Histological study of the thin membranous structure made of dense connective tissue around the esophagus in the upper mediastinum

Robotic esophagectomy with outermost layer-oriented dissection for esophageal cancer: technical aspects and a retrospective review of a single-institution database

BACKGROUND

Systematic lymph node dissection in patients with gastric cancer could be sufficiently and reproducibly achieved along the outermost layer of the autonomic nerves and similar concept has been extensively used for robotic esophagectomy (RE) since 2018. This study aimed to determine the surgical and oncological safety of RE using the outermost layer-oriented approach for esophageal cancer (EC).

METHODS

Sixty-six patients who underwent RE with total mediastinal lymphadenectomy for primary EC between April 2018 and December 2021 were retrospectively reviewed. All underwent the outermost layer-oriented approach with intraoperative nerve monitoring (IONM). Postoperative complications within 30 days were analyzed.

RESULTS

Among the patients, 51 (77.3%) were male. The median age was 64 years, and the body mass index was 21.8 kg/m2. Furthermore, 58 (87.9%) patients had squamous cell carcinoma and eight (12.1%) patients had adenocarcinoma. Clinical stages I, II, and III were seen in 23 (34.8%), 23 (34.8%), and 16 (24.2%) patients, respectively. Thirty-four (51.5%) patients received preoperative treatment. No patient shifted to conventional thoracoscopic or open procedure intraoperatively. The median operative time was 716 min with 119 mL of blood loss. Additionally, 64 (97%) patients underwent R0 resection. The morbidity rates based on Clavien-Dindo grades ≥ II and ≥ IIIa were 30.3% and 10.6%, respectively, within 30 postoperative days. None died within 90 days postoperatively. Three (4.5%) patients exhibited recurrent laryngeal nerve (RLN) palsy (CD grade ≥ II). The sensitivity and specificity of IONM for RLN palsy were 50% and 98.3% at the right RLN and 33.3% and 98.0% at the left RLN, respectively.

CONCLUSION

RE with the outermost layer-oriented approach can provide safe short-term outcomes.

Oncological and physiological impact of thoracic duct resection in esophageal cancer

Despite advances in multidisciplinary treatment, esophagectomy remains the main curative treatment for esophageal cancer. The advantages and disadvantages of thoracic duct (TD) resection have been controversial for decades. We have herein reviewed relevant published literature regarding 'thoracic duct,' 'esophageal cancer,' and 'esophagectomy' describing the anatomy and function of the TD, and incidence of thoracic duct lymph nodes (TDLN) and TDLN metastases, as well as the oncological and physiological effects of TD resection. The presence of lymph nodes around the TD, referred to as TDLN, has been reported previously. The delineation of TDLNs is clearly defined by a thin fascial structure covering the TD and the surrounding adipose tissue. Previous studies have examined the number of TDLNs and the percentage of patients with TDLN metastasis and revealed that each patient had approximately two TDLNs. The percentage of patients with TDLN metastasis was reported to be 6-15%. Several studies have been conducted to compare the survival after TD resection with that after TD preservation. However, no consensus has been reached because all studies were retrospective, precluding firm conclusions. Although the issue of whether the risk of postoperative complications is affected by TD resection is still unclear, resecting the TD has been shown to have a long-term impact on nutritional status after surgery. In summary, TDLNs are quite common and present in most patients, while metastasis in the TDLNs occurs in a minority. However, the oncological value of TD resection in esophageal cancer surgery remains controversial due to varying findings and methodological limitations of previous comparative studies. Considering the potential but unproven oncological benefits and possible physiological drawbacks of TD resection, including postoperative fluid retention and disadvantages in the long-term nutritional outcome, clinical stage, and nutritional status should be considered before deciding whether to perform TD resection or not.

Left recurrent nerve lymph node dissection in robotic esophagectomy for esophageal cancer without esophageal traction

BACKGROUND

Because the robotic arm is located on the dorsal side of the patient, when the esophagus is pulled dorsally for the left recurrent nerve lymph node (LRLN) dissection, the robotic arm interferes with the surgical field. This made it difficult to prepare for the left recurrent lymph node dissection. We developed LRLN dissection in robotic surgery with natural space creation by physiological organ movement and evaluated the short-term results.

METHODS

In this retrospective study, we analyzed 102 cases of robot-assisted thoracoscopic subtotal esophagectomy (RATE) among radical subtotal esophagectomies performed between December 2018 and December 2022 using medical records. LRLN dissection is preceded by a dissection of the esophagus from the trachea. Leaving the esophagus on the vertebral side and away from the trachea resulted in a physiological elevation of the esophagus, providing space between the trachea and esophagus.

