Initial experience with magnetic resonance imaging-guided selective lateral pelvic lymph node dissection in the era of total neoadjuvant therapy: a single-centre descriptive cohort and technical review

Introduction

Colorectal cancer is among the most common malignancies worldwide and accounts for a substantial proportion of global cancer incidence and mortality (1). Over recent decades, the adoption of total mesorectal excision (TME) and high-quality pre-operative magnetic resonance imaging (MRI) has transformed the management of rectal cancer, improving local control and reducing positive circumferential resection margins (2-5). Neoadjuvant chemoradiotherapy followed by TME became the standard approach for locally advanced rectal cancer, significantly lowering pelvic recurrence, particularly in mid and low tumours (2-6).

Total neoadjuvant therapy (TNT), in which all systemic chemotherapy is delivered before surgery along with long-course chemoradiotherapy or short-course radiotherapy, has emerged as a new standard for many patients with stage II–III rectal cancer (7). Randomised trials such as PRODIGE 23 and RAPIDO have demonstrated improved pathological response, higher complete response rates and improved diseasefree survival with TNT compared with conventional sequencing (8,9). Longer-term follow-up confirms durable benefits in disease-free and metastasis-free survival, although, no overall survival benefit was seen in RAPIDO (9,10). TNT has also facilitated organ-preserving strategies, including watch-and-wait, in a substantial subset of patients with complete clinical response (11-13).

Despite these improvements, locoregional failure still occurs, and a significant proportion of pelvic recurrences arise from the lateral compartment (14). The lateral pelvic lymphatic pathway, including internal iliac, obturator and external iliac nodes, lies outside the mesorectal envelope and is not routinely removed by standard TME (14,15). Metastatic involvement of lateral pelvic lymph nodes (LPLNs) is reported in approximately 7–15% of patients with low, locally advanced rectal cancer, particularly when there is radiologic evidence of enlarged lateral nodes at baseline (16,17). Untreated disease in this compartment is a major cause of lateral pelvic recurrence and impaired quality of life (17).

There has been longstanding controversy about whether LPLNs should be regarded as regional or metastatic disease and how best to manage them. The current Japanese colorectal cancer treatment guidelines explicitly recommend lateral pelvic lymph node dissection (LPLND) (18). Furthermore, several other Eastern centres consider LPLNs below the peritoneal reflection as regional nodes, and TME with prophylactic bilateral LPLND is a standard operation for stage II–III low rectal cancers (14,15). The landmark JCOG0212 trial showed that adding bilateral LPLND to TME reduced lateral pelvic recurrence compared with TME alone, but at the cost of longer operative time, greater blood loss (19), however, higher rates of urinary dysfunction were not seen (20). Meta-analyses confirm that LPLND reduces lateral local recurrence but is associated with increased operative morbidity and functional impairment (21,22).

Western practice has historically differed, treating LPLNs as a site of metastatic disease and favouring neoadjuvant chemoradiotherapy (or TNT) and TME alone, reserving LPLND for a small subset of patients with persistent radiologically suspicious lateral disease (15,23,24). High-resolution MRI has clarified the prognostic role of nodal size, location and morphology. However, the size criteria for enlarged LPLNs remain under discussion and are context-specific, varying according to baseline versus restaging MRI and nodal compartment, with widely cited thresholds including 7 mm short-axis at baseline and lower compartment-specific cut-offs on restaging (16,17,25-27). However, those who meet criteria on baseline imaging or with malignant morphological features and nodal multiplicity, are associated with high lateral pelvic recurrence rates when managed with chemoradiotherapy and TME alone and thus carry additional prognostic information (16,17,25,28). Conversely, nodes that shrink below low-risk thresholds and lose aggressive features after neoadjuvant therapy appear to carry a much lower risk of lateral failure (16,17,25,29). Accordingly, any single universal 5 mm rule should be interpreted cautiously; in the present cohort, this threshold was used pragmatically to identify potentially abnormal nodes for descriptive follow-up rather than to define a practice standard.

