Navigating self-expandable metallic stent placement in inoperable esophageal malignancies: A landmark-based technique using the vertebral column and diaphragm

Abstract

BACKGROUND

Self-expandable metallic stent (SEMS) placement is a palliative treatment for inoperable esophageal malignancies with the goal of improving the patient’s quality of life. Utilizing anatomical landmarks can simplify the procedure performed under fluoroscopy. Therefore, we proposed the utilization of the vertebral column and diaphragm as landmarks for SEMS placement under fluoroscopy.

AIM

To evaluate the technical success of using the vertebral column and diaphragm landmarks for SEMS placement.

METHODS

This retrospective cross-sectional study included 801 patients with inoperable esophageal malignancies who underwent SEMS placement for dysphagia due to malignant esophageal strictures from January 1, 2006, to December 31, 2024. The SEMS placement procedure utilized the vertebral column and diaphragm as landmarks. The primary endpoint was to assess the technical success of this novel technique for SEMS placement for the index procedure.

RESULTS

Among 801 patients (18-95 years; mean 50 ± 15 years), 408 (50.90%) were female. All presented with dysphagia (average duration: 3.84 months). Squamous cell carcinoma was the predominant etiology (594; 74.16%), followed by adenocarcinoma (207; 25.84%). Tumors involved the middle third of the esophagus in 365 patients (45.57%), and distant metastasis was the leading cause of inoperability (52.81%). Gastroesophageal junction involvement was observed in 240 patients (30.00%). Tracheoesophageal fistula was present in 48 cases (6.00%). Mean stricture length was 8.4 cm. 139 patients (17.40%) required pre-stent dilatation. SEMS length ranged from 8 cm to 18 cm. Technical success was 100% without major immediate adverse events. Repeat stenting was needed in 15 patients (1.87%) due to tumor overgrowth, and 11 (1.37%) required dilatation for tumor ingrowth.

CONCLUSION

Using the vertebral column and diaphragm as landmarks provides a simplified, safe, and reproducible method for SEMS placement. Larger prospective studies are needed to validate these results and assess long-term outcomes.

Key Words: Esophageal malignancies; Dysphagia; Malignant esophageal strictures; Self-expandable metallic stent; Vertebral column; Diaphragm; Landmarks; Palliative care

Core Tip: A novel, landmark-based technique for self-expandable metallic stent placement in patients with inoperable esophageal cancer was investigated in this study. By utilizing the vertebral column and diaphragm as anatomical guides, the procedure became more streamlined, cost-effective, and reproducible without compromising safety or technical success. We achieved a 100% success rate and minimal complications in 801 patients, indicating that this approach offers a practical alternative to traditional fluoroscopic or endoscopic guidance, especially in resource-limited settings.

INTRODUCTION

Esophageal cancer is the seventh most prevalent malignancy globally and the sixth-leading cause of cancer-related mortality[1]. The overall 5-year survival rate is less than 20%[2]. Esophageal cancer poses a significant disease burden in Pakistan, where its incidence is relatively high[3]. The presence of distant metastases renders most cases inoperable and results in a dismal 5-year survival rate of 5%[4]. For patients with inoperable esophageal cancer (50%-60% at presentation)[5], palliation is the primary focus, indicating a need for palliative strategies to improve patient quality of life. Dysphagia is a debilitating symptom of esophageal cancer and necessitates effective relief to alleviate distress, malnutrition, and aspiration pneumonia. Various non-surgical palliative techniques exist, including laser ablation, photodynamic therapy, argon plasma coagulation, cryoablation, intraluminal brachytherapy, external beam radiation therapy, chemotherapy, and self-expandable metallic stent (SEMS) placement[6]. SEMS is a convenient and durable palliative resolution for malignant dysphagia, and its use has significantly amended patient outcomes[7].

Multiple strategies are available for SEMS placement, employing either fluoroscopic or endoscopic guidance. Fluoroscopic techniques often rely on indirect methods to define tumor length, including the use of external radio-opaque markers[8], injecting contrast into the submucosal plane to create an internal landmark[9], or instilling dye within the esophageal lumen to outline the stricture[10]. While these approaches assist in estimating the extent of the lesion, each carries practical drawbacks and potential risks. Hence, there is a need for performing the fluoroscopy-guided procedure via a streamlined method. Employing the vertebral column and diaphragm as landmarks for SEMS placement under fluoroscopic guidance offers a novel, simplified, easy-to-learn, and safe approach. This technique reduces procedural complexity and potential risks. This study evaluated the technical success of using the vertebral column and diaphragm as landmarks for SEMS placement under fluoroscopic guidance in patients with inoperable esophageal malignancies.

