC diagnosis, fewer MAFLD patients had cirrhosis, alpha fetoprotein concentration ≥ 400 ng/mL, tumor size ≥ 5 cm, mulinodular, microvascular invasion, receiving major hepatectomy, and receiving adjuvant transarterial chemoembolization. After a median follow-up of 47 months after liver resection, MAFLD (or MAFLD plus CHB/MAFLD) patients had significantly higher overall and recurrence-free survival than CHB patients before or after propensity score analysis (all P<0.05). Conclusion Patients with HCC in the setting of MAFLD have less-severe background liver disease at HCC diagnosis and better long-term survival after curative liver resection compared to counterparts with CHB/MAFLD or CHB.


INTRODUCTION
Hepatocellular carcinoma (HCC) is the sixth most common malignancy and the third leading cause of cancer-related death (1), with East Asia demonstrating the highest incidence of HCC worldwide (2). Past epidemiological data suggest that hepatitis B virus (HBV), hepatitis C virus (HCV), and alcohol consumption are three predominant causative factors of HCC. In recent decade, nonalcoholic fatty liver disease (NAFLD) is already a rapidly increasing risk factor of HCC in the USA, France and the UK (3,4). The estimated annual incidence of HCC among patients with NAFLD is lower than that among those with HBV or HCV infection (5,6). However, it is estimated that 25% of the global population have NAFLD, with the highest prevalence in high income regions (6). Namely, more worldwide people have NAFLD than other liver diseases, such as HBV or HCV infection, leading the necessary to analyze the prognoses of patients with NAFLD-related HCC.
NAFLD is defined as excess hepatic fat accumulation (>5%) after the exclusion of significant alcohol consumption or any other causes of steatosis, such as certain toxins and drugs (7)(8)(9)(10). Metabolic dysfunction-associated fatty liver disease (MAFLD), formerly named NAFLD, is a chronic disease characterized by fat accumulation in the liver with an underlying metabolic dysregulation, for which there is no approved pharmacotherapy (10). Recently, several official guidelines and consensus provide simple and practical diagnostic criteria for the disease (10)(11)(12). MAFLD more closely implies the presence of type 2 diabetes mellitus, overweight/obesity, or metabolic dysregulation, contributing to better identification of individuals with this metabolic liver disease (13). More importantly, MAFLD may eventually progress to liver-related complications, including HCC. A populational cohort from Switzerland found the burden of NAFLD-and MAFLD-related HCCs significantly increased over the years, particularly in women (14).
Liver resection is one of the main curative treatments for patients with HCC (15,16). However, HCC recurrence after liver resection is high. Systematic reviews with large sample size revealed that the 5-years recurrence-free survival are 37%, 25%, and 18% in patients with early, intermediate, or advanced disease, respectively (16,17). And the corresponding 5-years overall survival are 67%, 30%, and 18%, respectively (16,17). Tumor stage and treatment measures are the most important factors affecting the prognosis of patients with HCC. However, our understanding of the association between etiological factors and the prognoses of patients with HCC after liver resection is limited. Furthermore, the contribution of MAFLD to the HCC burden according to clinical and tumor characteristics remain unclear. We therefore aimed to compare the clinical and tumor characteristics and the outcomes of patients with HBV-or MAFLD-related HCC after liver resection.

Study Design and Population
This was a retrospective study. All patients with a diagnosis of HCC based on postoperative histopathology between 1 January 2014 and 31 December 2018 might be eligible for the study.
Consecutive patients with HCC were identified via the electronic medical records of Guangxi Medical University Cancer Hospital, Nanning, China, and the Fourth Affiliated Hospital of Guangxi Medical University, Liuzhou, China. Patients were selected based on the following eligibility criteria: (1) patients were without preoperative neoadjuvant therapy (including transarterial chemoembolization, radiotherapy, sorafenib, lenvatinib, immune checkpoint inhibitors, etc), (2) had primary HCC and underwent potential curative liver resection (macroscopically tumor-free), (3) diagnoses of HCC were confirmed by postoperative histopathology, and (4) suffered from chronic hepatitis B (CHB) or MAFLD. Patients were excluded if they were with (1) intrahepatic cholangiocarcinoma, (2) positive anti-HCV or human immunodeficiency virus, (3) alcohol consumption, (4) autoimmune hepatitis, (5) drug-induced liver injury, (6) combined with other malignancies, or (7) incomplete medical information. All the procedures were carried out in accordance with the Helsinki Declaration of 1975. Written informed consent was not provided by the patients because this was a retrospective study. After obtaining institutional board review approval from Guangxi Medical Cancer Hospital (LW2021042) and the Fourth Affiliated Hospital of Guangxi Medical University (LW2021005), demographics, comorbid conditions, clinicopathologic data, radiology reports, and longterm outcomes of the included patients were reviewed.
Based on the aim of the study, included patients would be divided into three groups, namely, patients with MAFLD-related HCC (MAFLD group), patients with CHB-related HCC (CHB group), and those with dual etiology related HCC (CHB/ MAFLD group).

