The Comparison of Surgical Margins and Type of Hepatic Resection for Hepatocellular Carcinoma With Microvascular Invasion

Abstract Objective The objective of this study was to investigate the impact of surgical margin and hepatic resection on prognosis and compare their importance on prognosis in patients with hepatocellular carcinoma (HCC). Methods The clinical data of 906 patients with HCC who underwent hepatic resection in our hospital from January 2013 to January 2015 were collected retrospectively. All patients were divided into anatomical resection (AR) (n = 234) and nonanatomical resection (NAR) group (n = 672) according to type of hepatic resection. The effects of AR and NAR and wide and narrow margins on overall survival (OS) and time to recurrence (TTR) were analyzed. Results In all patients, narrow margin (1.560, 1.278-1.904; 1.387, 1.174-1.639) is an independent risk factor for OS and TTR, and NAR is not. Subgroup analysis showed that narrow margins (2.307, 1.699-3.132; 1.884, 1.439-2.468), and NAR (1.481, 1.047-2.095; 1.372, 1.012-1.860) are independent risk factors for OS and TTR in patients with microvascular invasion (MVI)-positive. Further analysis showed that for patients with MVI-positive HCC, NAR with wide margins was a protective factor for OS and TTR compared to AR with narrow margins (0.618, 0.396-0.965; 0.662, 0.448-0.978). The 1, 3, and 5 years OS and TTR rate of the two group were 81%, 49%, 29% versus 89%, 64%, 49% (P = .008) and 42%, 79%, 89% versus 32%, 58%, 74% (P = .024), respectively. Conclusions For patients with MVI-positive HCC, AR and wide margins were protective factors for prognosis. However, wide margins are more important than AR on prognosis. In the clinical setting, if the wide margins and AR cannot be ensured at the same time, the wide margins should be ensured first.


Introduction
Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, and its incidence is increasing every year.6][7] MVI is defined as a cluster of cancer cells found in e1044 The Oncologist, 2023, Vol. 28, No. 11   the microscopic endothelial cell-lined vascular lumen, which occurs mainly in the portal venous system. 8Different patients with HCC have different etiologies and pathogenic mechanisms that lead to different proportions of MVI in different patients with HCC.Studies had reported MVI-positive rates ranging from 11% to 60% in patients with HCC. 9 How to reduce the high rate of tumor recurrence and improve the overall survival (OS) for MVI-positive patients with HCC are currently a hotspot issue in clinical research.
1][12] Wide margins can also reduce postoperative tumor recurrence rates and improve prognosis compared to narrow margins in patients with MVIpositive. 13However, there is still controversy regarding the prognostic impact of hepatic resection and surgical margins in patients with MVI-positive.There is also a lack of studies comparing the hepatic resection and surgical margins in patients with MVI-positive.In this study, 906 patients with HCC were included.The effect of hepatic resection and surgical margins on the prognosis of patients with MVI-positive HCC was investigated.

Patients
Patients with HCC who underwent hepatectomy in our hospital from January 2013 to January 2015 were collected retrospectively.All patients included in this study underwent open surgery.The patients were selected according to the inclusion and exclusion criteria, and detailed clinical information of the patients was recorded.The inclusion criteria for this study were: (a) HCC was confirmed by postoperative pathological, (b) no extrahepatic distant metastasis, (c) no macrovascular invasion and no invasion of peripheral organs, (d) complete resection of tumor with negative surgical margins, and (e) no other anti-tumor treatments prior to hepatectomy.