MATERIALS AND METHODS

Study design

This was a retrospective study conducted at Dr. Ruth K.M Pfau, Civil Hospital Karachi, in the endoscopy department of Surgical Unit-IV and the Sindh Institute of Advanced Endoscopy and Gastroenterology. This study included all patients with endoscopically, histologically, and radiologically proven inoperable esophageal malignancy who received esophageal SEMS placement for amelioration of dysphagia from January 1, 2006, to December 31, 2024. Inoperable esophageal malignancy was defined as unresectable esophageal carcinoma due to locally advanced disease, distant metastasis, or comorbidities rendering the patients unfit for surgery.

Data from a total of 801 patients were reviewed in this study. Figure 1 depicts the selection, exclusion, and final inclusion of study participants. Data, including demographics, primary diagnosis, stent insertion details, and immediate adverse events related to stent placement, were collected through our electronic medical records. Informed consent for SEMS placement was obtained from all patients or their available family members. The expected benefits, risks, and possible short-term and long-term adverse events were explained in detail. An exemption letter was obtained from the Institutional Review Board according to the nature of the study and its design. The inclusion criteria were: Patients with biopsy-proven inoperable esophageal malignancy due to either distant metastasis, poor functional status, or extensive extraesophageal spread with the involvement of the trachea, aorta, or pericardium on computed tomography scan; and dysphagia due to esophageal malignant strictures or tracheoesophageal fistula. The exclusion criteria were: Tumor within 2 cm of the cricopharynx, and the inability to maneuver the guidewire beyond the tumor.

Figure 1  The Strengthening the Reporting of Observational studies in Epidemiology flow diagram illustrating the selection of study participants, including eligibility assessment, exclusions with reasons, and the final cohort included in the analysis.

Technical success was defined as the precise deployment and expansion of SEMS at the fluoroscopic anatomical landmarks, effectively bridging the strictured area, covering at least 2 cm of normal mucosa on either side of the tumor, without any immediate adverse events like major bleeding or perforation. Immediate adverse events were defined as complications occurring during the procedure or within 24 hours of stent placement and included major bleeding requiring transfusion or intervention, perforation, aspiration pneumonia, severe chest pain, or death. Re-intervention was defined as any additional endoscopic or radiological procedure required to restore luminal patency or manage a stent-related complication. Inoperability was defined as esophageal carcinoma deemed unresectable due to locally advanced disease, distant metastasis, or significant comorbidities rendering the patient unfit for surgery, as determined by the treating multidisciplinary team.

Stent insertion protocol

Stent insertion was performed under fluoroscopic guidance by endoscopists who had each independently performed a high volume of complex endoscopic therapeutic procedures, including esophageal SEMS placements, with documented proficiency and low complication rates. In practice, junior faculty members and advanced gastrointestinal fellows had also performed SEMS placements under the direct supervision of experienced faculty members. All procedures were performed under conscious sedation (midazolam and nalbuphine) or monitored anesthesia care. An upper gastrointestinal endoscopy was performed to delineate the stricture site and length using a standard or slim gastroscope in the left lateral position. In cases where a standard or slim gastroscope was unable to pass beyond the strictured area, a guidewire was advanced gently across the esophageal growth. Then, dilatation using Savary Gilliard dilators under fluoroscopic guidance was performed. The guidewire was placed in the stomach, and the scope was pulled back slowly. Finally, the esophageal SEMS was introduced over the guidewire. The vertebral column and diaphragm were used as anatomical landmarks to delineate the site at which the proximal and distal ends of the stent should be deployed. The decision of the stent type and size was made by the endoscopist performing the procedure based on stricture characteristics, fistula presence or absence, and device availability.

Methodology for stent placement in esophageal tumors

Representative images of the SEMS placement of 2 patients are presented in Figures 2 and 3.

Figure 2 Representative images of self-expandable metallic stent placement utilizing the vertebral column and diaphragm as landmarks in a 62-year-old male with a history of dysphagia and weight loss diagnosed with squamous cell carcinoma with distant metastasis. A: Endoscopy revealed a circumferential and friable growth 35 cm from the incisors. The gastroesophageal junction was involved at 39 cm, extending to 1 cm of the cardia. An ultrathin gastroscope was passed with resistance. A guidewire was placed into the stomach under endoscopic guidance; B: Fluoroscopic imaging showed the ultrathin gastroscope at the proximal extent of the tumor. The blue arrow indicates the corresponding vertebra in line with the proximal extent of the tumor (i.e., two vertebrae above the diaphragm); C: Fluoroscopic imaging showed the ultrathin gastroscope at the distal extent of the tumor. The blue arrow indicates the corresponding vertebra in line with the distal extent of the tumor just above the diaphragm; D: Fluoroscopic imaging after self-expandable metallic stent (22 mm × 100 mm) placement under the guidance of vertebral markings, after adding one vertebra above and one vertebra below the proximal and distal extent of the tumor. The blue arrows indicate the corresponding vertebrae in line with the proximal and distal ends of the stent (i.e., four vertebrae in total); E: Endoscopic view after self-expandable metallic stent placement showed the proximal end of the stent covering 2 cm of the normal mucosa proximally. SEMS: Self-expandable metallic stent.

