Technique of Injection of Hyaluronic Acid as a Prostatic Spacer and Fiducials Before Hypofractionated External Beam Radiotherapy for Prostate Cancer

Multicenter, dual fractionation scheme, single core lab comparison of rectal volume dose reduction following injection of two biodegradable perirectal spacers

PURPOSE

A multicenter, double-arm, central core lab, retrospective study was performed to compare the rectal dosimetry of patients implanted with two injectable, biodegradable perirectal spacers, in conventional fractionation (CF), as well as ultrahypofractionation (UH) treatment plans.

METHODS AND MATERIALS

Fifty-nine patients were enrolled into the study in five centers: two centers in Europe, which implanted a biodegradable balloon spacer in a total of 24 subjects and three centers in the US, which implanted the SpaceOAR in 35 subjects. Anonymized CTs (pre and post-implantation) were reviewed by the central core lab. For VMAT CF plans rectal V50, V60, V70, and V80 were calculated. For UH plans, a corresponding rectal V22.6, V27.1, V31.37, and V36.25 were established representing 62.5%, 75%, 87.5%, and 100% of the 36.25 Gy prescribed dose.

RESULTS

For CF VMAT, a comparison between the balloon spacer and the SpaceOAR revealed a significant difference of 33.4% decrease in mean rectal V50 (71.9% vs. 38.5%, p < 0.001), 27.7% in mean rectal V60 (79.6% vs. 51.9%, p < 0.001), 17.1% difference in mean rectal V70 (84.1% vs. 67.0%, p = 0.001), and a significant difference of 3.0% (p = 0.019) in mean rectal V80 (87.2% vs. 84.2%). With UH analysis, the mean rectal dose reduction for the balloon spacer compared to the SpaceOAR was 79.2% and 53.3% for V27.1 (p < 0.001), 84.1% and 68.1% for V31.71 (p = 0.001), and 89.7% and 84.8% for V36.25 (p = 0.012), respectively.

CONCLUSION

Rectal dosimetry is more favorable for treatment with the balloon spacer compared with SpaceOAR. Further research, particularly in the context of a prospective randomized clinical trial design, is needed to assess the acute and late toxicity experience as well as physician satisfaction with achieving symmetrical implantation, and ease of use in light of increasing clinical use.

Hyaluronic Acid Spacer for Hypofractionated Prostate Radiation Therapy: A Randomized Clinical Trial

Importance

Hypofractionated radiation therapy (RT) for prostate cancer has been associated with greater acute grade 2 gastrointestinal (GI) toxic effects compared with conventionally fractionated RT.

Objective

To evaluate whether a hyaluronic acid rectal spacer could (1) improve rectal dosimetry and (2) affect acute grade 2 or higher GI toxic effects for hypofractionated RT.

Design, Setting, and Participants

This randomized clinical trial was conducted from March 2020 to June 2021 among 12 centers within the US, Australia, and Spain, with a 6-month follow-up. Adult patients with biopsy-proven, T1 to T2 prostate cancer with a Gleason score 7 or less and prostate-specific antigen level of 20 ng/mL or less (to convert to μg/L, multiply by 1) were blinded to the treatment arms. Of the 260 consented patients, 201 patients (77.3%) were randomized (2:1) to the presence or absence of the spacer. Patients were stratified by intended 4-month androgen deprivation therapy use and erectile quality.

Main Outcomes and Measures

For the primary outcome, we hypothesized that more than 70% of patients in the spacer group would achieve a 25% or greater reduction in the rectal volume receiving 54 Gy (V54). For the secondary outcome, we hypothesized that the spacer group would have noninferior acute (within 3 months) grade 2 or higher GI toxic effects compared with the control group, with a margin of 10%.

Results

Of the 201 randomized patients, 8 (4.0%) were Asian, 26 (12.9%) Black, 42 (20.9%) Hispanic or Latino, and 153 (76.1%) White; the mean (SD) age for the spacer group was 68.6 (7.2) years and 68.4 (7.3) years for the control group. For the primary outcome, 131 of 133 (98.5%; 95% CI, 94.7%-99.8%) patients in the spacer group experienced a 25% or greater reduction in rectum V54, which was greater than the minimally acceptable 70% (P < .001). The mean (SD) reduction was 85.0% (20.9%). For the secondary outcome, 4 of 136 patients (2.9%) in the spacer group and 9 of 65 patients (13.8%) in the control group experienced acute grade 2 or higher GI toxic effects (difference, -10.9%; 95% 1-sided upper confidence limit, -3.5; P = .01).

