Hydrogel Spacers: Reducing Late Rectal Toxicity Following Prostate IMRT

Radiation oncologist Sean Collins, MD, described the critical challenge inherent in treating prostate cancer with radiation: the extremely close proximity of the rectum to the prostate gland. When radiation beams are directed at the cancerous prostate, the adjacent rectum inevitably receives some exposure, which frequently leads to chronic and debilitating side effects. These long-term complications, collectively known as late rectal toxicity, include issues such as increased bowel frequency, urgency, and occasionally, rectal bleeding, all of which significantly impair a patient's quality of life for the remainder of their life.

To mitigate this pervasive problem, Collins began incorporating the use of rectal spacers into his practice around 2016. These devices consist of a biocompatible hydrogel that is strategically placed during a minimally invasive procedure. The gel acts as a physical buffer, creating a separation of approximately 1 centimeter between the prostate and the anterior wall of the rectum. While 1 centimeter might seem negligible, the speaker emphasized that in the highly precise and intense field of modern radiation oncology, this distance is profoundly significant. By effectively pushing the sensitive rectal tissue out of the high-dose treatment zone, the spacer dramatically reduces the radiation dose delivered to the rectum.

Clinical experience and subsequent data strongly validated the initial hypothesis. The use of the rectal spacer demonstrably lowered the radiation dose received by the rectum and, as a direct consequence, successfully reduced the incidence of late rectal toxicity. Patients experienced lower rates of chronic bowel frequency, urgency, and rectal bleeding. Critically, these objective clinical improvements translated directly into a statistically better quality of life for men undergoing radiation therapy for prostate cancer.

Initially, the clinical team believed the function of the rectal spacer was complete once it achieved its primary goal of rectal protection. However, a new theoretical application quickly emerged. If the spacer could effectively move the rectum away from the target, it might simultaneously create an opportunity to safely increase the radiation dose delivered to the prostate itself. Delivering a higher, more potent dose of radiation to the tumor, a concept known as dose escalation, has long been linked to improved rates of tumor control and overall cure.