Partial resection of rectum for rectal GIST by posterior approach

Abstract

Objective

The standard surgical treatment for gastrointestinal stromal tumors (GISTs) is local resection. Colorectal GISTs, which account for 5–10% of all GISTs, tend to develop in the lower rectum, making transabdominal approaches both difficult and invasive. We perform partial resection of rectum by posterior approach for rectal GISTs. We herein present our surgical procedure of posterior approach and retrospectively analyze the efficacy and safety of this approach.

Methods

In this retrospective case series study from 2018 to 2023, data were collected from patients who underwent partial resection of rectum by posterior approach for rectal GIST. Patient characteristics, surgical outcomes, complications, prognosis and presence/absence of low anterior resection syndrome (LARS) were collected.

Results

Four male patients with rectal GIST were included. The median age was 50.5 years, and all patients were male. The median operation time was 203.5 min, the median intraoperative blood loss was 30 mL, and the median initial tumor diameter was 29.5 mm. One patient underwent diverting ileostomy, and the ileostomy was closed one year after surgery. Complete pathological resection was achieved in all cases. Postoperative complications were observed in one patient: outlet obstruction of the diverting ileostomy and LARS; there were no other postoperative complications including anastomotic leakage. No recurrence was observed in the median follow-up of 33.5 months.

Conclusions

This study demonstrated that posterior approach is safe, associated with a low incidence of LARS, and facilitates complete resection, making it a valuable surgical option for rectal GISTs.

Background

Posterior approach had historically been used for lower rectal cancer [1, 2]. However, since this method alone did not allow for mesorectal dissection or extensive rectal resection, low anterior resection (LAR) or abdomino-perineal resection (APR) of the rectum with mesorectal dissection are currently the standard of treatment for rectal cancer [3]. However, the advantages of the posterior approach are relatively less postoperative pain, a low incidence of low anterior resection syndrome (LARS), and cosmetic benefits [4–7]. LARS develops in approximately 42–48% of patients after LAR [8, 9], whereas one previous study reported no cases of LARS following the posterior approach [6].

Gastrointestinal stromal tumors (GISTs) are a malignant disease that does not require lymph node dissection. GISTs develop most often in the stomach (50–70%), followed by duodenum and small intestine (20–30%), colon and rectum (5–10%, most commonly in the rectum), and rarely in the esophagus, mesentery, or omentum [10]. As lymph node metastasis is extremely rare, local resection without lymph node dissection is recommended as a standard surgical procedure for primary GISTs [10].

For rectal GISTs, local resection including posterior approach is sufficient. Mesorectal dissection is not always required and thus LAR or APR may be too invasive. However, no consensus exists regarding the optimal surgical procedure for partial resection of rectum [11], and transabdominal approaches such as LAR or APR have been performed mainly for lower rectal GISTs [12, 13]. In addition to the transabdominal approach and posterior approach, other surgical techniques including transanal approach and transvaginal approaches have been described [14–19].

At our institution, rectal GISTs are considered a good indication for the local resection of rectum without mesorectal dissection by posterior approach, and we herein summarize the outcomes of four cases.

Methods

Patients

In this retrospective case series study, we analyzed patients who underwent partial resection of rectum for rectal GIST by posterior approach at Fukushima Medical University Hospital from January 2018 to December 2023. At our institution, all rectal GIST patients with adequate performance status were surgically treated by posterior approach. The enrollment criteria for this study were: (i) diagnosis of rectal GIST based on histopathology and immunohistochemical studies; (ii) resection of rectal GIST by the posterior approach. The indication for neoadjuvant chemotherapy was determined on a case-by-case basis, considering tumor location, resectability, and patient condition. Tumor location was classified according to Japanese Classification of Colorectal, Appendiceal, and Anal Carcinoma: the 3 d English Edition [20]. Rb (lower rectum) was defined as the segment extending from the peritoneal reflection to the superior border of the puborectal sling. P (anal canal) might refer to either the surgical or anatomical anal canal; however, in this definition it referred to the surgical anal canal. The surgical anal canal was defined as the tubular structure extending from the superior border of the puborectal sling to the anal verge. If the tumor involved more than one anatomical division, each involved segment was recorded in order of extent of involvement, beginning with the segment where the bulk of the tumor was located (e.g., Rb-P).This study was approved by the Institutional Ethics Committee of Fukushima Medical University (approval number 30148) for a retrospective analysis of the collected data in accordance with the ethical standards of the Declaration of Helsinki of the World Medical Association.