At the same time, the technical landscape of LPLND has evolved. Traditionally, open LPLND was associated with considerable blood loss and high rates of urinary and sexual dysfunction, limiting its acceptance outside high-volume Eastern centres (14,21-23). Modern laparoscopic and robotic techniques now allow more precise, nerve-sparing dissection, with reduced blood loss, shorter length of stay and functional outcomes that are comparable to, or better than, open surgery, while maintaining oncologic adequacy (30-33). Contemporary reviews and consensus statements emphasise MRI-guided selective LPLND rather than routine prophylactic dissection (15,23,24,34).

As TNT becomes widely adopted, centres increasingly encounter patients with enlarged LPLNs at baseline or on restaging. However, Western real-world data describing how LPLNs behave under TNT and how MRI-guided selective LPLND can be integrated safely into a TNT pathway remain limited—particularly in lower-volume settings where the operation is not routinely performed. Early implementation reports can help standardise imaging assessment, multidisciplinary decision-making and referral pathways while larger prospective datasets mature.

The aim of this work is twofold. First, we describe our initial institutional experience tracking the radiologic evolution of enlarged LPLNs during TNT in a single Australian centre and report currently available follow-up, explicitly recognising that the cohort is not powered to validate imaging thresholds or quantify oncologic benefit. Second, we synthesise contemporary evidence on technical approaches to LPLND—including open, laparoscopic, robotic, extraperitoneal and transanal techniques—with a focus on practical considerations relevant to selective LPLND in TNT-treated patients. We present this article in accordance with the STROBE reporting checklist (available at https://ales.amegroups.com/article/view/10.21037/ales-2025-1-79/rc).

Methods

Study design and patient selection

We conducted a retrospective study of all patients with rectal adenocarcinoma treated with TNT at the Cairns & Hinterland Hospital and Health Service in Australia between 1 January 2020 and 31 August 2023. Patients were identified from a prospectively maintained colorectal cancer database, cross-referenced with oncology and radiology information systems. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Human Research and Ethics Committee of Cairns & Hinterland Hospital and Health Service (No. EX/2023/QCH/102364 – 1770 QA) and individual consent for this retrospective analysis was waived.

Inclusion criteria were histologically confirmed rectal adenocarcinoma, treatment with TNT for locally advanced disease with curative intent and completion of the planned TNT regimen. Patients were excluded if they did not complete TNT (for example: due to toxicity, progression of disease or withdrawal of consent) or if they underwent palliative treatment. The flowchart for patient inclusion is demonstrated in Figure 1.

Figure 1 Flowchart of patients included in the study. MRI, magnetic resonance imaging; TNT, total neoadjuvant therapy.

Demographic and clinical data collected included age, sex, comorbidities, body mass index, performance status and clinical tumour stage including nodal status. Baseline characteristics for patients can be seen in Table 1. Details of TNT regimens were recorded, including chemotherapy agents, sequencing (induction versus consolidation relative to chemoradiotherapy), radiotherapy dose and field design.

Imaging and definition of LPLN status

All patients underwent baseline high-resolution pelvic MRI at diagnosis and repeat MRI after completion of TNT according to institutional protocols. MRI studies were only reported by consultant radiologists as part of routine care.

For this study, LPLNs were considered radiologically abnormal if they measured at least 5 mm in short-axis diameter on baseline MRI. We used this as a pragmatic threshold to capture potentially abnormal nodes for descriptive cohort analysis, not as a validated universal decision rule. Nodes were categorised by compartment (internal iliac, obturator or external iliac). On post-TNT MRI, LPLNs were classified as completely resolved if they were no longer visible, radiologically responsive if still visible but regressed to short-axis diameter <5 mm, or radiologically persistent if short-axis diameter remained ≥5 mm.

An independent consultant radiologist, blinded to clinical and pathological outcomes, reviewed all MRI scans and validated LPLN measurements. Discrepancies were resolved by consensus. Morphological features such as border irregularity, shape and signal heterogeneity were also noted as part of this retrospective analysis.

Surgical and pathological outcomes

After TNT and restaging MRI, patients were discussed at a multidisciplinary team meeting to determine the optimal local treatment strategy, including TME, extent of resection and whether LPLND was indicated. Decisions to perform LPLND were made on a case-by-case basis, taking into account residual nodal size, morphology, location, patient factors and surgeon experience.

For patients who proceeded to surgery, operative details were recorded, including procedure type (anterior resection, abdominoperineal resection, pelvic exenteration), operative time, estimated blood loss, use of minimally invasive or open approaches and whether LPLND was performed. Post-operative complications within 30 days were graded using the Clavien-Dindo classification.

