Minimally invasive pelvic exenteration for primary or recurrent locally advanced rectal cancer: A glimpse into the future

Abstract

Surgeons have grappled with the treatment of recurrent and T4b locally advanced rectal cancer (LARC) for many years. Their main objectives are to increase the overall survival and quality of life of the patients and to mitigate postoperative complications. Currently, pelvic exenteration (PE) with or without neoadjuvant treatment is a curative treatment when negative resection margins are achieved. The traditional open approach has been favored by many surgeons. However, the technological advancements in minimally invasive surgery have radically changed the surgical options. Recent studies have demonstrated promising results in postoperative complications and oncological outcomes after robotic or laparoscopic PE. A recent retrospective study entitled “Feasibility and safety of minimally invasive multivisceral resection for T4b rectal cancer: A 9-year review” was published in the World Journal of Gastrointestinal Surgery. As we read this article with great interest, we decided to delve into the latest data regarding the benefits and risks of minimally invasive PE for LARC. Currently, the small number of suitable patients, limited surgeon experience, and steep learning curve are hindering the establishment of minimally invasive PE.

Key Words: Locally advanced rectal cancer; Pelvic exenteration; Multivisceral resection; Minimally invasive surgical procedures; Robotic surgical procedures

Core Tip: Minimally invasive and robotic pelvic exenteration (PE) is currently feasible in appropriately selected locally advanced rectal cancer patients. It is associated with decreased postoperative complications and promising oncological outcomes. The disadvantages of establishing minimally invasive PE as the gold standard treatment for these patients are the relatively small sample sizes in studies, the limited experience of surgeons, and the lack of long-term data on oncological outcomes. Additional well-designed studies with larger sample sizes and long-term data are needed to establish the benefits of the robotic and laparoscopic approaches for PE.

INTRODUCTION

Locally advanced rectal cancer (LARC), primary or recurrent, is a challenging and complicated disease. A significant proportion of patients experience increased morbidity and a poor prognosis[1]. Although neoadjuvant treatment is the primary approach for locally advanced and recurrent rectal cancers, the results in T4b tumors are poor. Therefore, a radical surgical approach is necessary to treat patients with these types of tumors. In the past, local invasion of rectal cancer in organs confined to the pelvis was a contraindication for surgery. This led to a median overall survival (OS) < 1 year, even with the use of palliative therapies[2]. More recently, the benefits of surgical resection have been demonstrated when achieving negative margins and accomplishing an R0 resection. Studies have shown that R0 resection increases survival (5-year OS ranges from 22%-66%) and improves patient quality of life 6 mo postoperatively[3,4].

Pelvic exenteration (PE) or multivisceral resection (first described in 1948 for advanced cervical cancer) appears to be the only available technique to achieve negative margins[5]. A significant number of factors including better patient selection, a multidisciplinary approach, and advances in imaging, surgical technique, and perioperative care have contributed to decreased mortality and morbidity. Unfortunately, surgeons have remained skeptical of the effectiveness of PE due to the extensiveness of the surgery. An international retrospective observational study assessed the outcomes of patients who underwent PE for LARC and found an increase in survival, which provided evidence about the effectiveness of PE to skeptical providers[6,7].

Several different types and modifications of PE have been described (Table 1), allowing surgeons the opportunity to personalize this approach for each patient. Minimally invasive surgery has replaced the traditional open approach for PE, making the surgery easier when operating in the deep narrow pelvis. Studies have shown that laparoscopic or robotic PE is feasible with promising progress for postoperative complications and oncological outcomes. Robotic PE allows three-dimensional visualization with increased depth perception. There are also seven degrees of freedom that amplify surgeon ergonomics in the narrow pelvis. Furthermore, enhanced articulation and dexterity of the EndoWrist instruments enhance the ability to achieve R0 resection[8].

Table 1 Types of pelvic exenteration and modifications regarding extent of the tumor.

Type of pelvic exenteration		Description of the technique
Total pelvic exenteration		Complete en bloc resection of the rectum, reproductive internal organs, genitourinary viscera, regional lymph nodes, and peritoneum
Anterior pelvic exenteration		Bladder resection with or without internal reproductive organs
Posterior pelvic exenteration		Resection of the rectum, with or without reproductive internal organs, preservation of bladder
Modifications for the above types
Sacrectomy	High sacrectomy	Resection of the sacrum above the third sacral body
	High subcortical sacrectomy	Anterior sacral cortex and underlying bone are resected
Pelvic side wall resection	Extended lateral pelvic sidewall excision	Dissection in prone and supine position. Piriformis muscle is dissected, ischial spine and sciatic nerve are excised if needed
	Laterally extended endopelvic resection	Resection of obturator internus, pubococcygeus, iliococcygeus and coccygeus muscles. Sciatic nerve involvement is a contraindication

However, small sample sizes and heterogeneity in the published studies are significant drawbacks for establishing minimally invasive PE as treatment for LARC. Additional research needs to be conducted on preoperative decision-making and assessing patient suitability for the surgery[9,10]. The evolution of radiology and the cutting-edge technological advancements in three-dimensional imaging provides clinicians with the best information for planning and executing these demanding procedures[11]. In addition, morbidity, mortality, oncological outcomes, impact on time to adjuvant therapy, and quality of life need to be addressed in future studies.

