A Novel Self-Expandable, Radioactive Airway Stent Loaded with 125I Seeds: A Feasibility and Safety Study in Healthy Beagle Dog

Advances in studies on tracheal stent design addressing the related complications

Tracheal stents can be used to quickly reconstruct the airway and relieve symptoms of dyspnea in patients with tracheal stenosis. However, existing tracheal stents lead to complications such as granulation tissue formation, difficulty in removal, persistent growth of malignant tumors, stent migration, and mucus plugging. In this article, we reviewed the main methods used to reduce complications associated with tracheal stent design. Drug-eluting stents can inhibit granulation tissue formation and prevent infection and local chemotherapy. The biodegradable stent can support the trachea for some time, maintain tracheal patency, and degrade gradually, which avoids removing or replacing the stent. Radioactive stents loaded with I125 have good potential for inhibiting the persistent growth of malignant tumors. Three-dimensional printing technology enables the manufacturing of patient-specific stents, which increases the degree of matching between the complex tracheal anatomy and the stent, thus providing a new solution for stent migration caused by structural mismatch. Minimizing the barrier of the stent to mucociliary clearance, providing an anti-fouling coating, and culturing respiratory epithelial cells on the surface of the stent are the main methods used to reduce mucus plugging. We also proposed future research directions for tracheal stents to guide the design and manufacture of ideal tracheal stents.

Treatment of recurrent tracheal adenoid cystic carcinoma with a covered airway stent loaded with Iodine-125 seeds: a 5-year follow-up case report

Background

The treatment of recurrent tracheal adenoid cystic carcinoma (TACC), a rare pulmonary malignant tumor, typically involves bronchoscopic interventional therapy for patients ineligible for surgery or external radiotherapy. This report describes an innovative treatment approach for TACC, initially managed with interventional bronchoscopy and subsequently with a Y-shaped airway stent loaded with 125I seeds, following recurrence after 2 years.

Case presentation

A 50-year-old man presented with intermittent coughing for 2 months and was admitted to the hospital after the discovery of TACC a month earlier. Preoperative bronchial artery embolization was performed to reduce the risk of bleeding, followed by bronchoscopic tumor resection in January 2017 using an electric loop at the base, complemented by argon plasma coagulation (APC) and cryotherapy. Although short-term outcomes were favorable, the long-term prognosis remained suboptimal. Due to tumor recurrence, airway tumor resection and implantation of the 125I seed stent were performed under bronchoscope guidance in early 2019. The stent was removed 5 months later. The patient tolerated the procedure well and exhibited no signs of relapse or progression during the 5-year postoperative follow-up period. This case illustrates the successful application of a stent loaded with 125I seeds for treating unresectable TACC.

Conclusions

Treatment of TACC with a covered airway stent loaded with 125I seeds may be a safe, effective, and scalable method.

Degrees of Inflammation in the Treatment of Subglottic Stenosis in a Rabbit Model: Histopathological Assessment of a Novel Bioabsorbable Ultra-high Ductility Magnesium Alloy Stent

OBJECTIVE

Utilizing a novel histopathological scoring system and subglottic stenosis (SGS) rabbit model, we aimed to compare degrees of inflammation and severity of narrowing in the subglottis between two minimally invasive therapeutic modalities: endoscopic balloon dilation (EBD) alone versus EBD with placement of a bioabsorbable ultra-high ductility magnesium (UHD-Mg) alloy stent.

METHODS

SGS was induced endoscopically via microsuspension laryngoscopy in 23 New Zealand white rabbits. The control group (n = 11) underwent EBD alone, the study arm (n = 12) underwent EBD with implantation of bioabsorbable UHD-Mg alloy stents. Rabbits were euthanized at 2-, 3-, and 6-weeks after SGS induction, coinciding with wound healing stages. Using Optical Coherence Tomography (OCT), cross-sectional areas of airways were compared to calculate the mean percentage of intraluminal area at sequential time points. A novel histopathological scoring system was used to analyze frozen sections of laryngotracheal complexes. The degree of inflammation was quantified by scoring changes in inflammatory cell infiltration, epithelial ulceration/metaplasia, subepithelial edema/fibrosis, and capillary number/dilation. Univariate analysis was utilized to analyze these markers.