Histopathology reports were reviewed for tumour regression grade, ypT and ypN stage, mesorectal and lateral nodal status, presence of extranodal or extramural tumour deposits, circumferential resection margin status and distal margin status. Where LPLND was performed, the number of lateral nodes retrieved, and the presence of metastatic disease were recorded. Follow-up data included the use of adjuvant chemotherapy, dates and sites of local or distant recurrence and survival status at most recent follow-up (22 March 2026).

Outcomes

The primary outcome for the cohort was the change in LPLN size category between pre- and post-TNT MRI in patients with baseline radiologically abnormal LPLNs. Secondary outcomes included the presence of residual tumour in LPLNs on histopathology, 12-month mortality and any evidence of local or distant recurrence at most recent follow-up.

Statistical analysis

Given the relatively small sample size and descriptive nature of this cohort, no formal hypothesis testing was planned. Data are presented descriptively, with proportions or medians and ranges where appropriate.

Narrative review of technical approaches to LPLND

We performed a narrative review of technical approaches to LPLND, informed by searching PubMed, Embase, Ovid MEDLINE and the Cochrane Central Register of Controlled Trials for studies published between January 1990 and October 2025. The search combined terms for rectal cancer and LPLNs with terms for surgical modality: (“rectal cancer” OR “rectal neoplasms”) AND (“lateral pelvic lymph node” OR “pelvic sidewall dissection” OR “obturator lymph node”) AND (“open” OR “laparoscopic” OR “robotic” OR “extraperitoneal” OR “transanal” OR “TME”). Reference lists of relevant articles and major reviews were screened manually to identify additional publications. Only English-language articles were considered (15,21,23,30-34).

Randomised trials, prospective and retrospective cohort studies, case series and technical reports describing LPLND for primary or recurrent rectal cancer were included if they reported operative technique, peri-operative outcomes, functional outcomes or oncologic outcomes. Studies in which LPLND was performed after neoadjuvant therapy, including TNT, were of particular interest. Reference lists of relevant papers and contemporary reviews were screened to identify additional studies (15,34).

Because of heterogeneity in patient populations, indications, neoadjuvant regimens, surgical templates and outcome reporting, a formal meta-analysis was not attempted. Data were synthesised qualitatively to describe key technical principles, peri-operative and functional outcomes and oncologic results across open, laparoscopic, robotic, extraperitoneal and transanal LPLND.

Results

Patient cohort and TNT regimens

During the 3.5-year study period January 2020 until August 2023, 37 consecutive eligible patients with rectal adenocarcinoma commenced TNT at our institution. Six patients did not complete TNT and were excluded, leaving 31 patients in the final cohort. Most had cT3–4 and/or node-positive disease at baseline; the majority of tumours were located in the mid or low rectum. TNT regimens were generally consistent with contemporary evidence and guidelines (7-11). All patients received pelvic radiotherapy encompassing the rectum, mesorectum, presacral space and regional pelvic lymphatics, including the internal iliac and obturator basins. Many received oxaliplatin-based systemic chemotherapy either before or after chemoradiotherapy according to individualised TNT protocols. These have not been separately analysed in our data due to the low numbers of patients included in the study.

Prevalence and behaviour of enlarged LPLNs

Radiologically abnormal LPLNs, defined as short-axis diameter ≥5 mm, were identified on baseline staging MRI in nine of 31 patients (29.0%). These nodes were predominantly located in the internal iliac and obturator compartments.

After completion of TNT, all nine patients with enlarged LPLNs showed a reduction in nodal size on restaging MRI. Four patients (44.4%) had complete radiologic resolution of LPLNs, with nodes no longer visible. Three patients (33.3%) had radiologically responsive LPLNs that remained visible but had regressed to a short-axis diameter <5 mm. Two patients (22.2%) had radiologically persistent LPLNs with a short-axis diameter ≥5 mm. No new radiologically abnormal LPLNs were identified after TNT.

Surgical and pathological outcomes

Eight of the nine patients with baseline abnormal LPLNs proceeded to curative-intent surgery; one patient declined surgery after TNT. Operative procedures comprised ultra-low anterior resection, abdominoperineal resection and pelvic exenteration, reflecting the locally advanced nature of the tumours.