Preoperative Examination and Hepatectomy
Preoperative examination is routinely performed to assess the patient's surgical tolerance and resectability of the tumors.Preoperative examination included: blood routine, hepatic and renal function, coagulation function, tumor markers, hepatitis markers, blood grouping, electrocardiogram (ECG), lung function, gastroscopy, chest Computed Tomography (CT), abdominal ultrasound, and liver Magnetic Resonance Imaging (MRI).
All patients included in this study underwent AR or NAR and major hepatectomy or minor hepatectomy according to different hepatectomy methods.AR 16 : AR was charactered as any type of complete excision at least one segment based on Couinaud's classification, included segmentectomy, subsegmentectomy, sectoriectomy, and hemihepatectomy.After laparotomy, the liver was completely exposed, and the perihepatic ligament was released.According to the preoperative imaging combined with intraoperative ultrasound, the anatomy of the liver and the corresponding segment or lobe which should be resected was confirmed.The intraoperative ultrasound is used to identify the intrahepatic veins, hepatic artery, and bile ducts, and the corresponding liver segment is defined by combination with the hepatic vein and portal vein.The liver parenchyma is then dissected, and the intrahepatic veins, hepatic artery or bile ducts are dissected by electrocoagulation, ligation, and suturing, respectively.Then, the corresponding liver segment was completely resected.After complete resection of the tumors, the liver section is completely hemostasis.NAR 17 : The same exposure process as AR, then according to the position of the tumor, the resection line is set by electric knife in advance on the surface of the liver.The tumor was completely resected by electrocoagulation, ligation, and suturing, respectively, along the resection line.After complete resection of the tumors, the liver section is completely hemostasis.Major hepatectomy and minor hepatectomy were classified according to the extent of hepatectomy.Hepatectomy ≥3 liver segments is defined as major hepatectomy, 18,19 and hepatectomy <3 liver segments is defined as minor hepatectomy.
Based on the postoperative pathologic, wide or narrow margin was defined as the shortest distance from the margin of tumors to the surgical margin ≥ 1 cm or not. 13,20

Follow-Up and Endpoints
Tumor differentiation was graded by postoperative pathology according to the Edmondson-Steiner classification. 21ostoperative complications were assessed according to the Clavien-Dindo criteria. 22In this study, some patients returned to the hospital for adjuvant TACE about one month after surgery.The screening of these patients is based on factors such as tumor size, number of tumors, and MVI.If the patient is assessed as a high-risk recurrence after surgery, it is generally recommended that patients undergo an adjuvant TACE about one month after surgery. 23Routine postoperative follow-up was performed every 2-3 months for first 2 years and every 3-6 months after 2 years.Blood routine, hepatic and renal function, tumor markers, abdominal ultrasound, liver MRI, or CT was performed at follow-up.The American Association for the Study of Liver Diseases (AASLD) criteria were used for the diagnosis of HCC recurrences. 24OS and TTR were used as the primary endpoints.OS was defined as the day of hepatic resection until the patients died or lost to follow-up.TTR was defined as the day of hepatic resection until tumor recurrences or metastasis.

Statistical Analysis
The measure data were described by median (range), and independent samples t test or Mann-whitney U test were used to evaluate the statistical differences.The Kaplan-Meier method was used to plot survival and recurrence curves.And the Cox's univariate and multivariate analysis was used to evaluate the independent risk factors for OS and TTR.

OS and TTR in the Whole Cohort
The median follow-up time of the 906 patients with HCC was 63.7 months, with the 1, 3, and 5 years OS rates, and tumor recurrence rates were 87.2%, 63.5%, 49.2% and 21.7%, 55.6%, 68.6%, respectively.

OS and TTR in the Patients With MVI-Negative HCC
The 906 patients with HCC were divided into MVI-negative (n = 588) and MVI-positive (n = 318) groups.

OS and TTR in the Patients With MVI-Positive HCC
Supplementary Table S5 shows that there was no difference in all basic information between AR group and NAR group in patients with MVI-positive HCC (P > 0.05).Supplementary Table S6 shows the results of univariate analysis for OS and TTR in patients with MVI-positive HCC.The results of the multivariate analysis are shown in ) was an independent risk for OS.HBV-DNA >2000 IU/mL (1.466, 1.133-1.897)was an independent risk factor for TTR.