Figure 3 Representative images of self-expandable metallic stent placement utilizing the vertebral column and diaphragm as landmarks in a 70-year-old female with a history of dysphagia, cough, and weight loss diagnosed with squamous cell carcinoma and locally advanced disease with tracheoesophageal fistula. A: Endoscopy showed a circumferential growth starting at 25 cm from the incisors and extending up to 36 cm. The gastroesophageal junction was measured at 40 cm. A guidewire was placed into the stomach under endoscopic guidance; B: The endoscopic view showed esophageal growth on the left side and the tracheoesophageal fistula at 27 cm from the incisors on the right side; C: Fluoroscopic imaging showed the ultrathin gastroscope at the distal extent of the tumor with the guidewire in place. The blue arrow indicates the corresponding vertebra in line with the distal extent of the tumor (i.e., one vertebra above the diaphragm); D: Fluoroscopic imaging showed the ultrathin gastroscope at the proximal extent of the tumor. The blue arrow indicates the corresponding vertebra in line with the proximal extent of the tumor (i.e., six vertebrae above the diaphragm). The self-expandable metallic stent was placed under the guidance of vertebral markings, after adding one vertebra above and one vertebra below the proximal and distal extent of the tumor; E: Endoscopy after self-expandable metallic stent placement showed the proximal end of the stent effectively bridging the tumor and covering 2 cm of the normal mucosa proximally. TEF: Tracheoesophageal fistula.

For proximal or mid-esophageal tumors: (1) Identify key anatomical landmarks using fluoroscopy; (2) With the scope in place under fluoroscopic guidance, identify the vertebra in line with the distal extent of the tumor using the diaphragm as a reference, and identify the vertebra at the proximal extent of the tumor. Count the vertebrae between the distal and proximal extent of the tumor. Assign a length of 2.5 cm per vertebral body. Re-confirm the desired size of the SEMS by calculating the total length of the stricture by counting the vertebrae and adding one vertebral body above the proximal extent and one vertebral body below the distal extent of the tumor to obtain the proximal and distal vertebral markers respectively; and (3) Using fluoroscopy, position the stent. Place the distal end of the stent at the distal vertebral marker. Position the proximal end of the stent at the proximal vertebral marker. Release the stent at the appropriate position to ensure full coverage of the stricture.

For tumors extending beyond the gastroesophageal junction: (1) Identify key anatomical landmarks using fluoroscopy; (2) Identify the proximal extent of the tumor. Count the vertebra in line with the proximal extent of the tumor using the diaphragm as a reference for precise alignment. Identify the vertebra in line with the distal extent of the tumor beyond the gastroesophageal junction. Measure the distance from the proximal end of the tumor to the proximal stomach. Add one vertebra above and one vertebra below the fluoroscopic landmarks and reconfirm the required size of the stent; and (3) Place the stent under fluoroscopic guidance. Position the upper end of the stent at the proximal vertebral marker. Extend the distal end of the stent into the stomach past the gastroesophageal junction to ensure proper coverage. Release the stent.

Statistical analysis

Data were entered and analyzed in Statistical Package for the Social Sciences version 30 (IBM Corp., Armonk, NY, United States). Demographics for categorical variables were reported as n (%), whereas numerical variables were reported as mean ± SD.

RESULTS

A total of 801 patients with biopsy-proven, inoperable esophageal malignancy were included in the analysis (Table 1). Of these, 408 patients (50.90%) were female. The overall age ranged from 18 years to 95 years, with a mean age of 50 ± 15 years. All patients presented with dysphagia (100%), followed by unintentional weight loss (83.64%), vomiting (69.41%), and hematemesis (9.24%). Histopathological examination demonstrated squamous cell carcinoma in 594 patients (74.16%) and adenocarcinoma in 207 patients (25.84%). The primary reason for inoperability was distant metastasis (52.81%), while 39.46% had locally advanced disease and 7.73% had significant comorbidities precluding surgical intervention. Tumor location was most frequently in the middle one-third of the esophagus (365 patients, 45.57%), followed by the lower one-third (44.07%) and upper one-third (10.36%). Pre-dilatation of the malignant stricture was required in 139 patients (17.40%) prior to SEMS placement. Technical success was achieved in all 801 patients. No immediate adverse events, including major bleeding or perforation, were observed. The mean procedural duration was 10.4 ± 3.1 minutes, with a range of 7-15 minutes.

