
==== Front
J Gynecol Oncol
J Gynecol Oncol
JGO
Journal of Gynecologic Oncology
2005-0380
2005-0399
Asian Society of Gynecologic Oncology; Korean Society of Gynecologic Oncology; Japan Society of Gynecologic Oncology

39251348
10.3802/jgo.2024.35.e112
Original Article
Surgery
Step-by-step demonstration of “sciatic-nerve-preserved beyond-LEER” in a Thiel-embalmed cadaver: a novel salvage surgery for recurrent gynecologic malignancies
https://orcid.org/0000-0003-1372-6145
Kanao Hiroyuki 1
https://orcid.org/0000-0003-1447-9297
Tamate Masato 2
https://orcid.org/0000-0002-6589-6480
Matsuura Motoki 2
https://orcid.org/0000-0002-8519-710X
Nagao Sachiko 2
https://orcid.org/0009-0009-6561-9801
Nakazawa Miseon 2
https://orcid.org/0000-0001-9667-2407
Habata Shutaro 2
https://orcid.org/0000-0002-9148-1609
Saito Tsuyoshi 2
1 Department of Gynecologic Oncology, Cancer Institute Hospital, Tokyo, Japan.
2 Department of Obstetrics and Gynecology, Sapporo Medical University, Sapporo, Japan.
Correspondence to Hiroyuki Kanao. Department of Gynecologic Oncology, Cancer Institute Hospital, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan. hiroyuki.kanao@jfcr.or.jp
9 2024
15 7 2024
35 5 e11215 1 2024
06 5 2024
30 6 2024
© 2024. Asian Society of Gynecologic Oncology, Korean Society of Gynecologic Oncology, and Japan Society of Gynecologic Oncology
2024
Asian Society of Gynecologic Oncology, Korean Society of Gynecologic Oncology, and Japan Society of Gynecologic Oncology
https://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Objective

Complete resection is the curative treatment choice for recurrent gynecological malignancies. Laterally extended endopelvic resection (LEER) is an effective surgical salvage therapy for lateral recurrence. However, when a recurrent tumor occupies the ischial spine and sacrum, LEER is not indicated, and surgical salvage therapy is abandoned. Theoretically, complete resection of such a tumor is possible by additional pelvic bone resection along with the standard LEER. Nevertheless, owing to the anatomical complexities of the beyond-LEER procedure, 2 major issues should be solved: sciatic nerve injury and tumor disruption during pelvic bone amputation. To overcome these technical challenges, we applied a multidirectional beyond-LEER approach, a novel salvage surgical procedure, with an aim of demonstrating its technical feasibility.

Methods

We created a simulation model of a laterally recurrent tumor that occupied the right ischial spine and sacrum in a Thiel-embalmed cadaver.

Results

Multidirectional approaches, including laparoscopic, perineal, and dorsal phases, were safely applied. We laparoscopically marked the L4-L5-S1 complex and S2 nerve with different colored tapes, and by pulling them out into a dorsal surgical field, the sciatic nerve was safely preserved. The dissection lines of the multidirectional approaches were aligned using tapes as landmarks, and complete tumor clearance without tumor disruption was accomplished. By following the cadaveric training, the first laparoscopic-assisted beyond-LEER procedure was successfully performed in a patient with recurrent ovarian cancer.

Conclusion

Using a Thiel-embalmed cadaver, we demonstrated the technical feasibility of a sciatic nerve-preserved beyond-LEER procedure, which was successfully performed in a patient with recurrent ovarian cancer.

Synopsis

Beyond-laterally extended endopelvic resection (LEER), a novel salvage surgery, includes pelvic bone resection in addition to standard LEER. We demonstrated the technical feasibility of beyond-LEER method in a Thiel-embalmed cadaver. Complete resection without tumor disruption and sciatic nerve preservation can be safely accomplished.

Surgery
Laparoscopic Assisted
Sacrum
Salvage Therapy
Cadaver
==== Body
pmcINTRODUCTION

In recurrent gynecological malignancies, surgery can be the treatment of choice when complete resection is deemed possible. In cases of central recurrence, pelvic exenteration is considered [1]. However, when a recurrent tumor infiltrates the pelvic sidewall, surgical treatment is not indicated because complete resection is hitherto considered impossible [2].