Liver Resection
The indications of liver resection were based on the Chinese guideline for HCC (18). Patients should be with Child-Pugh score of no more than 7. The presence of appropriate residual liver volume was determined by volumetric dynamic enhanced computerized tomography or magnetic resonance imaging (MRI). The selection criteria and procedures of liver resection have been detailed elsewhere (19)(20)(21). The gallbladder was routinely excised before liver resection. Adequate drainage was routinely monitored. Intraoperative ultrasound was performed when necessary.

Definition
The diagnosis of MAFLD was based on hepatic steatosis [detected either by imaging techniques (ultrasound, computerized tomography or MRI) or by postoperative liver histopathology] in addition to overweight/obesity (body mass index ≥23 kg/m 2 ), presence of type 2 diabetes mellitus, or evidence of metabolic dysregulation (10,11). Hepatic steatosis and cirrhosis were determined directly by imaging or histopathology reports. Fibrosis-4, waist circumference, insulin resistance score, plasma high-sensitivity C-reactive protein level, or blood biomarkers/ scores of MAFLD was not assessed in this study. Alcohol consumption was defined as excessive alcohol intake (>30 g/day in men, >20 g/day in women) (22). In this study, dual etiology of HCC was defined as a patient suffered from both CHB and MAFLD (23). CHB was defined as the presence of positive of hepatitis B surface antigen HBV DNA, and/or hepatitis B core antibody. CHB-related HCC was defined as a patient with HCC accompanied by CHB. Information on alcohol consumption, autoimmune hepatitis, and drug-induced liver injury was obtained from the past medical history or personal history of medical records. Major hepatectomy was defined as the resection of three or more Couinaud segments (24).

Data Collection and Outcomes
The number or level of the following data were collected and analyzed via the electronic medical records: gender, age, body mass index, hypertension, type 2 diabetes mellitus, hepatic steatosis, liver cirrhosis, Child-Pugh liver function grade, tumor size, tumor number, macrovascular invasion, Barcelona Clinical Liver Cancer stage, hepatitis B surface antigen, alpha fetoprotein, alanine aminotransferase, aspartate aminotransferase, plasma triglycerides, high density lipoprotein cholesterol, total bilirubin, albumin, prealbumin, microvascular invasion, resection type, and adjuvant transarterial chemoembolization.
The primary outcome was overall survival, calculated from the date of liver resection to the date of death from any cause or the date of the last follow-up. No patient undergone live transplantation in this cohort. Follow-up data of overall survival was obtained from the hospital database (X.-M.L). The secondary endpoints included recurrence-free survival and perioperative mortality and morbidity. Recurrence-free survival was calculated from the date of liver resection to the date of tumor recurrence or death from any cause, whichever occurred first. HCC recurrence, which was assessed by the investigators (J.-H.Z, Y.-X.T, K.C), was diagnosed using enhanced computed tomography and/or MRI [including gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI] with or without alpha fetoprotein ≥400 ng/mL) (18). Patients with HCC recurrence would be received appropriate therapeutic approaches, with radiofrequency ablation and repeat liver resection as the preferred curative treatments (25,26). Postoperative mortality was defined as the rate of death within 30 days after liver resection. Perioperative morbidity was graded according to the Clavien-Dindo classification (27). Clavien-Dindo grade of at least 3a was defined as major morbidity. The follow-up period was up to March 2021 or death. Patients with CHB routinely received antiviral therapy with nucleos(t)ide analogue (28). Moreover, patients with high risk factors of HCC recurrence, such as tumor size at least 5 cm, multinodules, involving macrovascular invasion or microvascular invasion, would receive adjuvant transarterial chemoembolization (29,30). However, patients with MAFLD did not receive corresponding treatment for MAFLD.

