Endoscopy dissection of small stromal tumors emerged from the muscularis propria in the upper gastrointestinal tract: Preliminary study

Endoscopic Treatment for Gastric Subepithelial Tumor

Most gastric subepithelial tumors (SETs) are asymptomatic and are often incidentally discovered during endoscopic procedures conducted for unrelated reasons. Although surveillance is sufficient for the majority of gastric SETs, certain cases necessitate proactive management. Laparoscopic wedge resection, although a viable treatment option, has its limitations, particularly in cases where SETs (especially those with intraluminal growth) are not visualized on the peritoneal side. Recent advances in endoscopic instruments and technology have paved the way for the feasibility of endoscopic resection of SETs. Several promising endoscopic techniques have emerged for gastric SET resection, including submucosal tunneling endoscopic resection, endoscopic full-thickness resection (EFTR), laparoscopic and endoscopic cooperative surgery (LECS), and non-exposure EFTR (non-exposed endoscopic wall-inversion surgery and non-exposure simple suturing EFTR). This study aimed to discuss the indications, methods, and outcomes of endoscopic therapy for gastric SETs. In addition, a simplified diagram of the category of SETs according to the therapeutic indications and an algorithm for the endoscopic management of SET is suggested.

Diagnosis and Endoscopic Treatment of Gastrointestinal Stromal Tumors Arising from Esophagus

Aim: The primary purpose of this study was to investigate the diagnosis and endoscopic treatment of gastrointestinal stromal tumors (GISTs) arising from esophagus. Materials and Methods: From January 2013 to December 2017, 16 cases of GISTs of esophagus were retrospectively identified from a total of >3000 GISTs treated in our center. Demographic characteristics, clinical data, endoscopic therapy outcomes, histopathology, and follow-up were analyzed. Results: The mean age of the patients was 53 years (range 35-71 years), mostly female (56.3%). Seven tumors were in the lower esophagus, five in the middle esophagus, and one in the upper esophagus. The most common symptom was abdominal discomfort (8/16; 50.0%), followed by acid reflux (6/16; 37.5%). All of the patients underwent CT scan, gastroscopy, and/or endoscopic ultrasound. Two patients were diagnosed with esophageal GISTs with a preoperative endoscopic biopsy. Tumors were resected completely in all patients by endoscopic surgery. The median operating time was 85 minutes (range 28-153 minutes), and the average tumor size was 11.6 mm (range 6-21 mm). Postoperative histopathology demonstrated esophageal GISTs were positive for CD117 and CD34. The mean length of postoperative hospital stay was 4.7 days (range 2-7 days). The median postoperative follow-up duration was 28 months (range 1-59 months). Conclusion: Endoscopic treatment seems to be safe and effective for tumors size <20 mm in diameter. However, long-term prospective randomized controlled trials are further needed.

Endoscopic Submucosal Dissection of Seborrheic Keratosis-Like Lesion of the Esophagus: A New Entity?

Seborrheic keratosis, one of the most common lesions of the epidermis, is rarely seen on mucosal surfaces. We report a case of a distinctive epithelial neoplasm of the esophagus showing close resemblance to seborrheic keratosis that was resected with endoscopic submucosal dissection. A 65-year-old patient's previous esophageal biopsy showed suspicious low grade dysplasia and the patient was referred for endoscopic submucosal dissection of a flat lesion in the mid-esophagus. Macroscopic examination revealed a well circumscribed, pigmented and elevated lesion with a diameter of 20 mm. Microscopically, the lesion was well circumscribed, with plaque-like elevation, and showed hyperkeratosis, acanthosis, and papillomatosis. Broad coalescing solid sheets and interconnecting trabeculae of basaloid cells were the consistent feature throughout the lesion. Squamous eddies and occasional central keratinization were present. Mitotic activity and koilocytes were not identified. Immunohistochemically, the lesion showed diffuse nuclear positivity with p63 and negativity with p16. Ki-67 index was confined to the basal cell layer. With the help of histopathologic and immunohistochemical findings, we diagnosed this morphologically benign case as "seborrheic keratosis-like lesion of the esophagus". It should be kept in mind that seborrheic keratosis-like lesions might be rarely seen on mucosal surfaces such as the esophagus. Endoscopic submucosal dissection is a new, curative, and safe endoscopic resection technique in en-bloc resection of superficial esophageal lesions. To our knowledge, this is the first case of the aforementioned lesion in the esophagus being resected with endoscopic submucosal dissection.