RESULTS

We found rabbits implanted with the bioabsorbable UHD-Mg alloy stent had statistically significantly higher scores in categories of hyperplastic change (stents vs controls: 1.48 vs 0.46 p < 0.001), squamous metaplasia (22 vs 5 p < 0.001), and neutrophils/fibrin in lumen (31 vs 8, p < 0.001). Rabbits who received EBD alone had higher scores of subepithelial edema and fibrosis (2.70 vs 3.49, p < 0.0256). The stented rabbits demonstrated significantly increased mean percent stenosis by intraluminal mean area compared to controls at 2 weeks (88.56 vs 58.98, p = 0.032), however at all other time points there was no significant difference between intraluminal subglottic stenosis by mean percent stenosis area.

DISCUSSION

Rabbits with SGS treated with UHD-Mg alloy stents demonstrated histopathologic findings suggestive of lower levels of tracheal fibrosis. This could indicate a reduced tendency towards the development of stenosis when compared to EBD alone. There was not a difference in luminal size between stent and non-stented rabbits at the six-week end point. Histologically, however, overall the use of bioabsorbable UHD-Mg alloy stenting elicited a greater tissue response at the level of the superficial mucosa rather than fibrosis of the lamina propria seen in the stented rabbits. This suggests more favorable healing and less of a tendency towards fibrosis and stenosis even though there may not be a benefit from a luminal size standpoint during this early healing period. Compared to known complications of currently available non-bioabsorbable metal or silicone-based stents, this proof-of-concept investigation highlights the potential use of a novel biodegradable UHD-Mg stent as a therapeutic modality for pediatric SGS.

A Functional Stent Encapsulating Radionuclide in Temperature-Memory Spiral Tubes for Malignant Stenosis of Esophageal Cancer

Stent implantation is a commonly used palliative treatment for alleviating stenosis in advanced esophageal cancer. However, tissue proliferation induced by stent implantation and continuous tumor growth can easily lead to restenosis. Therefore, functional stents are required to relieve stenosis while inhibiting tissue proliferation and tumor growth, thereby extending the patency. Currently, no ideal functional stents are available. Here, iodine-125 (125 I) nuclides are encapsulated into a nickel-titanium alloy (NiTi) tube to develop a novel temperature-memory spiral radionuclide stent (TSRS). It has the characteristics of temperature-memory, no cold regions at the end of the stent, and a uniform spatial dose distribution. Cell-viability experiments reveal that the TSRS can reduce the proliferation of fibroblasts and tumor cells. TSRS implantation is feasible and safe, has no significant systemic radiotoxicity, and can inhibit in-stent and edge stenosis caused by stent-induced tissue proliferation in healthy rabbits. Moreover, TSRS can improve malignant stenosis and luminal patency resulting from continuous tumor growth in a VX2 esophageal cancer model. As a functional stent, the TSRS combines the excellent properties of NiTi with brachytherapy of the 125 I nuclide and will make significant contributions to the treatment of malignant esophageal stenosis.

Clinical outcomes of intraluminal Iodine-125 seed strand brachytherapy and percutaneous nephrostomy in patients with ureteral carcinoma

BACKGROUND

We aimed to evaluate the safety and efficacy of intraluminal iodine-125 seed strand brachytherapy and percutaneous nephrostomy in patients with ureteral carcinoma.

METHODS

From January 2014 to January 2023, 48 patients with ureteral cancer not suitable for surgical resection were enrolled. Iodine-125 seed strand was inserted in 26 patients under c-arm CT and fluoroscopic guidance (Group A), and 22 patients underwent percutaneous nephrostomy without seed strand (Group B). The clinical outcomes (technical success rate, tumor sizes, hydronephrosis Girignon grade, complications, objective response rate (ORR), disease control rate (DCR), and survival time) were evaluated and compared.

RESULTS

A total of 53 seed strands were successfully inserted and replaced in Group A, with a technical success rate of 100%. No procedure-related death or severe complications occurred in both group. Migration of seed strand or drainage tube was the most common complication. The Girignon grade of hydronephrosis was significantly improved 1, 3 and 6 months after procedure in both groups. DCR in Group A were 96.2%, 80.0%, and 70.0% at 1-, 3-, and 6-month follow up, respectively. At 1 and 6 months later, ORR in Group A were significantly higher than those in Group B (p < 0.05). The median overall survival were 30.0 months in Group A and 16.1 months in Group B, respectively (p = 0.04). The median progression-free survival were 11.1 months in Group A and 6.9 months in Group B, respectively (p = 0.09).