Statistical Analysis
Categorical variables were expressed as number and percentage and compared with Pearson's chi-square tests. Bonferroni test was used for multiple comparisons. Continuous variables were expressed as mean ± standard deviation and compared by using the one-way analysis of variance for normal distributions. For skewed distributions, variables were expressed as median (interquartile range) and compared by using the Kruskal-Wallis test. Overall and recurrence-free survival were calculated with the Kaplan-Meier method, with the values compared using the logrank test. To reveal the association between different counterparts (MAFLD, CHB/MAFLD, and CHB) and overall or recurrence-free survival after liver resection, multivariate analyses were performed using a Cox proportional hazards model. Any confounders that a change in effect estimate was more than 5% or recognized to be associated with the outcomes were entered into a Cox regression analysis. A two-tailed p value < 0.05 was considered to indicate statistically significant. GraphPad Prism 8.0 and IBM SPSS (ver. 26.0 SPSS Inc., Chicago, IL, USA) softwares were used to perform the analyses.
To reduce the potential effect of baseline variable imbalance on prognosis, propensity score matching between groups at a 1:3 ratio was used. All collected variables were involved in propensity score matching except body mass index, hypertension, type 2 diabetes mellitus, triglycerides, and high density lipoprotein cholesterol, which were used to define MAFLD. The propensity score was generated by a logistic regression. Nearest-neighbor caliper matching without replacement (random order or closest distance) was used to pair MAFLD (or MAFLD plus CHB/MAFLD) and CHB patients with similar propensity score values (31).

Patient Demographic and Baseline Clinical Characteristics
A total of 1887 patients underwent potential curative liver resection of HCC from January 2014 from December 2018; 368 had with anti-HCV or HIV positive, alcohol consumption, combined with other malignancies, autoimmune hepatitis or drug-induced liver injury and were excluded from this study. Other 194 patients without CHB or MAFLD were also excluded. Of the remaining 1325 patients, 67 (5.0%) had MAFLD alone, 1082 (81.7%) had CHB alone, and 176 (13.3%) had CHB concurrent with MAFLD ( Figure 1). The diagnosis of hepatic steatosis was detected by imaging techniques alone (13, 3.8%), liver histopathology alone (299, 88.2%) or confirmed by both (

Survival Outcomes Between MAFLD and CHB Patients After Propensity Score Matching
Baseline clinical characteristics between MAFLD (n=58) and CHB (n=180) groups were comparable after propensity score matching ( Table 3). MAFLD patients had significantly higher overall and recurrence-free survival than CHB patients (P=0.004, Figure 3A; P=0.043, Figure 3B).

Survival Outcomes Between MAFLD Plus CHB/MAFLD and CHB Patients
To further explore the difference in prognosis between MAFLD and CHB, patients with MAFLD or CHB/MAFLD were combined in one group. Baseline clinical characteristics of the two groups before and after propensity matching were described in Table 4. Patients with MAFLD or CHB/MAFLD had significantly higher overall and recurrence-free survival than CHB patients before or after propensity score matching (all P<0.05, Figure 4).