Surgical procedure for rectal GIST

All surgery were performed with the patient in the jackknife position. An approximately 10-cm skin incision was made at a point 3 cm proximal to the anal verge and 1 cm lateral to the left or right border of the sacrum. If the incision was too close to the sacrum, the gluteus maximus would be severed at its attachment point, making repair difficult. The subcutaneous fat and part of the gluteus maximus muscle were dissected. The iliococcygeus muscle was separated then the presacral space, rectum, and mesorectum were visualized. In cases where an optimal surgical view was not obtained, the coccyx was additionally excised. Blunt separation around the rectum was performed to secure an adequate surgical field. After sufficient separation around the rectal GIST, a full-thickness resection was performed. An intraoperative digital rectal examination was performed to confirm the tumor location during resection. The defect in the rectal wall was closed with 4 − 0 PDS^® sutures (Johnson & Johnson, New Jersey, U.S.). A Blake^® Silicone Drain (Johnson & Johnson, New Jersey, U.S.) was inserted into the pelvic floor near the suture site, and a SILASCON^® Duple Drain (Kaneka Medix Corporation, Osaka, Japan) was inserted as a transanal drainage tube. The iliococcygeus muscle was sutured with 4 − 0 PDS^®, and the gluteus maximus muscle was sutured with 0 Vicryl^® (Johnson & Johnson, New Jersey, U.S.). Finally, the skin was closed with buried dermal sutures. A diverting ileostomy was considered when the defect area was large and suturing tension was high (Fig. 1A, B).

Fig. 1.

A Schema of partial resection of rectum by posterior approach for rectal gastrointestinal stromal tumor. Skin and iliococcygeus muscle are shown as translucent to illustrate underlying structures. B: Intraoperative image of partial resection of rectum by posterior approach for rectal gastrointestinal stromal tumor

Outcome measurement

The surgical outcomes were assessed by the following factors: operative time (min), operative blood loss (mL), day of first postoperative meal (postoperative day (POD)), duration of urinary catheter placement (days), urinary catheter reinsertion, duration of pelvic floor drainage tube placement (days), postoperative hospital stay (days), and presence of LARS, evaluated by the LARS Scoring Instructions [21] two years after surgery.

Result

Patient characteristics

Four patients with rectal GIST were included in this study. The median age was 50.5 years (range: 36–71), and all patients were men. The median operation time was 203.5 min (121–257) and the median intraoperative blood loss was 30 mL (10–50) (Table 1). The median duration of urinary catheter insertion was 2 days (2–2), and no patients required urinary catheter reinsertion. The median duration of pelvic floor drainage tube placement was 6 days (5–14). The preoperative tumor diameter ranged from 20 to 61 mm, with a median diameter of 29.5 mm. Representative sagittal T2-weighted images and colonoscopy images of each patient are shown in Fig. 2. Two patients underwent excision of the coccyx. Two patients received preoperative imatinib chemotherapy, and one patient received postoperative imatinib chemotherapy. One patient underwent diverting ileostomy, and the ileostomy was closed one year after surgery. A pathological complete resection was achieved in all cases. Postoperative complications were observed in one patient: outlet obstruction of the diverting ileostomy and major LARS (the LARS score was 39 points two years after the closure of the diverting ileostomy). No other postoperative complications, including anastomotic leakage, were observed. No recurrence was observed in a median follow-up of 33.5 months (13–71).