In one patient with persistent high-risk LPLNs on restaging MRI, LPLND was performed in addition to TME after multidisciplinary discussion. This dissection followed standard lateral pelvic templates with nerve-sparing principles and was performed using a minimally invasive approach.

Histopathology of the lateral compartment was available only for the single patient who underwent LPLND. Among the two patients with radiologically persistent LPLNs, one had histopathological evidence of metastatic disease in the lateral compartment, including extranodal tumour extension and a separate extramural tumour deposit. For patients whose nodes had completely resolved or regressed to <5 mm on MRI, pathologic confirmation of lateral nodal sterilisation was not available because LPLND was not routinely performed; however, no lateral pelvic recurrences have been observed in this group during currently available follow-up. All resections achieved R0 margins with negative circumferential resection margins.

Five of the eight patients with baseline LPLN involvement received adjuvant chemotherapy; one declined. There were no deaths as 30 days. Peri-operative complication rates were acceptable, with no anastomotic leaks in this small subgroup.

Oncologic outcomes

At 12-months, there were no local or distant recurrences among the nine patients with baseline enlarged LPLNs, and there were no deaths. Also, within this subgroup, at last follow-up (22 March 2026) there were no recorded deaths and two recurrences (retroperitoneal lymph node, solitary liver metastasis), however, no lateral pelvic recurrences. The patient with the retroperitoneal lymph node recurrence occurred at three years post-operatively and continues on palliative systemic therapy. The patient with the solitary liver metastasis recurred at three years post-operatively, underwent open resection of the colorectal liver metastasis and remains well post-operatively without further systemic treatment.

For all patients included in our study at last follow-up (22 March 2026), there had been no deaths related to colorectal cancer, one death from metastatic non-small cell lung cancer, six recurrences (3× pulmonary, 2× liver, 1× retroperitoneal) and no confirmed lateral pelvic recurrences. Longer-term outcomes are still maturing.

Discussion

Technical approaches to LPLND: summary of evidence

Open LPLND was developed in Japan as a standard component of surgery for low rectal cancer at risk of lateral spread (14,15). Bilateral lymphadenectomy is performed along the internal iliac vessels and obturator fossa after TME, within defined anatomical boundaries. Early series and the JCOG0212 trial established that adding open LPLND to TME reduces lateral pelvic recurrence in stage II/III lower rectal cancer but increases operative time and blood loss compared with TME alone (14). Functional effects are more nuanced, with randomised data not demonstrating a significant increase in urinary dysfunction when modern nerve-sparing techniques are used (20). Meta-analyses suggest that while LPLND improves lateral control, it does not clearly improve overall survival and is associated with higher rates of urinary and sexual dysfunction (21,22).

Open LPLND thus provides a benchmark for oncologic adequacy but has substantial functional costs, which has limited its adoption outside high-volume Eastern centres.

The advent of laparoscopy allowed extension of minimally invasive benefits to lateral dissection. Early laparoscopic LPLND series from Japan showed that the approach is technically feasible and provides lymph-node yields and oncologic outcomes comparable to open LPLND, with reduced blood loss and shorter hospital stay (30,31). A multicentre cohort study demonstrated that laparoscopic LPLND achieved similar local recurrence rates and disease-free survival to open LPLND while reducing blood loss and surgical site infection (31). Laparoscopic LPLND is typically performed after laparoscopic TME using a transperitoneal route. The peritoneum over the external iliac vessels is incised, the obturator fossa is exposed and nodal tissue is cleared along the internal iliac artery and vein to the origin of the superior vesical and internal pudendal arteries (30,31). Identifying and preserving the ureter, hypogastric nerves and pelvic plexus are the key technical steps. Nerve-sparing techniques and improved optics have reduced, but not eliminated, urinary and sexual dysfunction (31).

Robotic platforms offer three-dimensional magnified vision, articulated instruments and improved ergonomics, which are particularly valuable when dissecting around the internal iliac vessels, obturator nerve and autonomic nerves in a fibrotic pelvis after chemoradiotherapy (32,33). Several series have reported robotic LPLND with acceptable operative times, low blood loss and lymph-node yields comparable to open and laparoscopic approaches (32,33). In a comparative study, robotic LPLND achieved similar short-term outcomes to laparoscopic LPLND, with a trend towards better nerve preservation and higher lateral node yield (32). Recent Western experience confirms that robotic LPLND is feasible and safe, even in centres without the longstanding LPLND tradition seen in Japan (33).