CONCLUSION

Intraluminal Iodine-125 seed strand brachytherapy and percutaneous nephrostomy is safe and effective in patients with ureteral carcinoma, with higher ORR and median overall survival than patients underwent percutaneous nephrostomy without seed strand.

Safety and efficacy of iodine-125 seed strand for intraluminal brachytherapy on ureteral carcinoma

OBJECTIVE

Our aim is to evaluate the safety and efficacy of iodine-125 seed strand for intraluminal brachytherapy on ureteral carcinoma.

METHODS

From November 2014 to November 2021, 22 patients with ureteral cancer not suitable for surgical resection were enrolled. Iodine-125 seed strand was inserted under c-arm CT and fluoroscopic guidance. The technical success rate, complications, disease control rate, and survival time were evaluated. Hydronephrosis Girignon grade and ureteral cancer sizes before and after treatment were compared.

RESULTS

A total of 46 seed strands were successfully inserted and replaced, with a technical success rate of 100% and median procedure time of 62 min. No procedure-related death, ureteral perforation, infection, or severe bleeding occurred. Minor complications were observed in eight (36.4%) patients, and migration of seed strand was the most common complication. Six months after seed strand brachytherapy, one complete response, three partial responses, and five stable diseases were evaluated, and the disease control rate was 64.3%. The Girignon grade of hydronephrosis was significantly improved 1 to 3 months after seed strand insertion. Disease control rates were 94.4, 62.5, and 64.3% at 1-, 3-, and 6-month follow-up. Twenty patients were successfully followed up, with a mean follow-up of 18.0 ± 14.5 months. The median overall survival and progress-free survival were 24.7 and 13.0 months, respectively.

CONCLUSION

Iodine-125 seed strand is safe and effective for intraluminal brachytherapy and can be used as an alternative to patients with ureteral carcinoma who are not suitable for surgical resection or systemic combined therapy.

CT-guided Radioactive 125I Seed Implantation for Abdominal Incision Metastases of Colorectal Cancer: Safety and Efficacy in 17 Patients

INTRODUCTION

To retrospectively evaluate the safety and efficacy of computed tomography (CT)-guided iodine-125 (¹²⁵I) seed implantation for patients with abdominal incision metastases from colorectal cancer.

MATERIALS AND METHODS

Data of patients with abdominal incision metastases of colorectal cancer from November 2010 to October 2020 were retrospectively reviewed. Each incisional metastasis was percutaneously treated with ¹²⁵I seed implantation under CT guidance. Follow-up contrast-enhanced CT was reviewed, and the outcomes were evaluated in terms of objective response rate, complications, and overall survival.

RESULTS

A total of 17 patients were enrolled in this study. The median follow-up was 18 months (range, 2.7-22.1 months). At 3, 6, 12, and 18 months after the treatment, objective response rate was 52.9%, 63.6%, 33.3%, and 0%, respectively. A small amount of local hematoma occurred in two patients and resolved spontaneously without any treatment. Two patients experienced a minor displacement of radioactive seeds with no related symptoms. Severe complications, such as massive bleeding and radiation injury, were not observed. No ≥ grade 3 adverse events were identified. By the end of follow-up, 14 patients died of multiple hematogenous metastases. The one-year overall survival rate was 41.6%, and the median overall survival was 8.6 months.

CONCLUSION

CT-guided ¹²⁵I seed implantation brachytherapy is safe and feasible for patients with abdominal incision metastases from colorectal cancer.

Establishing a novel model of malignant airway stenosis in rabbit

Background

Malignant central airway stenosis is a life-threatening condition. However, treatment of malignant airway stenosis remains challenging. There is currently a severe lack of an excellent animal model of malignant airway stenosis to facilitate treatment approaches. This is the first study to establish a rabbit model of malignant airway stenosis for bronchoscopic interventional studies.

Materials and methods

New Zealand White rabbits were used in this study, randomly divided into group A (18 rabbits) and group B (6 rabbits). A VX2 fragment suspension was injected into the submucosal layer of rabbits’ airway by bronchoscopy. Bronchoscopic examinations were performed once a week after VX2 tumor implantation to observe tumor growth and the degree of airway stenosis. Randomly, three rabbits were generally dissected after a weekly bronchoscopic examination in group A. The rabbits that reached grade III airway stenosis underwent stent implantation in group B.

