A new study published in the ‘Journal of Medical Radiation Sciences’ has found that stabilised hyaluronic acid (sHA) gel can be safely and effectively used as a rectal spacer during radiation treatment for gynaecological cancers. Conducted by clinician-researchers from Austin Health in Australia, the research is the “first” to test this technique in women undergoing MRI-guided brachytherapy, a form of internal radiation therapy used to treat cancers of the cervix, uterus, vagina, and surrounding pelvic organs.
The gel, already approved by Australia’s Therapeutic Goods Administration (TGA) for prostate cancer radiotherapy, was used to gently create additional space between the tumour and the rectum. This separation aims to protect healthy tissue from radiation damage while allowing doctors to deliver higher, more targeted doses of radiation to cancerous cells.
Considering the global burden of gynaecological cancers, the findings carry major clinical relevance. In 2022 alone, an estimated 14 lakh women worldwide were diagnosed with gynaecological cancers, while more than 6 lakh deaths were recorded.
These cancers remain a leading cause of morbidity among women, particularly in low- and middle-income countries where access to advanced radiation technologies remains uneven. The ability to improve treatment precision while reducing side effects could represent a meaningful step forward in patient care.
What the study found
The Austin Health-led research was designed as a single-institution prospective feasibility study involving patients receiving MRI-guided gynaecological brachytherapy (GynBT). According to the published methodology, “this single institution prospective study included patients with gynaecological cancers receiving magnetic resonance imaging (MRI)-guided GynBT.”
Feasibility was evaluated across multiple parameters, including technical success, clinician experience, spacer visibility on imaging, and stability of the spacer throughout the treatment course.
A total of 12 patients were enrolled in the study. In all participants, the insertion of stabilised hyaluronic acid gel into the rectovaginal space was successfully achieved without any spacer-related complications. Clinicians reported that the gel was easy to administer and demonstrated high visibility on transrectal ultrasound (TRUS), receiving ratings between four and five, while offering excellent visibility on MRI scans.
One of the most clinically important outcomes was the increase in distance between the tumour target and the rectum. Following spacer insertion, the average separation increased by 7.82 millimetres, a statistically significant change. During the brachytherapy course, although the volume of the gel reduced slightly and minor changes were observed in craniocaudal dimensions, the critical target-to-rectum distance remained stable. This stability is essential to ensure consistent radiation protection throughout treatment sessions.
“Insertion of sHA gel rectal spacer is technically feasible and safe in GynBT, increasing the separation between the target and rectum. The sHA gel spacer is easy to use, highly visible on both TRUS and MRI, and stable during the entire GynBT course,” the researchers concluded.
From a clinical perspective, this spacing effect is vital. By physically separating the rectum from the radiation field, oncologists can reduce radiation exposure to surrounding healthy tissue. This enables the delivery of more aggressive tumour-targeted radiation doses, potentially improving cancer control rates while lowering the risk of painful and long-term bowel complications.
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Importantly, patients did not report discomfort related to the spacer placement, and the gel naturally dissolves within the body over time, as previously observed in prostate cancer treatment settings.
Dr Carminia Lapuz from Monash University said, "This study is a world-first in exploring stabilised hyaluronic acid (sHA) gel's potential to improve outcomes for patients undergoing brachytherapy for gynaecological cancers. Our findings show the procedure is safe, feasible, and offers promising technical advantages.”
"By increasing the distance between the tumour and the rectum, we hope to pave the way for safer, more effective treatments and greater equity in cancer care,” Lapuz added.
Strengths and limitations of the study
The researchers highlighted several strengths that make this study clinically meaningful. One of the major advantages was the exploration of a new application of sHA gel in a patient population that is particularly vulnerable to radiation-induced rectal toxicity.
“Study strengths include the exploration of a new and important application of sHA in a population at high risk for radiation-induced rectal toxicities or with challenges achieving adequate tumour dose due to adjacent OAR constraints,” the authors noted.
The study also demonstrated consistent spacer stability across multiple brachytherapy sessions, high imaging visibility, and absence of significant spacer-related adverse events.
If these results are validated in larger clinical trials, the authors believe the technique could become a key strategy for tumour dose escalation while protecting organs at risk. They also emphasised its potential impact on gender equity in radiation oncology. “It would also provide evidence for gender-equitable access to this spacer technology when current indications for use are only in prostate cancer,” the researchers wrote.
However, several limitations were acknowledged. The study was conducted at a single centre with a small sample size of just 12 patients, which limits the generalisability of the findings across different healthcare settings. The focus was primarily on technical feasibility and clinician experience rather than long-term patient outcomes.
“There are several limitations to this study. This is a single-centre feasibility study and therefore patient numbers are small, with findings not generalisable to all clinical settings,” the authors stated. They also noted that further research is required to evaluate radiation dose distribution, long-term toxicities, and patient-reported outcomes.
Future studies, the team suggested, should also focus on refining the technique, improving training protocols, and ensuring reproducibility across institutions and radiation oncology teams.
Why is this significant?
Gynaecological cancers continue to impose a heavy burden globally and particularly in India. Ovarian and cervical cancers remain among the most common malignancies affecting women. Cervical cancer, in particular, is the second most common cancer among Indian women after breast cancer. Each year, approximately 1.23 lakh women in India are diagnosed with cervical cancer, and around 67,477 deaths are reported from the disease.
Brachytherapy plays a central role in the treatment of locally advanced cervical and other pelvic cancers. An Indian retrospective study conducted at a tertiary teaching hospital between January 2021 and January 2023 examined the outcomes of image-guided brachytherapy (IGBT) among 130 patients referred after external beam radiation therapy.
According to the study, all patients successfully received brachytherapy using intracavitary or interstitial techniques. The researchers reported acceptable radiation dose distributions to critical organs such as the bladder, rectum, and sigmoid colon. However, the study also highlighted systemic challenges, including delays in referral pathways and treatment timelines.
The authors concluded, “This study highlights the established advantages of image-guided interstitial brachytherapy and associated challenges. To optimise the overall treatment duration, it is imperative to prioritise and update the referral processes for brachytherapy centres.”
Globally, earlier research has already demonstrated the potential of hyaluronic acid gel in reducing radiation exposure to healthy tissues. A 2019 study evaluating perirectal hyaluronate gel injection in gynaecologic brachytherapy reported significant reductions in rectal radiation dose without affecting tumour coverage.
“In all cases, HGI was well tolerated, with no acute or late adverse events documented,” the researchers reported. Rectal radiation exposure decreased significantly, while tumour dose coverage remained unchanged. The study concluded that the technique was “plausible” and “effective for rectal dose reduction in radiotherapy of intrapelvic tumours.”
Further supporting this evidence, a 2020 long-term clinical study examined the use of hyaluronic acid gel injection into the rectovaginal septum to reduce radiation-induced rectal bleeding. Among 72 patients followed for nearly five years, those who received the gel spacer experienced significantly lower rates of late rectal bleeding compared to those who did not.
“Patients with HGI (hyaluronic acid gel injection) in the RVS (rectovaginal septum) had a statistically significant lower incidence of rectal bleeding compared with those without it,” the researchers reported. Importantly, no procedure-related adverse effects were observed.
This story is done in collaboration with First Check, which is the health journalism vertical of DataLEADS.
