Patient Characteristics and the Safety of Stent Placement for Malignant Vena Cava Syndrome in Japan: A Nationwide Analysis

Technical Summary: Patient Characteristics and the Safety of Stent Placement for Malignant Vena Cava Syndrome in Japan

Problem Statement
Malignant superior vena cava (SVC) and inferior vena cava (IVC) syndromes, caused by tumor invasion or compression, result in severe symptoms and reduced quality of life. While stent placement is a widely accepted palliative treatment with high technical success rates, its safety profile in large, multicenter populations remains insufficiently characterized. Previous evidence relies heavily on small observational studies or randomized controlled trials (RCTs) with limited sample sizes (e.g., n=28), which restrict the generalizability of complication rate estimates. Furthermore, existing systematic reviews often include heterogeneous populations with varying etiologies, including benign conditions. There is a critical need for robust safety data derived from large-scale, standardized cohorts to support clinical decision-making for patients with advanced malignancies.

Methodology
This study conducted a retrospective cohort analysis using the Japanese Diagnosis Procedure Combination (DPC) database, a nationwide inpatient database covering approximately 90% of tertiary care hospitals in Japan.

• Cohort: The study included 301 patients who underwent SVC or IVC stent placement for malignant vena cava syndrome between April 2019 and March 2023 across 137 hospitals.
• Data Collection: Patient characteristics (age, sex, BMI, Charlson Comorbidity Index), underlying malignancies, and procedural details (number of stents, repeat placements) were extracted.
• Outcome Measures: Adverse events were identified using International Classification of Diseases, 10th Revision (ICD-10) codes. Specific complications assessed included infection, arrhythmia, cardiac tamponade, heart failure, pneumothorax, hemothorax, pleural effusion, mediastinitis, respiratory failure, disseminated intravascular coagulation (DIC), pulmonary embolism, and renal dysfunction.
• Interventions and Mortality: Therapeutic interventions within 7 days of stenting (red blood cell transfusion, embolization, drainage, surgery) and mortality rates (7-day post-stent and 30-day post-admission) were evaluated.
• Statistical Analysis: Differences between the SVC (n=187) and IVC (n=114) groups were assessed using chi-square tests, Fisher's exact tests, and the Mann–Whitney U test.

Key Results

• Patient Demographics and Etiology: The mean patient age was 67.7 years, with over 95% having a Charlson Comorbidity Index score ≥2.
  • SVC Group: Lung tumors were the predominant underlying malignancy (79.1%).
  • IVC Group: Liver tumors (both primary and metastatic) were the most common cause (47.4%).
  • Procedural Differences: The use of multiple stents (two or more) was significantly more frequent in the IVC group (49.1%) compared to the SVC group (20.9%) (p < 0.001).
• Adverse Events: Overall, adverse events occurred in 34 patients (10.6%).
  • Respiratory Failure: This was significantly more common in the SVC group compared to the IVC group (p = 0.001).
  • Other Complications: No significant differences were observed for other complications between the two groups.
• Interventions and Mortality:
  • Red blood cell transfusions were required in 10 patients (3.3%), with no significant difference between groups.
  • Crucially, no patient required invasive interventions such as transcatheter arterial embolization, percutaneous drainage, or surgical procedures.
  • Mortality: The 7-day mortality rate after stenting was 5.0% (15 patients), and the 30-day in-hospital mortality rate was 11.6% (35 patients). There were no statistically significant differences in mortality between the SVC and IVC groups.

Key Contributions
This study provides the first nationwide analysis of safety outcomes for malignant vena cava stent placement in Japan. By utilizing a large, standardized administrative database, the authors overcame the limitations of small-sample studies and heterogeneous populations found in prior literature. The study specifically characterizes the distinct patient profiles and procedural requirements for SVC versus IVC syndrome, noting the higher prevalence of lung cancer in SVC cases and liver cancer in IVC cases, as well as the greater need for multiple stents in IVC procedures.

Significance and Claims
The paper claims that stent placement for malignant vena cava obstruction demonstrates a relatively low complication rate (10.6%) and, most importantly, a lack of serious adverse events requiring invasive intervention. The authors conclude that the procedure is a safe and effective palliative option, even for patients with advanced malignancies and multiple comorbidities. The findings support the use of vena cava stenting as a standard therapeutic option, reinforcing existing guidelines with robust, real-world evidence from a large multicenter cohort. The study acknowledges limitations, including the lack of data on stenosis severity, operator experience, and long-term outcomes, but asserts that the current data sufficiently supports the safety profile of the intervention.