Current Status of Endoscopic Resection of Gastric Subepithelial Tumors

Most gastrointestinal (GI) subepithelial tumors (SETs) are identified incidentally during endoscopic examination and are located in the stomach. Some SETs are malignant or have the potential to become malignant. Tumors originating from deeper layers, such as the muscularis propria or serosa, are not easy to diagnose and resect. Current guidelines recommend yearly endoscopic surveillance of SETs smaller than 2 cm. This recommendation may not be cost-effective in managing GI SETs. Endoscopic resection results not only in obtaining sufficient tissue for pathological diagnosis but also in resection and curing the tumor. Many different endoscopic methods for resection of GI SETs have been published in the literature. To avoid confusion, we have divided these methods into standard endoscopic submucosal dissection, modified endoscopic submucosal dissection, submucosal tunneling endoscopic resection, and nonexposed and exposed endoscopic full-thickness resection. These procedures offer less invasive approaches than surgery for resection of GI SETs and may be the most cost-effective in taking care of patients with GI SETs.

Endoscopic Enucleation Is Effective and Relatively Safe in Small Gastric Subepithelial Tumors Originating from Muscularis Propria

BACKGROUND

Gastric subepithelial tumors originating from muscularis propria (MP) are usually benign, but some have malignant potential.

AIMS

The aim of this study was to evaluate the utility of endoscopic enucleation for the diagnosis and treatment of MP tumors.

PATIENTS AND METHODS

From January 2010 to February 2018, eighty patients with gastric MP tumors underwent endoscopic enucleation at our hospital. Band ligation and resection (BLR) or endoscopic muscularis resection (EMD) was performed based on considerations of tumor size (≤ 12 mm or > 12 mm). Tumor characteristics, procedure times, complete resection rates, adverse events and recurrence were analyzed.

RESULTS

Eighty patients with 82 lesions were eligible for inclusion in this study. BLR was used to treat 41 lesions. For these lesions, mean tumor size was 9.5 mm, median procedural time was 17.6 min (range 4-52), and the endoscopic complete resection rate was 100% (41/41). Perforation was developed in four patients, and was closed by endoscopic clipping. EMD was used to treat 41 lesions. Median procedure time was 66.1 min (range 12-260) and the endoscopic complete resection rate was 85.4% (35/41). Perforation occurred in eight patients, four patients received endoscopic treatment and four underwent surgery. Tumor recurrence was not observed in any patient over follow-up (mean 26.3 months).

CONCLUSION

Endoscopic enucleation appears to offer an effective, relatively safe means for diagnosing and treating gastric subepithelial tumors originating from the MP, and BLR provides a straightforward, effective, and relatively safe treatment for small MP tumors (≤ 12 mm).

Clinicopathological features and prognosis of 276 cases of primary small (≤ 2 cm) gastric gastrointestinal stromal tumors: a multicenter data review

BACKGROUND

Till present, there are still controversies over the epidemiology, pathological features, types of surgical treatment, and prognoses of primary small gastric GISTs (gGISTs).

METHODS

From January 1998 to January 2015, patients with primary small gGIST admitted from four high-volume medical centers of the Southern China were enrolled and their data were analyzed to evaluate their clinicopathological features, treatment and prognostic factors to provide evidence-based medical experience for clinical practice.

