Rectal spacer relieves GI issues following RT for prostate cancer

In a large retrospective study, the incidence of bowel disorders and related procedures dropped when a polyethylene glycol-based hydrogel spacer (PHS) was used in men undergoing radiotherapy (RT) for prostate cancer.

Compared with men who did not receive PHS, those who did had a lower cumulative incidence of bowel disorders up to 4 years after RT (12.6 percent vs 17.4 percent), translating to an adjusted hazard ratio (aHR) of 0.75 (p<0.001) after adjusting for covariates. A similar pattern favouring the PHS was seen for related gastrointestinal (GI) procedures (1.1 percent vs 2.1 percent; aHR, 0.54; p<0.001).

“Three sets of additional analyses to assess model robustness check had consistent results,” the researchers said. “These results highlight the potential of PHS to mitigate long-term GI complications in prostate cancer patients undergoing RT in a clinical practice setting.”

The adjusted cumulative incidences of both outcomes mirror those seen in the general population (10.3 percent [bowel disorders] and 0.7 percent [related procedures]). “This suggests that PHS use may reduce the incidence of bowel disorders experienced by patients receiving RT to levels similar to those of the age-matched general population,” they said.

When evaluating individual ICD-9-CM* and ICD-10-CM* diagnosis codes, the incidence across all 13 categories of bowel symptoms was lower among men who did vs did not receive PHS, the researchers added. In the subgroup who had at least one diagnosis code for bowel disorders, the likelihood of having multiple diagnosis codes for bowel disorders was lower in men with vs without PHS (mean 1.37 vs 1.50; p<0.001).

Improved patient outcomes

Using multiple claims datasets, the investigators evaluated 261,906 men diagnosed with prostate cancer between 2015 and 2021 who underwent RT after diagnosis. RT modalities included stereotactic body RT, intensity-modulated RT, proton beam RT, brachytherapy, and three-dimensional conformal RT.

Roughly 10 percent (n=25,167) of the population received PHS (mean age 70.7 years) while the rest did not. The results were benchmarked against an age-matched general population. [JAMA Netw Open 2025;doi:10.1001/jamanetworkopen.2025.0491]

A PHS temporarily separates the rectum from the prostate during RT, with the goal of reducing the radiation dose delivered to the anterior rectum. [World J Clin Oncol 2015;6:189-193] Evidence shows that rectal separation during RT using the PHS system effectively reduces the severity of rectal toxic effects, is well tolerated, and is associated with quality of life improvements. [Int J Radiat Oncol Biol Phys 2015;92:971-977; Int J Radiat Oncol Biol Phys 2017;97:976-985; BJU Int 2020;126:367-372; Front Oncol 2023;13:1239104]

“The current study expands on these findings by evaluating the association of PHS use with post-RT bowel disorders and related procedures in the broader population of clinical practice settings compared with patients who did not receive PHS,” the researchers noted.

They added that an improved understanding of the long-term bowel toxic effects in the post-approval setting may guide clinical decision-making regarding PHS use when attempting to mitigate RT-related adverse effects.

“These findings corroborate the potential benefits of PHS in improving patient outcomes and reducing GI toxic effects seen in prior prospective studies, supporting its value as an effective intervention in the treatment of men with PCa undergoing RT,” they concluded.