RESULTS

The thoracic surgery time in RATE was 181 (115-394) min. The number of LRLNs dissected was 4 (1-14). Six patients (6%) had a postoperative recurrence in the mediastinal lymph nodes. Seven patients (7%) had grade ≥ 1 left recurrent nerve palsy.

CONCLUSIONS

LRLN dissection with RATE using natural space creation was performed safely with a sufficient number of dissected lymph nodes and little left recurrent nerve palsy.

Histological study of the thin membranous dense connective tissues around the curving portion of the bilateral recurrent laryngeal nerves

OBJECTIVE/AIM

We aimed to demonstrate the anatomical relationship between the recurrent laryngeal nerves (RLNs), thin membranous dense connective tissue (TMDCT [e.g., the visceral or vascular sheaths around the esophagus]), and the lymph nodes around the esophagus at the curving portion of the RLNs for rational and efficient lymph node dissection.

METHODS

Transverse sections of the mediastinum at 5 mm or 1 mm intervals were obtained from four cadavers. Hematoxylin and eosin staining and Elastica van Gieson staining were performed.

RESULTS

The visceral sheaths could not be clearly observed the curving portions of the bilateral RLNs, which were observed on the cranial and medial side of the great vessels (aortic arch and right subclavian artery [SCA]). The vascular sheaths could be clearly observed. The bilateral RLNs diverged from the bilateral vagus nerves, which ran along with the vascular sheaths, went up around the caudal side of the great vessels and the vascular sheath, and ran cranially on the medial side of the visceral sheath. Visceral sheaths were not observed around the region containing the left tracheobronchial lymph nodes (No. 106tbL) or the right recurrent nerve lymph nodes (No. 106recR). The regions containing the left recurrent nerve lymph nodes (No. 106recL) and the right cervical paraesophageal lymph nodes (No. 101R) were observed on the medial side of the visceral sheath, with the RLN.

CONCLUSION

The recurrent nerve, which branched off from the vagus nerve descending along the vascular sheath, ascended the medial side of the visceral sheath after inversion. However, no clear visceral sheath could be identified in the inverted area. Therefore, during radical esophagectomy, the visceral sheath along No. 101R or 106recL may be recognized and available.

Lymph drainage and cervical fascia anatomy-oriented differential nodal CTV delineation at the supraclavicular region for esophageal cancer and nasopharyngeal cancer

PURPOSE

To determine the differences in supraclavicular lymph node metastasis between esophageal cancer (EC) and nasopharyngeal cancer (NPC) and explore the feasibility of differential supraclavicular clinical target volume (CTV) contouring between these two diseases based on the involvement of different fascial spaces.

MATERIALS AND METHODS

One hundred patients with supraclavicular nodes positive for EC or NPC were enrolled, and their pre-treatment images were reviewed. The distribution patterns of nodes between the two diseases were compared in the context of node levels defined by the 2017 Japanese Esophageal Society and 2013 International Consensus on Cervical Lymph Node Level Classification. Grouping supraclavicular nodes based on sub-compartments formed by the cervical fascia was discussed, and the feasibility of differential CTV contouring based on the differences in the involvement of these sub-compartments between EC and NPC was explored.

RESULTS

The 2013 Consensus on cervical node levels and 2017 Japanese Esophageal Society node station could not practically guide supraclavicular CTV contouring. We divided the supraclavicular space into six sub-compartments: the para-esophageal space (PES), carotid sheath space (CSS), sub-thyroid pre-trachea space (STPTS), pre-vascular space (PVS), and vascular lateral space (VLS) I and II. EC mainly spread to the PES, STPTS, CSS, and VLS I, whereas NPC tended to spread to the CSS, VLS I, and VLS II. These combinations of sub-compartments may help constitute the supraclavicular CTVs for EC and NPC.

CONCLUSIONS

The fascia anatomy-based sub-compartments sufficiently distinguished metastasis to the supraclavicular space between EC and NPC, thus facilitating differential CTV contouring between these two diseases.

Outcomes of minimally invasive total mesoesophageal excision: a propensity score-matched analysis

BACKGROUND

This study aimed to investigate the safety and efficacy of minimally invasive total mesoesophageal excision (TME) for esophageal cancer.

