¹²⁵Iodine Seeds In Combination With Segmented Fully Covered Stents In The Treatment Of Esophageal Cancer

Background: Esophageal cancer is the seventh most common cancer and the sixth leading cause of cancer-related mortality worldwide.In China,over 95% of patients with esophageal cancer have esophageal squamous cell carcinoma（ESCC）,and most of them are diagnosed with an advanced stage,so not eligible for surgery.Dysphagia is the major symptom of patients with unresectable esophageal cancer,and these patients should be considered for palliative treatment.Placement of a self-expandable metallic stent（SEMS）and intraluminal brachytherapy are wellestablished procedures for the palliative treatment of malignant dysphagia.In recent years,brachytherapy via radioactive iodine-125(¹²⁵I)seeds,a kind of continuous low-dose-rate irradiation,has been applied to the treatment of various unresectable or locally recurrent cancers.A series of studies reported that the combination therapy of ¹²⁵Iseed brachytherapy and partially covered SEMS placement shows good tumor control and survival benefits in patients with advanced esophageal cancer.In the past few years,various fully covered SEMSs have been designed and used in patients with advanced esophageal cancer,especially if patients have a longer life expectancy,and they are receiving additional palliative therapy and require stent removal.Theoretically,for patients with longer life expectancy,¹²⁵I seeds in combination with a fully covered stent would be more suitable than those with a partially covered stent.Besides,although many studies focused on the efficacy of the stent loaded with ¹²⁵Iseeds,the anti-cancer mechanisms of ¹²⁵Iseed radiation in ESCC have yet not been studied.In this study,firstly,we systematically investigated the effects and anti-cancer mechanisms of ¹²⁵I seed radiation in ESCC cells in vitro and in vivo.Next,we designed a novel fully covered irradiation stent through combining ¹²⁵I seeds and segmented fully covered SEMS,and investigated the feasibility,safety,and preliminary efficacy of this irradiation stent through the clinical trial.Objective: To investigate the effects and mechanisms of ¹²⁵I seed radiation on human ESCC cells（Eca-109 and KYSE-150）.Methods: Cells were exposed to the cumulative radiation dose of 0,2,4,6,and 8 Gy in the in vitro irradiation model.In certain experiments,the cells were treated with si RNA,N-Acetyl-Lcysteine（NAC）,or cycloheximide.Colony formation and trypan blue assays were used to assess cell proliferation and viability.Flow cytometry was used to assess cell cycle,apoptosis,reactive oxygen species（ROS）,and intracellular Ca²⁺ levels.Western blot and immunofluorescence were used to analyze DNA damage,caspase activation,autophagy,and endoplasmic reticulum（ER）stress.Changes of morphology and ultrastructure were investigated by light and transmission electron microscopy.In animal experiments,mice bearing Eca-109 and KYSE-150 ESCC xenograft were treated with ¹²⁵I seed implantation（0.8 m Ci）.Changes in tumor volume and weight were recorded.Histology assays,including H&E staining,ROS fluorescence staining,TUNEL,and immunohistochemistry,were performed.Results: ¹²⁵I seed radiation significantly inhibited cell proliferation,and induced DNA damage and G2/M cell cycle arrest in both cell lines.¹²⁵I seed radiation induced cell death through both apoptosis and paraptosis.After irradiation,Eca-109 cells were primarily killed by inducing caspase-dependent apoptosis,with a peak value at 6 Gy.KYSE-150 cells were eliminated by inducing both apoptosis and paraptosis,which is characterized by extensive cytoplasmic vacuolation.¹²⁵I seed radiation induced autophagic flux in both cell lines,and autophagy inhibition by si ATG5 enhanced radiosensitivity.Moreover,¹²⁵I seed radiation induced intracellular Ca²⁺ overload and ER stress in both cell lines.Furthermore,in both cell lines,¹²⁵I seed radiation induced ROS overproduction,and ROS scavenger,NAC,significantly attenuated the effect of ¹²⁵I seed radiation on ER stress,autophagy,apoptosis,and paraptotic vacuoles.Animal experiments showed that ¹²⁵I seeds radiation induced ROS generation,triggered cell apoptosis and potential paraptosis,and inhibited cell proliferation and tumor growth.Conclusions: In ESCC cells,¹²⁵I seed radiation induces cell death through both apoptosis and paraptosis,following induction of DNA damage,G2/M cell cycle arrest,intracellular Ca²⁺ overload,and ER stress.Meanwhile,it triggers protective autophagy.