DISCUSSION
MAFLD increased substantially over the past 20 years (32,33). Moreover, concurrent diabetes mellitus, overweight/obesity, or hepatic steatosis is associated with increased HCC risk among CHB or HCV patients (34)(35)(36)(37). These factors contribute to MAFLD becoming a major cause of HCC in the world. Our understanding of the prognoses of patients with MAFLD-related HCC after liver resection is limited. In agreement with other report (38), MAFLD patients more often had metabolic syndrome, had better synthetic liver function, less often had alpha fetoprotein concentration ≥ 400 ng/mL, tumor size ≥ 5 cm, multinodular, underwent major hepatectomy, and microvascular invasion compared to CHB counterparts at HCC diagnosis. These discrepancies in demographics, comorbidities, and measures of hepatic synthetic function may lead to lower perioperative major morbidity, but higher overall and recurrence-free survival compared to CHB counterparts. MAFLD patients still had a survival advantage after propensity score matching. Moreover, multivariate analyses confirmed the association between MAFLD and overall or recurrence-free survival independent of other clinicopathologic factors.
Among the patients with MAFLD-related HCC, 49.3% were without cirrhosis. This finding reinforces the fact that MAFLDor NAFLD-related HCC could arise in the absence of cirrhosis in patients with clinically MAFLD or NAFLD (39)(40)(41)(42). This phenomenon highlights the importance of HCC screening or surveillance programs for MAFLD or NAFLD patients without cirrhosis. However, the proportion of cirrhosis among the MAFLD patients with HCC was significantly lower than CHB or CHB/MAFLD counterparts, which is consistent with the findings that NAFLD patients with HCC had the lowest proportion of cirrhosis than those with any other etiologies including CHB, HCV and alcoholic liver disease in Eastern or Western centers (3,38,39,41,(43)(44)(45)(46). Hence, active HCC surveillance is recommended in MAFLD patients for the early detection of HCC.
Though the low proportion of cirrhosis, major hepatectomy, and better hepatic synthetic function at HCC presentation may translate into lower major morbidity and higher long-term survival after liver resection before propensity matching, MAFLD (or MAFLD plus CHB/MAFLD) patients still had significantly higher overall and recurrence-free survival than CHB patients after propensity matching. Therefore, other essential factor, such as the difference of pathophysiology between MAFLD and CHB (47,48), may be at the root of the difference in prognoses between the groups. Future studies are expected to compare the difference in prognosis between groups from the perspective of pathophysiology.
MAFLD was originally known as NAFLD. In our cohort, the incidence of MAFLD was 12.9% (243/1887)-similar to that found in other series (41,45). However, its incidence was higher in series from Korea (52.3%) (46) or USA (33.4%) (44). Though patients with concomitant nonalcoholic steatohepatitis and CHB have more advanced fibrosis, higher HCC risk, and shorter time to development of liver-related outcomes or death compared to patients with CHB alone (35,37,49,50), we did not found CHB/MAFLD patients had moresevere background liver disease or more advanced HCC than CHB patients. On the contrary, CHB/MAFLD counterparts had    Table 1). A cohort from Korea also found concurrent NAFLD was associated with both better overall and recurrence-free survival in patients with CHB-related HCC than those without NAFLD before adjusting for baseline characteristics (51). However, this survival benefit of the concurrent NAFLD was not significant in multivariable Cox analysis or analysis after propensity score matching (51). In our study, MAFLD counterparts had the highest overall and recurrence-free survival than CHB/MAFLD or CHB counterparts, which was consistent with the findings that NAFLD-related HCC had better long-term survival outcomes compared to non-NAFLD etiologies after liver resection or radiofrequency ablation (36,38,41,44,45). Our findings was confirmed by propensity score analysis.
The present study has some limitations. First, only patients with HCC underwent potential curative liver resection were included. The clinical impact of MAFLD on the prognoses of HCC patients underwent other therapies, such as transarterial chemoembolization or liver transplantation, could not be

IN CONCLUSION
Patients with HCC in the setting of MAFLD have less-severe background liver disease and better long-term outcomes after potential curative liver resection compared to counterparts with CHB. However, the association between MAFLD and HCC patient prognoses was not fully assessed because the relatively small number of MAFLD patients examined and the potential selection bias. Further well-designed study with a larger sample size is warranted.

DATA AVAILABILITY STATEMENT
The datasets presented in this article are not readily available because all data were in the manuscript. Supplementary Material for this article is available by request to J-HZ. Requests to access the datasets should be directed to J-HZ, zhongjianhong@gxmu.edu.cn.

ETHICS STATEMENT
This study was approved by the Ethics Committees of our hospitals (LW2021042; LW2021005). Written informed consent for participation was not required for this study in accordance with the national legislation and the institutional requirements.

AUTHOR CONTRIBUTIONS
J-HZ conceived the study. All authors participated in the acquisition of the data. R-RH and J-HZ analyzed data. LL and J-HZ drafted and revised the manuscript. All authors contributed to the article and approved the submitted version.