Iodine-125 seeds strand for treatment of tumor thrombus in inferior vena cava: an experimental study in a rabbit model

Development of a Novel Endovascular Brachytherapy Stent: A Proof-of-concept Study

BACKGROUND AND AIMS

Endovascular implantation of iodine-125 (¹²⁵I) seeds strand combined with stent is an effective method of treatment for portal vein tumor thrombosis. The aim of this study was to develop a novel endovascular brachytherapy stent (EVB-Stent) and to evaluate its feasibility of use.

METHODS

An EVB-Stent was implanted into the main portal vein (MPV) in a live porcine model via the percutaneous transhepatic route. Blood samples were collected and tested before and after operation, as well as before euthanasia. Single-photon emission computed tomography (SPECT) combined with CT (SPECT/CT) scan were performed directly after operation and CT scan was performed 2 months after implantation. After the CT scan was performed, all animals were euthanized and histologically examined.

RESULTS

The novel stent was successfully positioned in all six pigs. No deterioration of liver function was observed during the 2-month follow-up period. SPECT/CT revealed the uniform distribution of radiation around the seeds strand, and the hottest spot was near the center of the MPV. The patency of the stented MPV was confirmed using CT scans. The tissue-accumulated absorbed dose was 31,822.11 mGy at 10 mm transversely away from the midpoint of the ¹²⁵I seeds strand, with a half-life of 59.4 days. Pathological examination results showed no significant atrophy or inflammation of adjunct liver tissue, and no obvious intima thickening or thrombosis were detected in the stented MPV.

CONCLUSIONS

A liver porcine model was used to demonstrate that the transhepatic placement of a novel endovascular brachytherapy stent, EVB-Stent, is both technically feasible and safe.

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.

Intra-caval Percutaneous Radiofrequency Ablation for a Neuroendocrine Tumor (NET) Metastasis in Transplanted Liver

Less than 1% of patients with liver metastases from neuroendocrine tumors (NETs) are susceptible to liver transplantation. We report a case of a patient transplanted 13 years ago for NET metastases, with a lesion histologically proved for NET metastasis located at the cava vein anastomosis. He was treated with percutaneous radiofrequency ablation (RFA) after a first failed attempt of endovascular approach. The vascular heat sink, which RFA is susceptible to, was considered an advantage in this case, since it restricted the propagation of heat only to the tissue located in the very proximity of the RFA antenna, protecting the inferior vena cava vessel walls. This positive result may suggest an additional use of RFA in selected challenging cases.

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

Background:

Portal-vein stent combined with one iodine-125 (¹²⁵I) seed strand has become a new treatment for portal vein tumor thrombosis. However, dosimetric aspects of this irradiation stent have not been reported. Therefore, we aimed to undertake dosimetric analyses comparing portal-vein stents combined with different numbers of ¹²⁵I seed strands.

Methods:

A water cylinder was created by a treatment-planning system to simulate a portal-vein stent. The stent was combined with one, two, or three ¹²⁵I seed strands (Groups I, II, and III, respectively). At different prescribed doses (PDs), ¹²⁵I seeds of identical activities were loaded on Groups I–III. Conformation number (CN), external volume index, and homogeneity index were calculated. Linear regression analyses were used to evaluate the obtained data.

Results:

For identical ¹²⁵I seed activity, when the ¹²⁵I seed strand increased from one chain to two, D₉₀ (dose delivered to 90% of the target volume) increased by ≥184%; when it increased from two chains to three, D₉₀ increased by ≥63%. When the PD was 105 Gy and ¹²⁵I seed strands increased from one chain to two, V₁₀₀ (percentage of the target volume receiving ≥90% of the PD) increased by 158–249%; when it increased from two chains to three, V₁₀₀ increased by 7–175%. CN was correlated positively with ¹²⁵I seed activity (B = 0.479, P < 0.001) and number of ¹²⁵I seed strands (B = 0.201, P < 0.001) and was independent of PD (B = −0.002, P = 0.078).

Conclusions:

A portal-vein stent combined with a single ¹²⁵I seed strand could not meet dosimetry requirements. For a stent combined with two ¹²⁵I seed strands, when the PD was 105 Gy and seed activity was 0.7 mCi, the dose distribution could satisfy dosimetry requirements. For a stent combined with three ¹²⁵I seed strands, if the PD was 105, 125, or 145 Gy, the recommended seed activities were 0.5, 0.5, and 0.6 mCi, respectively.