RESULTS

A total of 276 primary small gGIST cases over a period of 18 years were investigated and had a median age of 60 years (range 27-91 years old). Regarding the tumor sites, 24 (8.7%) cases were in the cardia of the stomach, 107 (38.8%) in the fundus, 117 (42.4%) in the gastric body, and 28 (10.1%) in the gastric antrum. Eleven patients (4.0%) underwent a preoperative biopsy. A total of 137 (49.6%), 75 (27.2%), and 64 (23.2%) patients underwent laparoscopic, open resection, and endoscopic resection, respectively. Sixty-four patients (23.2%) had local endoscopic resection, 172 (62.3%) had wedge resection, 7 (2.5%) had proximal gastrectomy, 19 (6.9%) had distal gastrectomy, and 14 (5.1%) had total gastrectomy. Mitotic counts were ≤ 5/50, (5-10)/50, and > 10/50 per HPF in 259 (93.8%), 7 (2.5%), and 10 (3.6%) cases, respectively. There were 259 cases (97.1%) of spindle cell type, 7 (2.5%) epithelial cell types and one case (0.4%) of mixed type. Immunohistochemistry showed 74.6% (206/276), 98.2% (271/276), and 97.4% (269/276) of the patients had co-expression of CD34+, CD117+, and DOG-1+, respectively. Thirty-nine patients underwent genetic testing (39/276, 14.1%). Three patients (1.1%) had positive resection margin. Five high-risk patients received follow-up treatment with imatinib with a median follow-up time of 38 months (range 3-156 months). The overall 1-, 3-, and 5-year overall survival rates were 100%, 99.6%, and 99.1%, respectively.

CONCLUSION

Though the incidence of primary small gGISTs increased per annum, the overall survival prognoses were high. Surgery or endoscopic resection was the primary mode of treatment. Pathological features of primary small gGISTs were similar to large gGISTs, and to achieve a timely surgical intervention, the identification of intermediate- and high-risk cases should be a future focus of study.

Gastroduodenal Intussusception with a Gastric Gastrointestinal Stromal Tumor Treated by Endoscopic Submucosal Dissection

A 95-year-old Japanese woman presented to our hospital with intermittent vomiting and several episodes of melena. Abdominal computed tomography revealed intussusception of the gastric tumor into the duodenum. After endoscopic reduction, endoscopic ultrasonography identified a hypoechogenic lesion limited to the submucosal layer. Endoscopic resection was performed as a localized treatment for the prevention of recurrent gastroduodenal intussusception. To our knowledge, there have been no other reports describing a gastric gastrointestinal stromal tumor presenting with gastroduodenal intussusception and treated using an endoscopic submucosal dissection technique.

Comparison of endoscopic submucosal dissection and surgery for the treatment of gastric submucosal tumors originating from the muscularis propria layer: a single-center study (with video)

INTRODUCTION

Endoscopic submucosal dissection (ESD) has been used for the treatment of gastric submucosal tumors (SMTs). This study aims to compare clinical outcomes of ESD versus laparoscopic wedge resection (LWR) for gastric SMTs.

METHODS

This is a retrospective cohort study. Patients with SMTs who underwent ESD or LWR were enrolled in this study at a university-affiliated hospital from January 2010 to October 2015. Preoperative endoscopic ultrasound and computed tomography were performed to determine origin of layer and growth pattern. Clinical outcomes including baseline demographics, tumor size, operation time, blood loss, hospital stay, cost, pathology and postoperative complications were compared.

RESULTS

From January 2010 to October 2015, 68 patients with SMTs received ESD and 47 patients with SMTs received LWR. There was no difference in age, gender, body mass index, origin of layer and proportion with symptoms between ESD group and LWR group. However, tumor size was significantly larger in the LWR group (37.1 mm) than in the ESD group (25.8 mm, P = 0.041). For patients with tumors smaller than 20 mm, ESD was associated with shorter mean operation time (89.7 ± 23.5 vs 117.6 ± 23.7 min, P = 0.043), less blood loss (4.9 ± 1.7 vs 72.3 ± 23.3 ml, P < 0.001), shorter length of hospital stay (3.6 ± 1.9 vs 6.9 ± 3.7 days, P = 0.024) and lower cost (2471 ± 573 vs 4498 ± 1257 dollars, P = 0.031) when compared with LWR. For patients with tumors between 20 mm and 50 mm, ESD was associated with shorter mean operation time (99.3 ± 27.8 vs 125.2 ± 31.5 min, P = 0.039), less blood loss (10.1 ± 5.3 vs 87.6 ± 31.3 ml, P < 0.001), shorter length of hospital stay (4.0 ± 1.7 vs 7.3 ± 4.5 days, P = 0.027) and lower cost (2783 ± 601 vs 4798 ± 1343 dollars, P = 0.033) when compared with LWR. There were no significant differences in terms of rates of en bloc resection, complete resection and complication and histological diagnosis regardless of tumor size.

CONCLUSIONS

ESD can achieve similar oncological outcomes when compared with surgery for treatment of gastric SMT smaller than 50 mm.

