Stenting of the Portal Vein Combined with Different Numbers of Iodine-125 Seed Strands: Dosimetric Analyses

Low-activity 125I implantation into VX2 tumor rabbits and quantitative evaluation of the precise therapeutic effect

There is still controversy about quantitatively evaluating the therapeutic effect of radioactive low-activity iodine-125 seeds (¹²⁵I seeds). In the present study, a paired VX₂ tumor model in a rabbit hind leg muscle was established, which is virus-induced anaplastic squamous cell carcinoma characterized by hypervascularity, rapid growth and easy propagation in the skeletal muscle. ¹²⁵I seeds with 0.4 and 0.7 mCi activity were implanted into the left and right legs, respectively, using a radiation treatment planning system under positron emission tomography (PET)/computed tomography (CT) guidance. PET/CT scans and hematoxylin and eosin staining were observed at 72 h and 2 and 4 weeks after implantation to assess the therapeutic effect. The results showed that the average tumor length and standard uptake value (SUV) decreased over time, and both ¹²⁵I seed groups achieved therapeutic effects at 4 weeks post-implantation. Quantitative evaluation of tumor inhibition rate, SUV variation and tumor marker ratio (Bcl-2/Bax) suggested that 0.7 mCi ¹²⁵I seeds were more suitable than 0.4 mCi seeds in a clinical setting.

Radioactive Seed Strand Efficacy in Superior Vena Cava Stenting Due to Non-small-cell Lung Cancer Obstruction

PURPOSE

This study aims to determine the clinical effectiveness of a stent with radioactive seed strand (RSS) inserted in patients with superior vena cava (SVC) obstruction (SVCO) secondary to non-small-cell lung cancer (NSCLC).

METHODS

Between January 2013 and December 2019, 63 patients with SVCO related to NSCLC received stent implantation with (n = 30) or without (n = 33) RSS insertion at our center. The clinical efficacy, stent patency duration, and overall survival (OS) were compared between these two groups.

RESULTS

Both groups achieved 100% clinical and technical success rates. There were no obstacles associated with the procedure performed for the patients. Two patients in the RSS group and 7 patients in the stent-alone group experienced stent re-stenosis. The rate of re-stenosis between the two groups was not significantly different (P = .099). Patients in the RSS group had significantly longer median patency than those in the stent-alone group (381 vs 309 days, P = .045). All patients died because of the development of tumors during the follow-up. Patients in the RSS group had a significantly longer median OS than those in the stent-alone group (229 vs 178 days, P = .026). During the follow-up, no patient in the RSS group suffered RSS migration or brachytherapy-related complications.

CONCLUSION

For patients with SVCO secondary to NSCLC, a stent with RSS insertion is efficacious and safe, and it may improve stent patency and OS.

Portal Vein Irradiation Stent Plus Chemoembolization versus External Radiotherapy Plus Chemoembolization in Hepatocellular Carcinoma with Portal Vein Tumour Thrombus: A Retrospective Study

PURPOSE

To compare the clinical outcomes of portal vein irradiation stent implantation (PVIS) plus transcatheter arterial chemoembolization (TACE) and radiotherapy (RT) plus TACE in hepatocellular carcinoma (HCC) with portal vein tumour thrombus (PVTT).

METHODS

Data from 79 patients with HCC complicated by PVTT treated with PVIS implantation plus TACE (n = 53) or treated with RT plus TACE (n = 26) were retrospectively analysed. The primary outcome measure was overall survival, and the secondary outcome was the stent patency period. HCC response and complications were evaluated.

RESULTS

At a median follow-up of 14.3 (range, 1.2 ~ 60) months, the median OS was 13.1 (95% CI: 9.8 ~ 16.4) months in the PVIS plus TACE group compared to 8.0 (95% CI: 6.1 ~ 9.9) months in the RT plus TACE group (p = 0.021). Stent occlusion was observed in 11 patients with a median patency time of 8.5 (range, 2 ~ 22) months. Multivariate Cox regression analysis demonstrated that Vp4 PVTT (HR: 5.22; 95% CI: 1.74-15.74) and poor response to therapy (HR: 4.89; 95% CI: 2.66-8.99) were independent risk factors for OS, whereas PVIS plus TACE treatment (HR: 0.32; 95% CI: 0.18-0.56) was related to better prognosis. None of the patients in the two groups had grade 3-4 complications.