Conclusions and Relevance

The trial results suggest that rectal spacing with hyaluronic acid improved rectal dosimetry and reduced acute grade 2 or higher GI toxic effects. Rectal spacing should potentially be considered for minimizing the risk of acute grade 2 or higher toxic effects for hypofractionated RT.

Trial Registration

ClinicalTrials.gov Identifier: NCT04189913.

Hyaluronic acid rectal spacer in EBRT: Usability, safety and symmetry related to user experience

OBJECTIVES

To report on the usability, safety, symmetry, and effectiveness of hyaluronic acid (HA) injected between the prostate and the rectum for patients undergoing treatment for prostate cancer with external beam radiotherapy (EBRT), and present a novel definition of rectal spacer symmetry that is reproducible and independent of patient anatomy.

PATIENTS AND METHODS

102 consecutive patients with clinical stage of T1c-3b prostate cancer underwent general anaesthesia for fiducial marker insertion and injection of HA into the perirectal space before EBRT. HA safety, symmetry, separation, and usability based on user experience were assessed.

RESULTS

HA insertion was completed with a 100% success rate independent of user experience, rated as 'easy' or 'very easy' in all cases. There were no postoperative complications reported. The mean (SD) recto-prostatic separation for all patients at the base, midgland and apex were 12 (±2) mm, 11 (±2) mm, and 9 (±1) mm respectively. The mean sagittal length of the implant was 43 (±5) mm. The implant was rated as symmetrical in 98% of cases. The mean rV70Gy was 1.6% (IQR 0.8-3.3%) for patients receiving 78-80Gy. The mean rV53Gy was 2.8% (IQR 1.2-4.8%) for patients receiving 60-62Gy. The median prostate size was 43.5 cc (IQR 32-57).

CONCLUSION

Injection of HA was able to achieve highly symmetrical recto-prostatic separation, with new users able to produce excellent separation, particularly at the apex, achieving similar dosimetry outcomes as competent and experienced users. HA is safe, easy to use, and significantly reduced mean rV70Gy and rV53Gy compared to non-spacer patients.

Highly hypofractionated schedules for localized prostate cancer: Recommendations of the GETUG radiation oncology group

Stereotactic body radiotherapy (SBRT) has become treatment option for localized prostate cancer but the evidence base remains incomplete. Several clinical studies, both prospective and retrospective, have been published. However, treatment techniques, target volumes and dose constraints lack consistency between studies. Based on the current available literature, the French Genito-Urinary Group (GETUG) suggests that.

Radiation Proctitis: The Potential Role of Hyaluronic Acid in the Prevention and Restoration of Any Damage to the Rectal Mucosa among Prostate Cancer Patients Submitted to Curative External Beam Radiotherapy

Aim: To evaluate if hyaluronic acid reduces proctitis episodes with respect to corticosteroids in prostate cancer patients submitted to radical or adjuvant radiotherapy. Methods: A consecutive series of eligible patients received hyaluronic acid enemas as supportive care (experimental group, from January 2013 to June 2015). A historical group (control group), treated from October 2011 to December 2012, received beclomethasone dipropionate suppositories. We registered each patient’s data regarding acute and chronic proctitis. All patients were treated with static-intensity-modulated radiotherapy coupled to a daily set-up verification with orthogonal anterior–posterior/lateral X-ray pairs. Results: A total of 269 patients, 175 in the experimental group and 94 in the control group, was evaluated; 2 Gy/day (up to a total median dose of 80 Gy) and 2.7 Gy/day (up to a total median dose of 67.5 Gy) fractionation schemes were used for 216 and 53 patients, respectively. All patients had a good tolerance to radiotherapy, reporting no G3 or greater proctitis. No significant difference was reported concerning the total rate of proctitis between the two groups but only with respect to its grade: a higher G2 rate within the control group. There was no correlation between daily dose fractionation and toxicity grade. Conclusions: Hyaluronic acid enemas might be effective in reducing the severity of radiation proctitis.

Prostate hypofractionated radiotherapy (62Gy at 3.1Gy per fraction) with injection of hyaluronic acid: final results of the RPAH1 study

OBJECTIVES

The present multicenter Phase II study evaluated the rate of late grade ≥2 gastrointestinal (GI) toxicities at 3 years, after hypofractionated radiotherapy (HFR) of prostate cancer with injection of hyaluronic acid (HA) between the prostate and the rectum.

METHODS

Between 2010 and 2013, 36 patients with low- or intermediate-risk prostate cancer were treated by HFR/IMRT-IGRT. 20 fractions of 3.1 Gy were delivered, 5 days per week for a total dose of 62 Gy. A transperineal injection of 10cc of HA was performed between the rectum and the prostate. Late toxicities were evaluated between 3 and 36 months after the end of treatment (CTCAE v4).

