Perirectal spacers are intended to lower the risk of rectal toxic effects associated with prostate radiotherapy. However, the clinical results of specific perirectal spacers are limited. A new study published in JAMA Network Open focused on the association between perirectal hydrogel spacer placement and clinical outcomes of men receiving radiotherapy for prostate cancer.
This systematic review and meta-analysis included results from 7 studies with 1011 patients receiving prostate cancer radiotherapy. The study compared men who received a hydrogel spacer (n=486) versus men who did not receive a spacer (controls) prior to prostate radiotherapy (n=525). The primary outcomes were the procedural results, the percentage volume of rectum receiving at least 70 Gy radiation (v70), early (≤3 months) and late (>3 months) rectal toxic effects, and early and late changes in bowel-related quality of life.
The success rate of hydrogel spacer placement was 97.0% (95% CI, 94.4%-98.8% [5 studies]), and the weighted mean perirectal separation distance was 11.2 mm (95% CI, 10.1-12.3 mm [5 studies]). Procedural complications were mild and transient, occurring in 0% to 10% of patients within the studies. The hydrogel spacer group received 66% less v70 rectal irradiation compared with controls (3.5% versus 10.4%; mean difference, −6.5%; 95% CI, –10.5% to –2.5%; p= 0.001 [6 studies]).
The risk of grade 2 or higher rectal toxic effects was comparable between groups in early follow-up (4.5% in hydrogel spacer group versus 4.1% in control group; risk ratio, 0.82; 95% CI, 0.52-1.28; p=0.38 [6 studies]) but was 77% lower in the hydrogel spacer group in late follow-up (1.5% versus 5.7%; risk ratio, 0.23; 95% CI, 0.06-0.99; p=0.05 [4 studies]). Changes in bowel-related quality of life were comparable between groups in early follow-up (mean difference, 0.2; 95% CI, –3.1 to 3.4; p=0.92 [2 studies]) but were greater in the hydrogel spacer group in late follow-up (mean difference, 5.4; 95% CI, 2.8-8.0; p< 0.001 [2 studies]).
In conclusion, injection of a hydrogel was associated with an acceptable adverse-event profile, fewer rectal toxic effects and higher bowel-related quality of life in late follow-up.
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