METHODS

We retrospectively collected data from patients with esophageal cancer who underwent esophagectomy at our center between January 2011 and June 2017. Among 611 eligible patients, 302 underwent minimally invasive total mesoesophageal excision (the TME group) and 309 underwent non-total mesoesophageal excision (the NME group). Outcomes were compared after 1-to-1 propensity score matching, and subgroup analyses were performed for cases involving pT1-2 or pT3-4a disease.

RESULTS

The propensity score matching produced 249 pairs of patients. The TME group had a shorter operative time (P < 0.001), lower intraoperative bleeding (P < 0.001), and a shorter postoperative hospital stay (P < 0.001). There were no significant differences between the two groups in the number of removed lymph nodes, 30-day mortality, or postoperative complications. In addition, both groups had similar 3-year rates of overall survival (OS) and disease-free survival (DFS). However, the 3-year recurrence rate in the esophageal bed was significantly lower in the TME group (P = 0.033). Furthermore, among patients with pT3-4a disease, the TME group had better 3-year rates of OS, DFS, and recurrence.

CONCLUSION

Minimally invasive total mesoesophageal excision appears to be a safe technique that can reduce tumor recurrence in the esophageal bed. Furthermore, this technique provided survival benefits for patients with pT3-4a disease.

Upper mediastinal lymph node dissection based on mesenteric excision in esophageal cancer surgery: confirmation by near-infrared image-guided lymphatic mapping and the impact on locoregional control

BACKGROUND

We previously reported a novel method of mesenteric excision for esophageal cancer surgery. The esophagus, trachea, recurrent laryngeal nerves (RLNs), and surrounding lymph nodes (LNs) are contained in a common mesenterium, which we termed the "mesotracheoesophagus". In addition, near-infrared (NIR) image-guided lymphatic mapping has recently been used. The purpose of this study was to confirm the feasibility of NIR image-guided lymphatic mapping for upper mediastinal LN dissection, and to confirm the oncological feasibility of our surgical approach.

METHODS

Fifteen patients with resectable esophageal cancer underwent submucosal injection of indocyanine green (ICG), and underwent robot-assisted esophagectomy. The frequency of ICG positivity in the LN basins along the RLNs, and metastatic frequency were assessed. Regarding the oncological feasibility of our thoracoscopic esophagectomy, the recurrence patterns and survival of 72 consecutive patients who underwent curative resection from 2011 to 2016 were analyzed.

RESULTS

ICG-positive LN basins along the right and left RLNs were found in 12 (80% of 15) patients (3 patients positive for metastatic LNs) and 11 (73% of 15) patients (2 positive for metastatic LNs and 1 false-negative), respectively. All ICG-positive LN basins were found within the mesotracheoesophagus. The sensitivity was 5/6 (83%), and the negative predictive value was 6/7 (86%). Among the 72 patients, with a median follow-up period of 1644 days, only 3 (4.2%) patients developed locoregional recurrence.

CONCLUSIONS

The NIR image-guided lymphatic mapping was feasible. Our results with no ICG-positive basins outside of the '"mesotracheoesophagus", supported our surgical approach. It might become standard, with acceptable locoregional control.

Histological study of the thin membranous dense connective tissue around the middle and lower thoracic esophagus, caudal to the bifurcation of the trachea

OBJECTIVE

We previously reported on the thin membranous dense connective tissue around the esophagus in the upper mediastinum. This time, we histologically investigated the existence of similar structures in the middle and lower mediastinum, caudal to the bifurcation of the trachea.

METHODS

Semi-sequential transverse sections of the mediastinum were obtained from two cadavers. Hematoxylin and eosin staining and Elastica van Gieson staining were performed.

RESULTS

In the middle mediastinum, the "visceral sheath" could not be observed completely around the esophagus. In the lower mediastinum, the thin membranous dense connective tissue was observed beneath the pericardium on the ventral side of the esophagus. On the dorsal side of the esophagus, two thin membranous dense connective tissues were similarly observed in two cadavers. One existed between the dorsal side of the esophagus and the three vessels (i.e., the descending aorta, the azygos vein and the thoracic duct) and was integrated with the thin membranous dense connective tissue of the ventral side of the esophagus at the bilateral side of the esophagus. This integrated dense connective tissue reached the left subpleural region and the adventitia of the aorta on the left side and the peripleural and pulmonary hilum on the right side. The other thin membranous dense connective tissue, which represents the "vascular sheath", was observed between the descending aorta and the thoracic duct.

CONCLUSION

These two thin membranous dense connective tissues, which are considered to represent the visceral sheath and vascular sheath, are thought to be available as optimal dissecting layers for radical esophagectomy.

