Hydrogel Injection May Curb Unwanted Radiation From Prostate Radiotherapy

By David Douglas

June 29, 2020

NEW YORK (Reuters Health) - In men receiving prostate radiotherapy, use of a perirectal hydrogel spacer (SpaceOAR, Boston Scientific) may help reduce rectal irradiation and toxic effects, according to a company-funded review and meta-analysis.

"Because the prostate and rectum are in close anatomical proximity to one another, radiation therapy for prostate cancer can inadvertently expose the rectum to excessive radiation," Dr. Larry E. Miller of Miller Scientific, in Johnson City, Tennessee, told Reuters Health by email. "This in turn may lead to side effects like gastrointestinal bleeding or diarrhea that can linger for years afterwards."

In their report in JAMA Network Open, Dr. Miller and his colleagues note that a variety of different perirectal spacer materials have been used to create prostate-rectum separation. To examine the performance of SpaceOAR, the researchers identified six cohort studies and one randomized trial involving the device.

In all, 486 men received the spacer and 525 acted as controls. They were followed for a median of 26 months. Based on five studies, hydrogel placement was successful in 97% and the weighted mean perirectal separation distance was 11.2 mm.

The frequency of procedural complications was not reported in three studies; in the remaining four, complications were mild or transient, with a frequency ranging from zero to 10%.

Based on six studies the percentage volume of rectum receiving at least 70 Gy of radiation was significantly smaller in the spacer group (3.5%) than in controls (10.4%).

In early follow-up, the risk of grade-2-or-higher rectal toxic effects was comparable between groups. At more than three months, it was significantly smaller in the spacer group (1.5%) than in controls (5.7%).

Positive changes in bowel-related quality of life were not initially different between the groups. But in two studies at a median follow-up of 48 months, they were greater in the hydrogel spacer group and exceeded the threshold for a minimal clinically important difference.

"Our meta-analysis demonstrated that placement of the SpaceOAR hydrogel spacer between the prostate and rectum prior to radiotherapy safely reduced rectal radiation exposure, lowered the risk of chronic gastrointestinal complications, and improved quality of life compared to men treated with prostate radiotherapy only," Dr. Miller concluded.

Dr. Miller reports serving as a consultant for and receiving personal fees from Boston Scientific. Other authors also disclosed ties to the company.

SOURCE: https://bit.ly/37SNwms JAMA Network Open, online June 17, 2020.