Effect of transarterial chemoembolization as postoperative adjuvant therapy for intermediate-stage hepatocellular carcinoma with microvascular invasion: a multicenter cohort study

Background: Intermediate-stage hepatocellular carcinoma (HCC) with microvascular invasion (MVI) is associated with high recurrence rates and poor survival outcomes after surgery. This study aimed to evaluate the efficacy of postoperative transarterial chemoembolization (TACE) on prognosis of intermediate-stage HCC patients with MVI after curative liver resection (LR). Materials and methods: Patients who had intermediate-stage HCC with MVI and underwent curative LR between January 2013 and December 2019 at three institutions in China were identified for further analysis. Overall survival (OS) and recurrence-free survival (RFS) were compared between patients treated with and without postoperative TACE by propensity score-matching. Results: A total of 246 intermediate-stage HCC patients with MVI were enrolled, 137 entered into the LR group and 109 entered into the LR+TACE group. The 1-year, 3-year, and 5-year RFS rates were 42.0, 27.2, and 17.8% in LR+TACE group, and 31.8, 18.2, and 8.7% in LR group. The 1-year, 3-year, and 5-year OS rates were 81.7, 47.2, and 26.1% in the LR+TACE group, and 67.3, 35.6, and 18.5% in the LR group. Compared with LR alone, LR+TACE was associated with significantly better RFS [hazard ratio (HR), 1.443; 95% CI: 1.089–1.914; P=0.009] and OS (HR, 1.438; 95% CI: 1.049–1.972; P=0.023). No difference was observed with RFS and OS in single TACE and multiple TACE in the matched cohort. Conclusion: Postoperative adjuvant TACE could be beneficial for intermediate-stage HCC patients with MVI.


Introduction
Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and the second leading cause of cancerrelated mortality in China due to endemic chronic hepatitis B virus (HBV) infection [1,2] .Advances in diagnostic imaging and widespread application of screening programs in high-risk populations have allowed detection of HCC at an early-stage, but some patients still present with intermediate-stage HCC [3] .According to the Barcelona Clinic Liver Cancer (BCLC) algorithm for the treatment of HCC, intermediate-stage (stage B) HCC is defined as extensive multifocal disease confined to the liver without macrovascular invasion in patients with preserved liver function and the absence of cancer-related symptoms [4] .The prognosis of patients with intermediate-stage HCC varies differently with different treatments [5] .Currently, transarterial chemoembolization (TACE) is considered a first-line treatment for patients with intermediate-stage HCC [4] .However, European and Japanese guidelines for the management of HCC indicate that not all patients with intermediate-stage HCC are eligible for TACE, nor do all benefit from this treatment [6,7] .Thus, there is a need for other first-line treatment options for patients with intermediate-stage HCC.
Typically, liver resection (LR) is only favorable for the treatment of patients with early-stage HCC who have good liver function [4,6] .With the improvement of surgical technique, LR has proven to be an effective option for certain patients with intermediate-stage HCC [8,9] .Some have even reported that in HCC patients with preserved liver function, the presence of large or multinodular tumors, macrovascular invasion, and/or portal hypertension should not be contraindications for LR [10] .However, the long-term survival rate of patients with intermediate-stage HCC after curative LR is still unsatisfactory due to the high incidence of tumor recurrence.Higher rates of tumor recurrence after curative LR usually lead to reduced overall survival (OS) in patients with intermediate-stage HCC, particularly those with microvascular invasion (MVI) [11] .MVI refers to the presence of micrometastatic HCC emboli within the vessels of the liver as seen on surgical histopathology [12] , and it is a major risk factor for poor prognosis in patients with intermediate-stage HCC after LR [13] .Therefore, it is of great significance to find effective therapies for such patients.
Some studies indicated that adjuvant radiotherapy [14] , sorafenib [15] , might decrease tumor recurrence after curative resection of HCC with MVI.However, none of these approaches have been recommended as universally accepted adjuvant therapy by current scientific guidelines after curative resection [6,16] .Currently, the main adjuvant therapy for the prevention of postoperative recurrence in patients with early-stage HCC with MVI is adjuvant TACE [17][18][19] .However, whether the postoperative adjuvant TACE could reduce recurrence and prolong the survival time of patients with MVI is still controversial.In addition, with more studies of MVI in recent years, the application of postoperative TACE in the adjuvant therapy of patients with early-stage HCC with MVI after curative LR has attracted much attention, but whether it can effectively reduce the recurrence of patients with intermediate-stage HCC with MVI and prolong the survival time is still unclear.In this multicenter study, we aimed to evaluate the effectiveness of postoperative TACE on the prognosis of patients with intermediate-stage HCC with MVI after curative LR.

