Prospective analysis of hydrogel spacer for patients with prostate cancer undergoing radiotherapy

Chao, Michael; Ho, Huong; Chan, Yuk Wah; Tan, Alwin; Pham, Trung; Bolton, Damien; Troy, Andrew; Temelcos, Catherine; Sengupta, Shamik; McMillan, Kevin; Cham, Chee Wee; Liu, Madalena; Ding, Wei; Subramanian, Brindha; Wasiak, Jason; Joon, Daryl Lim; Spencer, Sandra; Lawrentschuk, Nathan

doi:10.1111/bju.14192

Cited by 28 publications

(26 citation statements)

References 25 publications

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“…Previous work has shown no statistically significant variation in rectum dose with CTV volume ranging up to 100 cc, and is consistent with our findings [ 21 ].…”

Section: Discussionsupporting

confidence: 94%

“…Following hydrogel placement, almost all regions of the prostate have increased separation from the rectum, with the greatest mean increase seen at the prostate apex and midgland (Table 3C ). Several publications have described a wide range of post-hydrogel perirectal separation ranging from 0.6 to over 2 cm, but to-date few have described in detail the optimal location to obtain this perirectal measurement, or Δ measurement, resulting from hydrogel placement [ 11 , 14 , 21 – 23 ].…”

Section: Discussionmentioning

confidence: 99%

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A novel model to correlate hydrogel spacer placement, perirectal space creation, and rectum dosimetry in prostate stereotactic body radiotherapy

et al. 2018

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BackgroundThe SpaceOAR hydrogel is employed to limit rectal radiation dose during prostate radiotherapy. We identified a novel parameter – the product of angle θ and hydrogel volume – to quantify hydrogel placement. This parameter predicted rectum dosimetry and acute rectal toxicity in prostate cancer patients treated with stereotactic body radiotherapy to 36.25 Gy in 5 fractions.MethodsTwenty men with low- and intermediate-risk prostate cancer underwent hydrogel placement from 2015 to 2017. Hydrogel symmetry was assessed on the CT simulation scan in 3 axial slices (midgland, 1 cm above midgland, 1 cm below midgland). Two novel parameters quantifying hydrogel placement – hydrogel volume and angle θ formed by the prostate, hydrogel, and rectum – were measured, and the normalized product of θ and hydrogel volume calculated. These were then correlated with perirectal distance, rectum maximum 1–3 cc point doses (rDmax 1–3 cc), and rectum volumes receiving 80–95% of the prescription dose (rV80–95%). Acute rectal toxicity was recorded per RTOG criteria.ResultsIn 50% of patients, hydrogel placement was symmetric bilaterally to within 1 cm of midline in all three CT simulation scan axial slices. Lateral hydrogel asymmetry < 2 cm in any one axial slice did not affect rectum dosimetry, but absence of hydrogel in the inferior axial slice resulted in a mean increase of 171 cGy in the rDmax 1 cc (p < 0.005). The perirectal distance measured at prostate midgland, midline (mean 9.1 ± 4.3 mm) correlated strongly with rV95 (R2 0.6, p < 0.001). The mean hydrogel volume and θ were 10.3 ± 4.5 cc and 70 ± 49°, respectively. Perirectal distance, rV95 and rDmax 1 cc correlated with hydrogel angle θ (p < 0.01), and yet more strongly with the novel metric θ*hydrogel volume (p < 0.001). With a median follow up of 14 months, no rectal toxicity >grade 2 was observed. Low grade rectal toxicity was observed in a third of men and resolved within 1 month of SBRT. Men who had these symptoms had higher rDmax 1 cc and smaller θ*hydrogel volume measurements.ConclusionsOptimal hydrogel placement occurs at prostate midgland, midline. The novel parameter θ*hydrogel volume describes a large proportion of rectum dosimetric benefit derived from hydrogel placement, and can be used to assess the learning curve phenomenon for hydrogel placement.

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“…Previous work has shown no statistically significant variation in rectum dose with CTV volume ranging up to 100 cc, and is consistent with our findings [ 21 ].…”

Section: Discussionsupporting

confidence: 94%

Section: Discussionmentioning

confidence: 99%

A novel model to correlate hydrogel spacer placement, perirectal space creation, and rectum dosimetry in prostate stereotactic body radiotherapy

et al. 2018

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“…Creating a spacing between the prostate and rectum, the injection of a hydrogel rectal spacer into the anterior perirectal space is a novel approach permitting the administration of higher doses of radiation to the prostate while minimising rectal irradiation, and hence rectal toxicity 1. Its safety and efficacy have been evaluated in randomised phase III studies, with low rates of spacer-related complications reported in literature 2 3.…”

Section: Discussionmentioning

confidence: 99%

“…The use of hydrogel spacers in radiotherapy for prostate cancer has gained noticeable interest in recent years, allowing administration of higher radiation doses to the prostate while minimising rectal toxicity. Its safety and efficacy has been evaluated in several studies, with very rare spacer-related complications having been reported in literature 1. We present the case of a patient who developed a spacer-related periprostatic abscess.…”

Section: Introductionmentioning

confidence: 99%

Abscess formation following hydrogel spacer for prostate cancer radiotherapy: a rare complication

Hoe¹,

Yao

Huang

et al. 2019

BMJ Case Rep

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Periprostatic abscess is a rare complication of hydrogel spacers in radiotherapy for prostate cancer. We present the case of a 61-year-old man who developed this condition. Abdominopelvis CT scan revealed a 54×35×75 mm collection in the location of the SpaceOAR, for which ultrasound-guided transperineal percutaneous drainage of the periprostatic abscess was performed. The patient remains well with serial CT scans showing near resolution of the collection.

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“…In this issue of the BJUI , Chao et al. report their prospective single‐centre experience of using a rectal spacer device. This was not a randomized study, and there was no control arm to assist in quantifying the clinical impact of inserting a spacer; however, the patient population that was studied closely reflects that undergoing radical radiotherapy in most oncology departments worldwide.…”

mentioning

confidence: 99%

2018: A Spacer Odyssey

Hughes

2018

BJU International

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Prospective analysis of hydrogel spacer for patients with prostate cancer undergoing radiotherapy

Abstract: Injection of HS resulted in a reduction of irradiated rectal dose volumes along with minimal GI toxicities, irrespective of prostate size.

Cited by 28 publications

References 25 publications

A novel model to correlate hydrogel spacer placement, perirectal space creation, and rectum dosimetry in prostate stereotactic body radiotherapy

A novel model to correlate hydrogel spacer placement, perirectal space creation, and rectum dosimetry in prostate stereotactic body radiotherapy

Abscess formation following hydrogel spacer for prostate cancer radiotherapy: a rare complication

2018: A Spacer Odyssey

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