Migration of a strand of four seeds in low-dose-rate brachytherapy

SpaceOAR hydrogel complications in prostate cancer

SpaceOAR hydrogel, a novel biodegradable spacer, is increasingly used in managing prostate cancer patients undergoing radiation therapy to minimize rectal radiation dose and associated complications. However, its use has raised new concerns regarding its potential complications and impact on subsequent imaging interpretation. This article provides a pictorial review of the imaging complications of using SpaceOAR hydrogel in prostate cancer patients. We present multiple examples demonstrating the types of complications that can occur, potential underlying mechanisms, and their impact on patient outcomes and imaging interpretation. This review aims to provide radiologists and oncologists with an updated understanding of these complications, guiding better patient management and interpretation of imaging studies.

Low-activity 125I implantation into VX2 tumor rabbits and quantitative evaluation of the precise therapeutic effect

There is still controversy about quantitatively evaluating the therapeutic effect of radioactive low-activity iodine-125 seeds (¹²⁵I seeds). In the present study, a paired VX₂ tumor model in a rabbit hind leg muscle was established, which is virus-induced anaplastic squamous cell carcinoma characterized by hypervascularity, rapid growth and easy propagation in the skeletal muscle. ¹²⁵I seeds with 0.4 and 0.7 mCi activity were implanted into the left and right legs, respectively, using a radiation treatment planning system under positron emission tomography (PET)/computed tomography (CT) guidance. PET/CT scans and hematoxylin and eosin staining were observed at 72 h and 2 and 4 weeks after implantation to assess the therapeutic effect. The results showed that the average tumor length and standard uptake value (SUV) decreased over time, and both ¹²⁵I seed groups achieved therapeutic effects at 4 weeks post-implantation. Quantitative evaluation of tumor inhibition rate, SUV variation and tumor marker ratio (Bcl-2/Bax) suggested that 0.7 mCi ¹²⁵I seeds were more suitable than 0.4 mCi seeds in a clinical setting.

Reducing seed migration to near zero with stranded-seed implants: Comparison of seed migration rates to the chest in 1000 permanent prostate brachytherapy patients undergoing implants with loose or stranded seeds

PURPOSE

Pulmonary seed emboli to the chest may occur after permanent prostate brachytherapy (PPB). The purpose of this study is to analyze factors associated with seed migration to the chest in a large series of PPB patients from a single institution undergoing implant with either loose seeds (LS), mixed loose and stranded seeds (MS), or exclusively stranded seeds in an absorbable vicryl suture (VS).

METHODS AND MATERIALS

Between May 1998 and July 2015, a total of 1000 consecutive PPB patients with postoperative diagnostic chest x-rays at 4 months after implant were analyzed for seed migration. Patients were grouped based on seed implant technique: LS = 391 (39.1%), MS = 43 (4.3%), or VS = 566 (56.6%). Univariate and multivariate analysis were performed using Cox proportional hazards regression models to determine predictors of seed migration.

RESULTS

Overall, 18.8% of patients experienced seed migration to the chest. The incidence of seed migration per patient was 45.5%, 11.6%, and 0.9% (p < 0.0001), for patients receiving LS, MS, or VS PPB, respectively. The right and left lower lobes were the most frequent sites of pulmonary seed migration. On multivariable analysis, planimetry volume (p = 0.0002; HR = 0.7 per 10 cc [0.6-0.8]), number of seeds implanted (p < 0.0001, HR = 2.4 per 25 seeds [1.7-3.4]), LS implant (p < 0.0001, HR = 15.9 [5.9-42.1]), and MS implant (p = 0.001, HR = 7.9 [2.3-28.1]) were associated with seed migration to the chest.

CONCLUSIONS

In this large series, significantly higher rates of seed migration to the chest are observed in implants using any LS with observed hazard ratios of 15.9 and 7.9 for LS and MS respectively, as compared with implants using solely stranded seeds.

Seed migration after transperineal interstitial prostate brachytherapy by using loose seeds: Japanese prostate cancer outcome study of permanent iodine-125 seed implantation (J-POPS) multi-institutional cohort study

Background

The incidence and associated factors of loose seed migration were investigated in cohort 1 of the Japanese Prostate Cancer Outcome Study of Permanent Iodine-125 Seed Implantation (J-POPS).

Methods

The study subjects were 2160 patients, consisting of 1641 patients who underwent permanent iodine-125 seed implantation (PI) and 519 patients who underwent PI combined with external beam radiation therapy (PI + EBRT). The presence or absence of seed migration to the chest and abdominal/pelvic region was determined.

Results

Seed migration was observed in 22.7 % of PI group patients and 18.1 % of PI + EBRT group patients (p = 0.0276). Migration to the lungs and abdominal/pelvic region was observed in 14.6 % and 11.1 % of the patients in the PI group, and 11.2 % and 8.5 % of the patients in the PI + EBRT group, respectively. In the PI group, the number of implanted seeds was associated with the seed migration incidence. Neither the PI nor the PI + EBRT group showed any difference in the volume of the prostate receiving 100 % of the prescribed dose (V100 [%]) or the minimal dose received by 90 % of the prostate volume (D90 [Gy]) between the patients with and without seed migration.

Conclusions

This prospective cohort study investigating the largest number of past cases showed no difference in D90 (Gy) or V100 (%) between seed migration or the absence thereof in both the PI group and PI + EBRT group.

Trial registration

ClinicalTrials.gov: NCT00534196