Results

A total of 24 rabbits were successfully implanted with the VX2 fragment suspension in the airway without significant adverse events, and the success rate of the tumor growth was 100%. The degree of airway stenosis reaching grade III took 2 to 3 weeks after implantation of the VX2 tumor. The median survival time of rabbit models without stent implantation and rabbits with stent implantation was 32.5 and 32.0 days, respectively.

Conclusions

The implanting method is safe and effective for the establishment of a rabbit model of malignant airway stenosis. When the tumor grows to 2 to 3 weeks, the rabbit model is available for stent implantation. We recommend the models for more preclinical animal studies on bronchoscopic interventional treatments.

Malignant Central Airway Obstruction: What's New?

Malignant central airway obstruction (MCAO) is a debilitating and life-limiting complication that occurs in an unfortunately large number of individuals with advanced intrathoracic cancer. Although the management of MCAO is multimodal and interdisciplinary, the task of providing patients with prompt palliation falls increasingly on the shoulders of interventional pulmonologists. While a variety of tools and techniques are available for the management of malignant obstructive lesions, advancements and evolution in this therapeutic venue have been somewhat sluggish and limited when compared with other branches of interventional pulmonary medicine (e.g., the early diagnosis of peripheral lung nodules). Indeed, one pragmatic, albeit somewhat uncharitable, reading of this article's title might suggest a wry smile and shug of the shoulders as to imply that relatively little has changed in recent years. That said, the spectrum of interventions for MCAO continues to expand, even if at a less impressive clip. Herein, we present on MCAO and its endoscopic and nonendoscopic management-that which is old, that which is new, and that which is still on the horizon.

Animal study of a newly designed metal airway brachytherapy stent loaded with radioactive 125I seeds

AIM

To evaluate dynamic tissue changes after airway stenting (AS) with a newly designed metal brachytherapy stent (BS) loaded with radioactive ¹²⁵I seeds in normal rabbits.

METHODS

Forty-five normal New Zealand white rabbits were divided into 3 groups (group A: stent without seeds; group B: stent with 0.4 mCi active seeds; group C: stent with 0.8 mCi active seeds) and underwent AS under C-arm guidance. Then, five rabbits were killed from each group at 2, 4, and 8 weeks for further examination. Laboratory tests (including routine blood tests, liver function, kidney function, and electrolytes), gross observations, and tissue changes of Masson/hematoxylin-eosin staining, plus immunohistochemistry of α-SMA, NOX4, and TGF-β were performed at each time point.

RESULTS

All animals underwent AS successfully without procedure-related death, but one animal died at 6 weeks due to severe pulmonary infection in group C. Apart from a transient increase in white blood cells (P < 0.05) and a gradual increase in ROS levels (P < 0.05), other blood test items showed no significant changes (P > 0.05). The brachytherapy injury score increased with irradiation dose accumulation (P < 0.05), but tissue hyperplasia at the stent end in group C was less severe than that in groups A and B (P < 0.05). Airway lateral fibrosis was observed in all groups by histopathologic analysis; however, fibrosis in group C was more severe than that in groups A and B (P < 0.05).

CONCLUSION

The brachytherapy injury score increased with irradiation dose accumulation, while granulation tissue hyperplasia at the stent end was inhibited by ¹²⁵I brachytherapy within 8 weeks.

Extracranial 125I Seed Implantation Allows Non-invasive Stereotactic Radioablation of Hippocampal Adult Neurogenesis in Guinea Pigs

Adult hippocampal neurogenesis (AHN) is important for multiple cognitive functions. We sort to establish a minimal or non-invasive radiation approach to ablate AHN using guinea pigs as an animal model. ¹²⁵I seeds with different radiation dosages (1.0, 0.8, 0.6, 0.3 mCi) were implanted unilaterally between the scalp and skull above the temporal lobe for 30 and 60 days, with the radiation effect on proliferating cells, immature neurons, and mature neurons in the hippocampal formation determined by assessment of immunolabeled (+) cells for Ki67, doublecortin (DCX), and neuron-specific nuclear antigen (NeuN), as well as Nissl stain cells. Spatially, the ablation effect of radiation occurred across the entire rostrocaudal and largely the dorsoventral dimensions of the hippocampus, evidenced by a loss of DCX⁺ cells in the subgranular zone (SGZ) of dentate gyrus (DG) in the ipsilateral relative to contralateral hemispheres in reference to the ¹²⁵I seed implant. Quantitatively, Ki67⁺ and DCX⁺ cells at the SGZ in the dorsal hippocampus were reduced in all dosage groups at the two surviving time points, more significant in the ipsilateral than contralateral sides, relative to sham controls. NeuN⁺ neurons and Nissl-stained cells were reduced in the granule cell layer of DG and the stratum pyramidale of CA1 in the groups with 0.6-mCi radiation for 60 days and 1.0 mCi for 30 and 60 days. Minimal cranial trauma was observed in the groups with 0.3– 1.0-mCi radiation at 60 days. These results suggest that extracranial radiation with ¹²⁵I seed implantation can be used to deplete HAN in a radioactivity-, duration-, and space-controllable manner, with a “non-invasive” stereotactic ablation achievable by using ¹²⁵I seeds with relatively low radioactivity dosages.