Hybrid push-pull endoscopic and laparoscopic full thickness resection for the minimally invasive management of gastrointestinal stromal tumors: a pilot clinical study

Background. Gastric gastrointestinal stromal tumors (GISTs) that are predominantly endophytic or in anatomically complex locations pose a challenge for laparoscopic wedge resection; however, endoscopic resection can be associated with a positive deep margin given the fourth-layer origin of the tumors. Methods. Patients at two tertiary care academic medical centers with gastric GISTs in difficult anatomic locations or with a predominant endophytic component were considered for enrollment. Preoperative esophagogastroduodenoscopy (EGD), endoscopic ultrasound (EUS) with or without fine needle aspiration (FNA), and cross-sectional imaging were performed. Eligible patients were offered and consented for hybrid and standard management. Results. Over ten months, four patients in two institutions with anatomically complex or endophytic GISTs underwent successful, uncomplicated push-pull hybrid procedures. GIST was confirmed in all resection specimens. Conclusion. In a highly selected population, the hybrid push-pull approach was safe and effective in the removal of complex gastric GISTs. Endoscopic resection alone was associated with a positive deep margin, which the push-pull technique manages with a laparoscopic, full thickness, R0 resection. This novel, minimally invasive, hybrid laparoscopic and endoscopic push-pull technique is a safe and feasible alternative in the management of select GISTs that are not amenable to standard laparoscopic resection.

Heading toward the right direction--solution package for endoscopic submucosal tunneling resection in the stomach

BACKGROUND

The emerging submucosal tunneling and endoscopic resection (STER) technique provides definitive histological diagnosis as well as a therapeutic method for the gastric submucosal tumors (SMTs). We aim to present our experience and discuss key technical issues of STER.

METHODS

45 patients with gastric SMTs arising from MP received STER. First, a mucosal incision was made 3 cm proximal to the tumour, a submucosal tunnel was subsequently built from the incision to the tumor. The tumor was gradually exposed and dissected from surrounding tissue and retrieved from the tunnel. The initial mucosal incision was closed by metal clips. For SMTs in the gastric fundus near cardia, the submucosal tunnel was built from lower esophagus, through the angle of His, to the tumor for resection.

RESULTS

STER was successfully performed in 43 patients; the other two were converted to surgery. Mean operating time was 79.3 min (range 45-150 min). Mean tumor size was 1.4 cm (range 0.5-5 cm). Of the total 47 resected SMTs, 36 were GISTs, 10 were leiomyomas and 1 was schwannoma. Complete resection was achieved in all patients. Intra-procedural peumoperitoneum occurred in 3 cases because of iatrogenic perforation, no special treatment was given. 7 patients presented with mild abdominal pain/distention and fever were given antibotics. No severe post-operative complication happened. No tumor recurrence occurred in the median 11 month follow-up period.

CONCLUSION

Based on short-term follow-up observation, STER is a feasible, safe and minimally invasive method for the diagnosis and treatment of small (<3 cm) SMTs in gastric body, antrum and proximal cardia.

Endosonographic features of histologically proven gastric ectopic pancreas

Gastric ectopic pancreas is an uncommon developmental anomaly and its histological diagnosis is usually difficult by using a conventional biopsy forceps. In the literature, most cases of gastric ectopic pancreas were usually diagnosed by gross pattern during endoscopic examination or features of endoscopic ultrasound. In contrast, this disease was seldom diagnosed by histology in clinical practice. Although the typical endoscopic ultrasonographic features of ectopic pancreas include heterogeneous echogenicity, indistinct borders, and a location within 2 or more layers, it can also exhibit hypoechoic homogeneous echogenicity and a distinct border within the fourth sonographic layer (muscularis propria) similar to the endoscopic ultrasonographic features of gastrointestinal stromal tumors. In our study, we found that 53% of gastric ectopic pancreas originated within the fourth sonographic layer, demonstrating hypoechoic, homogeneous echogenicity, and distinct borders. Therefore, recognizing endoscopic ultrasonographic features, combining with deep biopsy, endoscopic ultrasound-guided fine needle aspiration/core needle biopsy can prevent conducting unnecessary resection. Surgical resection is the mainstay treatment for symptomatic gastric ectopic pancreas, but endoscopic resection using endoscopic mucosal resection or endoscopic submucosal dissection technique provides an alternative method of removing superficial-type and deep-type gastric ectopic pancreas.

