Anticoagulant therapy for cancer-associated splanchnic vein thrombosis: Outcomes during a one-year follow-up period

Introduction

Splanchnic vein thrombosis (SVT) represents an occlusion within veins draining the abdominal organs, a condition increasingly diagnosed in cancer patients, especially those with intra-abdominal malignancies such as pancreatic cancer. Advances in oncological care and routine imaging have contributed to higher detection rates of SVT in this population. Despite its rising prevalence, the long-term clinical outcomes of cancer-associated SVT and the value of anticoagulant treatment remain poorly understood. This article synthesizes evidence from a recent retrospective observational study examining outcomes at one-year follow-up to clarify these aspects.

Study Background and Disease Burden

Cancer-associated thrombosis is a major contributor to morbidity and mortality in oncology patients. SVT causes significant clinical challenges, including portal hypertension, gastrointestinal bleeding, and impacts on cancer treatment continuation. The prevalence of SVT correlates strongly with abdominal tumors, which themselves bear a high thrombotic risk. Understanding the natural history and optimal management of SVT in cancer is critical, given the delicate balance between thrombotic risk and bleeding, particularly in patients with metastatic disease.

Study Design

The study was a retrospective observational cohort analysis involving 201 consecutive patients hospitalized from 2015 to 2020, diagnosed with cancer-associated SVT either before or during admission. The cohort predominantly featured intra-abdominal tumors (78.2%), with pancreatic cancer constituting 43.8%. SVT types were categorized, highlighting portal vein thrombosis as most common (58.6%). Anticoagulant therapy decisions were at clinicians’ discretion, with 41.3% of patients receiving treatment at SVT diagnosis.

Primary endpoints included 12-month overall survival, SVT recanalization rates, incidence of bleeding events, thrombosis recurrence, and mortality predictors. Data were statistically analyzed to evaluate associations between anticoagulation and clinical outcomes.

Key Findings

The overall survival rate at 12 months was 39.7%, underscoring the advanced disease burden in this group. Anticoagulant therapy was significantly associated with higher recanalization rates, indicating partial restoration of venous patency. However, this came at the cost of an increased incidence of bleeding complications, highlighting a critical risk-benefit consideration for clinicians.

Notably, anticoagulation did not improve overall survival nor reduce thrombosis recurrence rates. This suggests that despite enhancing vessel recanalization, anticoagulation’s impact on long-term cancer-associated SVT prognosis may be limited.

Multivariate analysis identified tumor thrombus (Odds Ratio [OR]: 2.44; 95% Confidence Interval [CI]: 1.32–4.52) and metastatic cancer status (OR: 3.07; CI: 1.63–5.8) as independent predictors of mortality. These findings align with the understanding that SVT in metastatic and tumor-infiltrated vessels is a marker of aggressive disease course and poorer prognosis.

Expert Commentary

This study addresses a critical evidence gap in managing cancer-associated SVT. Clinicians must weigh the benefits of anticoagulation in achieving recanalization against heightened bleeding risks, especially since survival benefits remain unconfirmed. The poor prognosis tied to tumor thrombus and metastatic disease further complicates therapeutic choices, often reflecting systemic disease severity rather than thrombosis per se.

Limitations include the retrospective design and treatment heterogeneity, which may confound outcome interpretation. Nevertheless, these real-world insights support individualized anticoagulation strategies, emphasizing careful patient selection and monitoring.

Conclusion

SVT is a frequent and serious complication in cancer patients, predominantly associated with abdominal malignancies like pancreatic cancer. Although anticoagulant therapy enhances recanalization rates, it does not confer survival benefits and increases bleeding risk. Tumor thrombus presence and metastatic status significantly predict mortality. Future prospective studies are needed to refine therapeutic algorithms and identify patient subgroups who might benefit most from anticoagulation.

References

Garcia-Villa A, Criado-Álvarez JJ, Carnevali M, Aramberri M, Font C, Díaz-Pedroche C. Anticoagulant therapy for cancer-associated splanchnic vein thrombosis: Outcomes during a one-year follow-up period. Thromb Res. 2025 Sep;253:109411. doi: 10.1016/j.thromres.2025.109411 IF: 3.4 Q2 B3. Epub 2025 Jul 27. PMID: 40738093 IF: 3.4 Q2 B3.