Extraperitoneal (totally preperitoneal) approaches to salvage LPLND have been described for patients with isolated lateral pelvic recurrence after prior TME (23,34). By entering through the preperitoneal plane, surgeons can access the lateral compartment without extensive adhesiolysis, potentially reducing bowel-related morbidity and facilitating re-operative dissection in a hostile pelvis (23). Transanal extensions of LPLND have been used in conjunction with transanal TME (taTME) to improve access to distal obturator and internal iliac nodes in narrow male pelvises or obese patients (34). Early reports suggest that transanal or hybrid transabdominal-transanal LPLND is feasible, but data remain limited and the approach is best confined to specialised centres (34).

Contemporary evidence supports MRI-guided selection of patients for LPLND (16,17,25,29). Baseline nodal size, compartment and malignant morphological features (round shape, irregular borders, heterogeneous signal, diffusion restriction) all influence the risk of residual disease or lateral recurrence (16,17,25). In the multicentre lateral node study, nodes ≥7 mm on baseline MRI—especially in the internal iliac compartment—were associated with high lateral pelvic recurrence rates when treated with chemoradiotherapy and TME alone (17). Nodes that remained above specific size thresholds (for example >4 mm in the internal iliac basin or >6 mm in the obturator basin) after neoadjuvant therapy had recurrence rates approaching 20% without LPLND (16,17,25).

Conversely, when enlarged LPLNs respond to neoadjuvant therapy and regress below these thresholds, lateral pelvic recurrence rates are lower in larger series, although not uniformly zero and still modified by malignant morphology and multiplicity (16,17,25). Ishihara and colleagues found that patients with LPLN metastasis treated with chemoradiotherapy and subsequent LPLND had acceptable local control, highlighting the importance of surgical clearance for persistent high-risk nodes (16). A recent meta-analysis confirmed that MRI has good, though imperfect, diagnostic performance for LPLN metastasis (pooled sensitivity around two-thirds and specificity above 80%), supporting its use as a guide for selective dissection (29).

In the TNT era, intensified chemoradiotherapy and systemic chemotherapy may further reduce the burden of lateral nodal disease (7-13). However, TNT-era data suggest that patients with persistent enlarged or morphologically malignant nodes on post-TNT MRI remain a clinically important subgroup, considering their significant risk of lateral recurrence, even if the absolute number of patients benefiting from LPLND is small (16,17,25,34). Recent reviews and expert consensus therefore advocate an MRI-guided, selective LPLND strategy: patients with large or persistent lateral nodes after TNT should be considered for LPLND in experienced centres, while those with small, responsive nodes can safely avoid lateral dissection (15,23,24,34).

Interpretation of findings and implications

In this TNT-treated Western cohort, almost one-third of patients had radiologically enlarged LPLNs at baseline. All such nodes decreased in size after TNT, and the majority either disappeared or regressed below a short-axis diameter of 5 mm. Because only one patient underwent LPLND, our study cannot determine the true rate of pathological sterilisation among nodes that resolved or regressed on MRI. Rather, the clinically relevant observation is that no lateral pelvic recurrences have been observed to date in patients whose nodes resolved or regressed to <5 mm, while one of two patients with radiologically persistent nodes had proven lateral metastatic disease.

These findings, though limited by sample size, broadly align with larger MRI-based series demonstrating that baseline and post-treatment LPLN size strongly predict lateral recurrence (16,17,25,29). In particular, nodes ≥7 mm on baseline imaging and those remaining enlarged after neoadjuvant therapy confer higher risk, whereas threshold selection on restaging is more nuanced and compartment-specific (16,17,25-27). Our data should therefore not be interpreted as validating a universal 5 mm decision rule. Instead, in this small cohort, regression below 5 mm was descriptively associated with absence of observed lateral pelvic recurrence during available follow-up.