Minimally invasive surgery for submucosal (subepithelial) tumors of the stomach

Minimally invasive surgery has become common in the surgical resection of gastrointestinal submucosal tumors (SMTs). The purpose of this article is to review recent trends in minimally invasive surgery for gastric SMTs. Although laparoscopic resection has been main stream of minimally invasive surgery for gastrointestinal SMTs, recent advances in endoscopic procedures now provide various treatment modalities for gastric SMTs. Moreover, investigators have developed several hybrid techniques that include the advantages of both laparoscopic and endoscopic procedure. In addition, several types of reduced port surgeries, modification of conventional laparoscopic procedures, have been recently applied to the surgical resection of SMTs. Meanwhile, robotic surgery for SMTs requires further evidence and improvement.

Endoscopic management of upper gastrointestinal submucosal tumors arising from muscularis propria

Small (<2 cm) or incidentally found gastrointestinal submucosal tumors pose challenges to gastroenterologists due to the potential malignancy of tumors and current suboptimal diagnostic methods. On the basis of the development of endoscopic submucosal dissection, recent technical advances, including endoscopic submucosal excavation, submucosal tunneling and endoscopic resection, and endoscopic full-thickness resection, have been able to resect submucosal tumors in the muscularis propria. These techniques provide definitive histologic diagnosis as well as a minimally invasive therapeutic approach to such tumors. Current studies, despite with promising results, are limited to small, retrospective studies, focusing on introducing new methods and varied in technical details. This review provides a thorough discussion of technical details of each endoscopic method, and compares different methods in terms of tumor sites, to ensure safety and optimize treatment outcomes.

Clinical value of miniprobe sonography for detection of esophageal submucosal lesions

OBJECTIVES

The purpose of this study was to evaluate the clinical value of catheter-based miniprobe sonography for diagnosis of esophageal submucosal lesions.

METHODS

A total of 199 patients with esophageal submucosal lesions underwent miniprobe sonography via gastroscopy. The sonograms were reviewed, and the sonographic findings were compared with pathologic findings from specimens obtained by endoscopic or surgical dissection.

RESULTS

The diagnoses for the 199 patients were as follows: 54 cysts, 58 leiomyomas, 25 stromal tumors, 26 venous aneurysms, 15 lipomas, and 21 extramural compressions. A total of 145 lesions were verified by surgery and pathologic examinations. The results for 139 lesions were confirmed by miniprobe sonography; 6 lesions were misdiagnosed. The diagnostic accuracy rate for miniprobe sonography was 95.9%.

CONCLUSIONS

Miniprobe sonography can provide precise information about the size, location, border, and echogenicity of esophageal submucosal lesions. It has high diagnostic accuracy. Preoperative miniprobe sonography via gastroscopy may play an important role in the choice of therapy for esophageal submucosal lesions.

Endoscopic resection of submucosal tumors in muscularis propria: the choice between direct excavation and tunneling resection

BACKGROUND

Endoscopic submucosal excavation (ESE) and submucosal tunneling endoscopic resection (STER) are nowadays both adopted by endoscopists to resect upper gastrointestinal submucosal tumors (SMTs) arising from muscularis propria. This study aimed to compare the efficacy and safety of these two techniques.

METHODS

Seventy-seven patients were included in this retrospective study, among them, 35 received ESE and 42 received STER. Main outcome measurements included complete resection rate, perforation rate, adverse events, and tumor recurrence. Subgroup analysis based on tumor size was also performed.

RESULTS

In general, ESE and STER had similar complete resection rate (94.7 vs. 97.7%), perforation rate (10.5 vs. 13.3%), and incidence of postoperative air leakage symptoms (13.2 vs. 2.2%). No tumor recurrence occurred in any group. Subgroup analysis revealed that for tumors <10 mm, both techniques achieved satisfactory therapeutic effects (100 % complete resection, no adverse events); for tumors >10 mm, perforation rate increased in both ESE and STER (16 vs. 18.2%), yet incidence of air leakage symptoms was significantly low in STER (3%) compared to it in ESE (20%).

