The stability of seeds in external beam prostate radiotherapy and implications of migration in current practice: a systematic review

PURPOSE: To determine and summarise the literature on prostatic seed stability by investigating seed marker migration and loss in prostate cancer patients. In addition, documenting the implications of significant seed migration and loss in clinical practise. METHODS: PubMed and Sciencedirect databases were used to locate papers on the stability of gold seed markers in prostate patients treated with external beam radiation therapy. The search found 3,238 articles and ten articles were selected and reviewed based on inclusion and exclusion criteria for the scope of this literature review. RESULTS: Minimal migration and loss of seeds was observed in the literature reviewed, with the majority of authors reporting <2·0 mm migration within the prostate; however, there were individual cases reported outside of the 2·0 mm threshold. It was also found that significant migration had an impact on image matching, as well as, planning treatment volume margins. CONCLUSION: Seed stability within the prostate has been proven, with most authors reporting minimal migration within a 2·0 mm threshold and minimal loss of seeds. Although individual cases can have significant migration and loss, if marker migration exceeds the 2·0 mm threshold, a protocol is required to deal with both non-significant and significant migration.