MRI is imperfect, with pooled sensitivity around 0.66 and specificity around 0.82 for LPLN metastasis, but it remains the best available modality for lateral nodal assessment (29,34). The addition of diffusion-weighted imaging and careful evaluation of nodal morphology can improve risk stratification beyond size alone (25,34). Future TNT-era studies should prospectively integrate detailed radiologic scoring systems for LPLNs.

From a technical perspective, the review highlights that modern LPLND is no longer synonymous with the morbid open operation that has historically deterred Western surgeons. Laparoscopic and robotic LPLND have demonstrated feasibility, acceptable lymph-node yields and comparable short-term oncologic outcomes to open LPLND in comparative series, with lower blood loss and shorter hospital length of stay in experienced hands (30-33). These statements derive from published comparative cohorts and meta-analyses rather than from our own institutional dataset, in which only one patient underwent LPLND. Nerve-sparing techniques may reduce urinary and sexual dysfunction compared with historical series, although LPLND still carries meaningful functional risk (21,31,32). Other contemporary Western series, including robotic LPLND, suggest that these operations can be performed safely with good short-term outcomes in appropriately selected patients (33).

Nevertheless, lateral dissection remains technically demanding, especially in obese patients and previously irradiated pelvises, and outcomes are closely linked to surgeon and institutional experience (14,21,22,30,31). Obesity is highly prevalent in Australia and much of the Western world (35,36), making extensive lateral dissection more difficult than in populations with lower body mass indices (36). These realities reinforce the importance of careful patient selection, multidisciplinary decision-making and, where appropriate, referral, mentoring or proctorship when introducing selective LPLND.

From an implementation perspective, our early experience underscores the value of a simple, reproducible MDT pathway: baseline high-resolution MRI with compartmental nodal reporting; TNT with radiotherapy fields that include the lateral compartment when high-risk nodes are present; restaging MRI that considers compartment, morphology and treatment response; and selective consideration of LPLND (or referral to experienced centres) for patients with persistent high-risk nodes. We present this as a pragmatic description of our current approach rather than as a prescriptive algorithm.

For patients being considered for watch-and-wait after TNT, persistent suspicious LPLNs are an additional risk factor and should prompt cautious MDT discussion and close surveillance (11-13,17). In practice, durable response of both the primary tumour and the lateral nodes is likely required before non-operative strategies are considered. Our early data, showing no lateral recurrences when nodes regressed to <5 mm, are reassuring but must be interpreted with caution given the small sample and limited follow-up.

Study limitations

This study has several major limitations. It is a retrospective, single-centre analysis with a small number of patients with enlarged LPLNs, which limits generalisability and precludes robust statistical analysis. TNT regimens were not completely uniform, although they broadly reflected current guideline-concordant practice (6-10). Functional outcomes, particularly urinary and sexual function, were not systematically assessed, so we cannot comment on the morbidity of TNT or LPLND in our cohort.

Despite these limitations, this report provides an early TNT-era snapshot from a Western centre and highlights two practical signals: (I) radiologic regression of enlarged LPLNs is common during TNT; and (II) persistence of high-risk nodes can still represent viable metastatic disease. Rather than changing practice, these findings support continued prospective data collection and reinforce the rationale for MRI-guided selective LPLND in appropriately selected patients at experienced centres.

Conclusions

In summary, our initial TNT-era experience suggests that many radiologically enlarged LPLNs regress on restaging MRI, and that selective LPLND—although rarely required in our cohort—can confirm residual lateral compartment metastasis in patients with persistent high-risk nodes. These data should be viewed as an early implementation and hypothesis-generating report. Larger prospective multicentre studies and longer follow-up are needed to define imaging-based selection criteria and to clarify functional and oncologic outcomes of selective LPLND in TNT-treated patients.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://ales.amegroups.com/article/view/10.21037/ales-2025-1-79/rc

Data Sharing Statement: Available at https://ales.amegroups.com/article/view/10.21037/ales-2025-1-79/dss

Peer Review File: Available at https://ales.amegroups.com/article/view/10.21037/ales-2025-1-79/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://ales.amegroups.com/article/view/10.21037/ales-2025-1-79/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Human Research and Ethics Committee of Cairns & Hinterland Hospital and Health Service (No. EX/2023/QCH/102364 – 1770 QA) and individual consent for this retrospective analysis was waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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