Subcapsular hepatocellular carcinoma (HCC) has unique anatomical characteristics that may influence treatment selection and clinical outcomes. Surgical resection and liver transplantation are potentially curative treatments but may be limited by liver function, tumor characteristics, and perioperative risks. Microwave ablation has become an important minimally invasive treatment option for patients with HCC, particularly for lesions that are difficult to treat surgically. This prospective observational cohort study aims to compare the therapeutic efficacy, safety, and long-term outcomes of no-touch microwave ablation, tumor-puncture microwave ablation and surgical resection in patients with subcapsular HCC. Treatment outcomes, including local tumor control, treatment-related complications, recurrence, and survival outcomes, will be evaluated to provide evidence for individualized treatment strategies for patients with subcapsular HCC.
This single-center prospective observational cohort study will be conducted at the First Hospital of Jilin University. The study aims to evaluate and compare the therapeutic efficacy, safety, and long-term clinical outcomes of three treatment modalities, including no-touch microwave ablation, tumor-puncture microwave ablation, and surgical resection, in patients with subcapsular hepatocellular carcinoma (HCC). The study will compare local tumor control, recurrence patterns, treatment-related complications, and survival outcomes among the three groups, providing clinical evidence for individualized treatment selection and optimizing long-term management strategies for patients with subcapsular HCC. The study population will consist of patients with a confirmed diagnosis of hepatocellular carcinoma. The diagnosis of HCC will be based on the practice guidelines of the American Association for the Study of Liver Diseases (AASLD). The definition of subcapsular hepatocellular carcinoma will follow previously published criteria, in which the shortest distance between the tumor margin and the liver capsule is ≤3 mm, as confirmed by imaging examinations including ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI). All enrolled patients will undergo comprehensive pre-treatment evaluations according to standard clinical practice, including routine blood tests, liver and renal function tests, coagulation assessment, serum alpha-fetoprotein (AFP) measurement, conventional ultrasound combined with contrast-enhanced ultrasound, and contrast-enhanced CT or MRI. These examinations will be used to assess tumor characteristics, hepatic functional reserve, and overall physical condition. Treatment strategies will be determined by a multidisciplinary liver cancer team based on clinical evaluation and patient-specific factors. All microwave ablation procedures will be performed by experienced interventional ultrasound physicians with more than 10 years of experience in microwave ablation therapy. During the study period, treatment responses and prognostic outcomes will be evaluated through follow-up assessments. Short-term follow-up data will include hospitalization duration and the incidence of postoperative complications, including hemorrhage, infection, needle tract seeding, thermal injury to perihepatic structures, liver failure, and ascites. Long-term therapeutic outcomes will be evaluated according to the following criteria: 1. Local tumor control rate: Patients will undergo regular imaging follow-up to evaluate local tumor recurrence. Local recurrence will be defined as the appearance of viable tumor lesions within or adjacent to the ablation zone in the microwave ablation groups, or recurrence near the surgical resection margin in the surgical resection group. Local tumor progression (LTP) will be defined as the development of new tumor lesions within or along the margin of the ablation zone after complete ablation in the microwave ablation groups, or the appearance of new tumor lesions adjacent to the surgical resection margin during imaging follow-up in the surgical resection group. 2. Disease-free survival (DFS): DFS will be defined as the time interval from completion of treatment to tumor recurrence, metastasis, or death. It will be used to evaluate the duration of disease-free status after treatment. 3. Overall survival (OS): OS will be defined as the time interval from completion of treatment to death from any cause or the date of the last follow-up. It will be used to evaluate the impact of different treatment modalities on overall survival outcomes. Kaplan-Meier survival analysis will be performed to evaluate LTP, OS, and DFS. The log-rank test will be used to compare differences among treatment groups. Univariate and multivariate Cox proportional hazards regression models will be applied to identify independent prognostic factors associated with treatment outcomes. This study will compare OS, DFS, and local tumor progression rates among the three treatment modalities to evaluate the relationship between different treatment strategies and long-term clinical outcomes. Furthermore, recurrence patterns, recurrence locations, and subsequent treatment strategies after recurrence will be analyzed to provide evidence-based information for optimizing individualized treatment strategies for patients with subcapsular HCC.
Study Type
OBSERVATIONAL
Enrollment
180
Under real-time ultrasound guidance, two or more microwave antennas are percutaneously inserted into the normal liver parenchyma surrounding the tumor from different directions with intersecting angles. The antenna tips are maintained approximately 5-10 mm away from the tumor margin, forming a cross-shaped configuration around the tumor without penetrating the tumor itself. The microwave ablation system is activated under continuous output mode with a power setting ranging from 30 to 80 W. The ablation duration is adjusted according to tumor size and characteristics. Multiple antennas may be activated simultaneously or sequentially to achieve adequate tumor ablation. The use of artificial hydrothorax or artificial ascites is determined according to intraoperative ultrasound visualization and the distance between the tumor and adjacent organs.
Under real-time ultrasound guidance, the microwave ablation antenna is directly inserted into the tumor. The antenna position is adjusted according to tumor size to ensure that the antenna tip is located near the center of the tumor. The microwave ablation system is activated, and the ablation zone is designed to cover the entire tumor with an additional 5-10 mm safety margin around the lesion.
1. Open Hepatectomy The abdominal cavity is entered through a conventional layered incision. Intraoperative exploration of the liver and tumor lesions is performed, and the hepatic ligaments are dissected to adequately mobilize and expose the tumor. The tumor is resected together with surrounding liver parenchyma, maintaining a safety margin of at least 5 mm according to standard surgical procedures. After meticulous hemostasis and management of the liver transection surface, the abdominal cavity is irrigated, drainage tubes are placed, and the abdominal incision is closed layer by layer. 2. Laparoscopic Hepatectomy Pneumoperitoneum is established, and laparoscopic instruments are introduced into the abdominal cavity. The liver and tumor lesions are evaluated under laparoscopic visualization, followed by liver mobilization and exposure of the lesion. After hepatic inflow occlusion using the Pringle maneuver when necessary, precise tumor resection is performed with an adequate safety
Local Tumor Control Rate
Patients will receive regular imaging follow-up after treatment to assess local tumor recurrence. Local Tumor Progression (LTP) is defined as viable lesions within the ablation zone or tumor recurrence at the surgical resection margin. For patients receiving microwave ablation, LTP refers to new lesions emerging within or at the edge of the ablation zone after complete ablation. For patients undergoing surgical resection, LTP is defined as lesions adjacent to the surgical resection margin identified on follow-up imaging. Measure Unit: Proportion
Time frame: Up to 2 years after treatment
Disease-Free Survival (DFS)
The time interval from completion of curative treatment to tumor recurrence, distant metastasis, or all-cause death. Measure Unit: Month
Time frame: Up to 2 years after treatment
Overall Survival (OS)
The time interval from completion of curative treatment to all-cause death or the last follow-up visit. Measure Unit: Month
Time frame: Up to 2 years after treatment
Time to tumor recurrence
Time interval from treatment to the first detection of tumor recurrence. Measure Unit: Month
Time frame: Up to 2 years after treatment
Pattern of tumor recurrence
Classification of recurrence location, including local tumor progression, intrahepatic distant recurrence, and extrahepatic distant metastasis. The proportion of patients with each recurrence subtype will be analyzed. Measure Unit: Proportion
Time frame: Up to 2 years after treatment
Treatment modality after tumor recurrence
Therapeutic approaches adopted for patients after tumor recurrence. Measure Unit: Categorical
Time frame: Up to 2 years after treatment
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