Stents loaded with radioactive iodine attempt to kill two birds with one stone

Gao-Jun Teng

Gao-Jun Teng, Department of Radiology, Zhong-Da Hospital, Southeast University, Nanjing, China, presented on a novel stent that is loaded with 125 iodine seeds in malignancies at the “CIRSE meets China” session held at the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) meeting in Lisbon, Portugal where he was made a Distinguished Fellow. Teng traced the development of this device from the bench to the bedside.


“The use of iodine-125 (125I) seeds has been widespread for prostate cancer, but it has been a challenge to see if 125I seeds can be implanted in malignancies of a luminal organ such as oesophageal cancer, biliary tract obstruction caused by malignancies, and portal vein tumour thrombosis. A stent that is radioactive is expected to show a ‘combined effect’ on relieving the obstruction caused by tumour burden and treating the tumour directly,” he explained.

Teng’s team developed the novel stent system loaded with 125I seeds in 2005. The technical feasibility and safety of this new stent have been demonstrated in a healthy rabbit model. Both single centre and multicentre randomised controlled clinical trials were conducted, and they both demonstrated that dysphagia grades and the overall survival were significantly improved in the group of patients who received the irradiating stent when compared with those who received conventional stents.

Teng and colleagues then worked to modify the irradiating stent for the biliary tract from the one designed for the oesophagus because the biliary tract needs a much smaller access of 9F as compared with the 24F access of the oesophagus.

In order to evaluate the safety and effectiveness of this radioactive stent, a randomised controlled study was undertaken with patients either assigned to receive a biliary irradiating stent or a conventional biliary stent for malignant biliary tract obstruction caused by both primary and metastatic adenocarcinomas.

“The results of our trial showed that both the median and mean overall survival in the 125I stent group were longer compared with those in the control group. Recently, two other modified irradiating stent systems have been created to treat portal vein tumour thrombosis and malignant tracheal obstruction, and both have shown very promising preliminary results,” he concluded.

When profiled by Interventional News in 2014, Teng emphasised the importance of improving treatment options for dysphagia as a result of oesophageal cancer. “Oesophageal carcinoma in China is the fourth leading cause of death by cancer, which contributes to 48.9% of new cases worldwide. Whilst it is ranked as the sixth most common cause of mortality in the world, most patients with oesophageal squamous-cell carcinoma are usually identified at the advanced stages of the disease, where only 15–20% of patients have a chance of successful surgical resection. When the cancer is unresectable, dysphagia is the main symptom. Unfortunately, many patients with advanced stage oesophageal cancer are only able to undergo palliative treatments to relieve dysphagia. Stent placement provides a rapid and effective palliation, but recurrence in the long-term is common. Brachytherapy takes longer to relieve the symptoms of dysphagia but provides longer patency and fewer complications compared with stent placement.”

He further added that a novel oesophageal stent loaded with 125I seeds was developed by his team of interventional radiologists and engineers in Nanjing Micro-Tech to combine the advantages of the immediate relief of oesophageal dysphagia with stents with the longer-term benefits achieved through brachytherapy.

Teng noted that the results from a single-centre randomised controlled clinical trial with 27 patients in the radiation stent group vs. 26 patients in the control group showed a remarkable difference in mean survival (8.3 months for the 125I stents and 3.5 months for the conventional stents (Radiology 2008).

The investigators then set out to confirm the outcomes of this novel stent in a multicentre, randomised phase III trial. From 1 November 2009–1 July 2012, 170 patients from 16 hospitals in China were entered into the trial. Ten patients refused to participate. “We randomly assigned 160 patients to either receive the 125I stent or the control stent. The results showed a significant difference in median survival, and a more sustained relief from dysphagia in the 125I stent group, especially in those patients who survived for long periods. No increased complications related to radiation therapy occurred. The major results of this trial were published in Lancet Oncology 2014,” Teng concluded.

Russell E White, Bomet, Kenya, author of an accompanying editorial, commented that the researchers have “essentially killed two birds with one stone by combining the rapid, effective relief of dysphagia through endoluminal stent placement with the longer-term benefits of irradiation/brachytherapy.”