Table 1.

Characteristics of patients with rectal GIST

No.	age	sex	postoperative observation period (months)	tumor location	pre-NAC tumor diameter (mm)	preoperative tumor diameter (mm)	chemotherapy	operation time (min)	operative blood loss (mL)	postoperative complication	postoperative hospital stay (days)	diverting ileostomy	excision of the coccyx	beginning the meal (POD)	duration of urinary catheter placement (days)	duration of drainage tube placement (days)	LARS score at two years after surgery
1	51	M	71	Rb left posterior wall	31	25	preoperative imatinib for 3 months	121	20	-	7	-	-	5	2	7	0
2	50	M	37	Rb left wall	-	20	-	160	50	-	7	-	-	3	2	5	0
3	71	M	30	Rb-P right wall	-	61	postoperative imatinib for 3 years	257	10	outlet obstruction LARS	21	+	+	2	2	14	39*
4	36	M	13	Rb left wall	54	34	preoperative imatinib for 6 months	247	40	-	9	-	+	4	2	5	0**
POD: postoperative day
Rb: lower rectum
P: anal canal
LARS: Low anterior resection syndrome
pre-NAC: pre-neoadjuvant chemotherapy
*In Case 3, the diverting ileostomy was closed one year after surgery, and the LARS score was assessed two years after the closure.
**In Case 4, the LARS score was evaluated one year after surgery.

Fig. 2.

The images presented herein depict magnetic resonance imaging and colonoscopy images of the patients in this study. The presence of a tumor is indicated by the yellow arrows. In the third case, the tumor demonstrates extension into the anal canal (indicated by the white arrow)

The patient (Case 3) who experienced LARS had an Rb tumor that extended partially into the anal canal, measuring 61 mm in diameter (Fig. 2). Most of the puborectalis and rectococcygeus muscles had already been extremely stretched by the tumor, and only a very thin muscle layer could be seen on the surface of the tumor at the time of surgery. Part of the rectococcygeus muscle was resected to achieve complete tumor resection.

Discussion

The posterior approach was a useful procedure that enabled complete resection of rectal GISTs safely at our institution.

The posterior approach to the rectum was first reported in 1873 by Verneuil, and in 1885 Kraske described in detail the posterior approach to the rectum with partial sacral resection [1, 2]. However, as mesorectal dissection has become the standard treatment for colorectal cancer [3], the opportunities for posterior approaches to malignant diseases have become rarer.

Rectal GISTs tends to develop in the lower rectum [22], which makes it difficult to approach transabdominally. In many cases of rectal GISTs, it has been reported that LAR, super low anterior resection, inter-sphincter rectal resection, or occasionally APR were performed [12, 13], and the patients experienced various postoperative complications such as (LARS) [8, 9] and permanent stoma. LARS is characterized by frequent defecation and feeling of urgent need to defecate and fecal incontinence [9, 21] affecting 42–48% of patients who underwent LAR [8, 9]. Therefore, transabdominal resection of the rectum with mesorectal resection for rectal GISTs may be too invasive and potentially avoidable [4].

Particular care is warranted regarding LARS in cases where the puborectalis and/or the rectococcygeal muscle have been stretched by a giant tumor in the anal canal. Qin et al. reported that maximum LARS score of 17 patients after posterior approach was only 9; therefore, they reported that no LARS was observed in posterior approach [6]. In our study, LARS was observed in one case whose puborectalis and rectococcygeal muscle had already been extremely stretched due to the giant GIST and had to be resected along with the tumor in the anal canal. It is likely that the overstretch was considered as the main reason for LARS in the case.

