A prospective comparison of implant quality between suture-coated seeds and uncoated seeds in prostate cancer brachytherapy

Purpose: Displacement minimization of seeds is crucial during surgery in brachytherapy; however, only a few reports have compared the operability of different seeds. TheraStrand-SL is a seed, in which TheraAGX100 is wrapped in polyglactin 910 thread, and intra-prostatic displacement is expected to be reduced compared with that of Thera-AGX100, owing to the complex shape of TheraStrand-SL. We conducted a prospective study on the operability and treatment outcomes of TheraAGX100 and TheraStrand-SL placement by a single operator.

Material and methods: The study included 69 patients who received brachytherapy for prostate cancer. Endpoints were comparisons of intra- and post-treatment dose-volume histograms, seed displacement incidence rate, seed displacement distance, seed migration/dropout incidence rate, and adverse events incidence rate between TheraAGX100 (n = 25) and TheraStrand-SL (n = 44) groups.

Results: The intra-prostatic displacement incidence rate was significantly lower in the TheraStrand-SL group than in the TheraAGX100 group (TheraAGX100 group: 96.0%; TheraStrand-SL group: 11.4%). Further, the intra-prostatic displacement count per case tended to be lower in the TheraStrand-SL group than in the TheraAGX100 group. Additionally, a comparison of displacement distance per case showed that the TheraStrand-SL group (2.01 mm) had a statistically significantly shorter distance than the TheraAGX100 group (9.22 mm). No significant differences between the two groups were observed in terms of migration, explanted dropout seed count, dose-volume histograms, and adverse events incidence rate.

Conclusions: Our study demonstrated the usefulness of TheraStrand-SL against intra-prostatic displacement. We expect TheraStrand-SL to have further applications in brachytherapy, including focal therapy.