In a recently reported study, the use of an injection of an absorbable perirectal hydrogel spacer before primary radiotherapy for prostate cancer may reduce rectal irradiation and the associated rectal toxic effects that manifest clinically after longer-term follow-up.
A study had shown that the use of an injection of hydrogel, a spacer before radiation therapy (RT) in men with prostate cancer was both safe and also provided prostate-rectum separation that was sufficient to reduce rectal irradiation.1
The study results were published in JAMA Network Open, showed that patients who received the hydrogel spacer experienced fewer rectal toxic effects and had a higher bowel-related quality of life (QoL) in late follow-up.
"The rectum is the dose-limiting structure in men receiving radiotherapy for prostate cancer; therefore, strategies that allow dose escalation while decreasing rectal irradiation may optimize local tumor control with fewer bothersome bowel symptoms," the authors wrote. "Overall, these results suggest that injection of an absorbable perirectal hydrogel spacer before RT for prostate cancer may reduce rectal irradiation and the associated rectal toxic effects that manifest clinically after longer-term follow-up."
The study evaluated data for 1011 men from 7 studies. These data included six cohort studies and one randomized clinical trial. Overall, 486 men received the hydrogel spacer, and 525 did not. The median follow-up was 26 months (range, 3-63 months).
The data indicated that the hydrogel spacer placement was highly successful, with 97% of the men being successful in having the hydrogel injected. Procedural complications were found to be mild and transient, occurring in only 0% to 10% of the study participants.
The men who received the hydrogel spacer received 66% less v70 rectal irradiation compared with controls.
In the early follow-up, the risk of ≥grade 2 rectal toxic events was comparable between the 2 study arms, occurring in 4.5% versus 4.1% of the intervention versus control arms, respectively. In the late follow-up, however, the risk was 77% lower in the hydrogel spacer group.
A similar trend was observed with changes in bowel-related quality of life (QoL). In the early follow-up, bowel-related QoL was similar between the intervention and control arms. In contrast, in the late follow-up, the bowel-related QoL changes were better in the hydrogel spacer group.
Despite the observed results in late follow-up with the hydrogel spacer, it is plausible that the duration of individual studies was insufficient to fully characterize the true magnitude of rectal toxic effects after [radiotherapy]," the authors wrote. "Thus, the clinical benefit of the perirectal spacer may be underestimated in this review due to a limited follow-up duration. "
Unfortunately, the number of studies providing results was insufficient to explore the association between follow-up duration and late grade 2 or higher rectal toxic effects."
The study authors did add that, "The 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."
1. Miller LE, Efstathiou JA, Bhattacharyya SK, Payne HA, Woodward E, Pinkawa M. Association of the placement of a perirectal hydrogel spacer with the clinical outcomes of men receiving radiotherapy for prostate cancer. JAMA Netw Open. 2020;3(6):e208221. doi: 10.1001/jamanetworkopen.2020.8221