Table 1 Clinicopathological characteristics of the patients, mean ± SD/n (%).

Characteristics	Values
Age	50.25 ± 14.91
Sex
Male	393 (49.10)
Female	408 (50.90)
Presenting complaint
Dysphagia	801 (100)
Weight loss	670 (83.64)
Vomiting	556 (69.41)
Hematemesis	74 (9.24)
Cause of inoperability
Distant metastasis	423 (52.81)
Locally advanced disease	316 (39.46)
Unfit for surgery	62 (7.73)
Histopathology
Squamous cell carcinoma	594 (74.16)
Adenocarcinoma	207 (25.84)
Location of the tumor
Upper one-third of the esophagus	83 (10.36)
The middle one-third of the esophagus	365 (45.57)
The lower one-third of the esophagus	353 (44.07)
Involvement of GEJ
Yes	240 (30.00)
No	561 (70.00)
TEF
Yes	48 (6.00)
No	753 (94.00)
Length of stricture in cm	8.40 ± 2.44
Dilatation
Yes	139 (17.40)
No	662 (82.60)
Type of stent
Partially covered	726 (90.64)
Fully covered	75 (9.36)
Size of stent in cm	12.49 ± 2.26

GEJ: Gastroesophageal junction; TEF: Tracheoesophageal fistula.

DISCUSSION

Esophageal SEMS placement is an effective palliative measure for patients with malignant esophageal strictures[11]. Our study highlighted a simplified technique for SEMS placement under fluoroscopy by using the vertebral column and diaphragm as landmarks. To the best of our knowledge, this study represents the largest single-center study on esophageal SEMS placement. Previously, Włodarczyk and Kużdżał[12] reported a cohort of 442 patients. There are several techniques for SEMS placement that utilize fluoroscopic or endoscopic approaches. Fluoroscopic-guided techniques include ascertaining the extent of the tumor by placement of external radio-opaque markers[8], submucosal injection of a contrast material serving as an internal marker[9], and the luminal instillation of dye for delineating the stricture length[10]. However, the external markers can detach, leading to malposition. Additionally, submucosal contrast injection increases the procedural cost and has several risks[13], and luminal dye instillation increases the risk of aspiration. Endoscopic-guided approaches typically require two people: One for SEMS placement and one to provide endoscopic guidance; however, this can also lead to inadequate bridging of the tumor due to a less accurate understanding of the tumor orientation. Hence, there is a need for a simplified, feasible, cost-effective, and reproducible technique for SEMS placement under fluoroscopic guidance that utilizes simple anatomical landmarks with minimal adverse events.

Unlike the simplified landmark-guided deployment described by Kini et al[14], which relied solely on endoscopic distance measurements without fluoroscopic confirmation, our technique integrates both endoscopic delineation and fluoroscopic guidance, using vertebral bodies and the diaphragm as stable reference points. This dual-modality approach not only allows for accurate calculation of stricture length, tailored stent sizing, and precise deployment but also provides objective fluoroscopic markers that remain useful even in patients with spinal deformities or prior surgical alterations. As a result, the risks of misplacement, incomplete coverage, or migration are minimized, particularly for tumors involving the gastroesophageal junction.

In contrast with previous studies[15] where male patients predominated (69.3%), the majority of our patients were female (50.90%). This discrepancy may be due to late presentation, limited access to healthcare, biological factors, socioeconomic barriers, and the frailty of female patients, leading to contraindications for major surgery. Squamous cell carcinoma is the most prevalent esophageal malignancy in the Pakistani population, as previously reported by Qureshi et al[16] and Butt et al[17], and our study also confirmed this observation. However, adenocarcinoma is more common in Western countries where there is a high prevalence of risk factors, including Barrett’s esophagus, obesity, and gastroesophageal reflux disease[18,19].

A partially covered SEMS was placed in 90.64% of patients due to a decreased risk of stent migration compared with fully covered SEMS[20] and the low prevalence of restenosis due to tumor ingrowth compared with uncovered SEMS[21]. This choice likely led to better long-term clinical outcomes and decreased the requirement for re-intervention. Additionally, partially covered SEMS can be easily repositioned immediately after deployment[22]. A fully covered SEMS was placed in 75 patients (9.36%). Among them, 45 patients had tracheoesophageal fistula. In addition, for 35 cases, a fully covered SEMS was the only choice available at the time of the placement procedure.

