Evaluation Of The Efficacy Of CT-Guided ¹²⁵I Radioactive Seed Implantation In The Treatment Of Recurrent Mediastinal Lymph Node Metastases

Background:¹²⁵I seed implantation is widely used in the treatment of solid tumors in various parts of the body and can better the progression of local tumors,however,there are very few studies on whether ¹²⁵I can control and treat recurrent mediastinal lymph node metastases（MLNMs）,which is a relatively low level of evidence-based medicine.Objective:To evaluate the efficacy and safety of computed tomography（CT）-guided ¹²⁵I seed implantation for recurrent mediastinal lymph node metastases.Methods:The clinical data of patients with recurrent MLNM treated with CT-guided ¹²⁵I seed implantation at the Second Hospital of Shandong University from December 2015 to December 2021 were retrospectively analyzed.Patients underwent enhanced CT scan one week before surgery to locate the tumor area,and the individualized plan design and tumor target area were outlined by the computerized three-dimensional treatment planning system（TPS）.The dose of the target area was 110-160 Gy,and the activity of the particles was 0.5-0.7 mCi.CT-guided implantation of radioactive particles was performed one week after the operation,and the target area dose was verified.One month,three months,six months and every six months thereafter,enhanced CT examinations were performed to assess tumor response and follow-up was performed until June 2022.The objective remission rate and disease control rate were assessed using the solid tumor efficacy evaluation criteria version 1.1（RECIST version 1.1）,while survival,symptom remission and Karnofsky’s functional status score（KPS）were observed,and postoperative complications and adverse effects were recorded.Statistical methods used were Kaplan-Meier method with Chi-square test,Paired t-test,while one-way analysis of relevant factors was performed,and significant variables were screened for inclusion in a multifactorial Cox regression analysis to assess the effect on survival,with P<0.05 indicating statistically significant differences.Results:1.1.A total of 59 patients with MLNMs treated with CT-guided ¹²⁵I seed implantation at the Second Hospital of Shandong University from December 2015 to December 2021,were strictly screened according to the inclusion and exclusion criteria,and finally 41 patients were included in this study,and a total of 45 ¹²⁵I seed implantation procedures were performed,including 4 patients who underwent secondary supplemental procedures,and all procedures were successfully completed with the implantation of The median number of particles implanted was 40（range 16-85）.2.The median follow-up time was 38 months（6-78 months）until June 2022.The objective remission rates at 1,3,and 6 months postoperatively were 80.5%,87.8%,and 58.5%,respectively,with the best efficacy at 3 months postoperatively,while the lesion volume was reduced to 17.67±20.87 cm3（p=0.004）,11.32± 13.84 cm3（p=0.004）,and 10.33±13.62（p=0.004）cm3 at 1,3,and 6 months postoperatively,respectively,compared with the preoperative volume 31.80±35.86 cm3.3.By the follow-up deadline,a total of 29 patients died,and the median survival time for this cohort was 18.03 months（95%Cl:13.06-22.99 months）,including 14 deaths due to poor general condition and 15 deaths due to the development of distant metastases at the end stage of the tumor,but the lesions at the particle implantation were well controlled locally.4.Compared with the preoperative period,83.0%（20/24）of patients with cough,76.9%（10/13）of patients with shortness of breath,75.0%（6/8）of patients with pain,50.0%（1/2）of patients with hoarseness,and 100%of patients with symptoms related to superior vena cava syndrome（50.0%,1/2）had improved at one month after surgery,and 100%of patients with symptoms related to superior vena cava syndrome had been relieved at one year of follow-up.No restenosis of the superior vena cava occurred during the follow-up period.The preoperative KPS scores were 70（60-90）and the postoperative KPS scores were 70（60-90）,80（60-90）,and 70（60-90）at 1,3,and 6 months postoperatively,and there was a statistical difference in the change of KPS scores（P<0.05）.Mild to moderate pneumothorax occurred in 13（31.7%）patients after surgery,of which 11（26.8%）patients with mild pneumothorax required no treatment,2（4.9%）patients with moderate pneumothorax were cured after chest drainage;6（14.6%）patients had mild hemoptysis,which resolved spontaneously without special treatment.7（17.1%）patients had a small amount of intraoperative blood leakage from the surgical site,which did not increase again on routine postoperative scan.Four patients（12.1%）had postoperative fever,which resolved with symptomatic treatment.All patients did not develop serious complications such as radiation pneumonia and severe bone marrow suppression.5.Univariate analysis showed that patients’ age（P=0.043）,tumor TNM stage（P=0.020）,particle activity（P=0.035）and postoperative D₉₀（P=0.039）were influential factors for the recent efficacy of ¹²⁵I seed implantation for recurrent mediastinal lymphatic metastases,and multifactorial Cox survival analysis showed that tumor TNM stage,particle activity and postoperative D₉₀ were independent predictors of near-term outcome.Conclusions:1.CT-guided ¹²⁵I seed implantation for recurrent mediastinal lymph node metastasis is a safe,effective and minimally invasive response to radiation oncology treatment with significant local therapeutic effects and few complications;2.¹²⁵I seed can effectively relieve patients’ symptoms and improve their quality of life;3.Age,tumor stage,particle activity and postoperative D₉₀ are relevant influencing factors for the recent efficacy;among them,particle activity,postoperative D₉₀ and tumor stage are the main influencing factors.