Perirectal Hydrogel Spacer Benefits Suggested For Prostate Cancer Radiotherapy

Author: By Lynda Williams, Senior medwireNews Reporter 

medwireNews: Using a perirectal hydrogel spacer prior to prostate cancer radiotherapy can reduce the volume of rectum that receives 70 Gy or more radiation, reducing the risk of rectal toxicity and improving bowel-related quality of life (QoL), suggest the results of a systematic review and meta-analysis. 

“Perirectal hydrogel spacer placement prior to prostate radiotherapy may be a prudent preventive strategy for reduction of radiotherapy-induced rectal complications”, the investigators write in JAMA Network Open. 

The team collated data from one randomized clinical trial and six cohort studies; this included a total of 486 men who had an absorbable polyethylene glycol hydrogel spacer injected between the Denonvilliers fascia and the anterior rectal wall and 525 men who did not receive a spacer. 

Spacer placement was successful for 97.0% of attempts, achieving a weighted mean perirectal separation distance of 11.2 mm. There were five failed deliveries caused by unsuccessful hydrodissection, three needle entries into the rectal lumen without clinical consequences, and one unspecified failure. 

“[M]ild and transient” procedural complications occurred in up to 10% of patients and did not delay radiotherapy, report Larry Miller, from Miller Scientific in Johnson City, Tennessee, USA, and co-authors. 

Overall, 3.5% of men given a spacer received rectal radiation of at least 70 Gy compared with 10.4% of controls, giving a mean difference of 6.5% between the two groups that reached statistical significance. 

During the first 3 months of follow-up, grade 2 or more severe rectal toxicity occurred in a comparable 4.5% of the spacer group and 4.1% of controls. After this time, at a median of 38 months, however, this endpoint was significantly less common in the men with a spacer, at 1.5% versus 5.7% of controls, giving a significant risk ratio (RR) of 0.23 in favour of spacer use. 

And when considering all grades of rectal toxicity, defined as grade 1 or more severe, spacer use was associated with a significantly lower risk than no spacer for both early effects (20.5 vs 29.5%, RR=0.72) and late effects at a median of 40 months (4.8 vs 16.2%, RR=0.38). 

Changes in bowel-related QoL did not differ significantly between the treatment groups at 3 months. But after a median 48 months of follow-up, the spacer-treated patients had a greater positive change in QoL than controls, with a mean score difference of 5.4 on a 0 to 100 scale that “exceeded the threshold for a minimal clinically important difference”, the researchers say. 

Larry Miller et al note that “[t]he limitations of this review that may confound interpretation were a small number of eligible studies, the predominance of nonrandomized study designs with associated risks of bias, and follow-up durations that may be inadequate to detect long-term clinical manifestations of rectal irradiation.”

They say that “additional studies with adequate follow-up durations may be informative to provide more reliable estimates regarding the safety and effectiveness of hydrogel spacers.”

Reference 

Miller LE, Efstathiou JA, Bhattacharyya SK, et al. Association of the placement of a perirectal hydrogen spacer with the clinical outcomes of men receiving radiotherapy for prostate cancer. A systematic review and meta-analysis. JAMA Netw Open; 3: e208221 17 June 2020. doi:10.1001/jamanetworkopen.2020.8221