Comparison of three kinds of self-expandable metallic stents induced granulation tissue hyperplasia in the rabbit trachea

To compare stent-induced granulation tissue hyperplasia of bare (SEMS), polyurethane-covered (PU-SEMS) and electrospun nanofibre-covered (EN-SEMS) self-expandable metallic stents in the rabbit trachea. Twenty-seven rabbits were randomly assigned to 3 groups that received SEMS, PU-SEMS or EN-SEMS. Computed tomography and sacrifice were performed as scheduled. Haematoxylin–eosin and Masson’s trichrome staining protocols were performed for pathological analysis. The data for tracheal ventilation area ratio, qualitative histological scoring, number of epithelial layers, and thicknesses of papillary projection and submucosa were documented and statistically analysed. All stents were successfully placed under the guidance of fluoroscopy without complications. Post-stenting 3 and 7 days, computed tomography revealed that the fully expandable EN-SEMS was similar to the SEMS and PU-SEMS. The mean stented tissue score in the SEMS group was higher than those of both the PU-SEMS and EN-SEMS groups at 3 days post-stenting. The pathological findings suggested that there was no papillary projection formation 3 days after stent placement. The thickness of papillary projection in the SEMS group was significantly higher than those of the PU-SEMS and EN-SEMS groups at 7 days post-stenting. After stenting 4 weeks, the tracheal ventilation area ratio of SEMS, PU-SEMS and EN-SEMS was 0.214 ± 0.021, 0.453 ± 0.028 and 0.619 ± 0.033, respectively. There were significant between-group differences. In conclusion, the stent-induced granulation tissue formation in EN-SEMS is less severe than that of PU-SEMS and SEMS. EN-SEMS has smaller radial force, and the tracheal ventilation ratio after stent placement better than that of PU-SEMS.

The Effects of Mycophenolate on the Formation of Granulation Tissue Post-operatively in Canine Tracheal Stent Patients (2014-2020)

Objectives: To determine if mycophenolate mofetil reduces the incidence and severity of granulation tissue in-growth in canine tracheal stent patients. Study design: Randomized clinical trial. Animals: 111 dogs from the hospital population. Methods: Client-owned dogs that received an endoluminal self-expanding tracheal stent for canine tracheal collapse between 2014 and 2020 were randomly assigned into one of two treatment groups. Control group medication protocol consisted of prednisone 0.5 mg/kg PO BID/SID/EOD × 30 days, hydrocodone 0.25 mg/kg PO TID × 30 days, and cefovecin 8 mg/kg SQ post-placement. Mycophenolate group medication protocol was identical to the control group medication protocol with the addition of mycophenolate mofetil 10 mg/kg PO BID × 30 days, SID for life. Recheck tracheoscopy was performed at 1, 3, and 6 months post-stent placement. Presence and severity of granulation tissue were determined by tracheoscopy and were recorded as a percentage of tracheal lumen obstruction by blinded evaluators (none present, <25%, >25-50%, and >50%). Results: At none of the three time points was there a statistically significant difference in grade between controls and those receiving mycophenolate (p = 0.467, p = 0.330, and p = 0.410). Conclusions and Clinical Significance: Our results suggest that mycophenolate can be safely given to these patients but do not support that its administration will reduce the incidence and severity of granulation tissue. Although a difference was observed in the severity of granulation tissue between the two groups, loss to follow-up may have influenced conclusions. A larger study would be warranted to further evaluate the effect of mycophenolate on the development of granulation tissue.

Radioactive and normal stent insertion for the treatment of malignant airway stenosis: A meta-analysis

PURPOSE

To demonstrate the advantage of radioactive stent (RS) for treating malignant airway stenosis (MAS) in reducing the stent restenosis rate and increasing overall survival (OS).