Initial introduction of robot-assisted, minimally invasive esophagectomy using the microanatomy-based concept in the upper mediastinum

Background

We have recently standardized upper mediastinal lymph node dissection (UMLND) using a microanatomy-based concept in thoracoscopic esophagectomy in the prone position (TEPP), and introduced robot-assisted minimally invasive esophagectomy (RAMIE) using the same concept as in TEPP while aiming at solo surgery. The purpose of this study was to investigate the outcomes of RAMIE using the microanatomy-based concept in the initial introduction phase.

Methods

We have performed more than 500 TEPP procedures as minimally invasive esophagectomy (MIE). After performing about 400 cases of MIE, we established a microanatomy-based standardization of UMLND. In October 2018, we introduced RAMIE, and have performed 75 procedures in 20 months. Two groups were analyzed: a group after microanatomy-based standardization in TEPP (100 cases after completing 400 cases of TEPP) and a RAMIE group (75 cases). Finally, 51 paired cases were matched using a propensity score. Furthermore, the change in postoperative short-term outcome for RAMIE in the initial introduction phase was analyzed.

Results

Although there were no significant differences between the two groups in the number of upper mediastinal lymph nodes dissected, there was a significant decrease (P = 0.036) in intraoperative blood loss volume with RAMIE, representing a definite benefit for patients. The thoracoscopic operative time for RAMIE decreased by almost 100 min following less than 50 cases of experience, reaching the same level as that for recent TEPP, but with only one-tenth the operator experience. There were no significant differences in the total postoperative morbidity rate including the recurrent laryngeal nerve palsy rate.

Conclusion

RAMIE has been introduced safely and smoothly using the microanatomy-based concept established in TEPP.

Effect of azygos arch preservation during thoracoscopic esophagectomy on facilitation of postoperative refilling

PURPOSE

In esophageal cancer surgery, the significance of preserving the azygos arch during thoracoscopic esophagectomy remains unknown. To determine the significance, we examined the difference in postoperative courses between patients who underwent an azygos arch-preserving technique and patients whose azygos arch had been dissected.

METHODS

We retrospectively analyzed 119 patients with esophageal cancer who underwent thoracoscopic esophagectomy from January 2017 to December 2019. Statistical tests, including univariate or multivariate analyses and propensity score-matched analysis, were performed focusing on changes in fluid balance caused by the preservation of the azygos arch.

RESULTS

The azygos arch was preserved in 65 patients and dissected in 54 patients. Urine output on postoperative day 2 was higher, and the IN-OUT balance on postoperative day 2 or accumulated IN-OUT balance up to postoperative day 2 tended to be lower in the azygos arch-preserving group than in the dissected group. The azygos arch-preserving technique did not affect the number of dissected mediastinal lymph nodes.

CONCLUSION

The azygos arch-preserving technique during thoracoscopic esophagectomy facilitated postoperative refilling and avoided postoperative fluid excess. This technique might be a novel minimally invasive option for an otherwise highly invasive esophageal cancer surgery.

Recent advances in minimally invasive esophagectomy for squamous esophageal cancer

Over the past decade there has been tremendous development in the clinical application of minimally invasive esophagectomy (MIE) for the treatment of squamous esophageal carcinoma. The major challenges in the performance of MIE include limitations in visualization and manipulation within the confined, rigid thoracic cavity; the need for adequate patient positioning and anesthetic techniques to accommodate the surgical exposure; and changes in the surgical steps for achieving radical nodal dissection, especially for the superior mediastinum. The surgical procedure for MIE is more and more standardized, and there is an increasing practice of MIE worldwide. Randomized trials and meta-analyses have confirmed the advantages of MIE over open esophagectomy, including a significantly lower rate of complications and shorter hospital stays. The recent application of robotics technologies for MIE has further enhanced the quality and safety of the surgical dissection, while intraoperative nerve monitoring has contributed to a lower rate of recurrent laryngeal nerve palsy. With the application of new technologies, we expect further improvement in surgical outcomes for MIE in the treatment of squamous esophageal cancer.

Microanatomy-based standardization of left upper mediastinal lymph node dissection in thoracoscopic esophagectomy in the prone position

BACKGROUND

Although thoracoscopic esophagectomy in the prone position (TEPP) has become a standard procedure for esophageal cancer surgery, upper mediastinal lymph node dissection (UMLND) on the left side remains an issue. We have recently developed a new standardized approach to left UMLND in TEPP based on the microanatomy of the membranes and layers with the aim of achieving quick and safe surgery. The purpose of this study was to establish and evaluate our new standardized procedure in left UMLND.