Intraluminal Brachytherapy Using a Self-Expandable Stent Loaded With Linear Iodine-125 Seeds in a Patient With Reiterative Recurrence of Cancer-Associated Vein Obstruction: A Case Report With 3 Months of Follow-Up

Cancer-associated vein obstruction (CAVO) is a common complication in oncological patients, but the effective therapeutic options are scant. We report a patient with reiterative recurrent CAVO who was successfully treated with intraluminal brachytherapy using a self-expandable stent loaded with linear radioactive iodine-125 seeds (RIS) strand. During follow-up, her clinical symptoms were well improved. Three-month imaging follow-up revealed satisfactory patency of the iliofemoral vein, and the stents combined with RIS strands performed well. No serious complications associated with the implantation of stent and RIS strands were documented in any of the sessions. Intraluminal brachytherapy using a self-expandable stent loaded with linear RIS may be a safe and effective option for CAVO as long as it includes not only blood flow restoration but also brachytherapy administration for cancer.

Endovascular implantation of 125I seed combined with transcatheter arterial chemoembolization for unresectable hepatocellular carcinoma

AIM

The purpose of this study was to evaluate the efficacy and safety of the endovascular implantation of ¹²⁵I seed under ultrasound and x-ray guidance combined with transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) patients with portal vein tumor thrombosis (PVTT).

PATIENTS & METHODS

The study included 134 pathologically proven or clinically confirmed primary HCC patients with PVTT in our hospital from January 2013 to June 2015.

RESULTS & CONCLUSION

Compared with the TACE treatment alone, the combination therapy of ¹²⁵I seed implantation with TACE significantly prolonged the median survival time and improved the 6-, 12- and 18-month survival rates for HCC patients with PVTT. In addition, the type III PVTT and tumor size were independent predictors for poor prognosis of HCC patients with PVTT.

Endovascular brachytherapy combined with portal vein stenting and transarterial chemoembolization improves overall survival of hepatocellular carcinoma patients with main portal vein tumor thrombus

Hepatocellular carcinoma (HCC) patients with main portal vein tumor thrombus have a median survival time of only about 4 months. We therefore compared the safety and efficacy of endovascular brachytherapy (EVBT) and sequential three-dimensional conformal radiotherapy (3-DCRT). From a cohort of 176 patients, we treated 123 with EVBT using iodine-125 seed strands (group A) and the remaining 53 with sequential 3-DCRT (group B). Overall survival, progression free survival and stent patency characteristics were compared between the two groups. Our analysis demonstrated a median survival of 11.7 ± 1.2 months in group A versus 9.5 ± 1.8 months in group B (p = 0.002). The median progression free survival was 5.3 ± 0.7 months in groupA versus 4.4 ± 0.4 months in group B (p = 0.010). The median stent patency period was 10.3 ± 1.1 months in group A versus 8.7 ± 0.7 months in group B (p = 0.003). Therefore, as compared to sequential 3-DCRT, EVBT combined with portal vein stenting and TACE improved overall survival of HCC patients with main portal vein tumor thrombus.

Transarterial chemoembolisation (TACE) combined with endovascular implantation of an iodine-125 seed strand for the treatment of hepatocellular carcinoma with portal vein tumour thrombosis versus TACE alone: a two-arm, randomised clinical trial

PURPOSE

There was no standard treatment for hepatocellular carcinoma with portal vein tumour thrombosis (PVTT). This prospective, randomised, two-arm clinical trial aims to investigate the feasibility, safety and effectiveness of transarterial chemoembolisation (TACE) combined with the endovascular implantation of an iodine-125 seed strand for the treatment of hepatocellular carcinoma with portal vein tumour thrombosis versus conventional TACE.

PATIENTS AND METHODS

Eighty-five patients who met the eligibility requirements were randomly assigned to receive the treatment of TACE combined with the endovascular implantation of an iodine-125 seed strand (43 cases) or conventional TACE (42 cases). The end points were survival time, complications related to the procedure and adverse events.

RESULTS

No significant differences in baseline characteristics were observed between groups. The mean and median survival times were 221.7 ± 16.3 days [95 % confidence interval (CI) 189.8-253.6 days] and 210.0 ± 17.5 days (95 % CI 175.8-244.2 days) in group A and 155.1 ± 7.9 days (95 % CI 139.6-170.5 days) and 154.0 ± 11.2 days (95 % CI 133.2-176.0 days) in group B (P = 0.000). The 90-, 180- and 360-day cumulative survival rates were 97.6, 58.9 and 12.3 % in group A and 92.5, 30.7 and 0 % in group B (P = 0.000).

CONCLUSION

Transarterial chemoembolisation combined with the endovascular implantation of an iodine-125 seed strand is feasible, safe and effective in the treatment for hepatocellular carcinoma with PVTT.