This study aimed to assess the safety and feasibility of a MIS approach for retrorectal tumors regardless of tumor location. Here we report a cohort of 23 consecutive patients operated on with a minimally invasive approach regardless of the location of the inferior tumor pole in two tertiary centers with an expertise in minimally invasive procedures and especially excision of retrorectal tumors [9, 11,12,13]. In the present cohort, the success rate of transabdominal laparoscopic approach is 82.6%. This systematic MIS strategy was associated with encouraging results for tumors regardless of the location of the inferior tumor pole.

No serious complications occurred during surgery and severe postoperative morbidity was nil in the two groups. Also, median operative time was not significantly different between the two groups. Conversely, patients were discharged on postoperative day 4. Those results are concordant with recently published series of resected RRT [14, 15]. It is noteworthy, to observe that there were three cases of conversion to open surgery without significant difference between the > S3 and < S3 groups. This 13% conversion rate is higher than the rate reported by Galán et al. but similar to the results published by Aubert et al. [14, 15]. However, Aubert et al. reported a conversion rate of 19% for the laparoscopic approach [14]. This relative high conversion rate could be explained by a large median tumor size (60 mm). The median tumor size was even larger (75 mm) in patients who needed a conversion to open surgery. Secondly, our systematic MIS approach could also explain this conversion rate regardless of tumor size and history of previous abdominal surgery (43% rate in our cohort). While this approach may be considered a limitation in this case, our results show that lesions below S3 can also be successfully resected through MIS. Indeed, only one conversion was reported in the below S3 group.

In our study, we report four cases of chronic pain (17%) and three cases of urinary and fecal dysfunctions at 90 days postoperatively. Those results are in line with previous publications [1]. For example, a comprehensive literature review by Baek et al. found that the rate of postoperative complications in patients who underwent surgery for retrorectal tumors was 13%. The authors reported a 23% rate of neurogenic bladder and 18% of neurologic complications including pain [1]. Aubert et al. also reported a 17% rate of chronic pain after RRT excision without significant difference according to the surgical approach (anterior or posterior) [14]. Our results suggest that MIS is safe for the surgical management of RRT even below S3.

Long-term surveillance of RRTs is mandatory to monitor potential recurrence. Typically, local recurrence rates are lower for benign tumors (1–2%) than for malignant tumors (30–50%) [16]. In our study, no recurrence was observed after a median follow-up of more than 3 years mainly because final pathology exams did not reveal any malignant lesion.

The retrospective design of the study is the first limitation with possible selection and confusion biases. Indeed, the absence of malignant lesion after pathology exam in our cohort reflects the expertise of our radiological department and our intention to develop a personalized surgical approach. However, this limitation mitigates the results of our study and prevents us from recommending MIS approach for suspected or confirmed malignant RRT. Also, our study is constrained by the limited number of cases, owing to the rarity of RRTs. To ascertain the long-term effectiveness of the laparoscopic approach to RRT, future investigations employing a multicenter prospective design may offer valuable insights.

If the laparoscopic approach is now considered as the standard of care in rectal cancer surgery, this is only the case for RRT located above S3 [14, 17]. Nonetheless, the progress in MIS techniques has enabled the refinement of surgical strategies for very low rectal cancer lesions. Mullaney et al. reviewed all the RRT excised by a MIS approach and reported only nine patients who received a robotic-assisted surgery. Median tumor size range from 5 to 10 cm and eight patients were operated on for a benign lesion. However, localization regarding the S3 was not reported [18]. Hence, the use of a robotic-assisted approach seems feasible, safe, and associated with minimal postoperative complications and a short hospital stay.

In our clinical practice, we considered a laparoscopic transabdominal approach for all RRT above S3 as recommended by Woodfield et al. [4]. TAMIS approach alone or a paracoccygeal approach (modified Kraske procedure) was reserved for smaller lesions and those closer to the pelvic floor. Drawing from the findings of our research, we propose a paradigm shift by using S5 as a new divisor. Moreover, we think that the ongoing spread of robotic-assisted procedures will favor this paradigm shift (Fig. 2).

Tailored surgical practice algorithm for retrorectal tumors

On the basis of our study results, we cannot recommend a systematic MIS approach in cases where malignancy is suspected, especially when neighboring structures are compromised. It remains crucial to personalize the surgical strategy according to the patient and the tumor configuration with the main goals to prevent tumor wall rupture and obtain complete tumor resection.