Discussion
Hepatectomy is the most important and effective treatment for patients with HCC to obtain radical treatment. 4Depending on the hepatic resection, hepatectomy can be divided into AR and NAR. 25,26AR is the complete resection of the tumors and associated portal branches, and the corresponding at least one liver segment. 27AR can not only removes tumors that are visible to naked eye but also removes MVI that is difficult to detect before hepatectomy. 28In addition, AR can completely remove the tumor-carrying portal tributaries and reduce the ischemic area after surgery. 2930,31 Some studies suggested that AR does not improve the prognosis of patients with HCC. 26,30,31][12] The results of our research showed that AR did not affect the prognosis of patients with HCC in the whole group, which is consistent with the results of previous studies. 13,31owever, in patients with MVI-positive, AR improved patient prognosis and reduced tumor recurrence compared to NAR.4][35][36] This may be related to the fact that AR can remove intrahepatic lesions and microvascular metastases, which can reduce postoperative tumor recurrence. 12,33In addition, AR can reduce the rate of early tumor recurrence and intrahepatic  The Oncologist, 2023, Vol. 28, No. 11 e1049 not explicitly proposed that a better prognosis of AR may be related to a higher proportion of wide margins.Based on our results, we believed that a better prognosis of AR may be related to a higher proportion of wide margins.Our study also analyzed the impact of surgical margins on prognosis.The results showed that wide margins can improve the prognosis of patients in the whole group, which is consistent with previous studies reported. 13,37Further subgroup analysis showed that in patients with MVI-positive, wide margin can improve the prognosis which is consistent with previous studies reported. 13This may due to the fact that narrow margins could lead to residual MVI or residual micrometastases, which can cause intrahepatic metastases or early tumor recurrence. 13It was found that, although MVI is mainly found in intra-microvessel, it can also invade beyond the capsules of HCC. 38In contrast, wide margins can remove residual MVIinduced intrahepatic micrometastases, thereby improving the prognosis.
The results of our study also showed that wide margins and AR should be advocated in patients with MVI-positive.
However, some patients with HCC have insufficient residual liver volume to obtain AR and wide margins at the same time.In this case, should we give priority to AR or wide margins?Our study showed that for patients with MVIpositive, AR with narrow margins was an independent risk factor for OS and TTR compared with NAR with wide margins.In other words, although both wide margins and AR can improve the prognosis of patients with MVI-positive HCC, the wide margins had a greater impact on patients' prognosis compared with AR.Besides, we also did some additional data analysis in our study.For patients with MVIpositive, the 1-, 3-, 5-year OS rate and TTR rate of AR with wide margins and AR with narrow margins were 93.5%, 80.5%, 66.6% versus 81.4%, 48.8%, 28.8% (P < .001)and 9.7%, 32.6%, 53.6% versus 41.9%, 79.1%, 89.5% (P < .001),respectively.There were significant differences in OS and TTR between the two groups.For patients with MVIpositive, the 1-, 3-, 5-year OS rate and TTR rate of NAR with wide margins and NAR with narrow margins were 89.0%, 63.8%, 48.7% versus 71.9%, 33.3%, 21.1% (P < .001)and 32.3%, 57.8%, 73.3% versus 42.0%, 78.1%, 91.0% (P < .001),respectively.There were significant differences in OS and TTR between the two groups.For patients with MVIpositive, the 1-, 3-, 5-year OS rate and TTR rate of AR with wide margins and NAR with wide margins were 93.5%, 80.5%, 66.6% versus 89.0%, 63.8%, 48.7% (P = .062)and 9.7%, 32.6%, 53.6% versus 32.3%, 57.8%, 73.7% (P = .012),respectively.There was significant differences in TTR between the two groups.But there is no difference in OS.
From the analysis of the above subgroups, we can also find that among patients with MVI-positive, patients with wide margins receiving AR or NAR have better OS and TTR than patients with narrow margins, with significant differences.However, for patients with MVI-positive and wide margins, there is no statistical difference in OS between AR and NAR.This also suggests that for patients with MVI-positive, wide margins may be more important than AR for the prognosis of patients.Therefore, when wide margins and AR cannot be obtained at the same time in patients with MVI-positive, wide margins should be ensured firstly to obtain a better long-term prognosis.
We also analyzed the differences in cirrhosis between the AR group and NAR group in our study.Our results showed that the proportion of cirrhosis in patients with NAR is relatively high, but there is no significant difference in cirrhosis between the AR group and NAR group (43.2% vs. 46.7%,P = .346).This may be due to the inclusion of patients in this study who underwent rigorous liver function assessment and screening before surgery.The liver function of the patients included in this study is beyond B7 of Child-Pugh.The overall condition of liver function in these patients included in this study is good.In addition, all patients underwent evaluated for residual liver volume before surgery.It may be due to these reasons that clinicians have relatively few concerns about liver injury when deciding on surgical procedures.For patients with HCC with cirrhosis or fibrosis, clinicians will also perform AR.
Of course, this study was a single center retrospective study.Although the number of patients included in this study reached 906.The number of patients in some subgroups is relatively small during subgroup analysis.Besides, all patients included in this study come from one hospital.There may be some selection bias.Therefore, in the next step, we plan to conduct this research through multicenter.