While the mean thoracic vertebral body height is typically reported between 20 mm and 22 mm in Indian cohorts, and Kunkel et al[23] reported vertebral body heights ranging from 14.2 mm to 21.96 mm across thoracic levels with higher values distally, Singh et al[24] documented anterior heights approaching 29-30 mm at T12 in an Indian cadaveric population. Thoracic intervertebral discs contribute an additional 3-5 mm in height, particularly in lower thoracic levels[25]. Thus, approximating each vertebral level (vertebral body + disc) as 2.5 cm is consistent with published anatomical data and provides a pragmatic safety margin to ensure complete stricture coverage and minimize the risk of uncovered tumor margins during stent deployment. We recognize this represents an upper-range approximation and acknowledge anatomical variability; therefore, this study was consistently supplemented by real-time endoscopic and fluoroscopic verification to ensure accurate stent placement.

This landmark-based method offers notable cost advantages in resource-limited settings by eliminating the need for specialized consumables and contrast agents. Its shorter procedure time further enhances cost-effectiveness by reducing fluoroscopy exposure, staff demands, and room occupancy, making it particularly suitable for high-volume public hospitals. Moreover, this approach is easily teachable to junior endoscopists. Consistent vertebral-diaphragm alignment allows predictable fluoroscope orientation, enabling trainees to identify key anatomical landmarks and deploy stents accurately under supervision. Its simplicity and minimal operator-dependent variability result in a short learning curve, with most juniors achieving proficiency after a few supervised procedures, making it a valuable training tool in resource-limited centers.

A key finding of our study was the high technical success rate of 100%, highlighting the reliability and reproducibility of this technique across multiple endoscopists with minimal variability. No immediate procedure-related adverse events, such as bleeding or perforation, which can occur in up to 6% of patients[26], were observed in our patients. However, stent misdeployment could not be reliably commented upon, as it is possible that such events, if they occurred, may not have been consistently documented in the available records. 15 patients (1.87%) required placement of a stent within a stent due to tumor overgrowth and disease progression, which was previously reported by Na et al[27] in 5% of their patients. Stent blockage due to tumor ingrowth requiring Savary Gilliard dilatation was observed in 11 patients (1.37%). The technical ease, cost-effectiveness, minimal manpower requirements, and time efficiency make it a valuable alternative to current SEMS placement techniques. This technique is accessible to a broad range of endoscopists, including those working in resource-limited settings. These attributes collectively support the widespread adoption and standardization of this technique in clinical practice.

Our study had several strengths. First, the sample size was sufficient. Second, our results aligned with studies demonstrating high technical success rates for SEMS placement[28]. However, the use of the vertebral column and diaphragm as landmarks provided a unique contribution to the literature. Third, multiple endoscopists performed the procedure using the same technique, which proves its reproducibility. Fourth, no major immediate adverse events were observed in any patient, indicating the safety of this technique.

Despite these strengths and key findings, we should acknowledge the limitations of the study. The data were reviewed retrospectively, and the improvement in dysphagia, malnutrition, and quality of life, which are essential to judge clinical impact, could not be estimated. Head-to-head comparison with existing techniques for SEMS placement under fluoroscopic guidance could not be made, limiting our ability to demonstrate superiority, non-inferiority, or incremental benefit of the proposed technique. Moreover, there exists the possibility of underestimation of stated late adverse events, inherent to the retrospective nature of the study. Future prospective, multi-center studies, comparing existing techniques, will help confirm our findings. Ultimately, given the retrospective, single-center design of our study, external validation in other settings is necessary. Nonetheless, in conjunction with such, standardized training programs can be developed, which will also serve to propagate the benefits of this technique.

CONCLUSION

Our method of SEMS placement using the vertebral column and diaphragm as landmarks is a novel approach. We reported the safety and reproducibility of this technique on a large scale with multiple endoscopists performing the procedure. This technique offers a simplified, reliable, and reproducible approach with a high success rate, minimal inter-endoscopist variability, and procedure-related adverse events, making it an attractive option for standardization. Future prospective, multi-center studies are warranted to compare this method with existing techniques, evaluate long-term clinical outcomes, and establish standardized training protocols for wider adoption.

ACKNOWLEDGEMENTS

We acknowledge the valuable services and brilliant procedural skills of all the endoscopists who performed SEMS placement in the department of Surgical Unit-IV and Sindh Institute of Advanced Endoscopy and Gastroenterology. Their sincere contribution to serve in the best interest of the patients is appreciated.