MATERIALS AND METHODS

Relevant studies in Pubmed, Embase, and Cochrane Library databases were identified. The rate of stent restenosis was the primary endpoint, whereas secondary endpoints were rates of stent-related complications, OS, and complete relief of dyspnea. This meta-analysis was conducted using RevMan v5.3.

RESULTS

Five total studies including 131 and 119 patients that underwent RS and normal stent (NS) insertion, respectively, were identified and included in this meta-analysis. Four studies were randomized controlled trials and one study was retrospective study. Pooled rates of complete relief of dyspnea, chest pain, hemoptysis, and fistula formation were similar between these two groups (p = 0.72, 0.77, 0.92, and 0.62, respectively). Pooled Δstenosis grade was comparable between these two groups (p = 0.72). RS insertion was linked to a significant lower pooled stent restenosis rate, increased OS, and higher 3-month survival rate relative to NS insertion (p< 0.00001, 0.0001, and 0.03, respectively). Pooled 6-months survival rates was higher in RS group without significant difference (p = 0.06). Pooled stent restenosis rate was significant higher in RS group based on each subgroup analysis. No evidence of publication bias for these endpoints was detected via funnel plot.

CONCLUSIONS

This meta-analysis revealed that RS insertion was sufficient to reduce rates of stent restenosis and to prolong patient OS relative to NS insertion when used to treat MAS.

Investigation of a novel brachytherapy ureteral stent: trial studies on normal beagle dogs

PURPOSE

To evaluate the safety and feasibility of a newly designed ¹²⁵I brachytherapy ureteral stent (BUS) in normal dogs.

METHODS

A BUS loaded with 10 ¹²⁵I seeds (Group A: 0.8 mCi, Group B: 0.4 mCi, Group C: 0 mCi) was designed and tested in 27 normal beagle dogs. Routine blood tests, gross observations, cumulative radiation doses, tissue reaction assessed by hematoxylin-eosin/Masson staining, mRNA analysis by RT-qPCR and protein expression of Caspase-3, Collagen I, PCNA, and α-SMA were performed at 2, 4 and 8 weeks.

RESULTS

The BUS was implanted successfully in all dogs (27/27) without surgery-related death. The ureter diameter and radiation injury score increased along with radiation accumulation (p < 0.05). Histopathologic analysis showed necrotic tissue and lateral fibrosis to different extents in the ureteral walls that gradually increased in all groups (p < 0.05); however, epithelial cell proliferation in groups A and B was lighter than that in the control group (p < 0.05).

CONCLUSION

Placement of the newly designed ¹²⁵I BUS was safe and feasible in dogs, and clinical studies are required to test its use in humans.

Brachytherapy for lung cancer

Brachytherapy (BT) is a minimally invasive anticancer radiotherapeutic modality where the tumor is directly irradiated via a radioactive source that is precisely implanted in or adjacent to the tumor. BT for lung cancer may be conducted in the form of endobronchial BT and radioactive seed implantation (RSI-BT), mainly for nonsmall cell lung cancer (NSCLC). For patients with early-stage lung cancer who are not suitable for surgery or external beam radiotherapy (EBRT), BT may be used as an alternative treatment, and curative results could be achieved in certain patients with cancer confined to the trachea lumen. For patients with locally advanced/metastatic lung cancer, BT could be selectively applied alone or as a boost to EBRT, which could improve the local tumor control and patient's survival. In addition, BT is also useful as a salvage treatment in select patients with locally recurrent/residual lung cancer that failed other treatments (e.g., surgery, chemotherapy, and EBRT). However, clinical outcomes are mainly obtained from retrospective studies. Prospective studies are limited and needed. In recent years, the introduction of modern image guidance, novel radioactive seeds, BT treatment planning systems (BT-TPS), after-loading technique, and three-dimensional printing template (3D-PT) assistance, among others, have potentially improved the clinical outcomes of BT. However, a comprehensive review of BT with newly published literature was lacking. This review is to discuss BT for NSCLC based on recent literature published in PubMed.

Oligorecurrence Non-small Cell Lung Cancer After Failure of First-Line Chemotherapy: Computed Tomography-Guided 125I Seed Implantation vs. Second-Line Chemotherapy

Purpose: To compare the efficacy and safety of computed tomography (CT)–guided ¹²⁵I seed implantation with second-line chemotherapy in treatment of oligorecurrence non–small cell lung cancer after failure of first-line chemotherapy.