In addition to the posterior approach, the transanal approach and transvaginal approach have also been utilized for the treatment of rectal GIST [14–19]. In terms of transvaginal approach, it is applicable only to female patients, limited to lesions of the anterior wall, and has been reported in only few case reports [19]. Although no direct comparisons have been made between the posterior and transanal approaches, the choice of surgical technique generally depends on institutional preferences and the surgeon’s expertise. The transanal approach, traditionally performed under direct vision; however, currently transanal endoscopic surgery can enlarge the microscopic view of the rectum, achieve complete tumor removal with less trauma and maximal preservation of anal function [14–18]. The transanal approach has been reported to offer shorter operative times, fewer postoperative complications, and higher rates of anal sphincter preservation compared to the transabdominal approach [14–18]. The complete resection rate of the transanal approach varies across studies. While many previous reports have described complete resection in all cases [15, 17], one study reported a relatively low complete resection rate, with only 4 out of 7 cases achieving complete excision [14].

On the other hand, the posterior approach offers technical advantages in low rectal surgery, particularly in terms of direct manipulation and clear anatomical visualization of the sphincter, as illustrated in Fig. 1A and B. This superior surgical view may contribute to the high rate of complete resection reported with the posterior approach. Although not extensively discussed in previous studies, the posterior approach may be more advantageous than the transanal approach in cases with extramural invasion, such as Case 3 (Fig. 2), due to its improved surgical view and access.

A potential limitation of the posterior approach is the difficulty in accessing anterior wall lesions, which often requires more extensive mobilization of the rectum. However, with sufficient mobilization, successful resection of anterior tumors is achievable, and previous studies have demonstrated that anterior rectal GISTs can also be safely managed by posterior approach [6].

There is no consensus regarding excision of the coccyx. Qin et al. [6] and Qiu et al. [7] have used a posterior approach involving the excision of the coccyx in all cases, which may provide a better view of surgical field. However, in our two cases, direct manipulation with optimal visualization was achieved without coccyx excision, suggesting that the decision to excise the coccyx should be made on a case-by-case basis.

The posterior approach can be applied potentially for other surgeries. In our institution, we applied it for two cases of local recurrence of rectal cancer. The presacral space was approached in the same way as the procedure for rectal GISTs. The two patients had previously undergone APR. In the same way as GIST surgery, the posterior pelvic space could be easily assessed with good surgical view. A pathological complete resection was achieved in all cases. No recurrence was observed at a median follow-up of 24.5 months (24–25). Therefore, posterior approach may be a promising option not only for rectal GIST surgery but also for other malignancies.

This study has several limitations. First, as a single-center retrospective case series study, it may be subject to selection and institutional biases. Second, although the small sample size limits the ability to draw definitive conclusions about short-term and long-term outcomes, we believe this study retains substantial originality and clinical relevance due to the rarity of rectal GISTs and the novel application of the posterior approach in their management. Third, the absence of a control group makes direct comparisons with the transabdominal or transanal approaches difficult. Future research, including multicenter and prospective studies, is warranted to address these limitations.

Conclusions

The posterior approach may be a useful procedure for rectal GISTs, as it is safe, enables direct manipulation with optimal surgical visualization, and may be associated with a low prevalence of LARS.

Abbreviations

GIST

gastrointestinal stromal tumor

LARS

low anterior resection syndrome

LAR

low anterior resection

APR

abdomino-perineal resection

POD

postoperative day

Author contributions

MH conceived the case presentation and wrote the manuscript. WS, HO, TM and KK have revised the manuscript. All authors participated in the treatment of the patient and read and approved the final manuscript.

Funding

This research did not receive any specific grants from funding agencies in the public, commercial, or not-for-profit sectors.

Data availability

All data generated or analyzed during this study are included in this published article.

Declarations

Ethics approval

This study was approved by the Institutional Ethics Committee of Fukushima Medical University (approval number 30148) for a retrospective analysis of the collected data in accordance with the ethical standards of the Declaration of Helsinki of the World Medical Association.

Consent for publication

Written informed consent was obtained from the patient for publication.

Competing interests

The authors declare no competing interests.