Since Höckel et al. [3] reported laterally extended endopelvic resection (LEER) in 1999, which includes the lateral extension of the surgical excision towards the medial aspect of the lumbosacral plexus, piriformis muscle, internal obturator muscle, and acetabulum, the clinical significance of surgical treatment for lateral tumor recurrence has changed considerably. Höckel et al. [4] reported that among 36 patients with gynecological malignancies fixed to the wall of the lesser pelvis who were treated with LEER, complete resection was achieved in 94% of the patients, with a 5-year overall survival rate of 46%. Owing to its technical feasibility and good oncological outcomes, LEER may be used as a novel surgical salvage therapy for laterally recurrent gynecological malignancies. However, among 100 patients with locally advanced and recurrent gynecological tumors treated using LEER by a 10-year-experienced surgeon, the morbidity (70%) and mortality rates (2%) were relatively high [5].

Given the reduced invasiveness and better visualization associated with laparoscopy, allowing for meticulous dissection, we performed laparoscopy and reported the technical feasibility and acceptable oncologic outcomes of laparoscopic LEER for laterally recurrent cervical cancer [6].

The cardinal and uterosacral ligaments are regarded as important pathways of tumor extension in gynecological cancer [7], and their inappropriate excision may lead to local recurrence [8]. In these cases, recurrent tumors may occupy the ischial spine, sacrospinous ligament, and sacrum, which are close to the origin of the cardinal and uterosacral ligaments; these cases have been excluded from the surgical indications of LEER, given the anatomical proximity of the sciatic nerve, which could be easily injured [3]. Theoretically, the complete resection of the abovementioned tumors is possible by resection of the ischial spine and sacrum in addition to the standard LEER.

The sciatic nerve, extending from the L4 to S3 segments of the sacral plexus, supplies sensation to the skin of the foot and innervates the muscles of the lower limb. It passes beneath the piriformis muscle and through the sciatic foramen [9]. Injury to the sciatic nerve can deteriorate the patients’ quality of life; thus, sciatic nerve preservation is mandatory when the surgical indication for lateral recurrence is expanded.

Tumor disruption during resection may trigger the dissemination of cancer cells, resulting in the deterioration of oncological outcomes [10]. When the tumor occupies and overhangs on the ischial spine and sacrum, the severance of the ischial spine and sacrum via an intraperitoneal approach can lead to tumor disruption. Therefore, we developed a multidirectional beyond-LEER procedure for sciatic nerve preservation and no-touch tumor removal; however, their technical feasibility is unknown.

Thus, in this study, using a Thiel-embalmed cadaver, we aimed to demonstrate a step-by-step surgical procedure, our novel multidirectional beyond-LEER procedure.

MATERIALS AND METHODS

A Thiel-embalmed cadaver was placed in the lithotomy position, and 4 trocars were placed as shown in Fig. S1. Laparoscopic procedures were performed under a pneumoperitoneum pressure of 10 mmHg using the surgical instruments used in an actual laparoscopic LEER.

A 7-cm mimicked recurrent tumor, made of felt fabric, was placed in the pelvic cavity through a small incision in the lower abdomen. The small incision was closed, and a laparoscopic procedure was initiated.

The right paravesical and pararectal spaces were developed, and the right cardinal ligament was exposed using the same surgical steps as those for laparoscopic radical hysterectomy.

The right cardinal ligament was divided completely, and a recurrent tumor-mimicking lesion was placed in the right parametrium. The recurrent tumor-mimicking lesion was fixed with a 2-0 polydioxanone (PDS) thread to the right ischial spine, right sacrospinous ligament, right side of the sacrum and rectum, right internal obturator muscle, and right uterine cervix (Fig. 1).

Fig. 1 Mimicked recurrent tumor on the right side. The 7-cm mimicked recurrent tumor, which is made of green felt fabric, is fixed with a 2-0 polydioxanone thread to the right ischial spine, right sacrospinous ligament, right side of the sacrum and rectum, right internal obturator muscle, and uterine cervix on the right side.

To investigate the technical feasibility of the sciatic nerve-preserved beyond-LEER method, we developed a simulation model with a tumor that recurred at the right pelvic sidewall and occupied the right ischial spine and sacrum.

The consent for cadaver donation based on the Japan Surgical Society and Japanese Association of Anatomists guidelines, consent to perform a normal autopsy, consent from the deceased person’s family, and consent to use the donated cadaver for clinical medical education and research were obtained following the Act on Body Donation for Medical and Dental Education. Furthermore, approval to conduct this cadaveric study was obtained from the Institutional Review Board of the Sapporo Medical University (approval number: 5-1-5).