PATIENTS AND METHODS

Patients were divided into 2 groups: a pre-standardization group (n = 100) and a post-standardization group (n = 100). Eventually, 83 paired cases were matched using propensity score matching. In our new standardized procedure, left UMLND was performed while focusing on the visceral sheath, vascular sheath, and the fusion layer between them using a magnified view.

RESULTS

The thoracoscopic operative time was significantly shorter (P < 0.001) in the post-standardization group [n = 83; 209.0 (176.0-235.0) min] than in the pre-standardization group [n = 83; 235.5 (202.8-264.5) min]. No significant differences were found in the number of mediastinal lymph nodes dissected or intraoperative blood loss between the two groups. There was a tendency for the total postoperative morbidity to decrease in the post-standardization group. Furthermore, the left recurrent laryngeal nerve palsy rate was significantly lower in the post-standardization group (18.1% to 8.7%, P = 0.015).

CONCLUSION

Microanatomy-based standardization contributes to safe and efficient left UMLND.

Mesenteric excision of upper esophagus: a concept for rational anatomical lymphadenectomy of the recurrent laryngeal nodes in thoracoscopic esophagectomy

BACKGROUND

The recurrent laryngeal nerve (RLN) lymph nodes are among the most frequently involved lymph nodes in esophageal cancer. Surgical removal of these lymph nodes is considered beneficial for postoperative prognosis, especially in patients with squamous cell carcinoma. Unfortunately, the precise surgical anatomy of the upper mediastinum is not well understood and no distinct high-resolution images are currently available.

METHODS

In this article, we provide a simple intuitive concept of upper mediastinal surgical anatomy that could facilitate rational anatomical lymphadenectomy of the RLN lymph nodes. The essential concept of this mesenteric excision is to mobilize mesoesophagus including RLN in an en bloc fashion and to save RLN laterally by incising visceral sheath. This is applicable identically to both right and left upper mediastinum.

RESULTS

Between January 2009 and December 2017, thoracoscopic esophagectomy with upper mediastinal lymphadenectomy for primary esophageal cancer was performed in 189 patients. Median thoracoscopic procedure time was 297 (range 205-568) min and median intraoperative blood loss was 70 ml (range unmeasurable up to 2545 ml). Median number of harvested upper mediastinal lymph nodes was 12. Postoperative complication of Clavien-Dindo classification grade III or higher events was observed in 14% of patients. RLN palsy of grade II or higher occurred in 20 patients (11%).

CONCLUSION

The mesoesophagus in the upper mediastinum is an anatomical unit surrounded by fibrous connective tissue containing the esophagus, trachea, tracheoesophageal vessels, lymphatic tissue, and RLNs. Thus, mesenteric excision of esophagus is defined to resect this area by sparing trachea and RLNs for rational anatomical lymphadenectomy. We believe that this concept makes upper mediastinal lymphadenectomy safer and more appropriate.

Thoracoscopic esophagectomy with total meso-esophageal excision reduces regional lymph node recurrence

PURPOSE

We investigated the operative outcomes of thoracoscopic esophagectomy (TE) in the prone position, using the concept of total meso-esophageal excision for esophageal cancer.

METHODS

The medical records of 140 consecutive patients with esophageal cancer who underwent radical esophagectomy by TE were reviewed retrospectively, and operative outcomes were compared between patients treated before (non-meso-esophagus; non-ME group) and after (ME group) the introduction of total meso-esophageal excision (ME).

RESULTS

There were no significant differences between the groups in postoperative morbidity (non-ME group vs. ME group, 28.3% vs. 41.4%, p = 0.119), 30-day mortality (non-ME group vs. ME group, 0% vs. 1.1%; p = 0.433), and in-hospital mortality (non-ME group vs. ME group, 1.9% vs. 0%, p = 0.199). Although overall survival and relapse-free survival did not differ significantly between the groups, the overall recurrence rate was significantly lower in the ME group than the non-ME group (non-ME group vs. ME group, 43.4% vs. 23%, p = 0.011). In particular, the rate of regional lymph node recurrence in the mediastinum was lower in the ME group (non-ME group vs. ME group, 11.3% vs. 2.3%; p = 0.026).

CONCLUSIONS

Our results suggest that the ME procedure might be one of the procedures that reduce regional lymph node recurrence in the mediastinum without any deterioration in short-term outcomes.