RESULTS

Median pretreatment prostate-specific antigen was 8 ng ml-1. Among the 36 included patients, 2 were not evaluated because they withdrew the study in the first 3 months of follow-up, and 4 withdrew between 3 and 36 months, the per protocol population was therefore composed.Late grade ≥2 GI toxicities occurred in 4 (12%) patients with 3 (9%) Grade 2 rectal bleedings and one diarrhoea. Therefore, the inefficacy hypothesis following Fleming one-stage design cannot be rejected. None of the patients experienced late Grade 3-4 toxicities. Among the 30 patients completing the 36 months' visit, none still had a grade ≥2 GI toxicity. Late grade ≥2 genitourinary (GU) toxicities occurred in 14 (41%) patients. The most frequent toxicities were dysuria and pollakiuria. Four patients still experienced a grade ≥2 GU toxicity at 36 months.The biochemical relapse rate (nadir +2 ng ml-1) was 6% (2 patients). Overall, HA was very well tolerated with no pain or discomfort.

CONCLUSION

Despite the inefficacy of HA injection was not rejected, we observed the absence of Grade 3 or 4 rectal toxicity as well as a rate of Grade 2 rectal bleeding below 10% at 36 months of follow-up. Late urinary toxicities are the most frequent but the rate decreases largely at 3 years.

ADVANCES IN KNOWLEDGE

With an injection of HA, hypofractionated irradiation in 4 weeks is well tolerated with no Grade 3 or 4 GI toxicity and a rate of Grade 2 rectal bleeding below 10% at 36 months of follow-up.

Transrectal Ultrasound Guided Hydrodistension - A New Surgical Way in Transgender Surgery

BACKGROUND

Creating the neovaginal canal in transwomen is one of the most delicate steps of Genital Gender Affirming Surgery (GGAS). Injury to the rectum is a rare but serious complication that can lead to further surgery and even creation of a colostomy.

AIM

Implementation of a novel hydrospacing technique (HST) based on transrectal ultrasound (TRUS)-guided hydrodistension.

METHODS

Between June 2018 and June 2020 54 transwomen received GGAS with HST. Immediately before GGAS transperineal hydrodistension was performed using a TSK-Supra-Needle (20 Gauge, 120 mm length), that was placed under direct TRUS-guided visual control between Denonvilliers' fascia and the anterior rectal wall. 40 - 60 ml normal saline were administered perineally to separate Denonvilliers' fascia from the anterior rectal wall to create a dissection of at least 20 mm. For better intraoperative visualization the hydrodissected space was also dyed using 2ml of methylenblue while retracting the needle. A retrospectively analysed, clinically and demographically comparable series of 84 transwomen who underwent GGAS between June 2016 and June 2018 served as control group. All 138 surgeries were performed by the same experienced surgeon.

OUTCOMES

The effect of the novel hydrospacing technique on neovaginal dimensions and operating time.

RESULTS

Patients in both groups did not differ in baseline patient characteristics such as age and body mass index (HST 35 vs 38 years in control group, P = .44 and body mass index 26 vs 25 kg/m², P = .73). Vaginal depth and width were significantly larger in the HST subgroup as compared to controls (14.4 cm vs 13.5 cm, P = .01 and 4.2 cm vs 3.8 cm, P < .001). No statistically significant difference occurred in intraoperative rectal injury (n = 0 in HST group, n = 2 in control group, P = .26). Median total OR-time was comparable for GGAS including HST before vaginoplasty to standard technique (211 minutes for HST vs 218 minutes; P = 0.19).

CLINICAL IMPLICATIONS

The proposed additional surgical step during GGAS is minimally invasive and safe, simplifies GGAS and potentially helps to avoid complications such as rectal injury.

STRENGTH & LIMITATIONS

Single-surgeon series, limited follow-up time and no prospective randomization.

CONCLUSION

HST is a safe and feasible procedure, which facilitates a safe preparation of the neovaginal canal during male to female GGAS. Panic A, Rahmani N, Kaspar C, et al. Transrectal Ultrasound Guided Hydrodistension - A New Surgical Way in Transgender Surgery. J Sex Med 2021;18:1135-1141.

EUS-guided hydrogel microparticle injection in a cadaveric model

BACKGROUND AND AIMS

A potential method to reduce gastrointestinal toxicity during radiation therapy in pancreatic head cancer is to create a physical space between the head of the pancreas (HOP) and the duodenum. To date, there have been early reports on the feasibility of endoscopic ultrasound (EUS)-guided hydrogel injection into the interface between the HOP and the duodenum to increase the peri-pancreatic space for radiotherapy. We aimed to evaluate the technical feasibility of EUS-guided hydrogel injection for the creation of space at the peri-pancreatic interface in a cadaveric model.