RESULTS

The multidirectional beyond-LEER methods consisted of 3 phases namely, laparoscopic, perineal, and dorsal.

1. Laparoscopic phase

The right internal iliac lymph node was removed, and the right internal iliac artery was isolated and transected at its bifurcation from the right external iliac artery (Fig. S2A). Furthermore, the right superior gluteal artery was identified and transected (Fig. S2B). The right internal iliac and superior gluteal veins were also transected. The right lumbosacral trunk (L4, L5, and S1 complexes), which descends along the sacral promontory, was exposed (Fig. S2C and D). In the present case, the superior gluteal artery and vein ran between L5 and S1, which is the most frequent pattern.

The right internal iliac vessels were dissected from the pelvic sidewall to the greater sciatic foramen, and the right S2 nerve as well as the right piriformis muscle were identified. The right piriformis muscle was partially dissected to secure the surgical margins. (A tumor located on the piriformis muscle is in close proximity to the S2 nerve, and the possibility of S2 nerve preservation is determined based on the surgical margin from the tumor. When the S2 nerve can be dissected and preserved from the tumor, the piriformis muscle is dissected inside the S2 nerve with a wide surgical margin. However, a tumor-involved S2 nerve must be resected, and the piriformis muscle should be resected near the S1 nerve to secure the surgical margin. In this simulation model, we demonstrated a case of S2 nerve preservation). The right L4, L5, S1, and S2 nerves were provisionally dissected and isolated from the recurrent tumor; and the L4, L5, and S1 complexes were marked with a yellow tape. Up to this point, the surgical steps were the same as those of a standard LEER.

Subsequently, the right S2 nerve, which was identified in addition to the right piriformis muscle, was traced toward the sacrum, and the right S2 sacral foramen was identified. The right S2 nerve was marked with a red tape at the sacral foramen. These yellow and red tapes are essential to indicate anatomical landmarks for the sciatic nerve-preserved beyond-LEER method (Fig. 2).

Fig. 2 Right sciatic nerve marked with colored tapes. The L4-L5-S1 complex and S2 nerve are marked with yellow and red tapes, respectively.

Thereafter, the right levator ani muscle was divided along the right tendinous arch of the pelvic fascia, and the right ischiorectal fossa was provisionally developed (Fig. S3A).

In addition, the Retzius space was developed, and the bladder and urethra were detached from the pelvic wall.

On the left side, the paravesical and pararectal spaces were developed, and the cardinal ligament was exposed and divided down to the pelvic floor. Moreover, the levator muscles were divided, and the ischiorectal fossa was provisionally dissected. The S2 nerve was marked with a red tape at the sacral foramen. The surgical procedures on the left side were similar to that of a pelvic exenteration for central tumor recurrence (Fig. S3B).

2. Perineal phase

A skin incision was made at the outer labia minora, the subcutaneous tissue was dissected (Fig. S4A), and the pelvic cavity was opened just below the pubis (Fig. S4B). The urogenital diaphragm was incised, and the ventral perineum was dissected into the pelvic cavity (Fig. S4C). The dorsal perineum, which can be easily dissected into the pelvic cavity using the dorsal approach, was provisionally dissected as far as possible through the ischiorectal fossa (Fig. S4D).

3. Dorsal phase

The trocars were removed, the skin wounds were temporarily closed, and the cadaver was placed in the supine position.

A dorsal median skin incision, which was continuous with the perineal incision, was made, and the sacrum was exposed (Fig. S5A).

The right gluteus maximus was exposed and divided (Fig. S5B and C), and the muscle complex, including the right piriformis, gemellus, and internal obturator muscles, which reached the right greater trochanter, was identified. The index finger of the surgeon was passed from the right ischiorectal fossa to the right lesser sciatic foramen, and the right sacrotuberous ligament was identified using a finger hook (Fig. S5D). The right sacrotuberous ligament was divided, and the right sacrospinous ligament and ischial spine were exposed. The yellow tape, which laparoscopically marked the L4-L5-S1 complex, was pulled out into the surgical field, and the right sciatic nerve was isolated and detached from the right ischial spine using the yellow tape as a landmark (Fig. 3). Subsequently, the right ischial spine was divided using a bone chisel while preserving the sciatic nerve (Fig. 4).