CONCLUSION

In conclusion, this retrospective study shows that PVIS plus TACE provides a significantly better survival outcome than RT plus TACE for HCC patients with PVTT.

Endovascular Treatment of Cancer-Associated Venous Obstruction: Comparison of Efficacy Between Stent Alone and Stent Combined With Linear Radioactive Seeds Strand

OBJECTIVES

To investigate the safety and efficacy of a stent combined with a linear strand of ¹²⁵I seeds to treat malignant cancer-associated venous obstruction.

METHODS

We retrospectively analyzed the data of 57 patients with malignant cancer-associated venous obstruction. Nineteen patients underwent the placement of a stent combined with a linear strand of ¹²⁵I seeds (group A), and 38 patients underwent the placement of a bare stent (group B). The following parameters were compared between the 2 groups of patients: symptom relief rate, duration of venous patency, survival time, quality of life, and adverse events.

RESULTS

A total of 34 stents and 527 seeds were implanted in group A, while a total of 57 stents were implanted in group B. The surgery success rate was 96.5%, and no serious complication related to the surgery was reported. Symptoms of venous obstruction improved significantly after surgery. The score of group A decreased from 14.74 ± 0.562 points before surgery to 2.79 ± 1.357 points after surgery(P < .001), and the score of group B decreased from 13.79 ± 1.398 points before surgery to 5.55 ± 3.674 points after surgery (P < .001). The patency rate of group A was significantly higher than that of group B at 1 to 6 months after surgery (100%, 84.2%, 68.4%, 63.2%, 36.8%, 21.1% vs 68.4%, 23.7%, 18.4%, 7.9%, 5.3%, 2.6%, respectively; P < .05). Before treatment, there was no statistically significant difference in the Karnofsky Performance Status (KPS) score between the groups (P = .791). After 1 to 6 months of treatment, the KPS score was significantly higher in group A than in group B (P = .013). The median patency duration in groups A and B was 125 days (95% CI: 80.018-169.982) and 35 days (95% CI: 20.501-49.499), respectively (P < .001). The median survival time of group A was 155 days (95% CI: 110.406-199.594), and that of group B was 98 days (95% CI: 55.712-140.288; P = .325). Multivariate analysis showed that the implantation of a stent combined with a linear strand of ¹²⁵I seeds and the KPS score (≥80 points) were independent factors of long-term patency after stent placement.

CONCLUSIONS

The placement of a stent combined with a linear strand of ¹²⁵I seeds is a safe and effective treatment for venous obstruction caused by malignant tumors. This treatment provides prolonged patency compared with the placement of bare stent, and while it does not significantly improve the survival time of patients, it can improve their quality of life.

Dose perturbation and inhomogeneity of multi-arrays of 125I seed-loaded stent for treatment of portal vein tumor thrombosis

PURPOSE

To investigate the dosimetry of ¹²⁵I seed-loaded stent system currently used for an adjuvant treatment of portal vein tumor thrombosis (PVTT).

METHODS

The stent system consisted of an inner metallic stent and outer seed-loaded capsules. Four arrays of ¹²⁵I seeds were attached longitudinally to the outer surface of the stent at 90° separation. 145 Gy was prescribed at 5 mm from the axes of seed-arrays. For the geometries of the 4-array, and potential 6- and 8-array configurations, treatment planning system (TPS) and Monte Carlo (MC) calculations were performed to evaluate 3D dose distributions and dosimetric impact of the metallic stent.

RESULTS

The MC simulations indicated the metallic stent reduced a dose to the prescription points by over 10%, compared to the water-based TPS results. The total activity calculated by the water-based TPS to deliver the prescription dose should compensate for this amount of reduction. The MC- and TPS-calculated doses normalized to the prescription points for the current configuration were in agreements within 4.3% on a cylindrical surface along 5 mm from the axes of seed-arrays. The longitudinal underdosage worsened as approaching the edge of arrays, and ranged from 2.8% to 25.5%. The angular underdosage between neighboring arrays was 2.1%-8.9%.

CONCLUSIONS

With this compensation and a special care of near-edge underdosage, the current 4-array system can provide adequate dose coverage for treatment of PVTT. Further dosimetric homogeneity can be achieved using 6-or 8-array configurations.