Conclusion
Clinically, surgical margins are more important for the prognosis of patients with HCC than the type of hepatic resection.For patients with MVI-positive HCC, both AR and wide margins are protective factors for prognosis.However, wide margins are more important for the prognosis than AR.Therefore, AR should be pursued only if wide margins are secured.In the clinical setting, if only one of the wide margins and AR can be selected, the wide margins should be ensured first.

Figure 2 .
Figure 2. Kaplan-Meier estimate of OS and tumor recurrence for anatomical resection and nonanatomical resection group in the whole group.(A) Kaplan-Meier estimate of OS for patients with HCC underwent anatomical resection and nonanatomical resection; (B) Kaplan-Meier estimate of tumor recurrence for patients with HCC underwent anatomical resection and nonanatomical resection.

Figure 3 .
Figure 3. Kaplan-Meier estimate of OS and tumor recurrence for patients with MVI-negative and MVI-positive HCC underwent anatomical resection and nonanatomical resection and for patients with MVI-positive HCC underwent anatomical resection with narrow margin and nonanatomical resection with wide margin.(A) Kaplan-Meier estimate of OS for patients with MVI-negative HCC underwent anatomical resection and non-anatomical resection; (B) Kaplan-Meier estimate of tumor recurrence for patients with MVI-negative HCC underwent anatomical resection and nonanatomical resection; (C) Kaplan-Meier estimate of OS for patients with MVI-positive HCC underwent anatomical resection and nonanatomical resection; (D) Kaplan-Meier estimate of tumor recurrence for patients with MVI-positive HCC underwent anatomical resection and nonanatomical resection.(E) Kaplan-Meier estimate of OS for patients with MVI-positive HCC underwent anatomical resection with narrow margin and nonanatomical resection with wide margin; (F) Kaplan-Meier estimate of tumor recurrence for patients with MVI-positive HCC underwent anatomical resection with narrow margin and nonanatomical resection with wide margin.

Table 1 .
Multivariate analysis of OS and TTR.

Table 2 .
Multivariate analysis of OS and TTR of patients with MVI-negative and MVI-positive HCC.

Table 3 .
Multivariate analysis of OS and TTR of patients with MVI-positive HCC underwent AR with narrow margin or NAR with wide margin.

Table 4 .
Complications of patients underwent AR and NAR.
This study was funded in full by the Program of Science and Technology Commission of Shanghai Municipality (grant number 21Y11912700), Natural Science and Medical Guidance Foundation of Shanghai (grant number 16ZR1400100 and 16411966200), the National Natural Science Foundation of China, Youth Science Fund Project (grant number 31301187), Youth Cultivation Program of Chinese National Natural Science Foundation (2021GZR002), Clinical Research Plan for SHDC (grant number SHDC2020CR2038B), Explorer Program of Shanghai Scientific and Technological Committee (grant number 21TS1400500), Clinical specialist project in Shanghai (grant number shslczdzk02402), Project of Shanghai Shenkang Hospital Development Center (grant number SHDC2020CR5007, SHDC12019110) and Star Cultivation Project of Science and Technology Innovation Action Plan in Shanghai 2022 (Yangfan: 22YF1459000).