Patients and study design
We retrospectively reviewed data on consecutive patients diagnosed with intermediate-stage HCC (BCLC stage B) who had undergone curative LR and postoperative TACE from January 2013 to December 2019 at three hospitals.The study protocol was consistent with the ethical guidelines of the 1975 Declaration of Helsinki and was approved by the Institutional Review Board of each participating institution.This study was reported in line with the strengthening the reporting of cohort, cross-sectional, and case-control studies in surgery (STROCSS) criteria [20] (Supplemental Digital Content 1, http://links.lww.com/JS9/B175).
Patients who met the following criteria were enrolled: (1) age 18-80 years; (2) patients with intermediate-stage HCC (BCLC stage B) with MVI, where MVI was diagnosed by postoperative pathology; (3) curative LR (complete resection of the tumor without any tumor tissue at the cutting edge [21] ); (4) no macrovascular invasion; (5) without any preoperative anticancer treatments; (6) Child-Pugh class A or B; (7) no history of other malignancies; patients were excluded from the analysis for any of the following reasons: (1) HCC patients with MVI negative; (2) recurrent HCC; (3) received preoperative adjuvant therapy; (4) early-stage HCC (BCLC stage 0-A); (5) incomplete clinical data; (6) lost to follow-up within 3 months after treatment.A total of 246 consecutive patients who were treated with either LR alone (LR group, n = 137) or LR plus adjuvant TACE (LR + TACE group, n = 109) were included in the analysis as the study population.The flowchart of patient selection is presented in Figure 1.

LR and postoperative adjuvant TACE
LR was performed by experienced surgeons.Surgical plan was based on tumor number, tumor size, tumor location, and liver function.The hepatectomy method contains nonanatomical resection and anatomical resection, and the extent was defined using the Brisbane 2000 Terminology of Liver Anatomy and Resections [22] .LR procedures have been described in detail in our previous study [23] .Curative LR was defined as the complete removal of all detected tumors without involving any major branch of the portal or hepatic veins, without invasion of adjacent organs and without lymph node or distant metastasis, and tumor-free margins confirmed by histopathology.
After 4-6 weeks of hepatectomy, when the liver function of the patient with MVI had recovered, TACE was performed for the entire remnant liver.Whether patients followed the adjuvant TACE or not depended on their treatment compliance, economic status, or other social factors.TACE was conducted using the Seldinger technique, and hepatic angiography, computed tomography (CT) angiography, or both were performed to detect any obvious tumor stains in the remnant liver.Hepatic artery angiography was performed using a 5 Fr (RH or Yashiro) catheter.The embolization emulsion was a mixture of Epirubicin (Farmorubicin; Pharmacia) 30 mg-60 mg, Lobaplatin (Chang'an International Pharmaceutical) 30 mg-50 mg, and Lipiodol (Laboratorie Guerbet) 5 ml-10 ml.The doses of the agents contained in the embolization emulsion were selected based on patient age, weight, comorbidity, and anticipated tolerance.The decision about the number of TACE was based on the presence of a poorly differentiated tumor on surgical pathology, narrower resection margins, or on abnormal postoperative alpha-fetoprotein (AFP) levels.Repeat whole liver TACE is not recommended for patients who do not recover after liver function impairment.After 1 month of follow-up evaluation, a CT scan was performed to determine the effects of TACE.

