Standardisation of surgical techniques
The success of cancer surgery largely depends on achieving appropriate resection margins and adhering to tumour-free surgical principles during the procedure, that is, standardised surgery. In cervical cancer surgery, the central challenge lies in achieving optimal radical resection. Both MIS RH and open RH require adequate dissection of the sub-peritoneal avascular spaces in the pelvis. Our experience emphasises that standardising avascular spaces is key to ensuring surgical homogeneity.9 Dissecting well-defined spaces facilitates uniform tissue removal, which enhances the homogeneity of surgeries. However, these spaces are traditionally believed not to exist naturally but to be surgically created. If these spaces are artificially formed, their standardisation becomes challenging, potentially introducing biases during procedures and leading to variations in resection margins and surgical scope. Additionally, we have clinically observed that MIS practitioners frequently used energy devices to dissect and expose blood vessels. Unlike abdominal RH, which employs en bloc tissue clamping and excision, we are concerned that this approach may leave perivascular adipose tissue unremoved, potentially harbouring occult metastatic tumours and compromising the radicality of the surgery. Therefore, we propose that the extensive use of energy devices and sharp dissection in MIS RH may further amplify inconsistencies in opening these spaces, potentially introducing biases in surgical quality. From an ontogenetic perspective, primordia are defined as clusters of primitive cells that develop into compartments with boundaries where cell mixing does not occur—an ideal concept for cancer resection.12 This implies the existence of natural spaces between organ boundaries. Embryologically based anatomical surgery, such as total mesorectal excision and TMMR, has excellent oncological outcomes.11 13 However, during the development of these techniques, the natural spaces and resection boundary landmarks were not clearly defined, making the identification of surgical landmarks ambiguous.14 The spaces surrounding the Müllerian duct, which are critical to dissect during RH, are particularly complex. Although Höckel and his team studied uterovaginal development using serial sections of female human embryos and fetuses, defining the distal Müllerian morphogenetic unit from the Müllerian mesenchyme, they did not clearly outline the relevant anatomical spaces or surgical landmarks.15 Their modified surgery for stage IB-IIB cervical carcinoma, TMMR, aims to remove the uterus, proximal vagina and extra-cervical mesenchyme within the borders of the distal Müllerian morphogenetic unit. However, the lack of clear anatomical markers and standardised dissection methods for TMMR limits its widespread adoption and makes Höckel’s surgical outcomes difficult to replicate. Therefore, TMMR is considered merely a meticulous RH; while the concept remains compelling, it is still largely hypothetical and requires further refinement to become a practical surgical approach.14
Recently, based on long-term laparoscopic anatomical observations, we have identified three crucial characteristics of natural space: smooth membranous planes on both sides, visible vascular networks underneath the membrane and the feasibility of blunt expansion of the space.16 Building on these features, we systematically explored the spaces within the pelvis. Specifically, the borders of the Müllerian unit are divided into ventral and dorsal sections by the uterine vasculature laterally limited by the medial aspect of the internal iliac vessels (figure 1). The ventral space is divided into the median and lateral spaces by the uterine artery’s vesical branch(es) with accompanying superficial vesical veins (figure 1). The bilateral uterosacral ligaments divide the dorsal space into the median and lateral spaces (figure 1).16 In clinical practice, we have repeatedly observed that dissecting along these characteristic spaces surrounding the Müllerian compartment often reveals six main vascular ‘outlets’ supplying the Müllerian compartment (ie,(1) the uterine artery and the superficial uterine vein; (2) the vesical branch of the uterine artery with the superficial vesical vein; (3) the ureteral branch of the uterine artery; (4) the deep uterine vein; (5) the middle and inferior vesical veins; (6) the vaginal branches of the uterine artery and their accompanying veins), while the inferior hypogastric plexus plane naturally emerges (figure 1).16 This represents a critical insight, as it suggests the potential for standardising RH. That is, this anatomical system provides reproducible anatomical markers for embryologically based organ resection, making it possible to standardise surgical procedures. By ligating and dividing these outlets, transecting the uterosacral ligaments near its sacral attachment, and detaching the vagina, preserving the nerve plane, the Müllerian unit can be removed intact. Based on this system,16 the Müllerian unit’s natural spaces and anatomical landmarks can be identified, achieving reproducible and standardised TMMR. We believe this anatomical system is applicable to both open and MIS procedures, and high-definition laparoscopy may be more suitable for implementation.
Schematic diagram of the ‘spaces’ and ‘outlets’ of the Müllerian compartment. Cross-sectional schematic diagrams depict the ‘spaces’ around the Müllerian compartment. (A) shows the schematic diagram at the cervical level, while (B) illustrates the schematic diagram at the vaginal level. The black dashed lines indicate the surrounding spaces and scope of the Müllerian compartment, while the yellow dashed lines represent the continuation of the compartment at the ‘outlet’ sites. Arteries are annotated in red, veins are annotated in blue, and nerves are annotated in yellow. (C) shows the right lateral view of the inferior hypogastric plexus (IHP) plane. The IHP was formed by contributions from the hypogastric nerves (HP), branches from the ventral rami of the second, third and fourth sacral nerves (S2, S3 and S4), and branches from the sacral sympathetic trunk (SST) which coursed medial or just anterior to the sacral foramina. IIA, internal iliac artery; IIV, internal iliac vein; U, ureter; USL, uterosacral ligament; a., artery; s., space.
Finally, the standardisation and success of cancer surgery relies heavily on strict adherence to tumour-free surgical principles. During the early development of MIS for cervical cancer, breaches of these principles were likely to have occurred. The use of transcervical uterine manipulators and unprotected vaginal openings was widely practised during the LACC trial and earlier, and these practices were considered violations of tumour-free surgical principles. Currently, uterine manipulator-free surgery has been widely adopted. Techniques such as vaginal incision through the vaginal route, transvaginal ligation and closure of the upper vagina and cervix prior to incision, or laparoscopic ligation of the upper-mid vagina followed by incision distal to the ligature have proven effective in preventing tumour cell contamination.17 Evidence from systematic reviews suggests that laparoscopic-assisted vaginal hysterectomy demonstrates no significant impact on DFS or overall survival in patients with early-stage cervical cancer, which is comparable with the open approach group of the LACC trial.18 It is important to recognise that MIS for cervical cancer surgery is continuously evolving and improving toward greater refinement.
