Comprehensive review of hydrogel spacers prior to radiation therapy for prostate cancer.

Abstract

Radiation therapy is a curative intent treatment option for men with prostate cancer. Despite advancement in radiation therapy delivery, rectal toxicity still occurs. Hydrogel spacers offer the potential to reduce rectal toxicity for prostate cancer patients receiving radiation therapy. Since its introduction, numerous studies have confirmed their safety and efficacy in reducing rectal complications. The concept is elegantly simple whereby a hydrogel compound is injected under ultrasound guidance during routine fiducial marker insertion or as a standalone procedure prior to radiotherapy. After radiation therapy the body naturally reabsorbs the hydrogel material. We aimed to provide a comprehensive narrative review and outline the practicalities of inserting hydrogel spacers and published data on the impact of hydrogel spacers on rectal dosimetry and toxicity. A growing body of evidence suggests the administration of hydrogel spacers is safe and associated with limited perioperative morbidity. The impact on rectal dosimetry has been clearly established and hydrogel spacers are associated with resulting reduces rectal morbidity. These results have been corroborated by several Phase II and III clinical trials and subsequent meta-analysis. Several future research questions exist, including the role of hydrogel spacer in prostate stereotactic beam radiotherapy or post-radiotherapy local recurrence. Hydrogel spacers provide a low morbidity method potentially reducing rectal toxicity following radiation therapy in men with prostate cancer. Data outlining sexual function and oncologic outcomes are limited to date. No doubt future studies, currently being conducted, may provide further clarification of the role of hydrogel spacers in prostate cancer management.