Outcomes and definitions
The primary endpoint for the study was OS, defined as the time from the date of curative resection to the date when the patients died or the last follow-up.The secondary endpoints included recurrence-free survival (RFS) and efficacy.RFS is defined as the time from the date of curative resection to the date at which HCC recurred.The diagnosis of HCC was confirmed according to histopathological evidence after LR.The BCLC staging system was used to evaluate the HCC stage [4] .The histologic grade of tumor differentiation was evaluated using the Edmondson-Steiner (ES) classification [24] .Cirrhosis was defined histologically by the findings of resected liver specimens.We used the Albumin-Bilirubin (ALBI) grade to evaluate liver function [25] .

Follow-up
The follow-up protocol and management of recurrent HCC have been described in our previous study [23] .All patients with MVI were first evaluated for recurrence 4 weeks after LR by contrastenhanced CT or MRI and a measurement of the serum AFP level.The patients were then re-evaluated every 3 months by measurement of their serum AFP level and by contrast-enhanced CT or MRI until death or dropout from the follow-up program.This investigation's follow-up period concluded on 30 March 2023.

Statistical analysis
Propensity score-matching analysis was involved to minimize alternative factors and sampling bias between the two groups.Propensity scores were computed using the following
The multivariate Cox regression analysis was performed in the entire cohort and the results revealed that treatment pattern, tumor differentiation, maximum tumor size, cirrhosis, and ALBI grade were significant factors associated with tumor recurrence in patient with intermediate-stage HCC with MVI (Table 2).

