Esophageal gel-shifting technique facilitating eradicative boost or reirradiation to upper mediastinal targets of recurrent nerve lymph node without damaging esophagus

The Use of Hydrogel-Based Materials for Radioprotection

Major causes of the radiation-induced disease include nuclear accidents, war-related nuclear explosions, and clinical radiotherapy. While certain radioprotective drug or bioactive compounds have been utilized to protect against radiation-induced damage in preclinical and clinical settings, these strategies are hampered by poor efficacy and limited utilization. Hydrogel-based materials are effective carriers capable of enhancing the bioavailability of compounds loaded therein. As they exhibit tunable performance and excellent biocompatibility, hydrogels represent promising tools for the design of novel radioprotective therapeutic strategies. This review provides an overview of common approaches to radioprotective hydrogel preparation, followed by a discussion of the pathogenesis of radiation-induced disease and the current states of research focused on using hydrogels to protect against these diseases. These findings ultimately provide a foundation for discussions of the challenges and future prospects associated with the use of radioprotective hydrogels.

Hyaluronic acid gel injection in rectovaginal septum reduced incidence of rectal bleeding in brachytherapy for gynecological malignancies

PURPOSE

The purpose of this study was to report our initial clinical results of hyaluronic acid gel injection (HGI) in the rectovaginal septum (RVS) to reduce the incidence of rectal bleeding in vaginal brachytherapy for gynecologic malignancies.

METHODS AND MATERIALS

Since 2008, CT based image-guided adaptive brachytherapy (IGABT) was initiated, and since 2015, HGI in the RVS was introduced in our institution. Vaginal cylinder with or without tandem or additional interstitial needles were applied for patients with gynecologic malignancies. Rectum dosimetric parameters and incidence of late rectum bleeding were compared between patients with and without HGI in the RVS.

RESULTS

Between May 2008 and October 2017, 83 patients with gynecologic malignancies were treated with IGABT involving vaginal cylinder. Eleven patients who were treated for palliative intention were excluded, and 72 patients were subjected to the analysis. Of the total 72 patients 46 were with uterine cervical cancer, 19 uterine corpus cancer, five vaginal cancer, one vulvar cancer, and one ovarian cancer. Fifteen and 57 patients were irradiated with and without HGI in the RVS, respectively. With a median follow-up period of 57.7 (4.7-123.1) months, 30 (41.7%) patients suffered from radiation-related rectal bleeding. Patients with HGI in the RVS had a statistically significant lower incidence of rectal bleeding compared with those without it (13.3% vs. 49.1%, p = 0.01).

CONCLUSIONS

HGI in the RVS reduced the incidence of late rectal bleeding for patients with gynecologic malignancies treated by vaginal cylinder and was not associated with HGI-procedure-related adverse events.

Hyaluronic gel injection into the vesicovaginal septum for high-dose-rate brachytherapy of uterine cervical cancer: an effective approach for bladder dose reduction

Purpose

The purpose of this study was to report our initial experience of hyaluronic acid gel injection (HGI) in the vesicovaginal septum (VVS) for bladder dose reduction in brachytherapy (BT) for uterine cervical carcinoma.

Material and methods

Between September 2016 and May 2018, 15 uterine cervical cancer patients received HGI in the VVS as a part of their definitive radiotherapy (RT) treatment consisting of external beam radiation therapy (EBRT) with additional BT. Of those, 9 patients received BT both with and without HGI, and remaining 6 patients were excluded because these 6 patients received HGI in the VVS for all BT fractions. All 9 patients received HGI in the rectovaginal septum. For these patients, the dosimetric parameters bladder D_2cc, HR-CTV D₉₀, and rectum D_2cc were selected, and two groups were generated (BT with vs. without HGI in the VVS) for dosimetric comparison.

Results

The median cumulative EQD₂ for HR-CTV, rectum D_2cc, and bladder D_2cc for the 9 patients were 73.3, 52.8, and 67.1, respectively. While no statistical difference could be detected for rectal dose reduction, bladder dose was significantly less in the group with HGI in the VVS compared to that without (449 cGy [range, 416-566, 1SD = 66.1] vs. 569 cGy [range, 449-647, 1SD = 59.5], p = 0.033), with no compromising of target coverage. Although it did not reach statistically significance, there was a trend toward better HR-CTV D₉₀ in the group with HGI compared to that without HGI in the VVS (713 cGy vs. 706 cGy, p = 0.085). No severe bleeding, hematuria, bladder wall injury, or urethral injury requiring hospitalization was experienced in association with HGI in the VVS.

Conclusions

HGI in the VVS can be performed safely and can effectively reduce the bladder dose in BT for uterine cervical cancer patients.

The role of radioprotective spacers in clinical practice: a review

The delivery of high dose radiotherapy to tumors is often limited by the proximity of the surrounding radiosensitive normal tissues, even using modern techniques such as intensity modulated radiation therapy (IMRT). Previous studies have reported that placement of a spacer can effectively displace normal tissues. So that they are some distance away from the lesion, thus allowing for the safe delivery of high-dose radiation. The application of radioprotective spacers was first reported 30 years ago regarding radiotherapy of tongue and abdominal cancers; more recently, they are increasingly being used in prostate cancer. This review focuses on the published data concerning the features of different types of spacers and their application in various tumor sites. Placement-related complications and the cost-effectiveness of the spacers are also discussed. With the increasing use of high-precision radiotherapy in clinical practice, especially the paradigm-changing stereotactic body radiotherapy (SBRT), more robust studies are warranted to further establish the role of radioprotective spacers through materials development and novel placement techniques.

Interdisciplinary consensus statement on indication and application of a hydrogel spacer for prostate radiotherapy based on experience in more than 250 patients

Background

The aim of the study was to reach a consensus on indication and application of a hydrogel spacer based on multicentre experience and give new users important information to shorten the learning curve for this innovative technique.

Methods

The interdisciplinary meeting was attended by radiation oncologists and urologists, each with experience of 23 – 138 hydrogel injections (SpaceOAR®) in prostate cancer patients before dose-escalated radiotherapy. User experience was discussed and questions were defined to comprise practical information relevant for successful hydrogel injection and treatment. Answers to the defined key questions were generated. Hydrogel-associated side effects were collected to estimate the percentage, treatment and prognosis of potential risks.

Results

The main indication for hydrogel application was dose-escalated radiotherapy for histologically confirmed low or intermediate risk prostate cancer. It was not recommended in locally advanced prostate cancer. The injection or implantation was performed under transrectal ultrasound guidance via the transperineal approach after prior hydrodissection. The rate of injection-related G2-toxicity was 2% (n = 5) in a total of 258 hydrogel applications. The most frequent complication (n = 4) was rectal wall penetration, diagnosed at different intervals after hydrogel injection and treated conservatively.

Conclusions

A consensus was reached on the application of a hydrogel spacer. Current experience demonstrated feasibility, which could promote initiation of this method in more centres to reduce radiation-related gastrointestinal toxicity of dose-escalated IGRT. However, a very low rate of a potential serious adverse event could not be excluded. Therefore, the application should carefully be discussed with the patient and be balanced against potential benefits.