ESTRO 2025 - Abstract Book

S208

Brachytherapy - Gynaecology

ESTRO 2025

volume parameters and aspects of 3D image-based anatomy, radiation physics, radiobiology. Radiother Oncol 2006;78:67–77.

347

Proffered Paper Efficacy and safety of the pudendal nerve block as a component of multi-modal analgesia for cervical brachytherapy Matthew C Knox 1,2 , Niluja Thiruthaneeswaran 1,2 , George Zhong 3 , Alison Brand 4,2 , Unine Herbst 4,2 , Emily Flower 1,2 , Jennifer Chard 5 , Alison Salkeld 1,2 1 Department of Radiation Oncology, Western Sydney Local Health District, NSW, Australia. 2 Sydney Medical School, University of Sydney, NSW, Australia. 3 Department of Anaesthesia, Western Sydney Local Health District, NSW, Australia. 4 Department of Gynaecological Oncology, Westmead Hospital, NSW, Australia. 5 Department of Radiation Oncology, Peter MacCallum Cancer Centre, VIC, Australia Purpose/Objective: Although an essential component of curative management, cervical brachytherapy is associated with considerable pain and discomfort. [1] Current pain management protocols vary widely between institutions, commonly including intravenous opioids or neuraxial approaches. [2] Whilst pilot studies have explored pudendal nerve block (PNB) as a potential analgesic adjunct, we present the first series examining the routine use of PNB in conjunction with general anaesthesia after cervical brachytherapy. Material/Methods: We conducted a retrospective review of patients receiving brachytherapy for cervical malignancies across two time periods, correlating to the local institutional introduction of PNB practice. Technically, the radiation oncologist instilled 10mL 1% ropivacaine bilaterally using a transvaginal landmark technique following induction of general anaesthesia. Patient-controlled analgesia (PCA) with intravenous fentanyl was used post-operatively whilst applicators were in-situ. MR-guided intracavitary +/- interstitial brachytherapy was performed as per the EMBRACE-2 protocol. [3] Median pain scores (11-point patient-reported numerical rating scale), acceptability of pain (defined as <20% of recorded scores ≥4), opioid consumption and incidence of adverse events are reported. Results: 78 patients receiving 149 brachytherapy insertions were included, with 95 insertions (63.8%) utilising PNB. Over 50% of patients had FIGO (2018) stage 3C disease and 48% of cases required interstitial needles in both cohorts (>33% of all cases had ≥3 needles), with no significant differences in patient demographics. There was no difference in median cumulative EQD2 to D90% of the HR-CTV between cohorts (90.8Gy vs 91.5Gy; p=0.281). As shown in Figure 1, median pain scores were lower in the PNB cohort (1 vs. 2.5; p=0.003). PNB was also associated with less episodes of unacceptable pain, as defined above (33% vs. 63%; p<0.001). This benefit was sustained on binomial logistic regression, adjusting for co-variates including number of interstitial needles, applicator model selection, primary proceduralist, intra-operative dexamethasone usage or baseline opioid usage. PNB was associated with a reduction in median hourly oral morphine equivalent dose delivered via PCA (6.2mg vs 14mg; p<0.001). There were no differences in the incidence of hypotension, respiratory depression or nausea between cohorts (see Table 1). There were no instances of haemorrhage, neuropraxia, local anaesthetic systemic toxicity or operator injury (e.g. needle-stick) identified.