Discussion
In the present study, we evaluated the impacts of postoperative adjuvant TACE on the prognosis of patients who underwent  Currently, the BCLC staging system recommends TACE as the first-line treatment for intermediate-stage HCC [4] .However, some investigators have argued that LR should be considered as a first-line treatment for intermediate-stage HCC, given that the evidence supporting TACE as a first-line treatment may not be strong enough, and that the outcomes with LR may be better [26] .Furthermore, a clinical randomized controlled trial showed that LR is more aggressive than TACE and should be considered as a first-line treatment for intermediate-stage HCC [27] .Additionally, studies in Asian patients with intermediate-stage HCC have demonstrated that even the large number of HCC tumors should not be a contraindication to treatment with LR [28][29][30] .Of course, other tumor-related and liver-related factors need to be considered when determining the appropriate treatment for intermediate-stage HCC.Our results are consistent with those of the previous studies.For patients with intermediate-stage HCC who have good liver function and appear to be candidates for a curative resection, LR should be prioritized as a first-line treatment.
Although advances in surgical techniques, perioperative care, and accurate patient selection have gradually reduced surgical complications and mortality in recent years, the substantial recurrence rate after LR for intermediate-stage HCC remains a challenge and has led to efforts to find other effective adjuvant therapies [31] .Postoperative TACE has been considered one of those options.However, whether the postoperative TACE could reduce recurrence and prolong the survival time of HCC patients is still controversial.At the same time, most of the studies on postoperative TACE focus on early-stage HCC, while the studies on intermediate-stage HCC are still lacking.In some recent studies, postoperative TACE failed to demonstrate efficacy in patients with HCC [32,33] .In contrast, others have reported that postoperative TACE may achieve higher OS and RFS rates than surgical resection alone, as well as that TACE can be used as an effective adjuvant treatment after LR [17][18][19] .In our study, the result showed that postoperative TACE significantly improved the RFS and OS of intermediate-stage HCC patients with MVI in both the entire and propensity-matched cohorts, suggesting that for patients with MVI-positive intermediate-stage HCC, the addition of TACE after LR may be preferable.Moreover, postoperative TACE was also identified as an independent factor affecting both their RFS and OS.
The presence of MVI in HCC, usually discovered on surgical pathology, is a major obstacle to the achievement of good longterm survival rates after LR for patients [12,34] .It correlates with histologic grade, tumor diameter, and number of nodules [12] .MVI is present in 30-60% of nodules 2-5 cm in size, and up to 60-90% of tumors larger than 5 cm [35] , and it has been recognized as one of the most powerful predictors of tumor recurrence in patients with HCC after curative hepatectomy [11,13,23] .However, since MVI cannot be recognized preoperatively, it can only be accurately diagnosed by postoperative histopathology.Therefore, to decrease tumor recurrence, postoperative adjuvant therapy is essential for HCC patients with MVI.As the main adjuvant therapy after curative hepatectomy, TACE may play an important role in preventing tumor recurrence in HCC patients with MVI.Two recent interesting studies have shown that postoperative TACE significantly improved the RFS and OS of HCC patients with MVI [17,19] .It must be noted that most (more than 71% in Wang et al., and more than 65% in Sun et al.) of the patients in their study were early-stage HCC patients.However, there is still a lack of sufficient evidence for patients with intermediate-stage HCC.Our study confirms that postoperative TACE is equally helpful for intermediate-stage HCC patients with MVI.Thus, the findings of our study complement those published by Sun et al.
Currently, although TACE has been proven to be an effective strategy for the prevention of recurrence in HCC patients with high-risk factors [17,19,36] , the timing and times of TACE as an adjuvant therapy remained indistinct.Tong et al. [37] reported that a single postoperative TACE treatment was beneficial for patients with HCC and repeated TACE did not increase patient benefit, but their study focused on patients in American Joint Committee on Cancer (AJCC) stage I and tumors less than 5 cm in size.Feng et al. [38] reported that patients who received multiple TACE treatments after curative hepatectomy had better RFS and OS rates than patients who had a single TACE treatment.However, their study was limited to patients with HCC that met the Milan criteria, including no tumor larger than 5 cm.In the present study, for intermediate-stage HCC patients with MVI, no difference was observed with RFS and OS in single TACE group and multiple TACE group both in the entire and matched cohorts.In theory, compared to a single TACE treatment, multiple TACE after LR should have improved the outcomes of patients with intermediate-stage HCC, by further eradicating residual any occult intrahepatic satellite lesions not identified by imaging [39] .However, patients with intermediate-stage HCC often have a large tumor burden as well as impaired liver function and immune systems [40] .In addition, TACE may accelerate the deterioration of liver function, contribute to the suppression of host immunity against tumor progression, and negatively impact the regeneration of hepatocytes [41,42] .Hence, patients with intermediate-stage HCC had undergone surgical removal of a large volume of liver tissue, and balanced against these potentially negative sequelae, it is possible that those who received multiple TACE treatments obtained relatively limited benefit from more than a single TACE treatment, ultimately resulting in outcomes that were not better.In any case, our findings suggest that for patients with intermediate-stage HCC, a single TACE treatment after surgery can maximize the patient benefit without the need for multiple TACE treatments.
In recent years, after sorafenib, more and more targeted drugs, such as lenvatinib, donafenib, and apatinib, are being explored for the adjuvant treatment of HCC after surgery.In addition, numerous studies on the use of single or combined targeted immune checkpoint inhibitors in the adjuvant treatment of HCC after hepatectomy are also being carried out.According to a recent study, patients with China Liver Cancer Staging (CNLC) stage Ⅱ b and/or Ⅲ a are treated with lenvatinib after curative resection, the 1-year RFS rate was 50.5% and the median RFS was 16.5 months [43] .Another study showed that patients with BCLC stage A to B HCC who received donafenib combined with treprinumab after curative resection had an 80% RFS rate at 1-year and a median RFS was not reached [44] .Our result showed that the 1-year RFS rate was 42.0% in LR + TACE group.Although the two studies had a longer RFS than ours, they included more patients with early-stage HCC.Another important reason is that the two studies used combination therapy for postoperative adjuvant treatment, so the efficacy may be better.
Our study has several limitations.First, this study was retrospectively and carried out without randomization, which may have resulted in selection bias, but we tried to minimize such limitation by PSM.Second, since the HCC patients in our study were mainly caused by HBV infection, the results of this study may not be applicable to HCC patients associated with HCV infection or alcohol-related HCC.Third, our study did not address which patients might benefit most from the addition of TACE after LR.Additional studies are needed to reach more reliable conclusions about this issue.