Fig. 3 Anatomy around the right ischial spine from the back view. The right sciatic nerve is isolated and detached from the right ischial spine using the yellow tape as a landmark. (For ethical considerations, mosaic is included in this figure).

Fig. 4 The divided right ischial spine. The right ischial spine is divided using a bone chisel while preserving the sciatic nerve. (For ethical considerations, mosaic is included in this figure).

On the left side, the gluteus maximus muscle, sacrotuberous ligament, and sacrospinous ligament were isolated in the same manner as that on the right side and were divided near the sacrum.

The red tape that laparoscopically marked S2 nerve near the sacral foramen was pulled out in this surgical field, and the location of the S2 sacral foramen was confirmed from the dorsal side using the red tape as a landmark (Fig. 5A). The sacrum below S3 was divided using a bone chisel while preserving the S2 nerves (Fig. 5B).

Fig. 5 The divided sacrum. (A) The location of the S2 sacral foramen is confirmed from the dorsal side using the red tape as a landmark. (B) The sacrum below S3 is divided using a bone chisel while preserving the S2 nerves. (For ethical considerations, mosaic is included in this figure).

By dividing the ischial spine and sacrum from the back, the tumor was detached from the pelvic wall without manipulation using the no-touch technique (Fig. 5B). The perineal and dorsal skin incisions were then closed, and the cadaver was repositioned in the original position.

4. Laparoscopic phase

At this stage, the tumor was almost completely detached from the pelvic sidewall. The remaining connective tissue around the tumor was dissected, and total pelvic exenteration as well as the beyond-LEER procedure was accomplished on the right side (Fig. 6). During the procedure, the tumor was never disrupted, and the PDS threads that fixed the tumor to the pelvic sidewall were preserved, thus indicating that the recurrent tumor could be removed without cancer cell spillage.

Fig. 6 Final operation view. Total pelvic exenteration and beyond-laterally extended endopelvic resection procedure were accomplished on the right side.

In this study, we confirmed secure preservation of the sciatic nerve and complete tumor clearance using the no-touch technique.

After this cadaveric training, we successfully performed the first laparoscopic-assisted beyond-LEER procedure in a patient with recurrent ovarian cancer. As shown in Fig. S6, the solitary recurrent tumor, which was located on the sacrum, invaded the right S3 sacral foramen and was in close proximity to the right S2 nerve. In this case, right ischial spine amputation was not required owing to the tumor location; however, other surgical procedures, such as LEER (laparoscopic phase), abdominoperineal resection of the rectum (perineal phase), and low sacrectomy (dorsal phase), which were simulated in the cadaveric training, were required for tumor clearance (Fig. S7).

The operation time and blood loss volume were 656 minutes and 1,700 mL, respectively, and no intra- and postoperative complications were observed. Complete resection without tumor exposure was achieved (Fig. S8).

DISCUSSION

LEER is now regarded as a surgical salvage therapy for patients with laterally recurrent gynecological cancer, a clinical entity for which complete resection was previously considered impossible [345]. However, complete resection cannot be achieved using the standard LEER in patients with gynecological carcinomas that occupy the ischial spine because tumor invasion around the sciatic foramen necessitates resection of the ischial spine and sciatic nerve to accomplish complete tumor clearance [34].

Recurrent rectal cancer with sacral invasion is regarded as a local disease, and a good prognosis can be expected after sacrectomy [1112]. Similar to rectal cancer, we believe that some gynecological cancers that recur at the ischial spine and sacrum could also have an improved prognosis when complete tumor clearance is accomplished with combined resection of the ischial spine and sacrum. This is because the ischial spine and sacrum are close to the origin of the cardinal and uterosacral ligaments, which are the pathways of gynecological cancer spread; thus, some gynecological cancers that recur at these sites owing to inappropriate resection during primary surgery may be treated as local diseases.

Resection of the ischial spine is associated with sciatic nerve injury due to its anatomical proximity; hence, the beyond-LEER procedure could be the treatment of choice when a sciatic nerve preservation technique is safely established.