¹²⁵I seed radiationinduced apoptosis,paraptosis,and autophagy are mediated considerably by ROS.Objective: To assess the feasibility,safety,and preliminary efficacy of ¹²⁵I seeds in combination with segmented fully covered stents in patients with dysphagia caused by esophageal cancer.Methods: Through reasonably combining ¹²⁵I seeds and segmented fully covered SEMS,a novel fully covered irradiation stent was designed and used in the clinic.Between June 2017 and January 2019,consecutive patients with dysphagia caused by esophageal cancer were recruited for treatment with this novel irradiation stent at a single hospital.Data on technical success,clinical success,overall survival,stent patency,tissue/tumor growth,stent migration,and adverse events（CTCAE v4.0）were collected and analyzed.Results: A total of 39 patients（31 [79.5%] men,mean age of 71.3±7.4 years）received treatment with this irradiation stent.The technical success rate was 97.4%（38/39）,and the clinical success rate was 100.0%（39/39）.Dysphagia scores decreased significantly within the first week（P<0.001）,and remained at a relatively low level thereafter.The median overall survival was 201 days（95% CI 173-228）,and the 3-and 6-month cumulative survival rates were 87.2% and 56.4%.The median stent patency period was 175 days（95% CI 128-222）.Tissue/tumor growth was observed in 5（12.8%）patients.Stent migration was observed in 4 patients（10.3%）,and all migrated stents were removed successfully.The common adverse events were chest pain（59.0%）,hemorrhage（28.2%）,and nausea（20.5%）.A total of 8 serious events（grade ≥3）occurred in 8（20.5%）patients.Conclusions: The combination therapy of ¹²⁵Iseeds and placement of a segmented fully covered stent is safe and effective for esophageal cancer.It may prolong the overall survival and stent patency period.Objective: To compare differences in efficacy between ¹²⁵I seeds in combination with a fully covered stent and those with a partially covered stent in patients with esophageal cancer,and assess prognostic factors.Methods: Data of 146 patients who underwent fully covered irradiation stent（FCIS;n=77）or partially covered irradiation stent（PCIS;n=69）placement for esophageal cancer from January 2012 to January 2019 were retrospectively analyzed.Outcomes were measured in terms of technical success,clinical success,overall survival,stent patency,recurrent dysphagia,and adverse events（CTCAE v4.0）.Overall survival and stent patency were evaluated using the logrank test and the Cox proportional hazards model.Recurrent dysphagia,subdivided into tissue/tumor growth and stent migration,was analyzed by both Cox proportional hazards regression on the cause-specific hazard ratio（CSHR）and Fine-Gray regression on subdistributional hazard ratio（SHR）.Results: The technical success rate was 97.4%（75/77）in the FCIS group and 98.6%（68/69）in the PCIS group（P>0.999）.The clinical success rate was 100.0% in both groups.The median overall survivals were comparable between the FCIS and PCIS groups（164 days vs.152 days;P=0.382）.A dysphagia score of 4（HR 1.624,95% CI 1.114-2.369,P=0.012）and metastasis（HR 5.752,95% CI 3.538-9.351,P<0.001）were independent risk factors for survival.A tendency towards a longer stent patency period was seen in the FCIS group（143 days vs.113 days;P=0.057）.There was no statistically significant difference in the recurrent dysphagia rate between the FCIS and PCIS groups（24.7% vs.36.2%;SHR 0.676,95% CI 0.371-1.233,P=0.202）,but lower cumulative hazard was found in the FCIS group（CSHR 0.529,95% CI 0.286-0.977,P=0.042）.Compared with PCISs,FCISs were associated with a decrease in tissue/tumor growth rate（14.3% vs.29.0%;CSHR 0.387,95% CI 0.185-0.810,P=0.012;SHR 0.446,95% CI 0.215-0.927,P=0.031）.In the multivariate analysis,stent types（FCIS vs.PCIS;CSHR 0.377,95% CI 0.179-0.794,P=0.010;SHR 0.443,95% CI 0.212-0.925,P=0.030）and stent diameter（20 mm vs.16 mm;CSHR 3.920,95% CI 0.851¹8.063,P=0.080;SHR 4.479,95% CI 1.028¹9.515,P=0.046）were independent factors for tissue/tumor growth.Stent migration rates were statistically comparable between the FCIS and PCIS groups（13.0% vs.7.2%;CSHR 1.674,95% CI 0.0.572-4.897,P=0.347;SHR 1.852,95% CI 0.636-5.398,P=0.259）.Chest pain was less common in the FCIS group than that in the PCIS group（54.5% vs.71.0%;P=0.040）.No significant differences were observed in the rates of other adverse events（P>0.05）.Conclusions: For patients with dysphagia caused by esophageal cancer,FCIS can provide survival benefits and safety comparable to those of a PCIS.Compared with the PCIS,FCIS is more successful in preventing tissue/tumor growth,and it could prolong the stent patency period.