Methods: Data of oligorecurrence non–small cell lung cancer patients after failure of first-line chemotherapy at two institutions were retrospectively reviewed from January 2013 to July 2018. A total of 53 patients who received the treatment of ¹²⁵I seed implantation or second-line chemotherapy were eligible for this study. In group A, 25 patients, 84 lesions, received CT-guided permanent ¹²⁵I seed implantation, whereas in group B, 28 patients, 96 lesions, received second-line chemotherapy. The outcomes were measured in terms of disease control rate, overall survival, quality of life, and complications.

Results: The median follow-up period was 13 months (range, 5–42 months). Disease control rate in group A was higher than that in group B (70.8 vs. 42.3%, P = 0.042) at 6 months after treatment. The median overall survival was 12.8 months (95% confidence interval, 10.5–15.1 months) in group A and 15.2 months (95% confidence interval, 12.2–18.2 months) in group B, with no significant difference (P = 0.847). Since the fourth month, the number of patients in group A with a non-decreasing Karnofsky Performance Scale score was more than that in group B (P < 0.05). The incidence of grade 3 or higher complications especially hematologic toxicity in group A was significantly lower than that in group B (P < 0.05).

Conclusion: Radioactive ¹²⁵I seed implantation is safe and feasible in selected non–small cell lung cancer patients with oligorecurrence after failure of first-line chemotherapy and seems to provide a better long-term quality of life in these patients compared with second-line chemotherapy.

Radiomics Facilitates Candidate Selection for Irradiation Stents Among Patients With Unresectable Pancreatic Cancer

Purpose: To develop a model to select appropriate candidates for irradiation stent placement among patients with unresectable pancreatic cancer with malignant biliary obstruction (UPC-MBO). Methods: This retrospective study included 106 patients treated with an irradiation stent for UPC-MBO. These patients were randomly divided into a training group (74 patients) and a validation group (32 patients). A clinical model for predicting restenosis-free survival (RFS) was developed with clinical predictors selected by univariate and multivariate analyses. After integrating the radiomics signature, a combined model was constructed to predict RFS. The predictive performance was evaluated with the concordance index (C-index) in both the training and validation groups. The median risk score of progression in the training group was used to divide patients into high- and low-risk subgroups. Results: Radiomics features were integrated with clinical predictors to develop a combined model. The predictive performance was better in the combined model (C-index, 0.791 and 0.779 in the training and validation groups, respectively) than in the clinical model (C-index, 0.673 and 0.667 in the training and validation groups, respectively). According to the median risk score of 1.264, the RFS was significantly different between the high- and low-risk groups (p < 0.001 for the training group, and p = 0.016 for the validation group). Conclusions: The radiomics-based model had good performance for RFS prediction in patients with UPC-MBO who received an irradiation stent. Patients with slow progression should consider undergoing irradiation stent placement for a longer RFS.

Application of Micro-Tech stents in malignant carinal stenosis

Malignant carinal stenosis is a disease process that is not always suitable for treatment with a Y-shaped stent. When one of the main bronchi is completely obstructed and cannot be recanalized, or its distal lung tissue has lost function, inserting a Y-shaped stent is infeasible. In this complex condition, a cone-shaped stent is selected to maintain the patency of the trachea and the other main bronchus. The efficacy of the bare cone-shaped Micro-Tech stent to treat malignant carinal stenosis was evaluated in the current study. The medical records of 47 patients with malignant carinal stenosis who underwent Micro-Tech stent placement between January 2004 and October 2017 in Beijing Tian Tan Hospital (Beijing, China) were analyzed retrospectively. A total of 47 bare Micro-Tech stents (28 Y-shaped and 19 cone-shaped) were successfully inserted in the patients. Following stent placement, immediate satisfactory results were achieved in all patients, especially an improvement of dyspnea (100%), cough (81.1%) and stridor (100%). The Karnofsky scores were significantly increased (P<0.001), and the American Thoracic Society Dyspnea Index values were significantly decreased (P<0.001). Following a median of 88 days, initial bronchoscopic interventions were performed for tumor overgrowth (84.6%), stent fracture (7.7%) and granulation tissue (7.7%). Restenting was performed in two patients due to tumor progression (n=1) and stent fracture (n=1). Removal of a Y-shaped stent was attempted in one patient, but failed, as the stent had become partly embedded in the airway mucosa. In conclusion, cone-shaped Micro-Tech stent placement maintained tracheal-unilateral main bronchus patency and benefitted patients with malignant carinal stenosis in whom Y-shaped stents were not suitable for insertion.