METHODS

Baseline abdominal computerized tomography (CT) was performed on three unfixed cadaveric specimens. The hydrogel was injected transduodenally into the interface between the HOP and duodenum using linear-array EUS and a 19G needle for fine needle aspiration (FNA). This procedure was repeated along the length of the HOP. CT imaging and gross dissection were performed after the procedure to confirm the localization of the hydrogel and to measure the distance between the HOP and the duodenum.

RESULTS

All cadavers underwent successful EUS-guided injection of the hydrogel. Cadavers 1, 2, and 3 were injected with 9.5, 27, and 10 cc of hydrogel, respectively; along the HOP, the formation of the peri-pancreatic space was a maximum size of 11.77, 13.20, and 12.89 mm, respectively. The hydrogel injections were clearly visualized as hyperechoic bullae during EUS and on post-procedure CT images without any artifacts in all cases.

CONCLUSIONS

We demonstrated that EUS-guided delivery of hydrogel is feasible, and that it increases the peri-pancreatic space in a cadaveric model. The polyethylene glycol (PEG) hydrogel was clearly visible on EUS and CT, without significant artifacts. This may lead to new treatment approaches for pancreatic carcinomas.

Subdermal injection of hyaluronic acid to decrease skin toxicity from radiation delivered with low-dose-rate brachytherapy for cancer patients

Purpose

To study the feasibility of hyaluronic acid (HA) injection to increase the distance between skin and radioactive sources, and dose reduction of skin during low-dose-rate (LDR) brachytherapy.

Material and methods: A total of 11 patients with subdermal malignant tumors were enrolled in this study. HA was injected after I-125 seed implantation, and dosimetric parameters were calculated by a brachytherapy treatment planning system (BTPS). The distance of the new space between radioactive sources and skin was measured on computed tomography (CT) and magnetic resonance imaging (MRI). Clinical signs were observed and followed up for every patient.

Results

After HA injection, the average of newly generated maximum distance was 1.0 cm along the entire length of the tumor. The D₉₀ and V₁₀₀ did not significantly change for tumors before or after injection (p = 0.39, p = 0.50, respectively). The maximum dose to a relatively small volume (0.1 cc) of the skin (OAR-Max) decreased from 100.66 Gy to 61.20 Gy (p < 0.05), and the mean skin dose (OAR-Mean) decreased from 49.20 Gy to 17.27 Gy (p < 0.05) after injection. On follow-up CT and MRI, HA was quite stable in shape and position for nearly 6 months.

Conclusions

Our study results showed that an additional 1.0 cm distance between the radioactive source and skin could be induced by HA injection in patients with subdermal tumor, and this distance could significantly decrease the skin dose in LDR brachytherapy. In addition, no obvious toxicity and side effects were produced by HA injection. Therefore, hyaluronic acid injection is a safe and effective technique.

MRI findings of absorbable hydrogel spacer for prostate cancer therapy: a pictorial review

Prior studies have shown that dose-escalated radiation therapy for prostate cancer improves clinical outcomes. However, this is associated with increased rectal toxicity. Hydrogel spacer for prostate cancer therapy is an effective way of decreasing rectal toxicity in the late post-therapeutic stages. In some occasions, the gel spacer may not be placed symmetrically between the rectum and prostate. There are several forms of a malpositioned spacer, including lateral displacement, rectal wall infiltration, and prostate capsule infiltration. This manuscript is aimed at evaluating appropriately positioned and malpositioned gel spacers, primarily via magnetic resonance imaging. There are limited educational imaging guides that address what radiologists should evaluate on post-spacer placement imaging. This pictorial review will specifically evaluate post-injection pitfalls such as asymmetry, rectal wall infiltration, and subcapsular injection.

Rectal radiation dose-reduction techniques in prostate cancer: a focus on the rectal spacer

Prostate cancer is the most common cancer in men. External beam radiotherapy by a variety of methods is a standard treatment option with excellent disease control. However, acute and late rectal side effects remain a limiting concern in intensification of therapy in higher-risk patients and in efforts to reduce treatment burden in others. A number of techniques have emerged that allow for high-radiation dose delivery to the prostate with reduced risk of rectal toxicity, including image-guided intensity-modulated radiation therapy, endorectal balloons and various forms of rectal spacers. Image-guided radiation therapy, either intensity-modulated radiation therapy or stereotactic ablative radiation therapy, in conjunction with a rectal spacer, is an efficacious means to reduce acute and long-term rectal toxicity.