Theoretically, it is appropriate to sever the ischial spine from the back because the sciatic nerve runs below the ischial spine. However, precise alignment of the sciatic nerve dissection lines between the laparoscopic and dorsal approaches is required to preserve the sciatic nerve completely. The sciatic nerve was laparoscopically marked with a yellow tape, and by pulling it out into the dorsal surgical field, the sciatic nerve dissection line was aligned, using the tape as a landmark.

Sacrectomy is correlated with loss of function depending on the resection level; hence, precise anatomical resection of the sacrum is important to reduce postoperative complication occurrence. When both S2 nerve roots were spared, 56.2% and 39.9% of patients maintained normal ambulation and bladder functions after sacrectomy, respectively [12]. In terms of residual function, low sacrectomy (below S3) is more clinically feasible than high sacrectomy (S1 and S2). Moreover, high sacrectomy seems to be a more invasive procedure than low sacrectomy, as the median operation time (13.3 hours vs. 11.5 hours), intraoperative blood loss (4,487 mL vs. 2,630 mL), complication rate (61% vs. 45%), and length of postoperative hospital stay (40 days vs. 24.5 days) for high sacrectomy are higher than those for low sacrectomy [13]. Hence, the beyond-LEER procedure should be initially indicated for patients undergoing low sacrectomy.

To enhance the safety and efficacy of low sacrectomy, it is important to accurately identify the anatomical position of the S2 nerve from the back. In this study, a red tape was laparoscopically used to mark the S2 nerve as an anatomical landmark to identify the accurate position for sacral amputation during low sacrectomy. Given that the anatomy of the dorsal approach is difficult to understand, it is essential to mark key anatomical structures in advance.

The advantages and disadvantages of laparoscopic resection for gynecological recurrent cancers are being discussed after the unexpected results of the Laparoscopic Approach to Cervical Cancer Trial, which revealed that laparoscopic radical hysterectomy for early-stage cervical cancer is associated with multiple intraperitoneal recurrences and worse prognosis compared with that of open surgery [14]. Subsequent studies have highlighted the possibility that cancer cell dissemination during surgery may deteriorate the oncologic outcomes of a laparoscopic procedure [15]. Thus, when laparoscopic surgery is performed for recurrent gynecological cancer, it is essential to establish a non-contact technique that does not expose or disperse the tumor during surgery [16]. In this study, we established a no-touch technique to sever the ischial spine and sacrum from the back, which allowed secure bone resection without tumor exposure.

The advantages of laparoscopy in this multidirectional procedure include not only the possibility of reducing blood loss but also the quick closure of the abdominal wound and the ease of keeping the wound clean while changing the patient’s position.

Finally, we emphasized the utility of cadaveric training in mastering new surgical procedures. To establish the successful sciatic nerve preservation using the multidirectional beyond-LEER procedure, it is crucial to master the 3-dimensional pelvic anatomy and align the dissection lines precisely in each approach, which is difficult to understand only from textbooks, lectures, and dry box training. In a Thiel-embalmed cadaver, the visibility, strain, and stiffness of the tissue are similar to those experienced in an actual surgery; the Thiel-embalmed cadaver is regarded as a faithful representation of patient soft tissue characteristics and provides excellent and repeatable conditions for the simulation of surgery [17].

In our first clinical laparoscopic-assisted beyond-LEER procedure, the recurrent tumor infiltrated the right S3 sacral foramen and was located on the S2-S3 junction, presenting a high possibility of tumor exposure and collapse if the laparoscopic and dorsal dissection lines were not correctly aligned. Moreover, on the right side, the S2 nerve was in close proximity to the tumor, increasing the possibility of right sciatic nerve damage without accurate 3-dimensional anatomical knowledge. Our preoperative Thiel-embalmed cadaveric training may have contributed to our understanding of the detailed pelvic anatomy, leading to a successful and complete tumor resection without any complication in this first clinical case.

The blood loss volume was 1,700 mL, giving the impression that laparoscopy was not beneficial; however, most of the blood loss occurred during sacrectomy, implying that enhanced laparoscopic vision might have improved dissection precision at the bottom of the pelvis, thereby resulting in complete tumor clearance. Based on our first experience, we believe that the laparoscopic-assisted beyond-LEER approach was advantageous.