Investigation of Migration-Preventing Tracheal Stent with High Dose of 5-Fluorouracil or Paclitaxel for Local Drug Delivery

Stent migration is one of the common reasons for the failure of tracheal stent. An antitumor drug/tracheal stent combination can promptly relieve dyspnea caused by tracheal stenosis and locally treat malignant occupying lesion or tumor. To prevent stent migration for more effective treatment, we prepared a migration-preventing nitinol tracheal stent (TS) with a high dose of 5-fluorouracil or paclitaxel (5-FU/TS or PTX/TS) by stent surface coating with a bilayered film, which is composed of a drug-loaded layer containing Carbopol 974P as mucoadhesive matrix and a blank Carbopol 974P layer. The resulting stent had a similar mechanical performance with the nitinol tracheal stent itself. The bilayered film containing 30% PTX (PTX30) could keep adhesion to porcine mucosa for 221.7 ± 11.4 min in PBS at a stirring speed of 150 rpm, and the corresponding PTX30/TS was difficult to be moved in the porcine tracheal lumen with a pulling force less than 0.7 N, indicating its good migration-preventing ability. The migration-preventing ability of the 5-FU/TS or PTX/TS was related to the compositions of bilayered films. The 5-FU release from the 5-FU/TS was dominated by a relaxation mechanism, while the PTX release was mainly controlled by a diffusion mechanism. Moreover, the 5-FU permeation from the 5-FU loaded film through the porcine tracheal mucosa was determined by the 5-FU dissolution, and PTX permeation was limited by the trans-mucosa process. After the deployment of PTX30/TS, inflammatory responses were observed in the rabbit tracheas and gradually alleviated during the follow-up period.

A Novel Tracheobronchial Stent Loaded with 125I Seeds in Patients with Malignant Airway Obstruction Compared to a Conventional Stent: A Prospective Randomized Controlled Study

Background

To evaluate the safety and efficacy of a novel radioactive bare metal stent (RBMS) compared with a conventional bare metal stent (CBMS) in patients with inoperable malignant airway obstruction.

Methods

This prospective study was approved by the Institutional Ethics Committee, and informed consent was obtained from each participant. Patients with malignant airway obstruction who had dyspnea were randomly assigned to receive RBMS or CBMS placement. The primary endpoint was stenosis grade, while the secondary endpoints were technical success, overall survival, and complications. A p value of <0·05 was considered statistically significant.

Results

Between September 2013 and July 2015, 66 patients with inoperable malignant airway obstruction received stent placement fluoroscopically (33 in either group). The median follow-up time was 154 days (range, 15–335 days). The baseline stenosis was immediately relieved in both groups after stent placement, and the stenosis grades in the RBMS group were significantly lower than that in the CBMS group since the second month (p < 0·05). The technical success rates of stent placement were 100% in both groups. The median survival in the RBMS group was significantly longer than that in the CBMS group (170 days vs. 123 days, p < 0·05). There was no significant difference in the incidence of complications between the two groups (p < 0·05).

Conclusions

The placement of RBMS in patients with inoperable malignant airway obstruction is feasible and safe, and it significantly reduces restenosis and improves overall survival compared with the placement of CBMS.

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The baseline stenosis was immediately relieved in both groups after stent placement.

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The stenosis grades in the RBMS group were significantly lower than that in the CBMS group since the second month.

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The technical success rates of stent placement were 100% in both groups.

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The median survival in the RBMS group was significantly longer than that in the CBMS group.

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There was no significant difference of the incidence of complications between the two groups.

Malignant airway obstruction (MAO) is a serious situation of 20-30% cases of lung cancer, resulting in dyspnea, decreased functional status, and asphyxiation risk. Conventional stent placement provides immediate palliation of dyspnea. However, stent restenosis occurs during the follow up. A novel radioactive bare metal stent (RBMS) loaded with ¹²⁵I seed was developed for preventing such restenosis. Our study showed that placement of RBMS in patients with inoperable malignant airway obstruction is feasible and safe, and it significantly reduces the restenosis and improves overall survival compared with placement of conventional stent.

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.