Conclusion
In conclusion, postoperative adjuvant TACE could be beneficial for intermediate-stage HCC patients with MVI.A single TACE treatment after surgery can maximize the patient's benefit without the need for multiple TACE treatments.Postoperative TACE should be considered selectively in intermediate-stage HCC patients with MVI after curative LR.

Ethical approval
This study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Hunan Provincial People's Hospital (approval number: 2022-99), and has been registered in the Chinese clinical trial registry (ChiCTR2300071111).
In order to judge the effect of the number of postoperative TACE treatments on the prognosis of intermediate-stage HCC patients with MVI, we further analyzed the frequency and efficacy of postoperative TACE treatment in the LR + TACE group.Patients were classified into two groups: (a) patients received only one postoperative adjuvant TACE before the tumor recurrence (single TACE group); (b) patients received two or more postoperative adjuvant TACE before the tumor recurrence (multiple TACE group).No difference was observed with RFS (Fig. 4A; HR, 1.311; 95% CI: 0.843-12.038;P = 0.22) and OS (Fig. 4B; HR, 1.300; 95% CI: 0.814-2.077;P = 0.27) in single TACE group and multiple TACE group in the entire cohort.After propensity matching, the medium RFS and OS were 8.0 months, 13.1 months, and 25.2 months, 35.3 months in single TACE group and multiple TACE group, respectively.Similarly, no difference was observed with RFS (Fig. 4C; HR, 1.462; 95% CI: 0.898-2.381;P = 0.12) and OS (Fig. 4D; HR, 1.359; 95% CI: 0.819-2.255;P = 0.23) in single TACE group and multiple TACE group in the matched cohort.

Figure 2 .
Figure 2. Kaplan-Meier analysis of overall survival (OS) in the entire cohort (2A) and in the propensity score-matched cohort (2B) of intermediate-stage hepatocellular carcinoma (HCC) patients with microvascular invasion (MVI) after curative liver resection.

Figure 3 .
Figure 3. Kaplan-Meier analysis of recurrence-free survival (RFS) in the entire cohort (3A) and in the propensity score-matched cohort (3B) of intermediate-stage hepatocellular carcinoma (HCC) patients with microvascular invasion (MVI) after curative liver resection.

Figure 4 .
Figure 4. Kaplan-Meier analysis of recurrence-free survival (RFS) in the entire cohort (4A) and in the propensity score-matched cohort (4C), and overall survival in the entire cohort (4B) and in the propensity score-matched cohort (4D) of intermediate-stage hepatocellular carcinoma (HCC) patients with microvascular invasion (MVI) who were treated with either single transarterial chemoembolization (TACE) or multiple TACE after curative liver resection.
14 variables: sex, age, tumor number, maximum tumor diameter, tumor differentiation, capsule, blood loss, blood transfusion, resection pattern, resection margin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), AFP, ALBI grade.For PSM, a nearest-neighbor 1:1 matching scheme with a caliper size of 0.2 was used (Supplementary Figure1, Supplemental Digital Content 2, http://links.lww.com/JS9/B176).OS and RFS were compared between the LR group and LR + TACE group in a propensity score-matched cohort by a log-rank test.The comparison of continuous variables with or without normal distribution was analyzed with the Student t-test and the Wilcoxon rank test, respectively.χ 2 and Fisher's test were applicated for the analysis of categorical variables.OS and RFS rates were calculated using the Kaplan-Meier method and compared using the log-rank test.Multivariate analyses were performed by the Cox proportional hazards regression model with a stepwise selection of variables.The statistical analyses were performed using the Statistical Package for the Social Science (SPSS) software (version 22.0, SPSS Inc.) for Windows and R software for Windows (Version 4.1.3;http://www.r-project.org).P <0.05 was considered significant.

Table 1 (
Supplemental Digital Content 2, http://links.lww.com/JS9/B176).The multivariate Cox regression analysis was performed in the entire cohort and the results revealed that treatment pattern, tumor number, tumor differentiation, cirrhosis, and ALBI grade were significant factors associated with OS in patient with intermediate-stage HCC with MVI (Table 2).

Table 1
Baseline characteristics of intermediate-stage hepatocellular carcinoma patients with microvascular invasion in different treatment groups.