The cadaveric training enabled us to successfully perform this novel technique in clinical practice without complications; nevertheless, the greatest shortcoming of the cadaver model is that it cannot provide training regarding hemostasis. As life-threatening hemorrhage is occasionally encountered during gynecological surgery, it is necessary to adapt this novel technique to cope with uncontrollable hemorrhage, thereby enhancing its clinical applicability. Laparoscopy is greatly advantageous in hemorrhagic control; hence, if life-threatening hemorrhage occurs, the following maneuvers may be effective: placing the patient in a low-head position, increasing pneumoperitoneum pressure, compressing the bleeding point, clamping the iliac arteries, and administering various hemostatic agents. If hemostasis is not achieved after applying these maneuvers, muscle fragment welding can be performed, which is a safe and highly effective method of controlling massive hemorrhage [18].

The strength of this study is that we demonstrated the safety and technical feasibility of the multidirectional sciatic nerve-preserved beyond-LEER procedure, which can be used to accomplish complete resection of laterally recurrent tumors that occupy the ischial spine and sacrum without tumor dispersion. Our findings suggest that the novel multidirectional salvage surgery can expand the surgical indications for laterally recurrent gynecological cancers. Nevertheless, a limitation of this study is that only the technical feasibility was demonstrated. Future studies should evaluate the efficacy of this novel surgical technique in terms of patient selection, surgical outcomes, and, most importantly, oncologic outcomes.

ACKNOWLEDGEMENTS

We thank the staff of Surgical Training Center, Sapporo Medical University, for providing technical assistance with cadaver preparation.

SUPPLEMENTARY MATERIALS

Fig. S1

Trocar placement.

Fig. S2

Exposure of the right sciatic nerve. (A) The right internal iliac lymph node is removed, and the right internal iliac artery is isolated and transected at the bifurcation of the right external iliac artery. (B) The right superior gluteal artery is identified and transected. (C) The right internal iliac vein is divided. (D) The right superior gluteal vein is resected. The right lumbosacral trunk (L4-L5-S1 complex), which descends along the sacral promontory, is exposed.

Fig. S3

Complete view of the laparoscopic phase. (A) The right levator ani muscle is divided along the right tendinous arch of the pelvic fascia, and the right ischiorectal fossa is provisionally developed. (B) The surgical procedures on the left side are similar to those of pelvic exenteration for central tumor recurrence.

Fig. S4

Perineal phase. (A) A skin incision is made in the outer labia minora, and the subcutaneous tissue is dissected. (B) The pelvic cavity is opened beside the pubis. (C) The urogenital diaphragm is incised, and the ventral perineum is dissected into the pelvic cavity. (D) The dorsal perineum is provisionally dissected as far as possible through the ischiorectal fossa. (For ethical considerations, mosaic is included in this figure).

Fig. S5

Dorsal phase. (A) A dorsal median skin incision, which is continuous with the perineal incision, is made, and the sacrum is exposed. (B) The right gluteus maximus muscle is exposed. (C) The right gluteus maximus muscle is divided. (D) The surgeon’s index finger is passed from the right ischiorectal fossa to the right lesser sciatic foramen, and the right sacrotuberous ligament is identified using a finger hook. (For ethical considerations, mosaic is included in this figure).

Fig. S6

Preoperative magnetic resonance image of recurrent ovarian cancer. (A) Axial view. The recurrent tumor infiltrates the right S3 sacral foramen and is in close proximity to the right S2 nerve. (B) Sagittal view. The recurrent tumor is located on the S2-S3 junction of the sacrum.

Fig. S7

Intraoperative view. (A) Laparoscopic phase: laterally extended endopelvic resection on the right side. (B) Dorsal phase: sacrectomy.

Fig. S8

Complete tumor clearance. (A) Postoperative computed tomographic image. Sacrectomy is precisely performed between S2 and S3 as planned preoperatively. (B) Excised specimen. The recurrent tumor is removed without tumor exposure. (All surgical margins are negative for cancer).

Conflict of Interest: No potential conflict of interest relevant to this article was reported.

Author Contributions: Conceptualization: K.H., T.M., M.M., N.S., N.M., H.S., S.T.

Data curation: K.H., T.M.

Formal analysis: K.H.

Funding acquisition: K.H., T.M.

Investigation: K.H., T.M.

Methodology: K.H.

Project administration: K.H., T.M., H.S.

Resources: K.H., H.S.

Software: T.M.

Supervision: S.T.

Validation: S.T.

Visualization: K.H., T.M.

Writing - original draft: K.H.

Writing - review & editing: T.M., M.M., N.S., N.M., H.S., S.T.
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