OUTCOMES OF MINIMALLY INVASIVE TECHNIQUES

Laparoscopic and robotic PE were first performed to treat LARC in 2003 and in 2011, respectively[12,13]. Since then, there has been a limited number of reports and published studies on the topic. The PelvEx Collaborative performed a systematic review and meta-analysis in 2018 to determine and compare the outcomes in open and minimally invasive PE[10]. There were four comparative studies that were included, and none of the studies presented long-term oncological outcomes.

Based on their meta-analysis, minimally invasive PE was associated with less intraoperative blood loss (median: 550 mL vs 2300 mL), decreased length of hospital stay (median: 22 d vs 28 d), and a slightly decreased risk of 30-d morbidity. The advantage of open PE was the decreased median operation time. No differences were found in achieving R0 resection. Because this meta-analysis was performed 6 years ago and only one study compared robotic PE vs open PE, there is a need to reevaluate the effectiveness of robotic and laparoscopic PE and to perform long-term studies to determine oncological outcomes.

Since that meta-analysis was published, more retrospective studies have been published demonstrating the effectiveness of robotic PE. A recent retrospective study included 13 patients who underwent robotic PE and showed a remarkable 100% rate of R0 resection. The median length of hospital stay was 15 d with 0% 30-d mortality. After a median follow-up of 21 (3-53) months, tumor recurrence was observed in 3 patients and death occurred in 4 patients[14]. Another retrospective study included 8 patients who underwent robotic-assisted PE and revealed a complete oncological resection with clear margins and recurrence-free survival after 12 months of follow-up[15].

In the recent issue of World Journal of Gastrointestinal Surgery, Chan et al[16] published an interesting paper titled “Feasibility and safety of minimally invasive multivisceral resection for T4b rectal cancer: A 9-year review.” This was a single-center retrospective study that included 49 patients with LARC T4b who underwent PE. The primary outcomes of the study were the margin status and the complication rate for the open, laparoscopic, and robotic approaches. The authors reported interesting and valuable conclusions thus setting the stage for further investigation of minimally invasive PE. Patients who underwent minimally invasive PE had significantly decreased blood loss, major morbidity, postoperative collections, postoperative ileus, and surgical site infections, and a shorter hospital stay compared to open PE. R0 resection rate, recurrence, OS, and recurrence-free survival were comparable across all PE groups. The authors clearly demonstrated that when candidates are appropriately selected minimally invasive PE is feasible even in complicated cases, which may convince clinicians to shift from traditional open PE to minimally invasive PE.

The authors also compared the robotic and laparoscopic approaches. While the overall complications were similar, robotic PE was associated with increased operating time. This may indicate the limited experience of the surgeons using the robotic platform or that the more complicated and challenging cases were selected for robotic PE. Furthermore, rates in achieving negative resection margins were similar for both approaches. A noteworthy finding of this study was that robotic PE was significantly associated with an increased 3-year OS and recurrence-free survival. This is particularly interesting because the most complex cases were selected for the robotic approach. It is possible that the meticulous dissection and dexterity offered by the robot contributed to this finding. The robotic approach also had a reduced rate of anastomotic leak (4.8% vs 23.0%), although not statistically significant. Limiting anastomotic leak decreases an inflammatory microenvironment, which is a crucial component in tumor development.

Although there were limitations of this study, the results are promising. We predict that more surgeons and departments will begin to adopt the robotic technique while also conducting well-designed long-term studies to add to the sparse data on minimally invasive PE. OS, disease-free survival, and recurrence-free survival after minimally invasive PE require further investigation to draw the correct conclusions.

CHALLENGING AND UNCHARTED FIELDS

As surgeons continue to adopt new innovative techniques to mitigate complications and morbidity after minimally invasive PE, additional issues will arise. For example, the extent of the tumor, especially in the lateral pelvis, is an extremely challenging feature that presents difficulties in achieving R0 resection. New techniques will need to be developed to address this problem. Furthermore, filling the empty pelvis after an extended PE is another topic of intense controversy that requires further study.

The adoption of a multidisciplinary approach with the incorporation of radiology and three-dimensional imaging for operation planning and decision making is of paramount importance to successful management of LARC. Hospital policies and surgical departments should encourage a multidisciplinary approach. Ultimately, surgeons should remember that although PE is currently the only curative treatment for LARC, the final treatment decision should be made after considering four important factors: Resectability; tumor biology; functional capacity; and most importantly the patient’s choice.

CONCLUSION

PE is the only curative option for LARC. It increases survival and improves patient quality of life. Currently, minimally invasive PE shows promising results. However, the small number of suitable patients, limited surgeon experience, and steep learning curve for minimally invasive PE has resulted in a small number of published studies determining the effectiveness of minimally invasive PE compared to open PE. Increasing patient sample sizes and including long-term follow-up will mitigate these issues and provide robust evidence regarding the role of minimally invasive PE for the treatment of LARC.