CONCLUSIONS

For SMTs <10 mm, both ESE and STER have satisfactory therapeutic results, it is not necessary to pursue a difficult procedure when a simple method is available. For SMTs >10 mm, STER is a preferable choice in terms of preventing air leakage symptoms, especially, when perforation is likely to happen.

Learning curve for endoscopic submucosal dissection of gastric submucosal tumors: is it more difficult than it may seem?

BACKGROUND

Endoscopic submucosal dissection (ESD), as a minimally invasive technique, is gaining wide acceptance for treating epithelial neoplasms. More recently, some pioneers have developed ESD for the treatment of submucosal tumors (SMTs), but characterization of the learning curve is lacking. In this study we aimed to evaluate the learning curve for ESD of gastric SMTs.

SUBJECTS AND METHODS

From September 2008 to April 2011, ESD was performed in 50 consecutive patients with gastric SMTs by a single experienced endoscopist at our high-volume institution. The cumulative sum (CUSUM) method was performed to analyze the shifts in operative time (OT) and consequently to investigate the learning curve.

RESULTS

Analysis of the OT using the CUSUM method identified two distinct phases: Phase 1 (the initial 32 cases) and Phase 2 (the remaining 18 cases). Phase 1 represented the initial learning period, whereas Phase 2 showed the more skilled and higher proficiency period, with a significant reduction in OT (90±29 minutes versus 55±20 minutes; P<.0001). The two phases did not differ significantly with respect to patient characteristics and other perioperative parameters.

CONCLUSIONS

Mastery of operative technique for ESD of SMTs is evident by a decrease in OT identified by CUSUM graphs. For endoscopists competent in basic endoscopic intervention skills, the learning curve should be achieved after approximately 32 cases. Offering this minimally invasive endoscopic intervention does not result in increased complication rate even in the early phase of the learning curve.

Endoscopic clip closure of gastrointestinal perforations, fistulae, and leaks

Development of endoscopic devices to close perforations has certainly revolutionized endoscopy. Immediate closure of perforations eliminates the need for surgery, which allows us to push the limits of endoscopic surgery from the mucosal plane to deep submucosal layers and eventually transmurally. The present article focuses on endoscopic closure devices, closure techniques, followed by a review of animal and clinical studies on endoscopic closure of perforations.

Endoscopic ultrasonography for gastrointestinal submucosal lesions

Advances in endoscopic imaging technology have led to the detection of more cases of gastrointestinal submucosal lesions (SMLs). Endoscopic ultrasonography (EUS) was previously known as the best imaging procedure to characterize SMLs. However, the progress of endoscopic submucosal dissection (ESD) has raised some new questions concerning the role of EUS in the diagnosis of SMLs. What is the diagnostic accuracy of EUS for SMLs? How is the nature of SMLs determined? How is the layer of origin identified? What is the preoperative value of EUS for ESD? In this review, we will discuss the endosonographic features of SMLs, the diagnostic accuracy of EUS, the ability of EUS to distinguish benign and malignant SMLs, the value of EUS-guided fine-needle aspiration (FNA), and the value of EUS in clinical surveillance.

Surgical treatment of gastric gastrointestinal stromal tumor

Gastrointestinal stromal tumor is the most common mesenchymal tumor in the gastrointestinal tract and is most frequently developed in the stomach in the form of submucosal tumor. The incidence of gastric gastrointestinal stromal tumor is estimated to be as high as 25% of the population when all small and asymptomatic tumors are included. Because gastric gastrointestinal stromal tumor is not completely distinguished from other submucosal tumors, a surgical excisional biopsy is recommended for tumors >2 cm. The surgical principles of gastrointestinal stromal tumor are composed of an R0 resection with a normal mucosa margin, no systemic lymph node dissection, and avoidance of perforation, which results in peritoneal seeding even in cases with otherwise low risk profiles. Laparoscopic surgery has been indicated for gastrointestinal stromal tumors <5 cm, and the indication for laparoscopic surgery is expanded to larger tumors if the above mentioned surgical principles can be maintained. A simple exogastric resection and various transgastric resection techniques are used for gastrointestinal stromal tumors in favorable locations (the fundus, body, greater curvature side). For a lesion at the gastroesophageal junction in the posterior wall of the stomach, enucleation techniques have been tried preserve the organ's function. Those methods have a theoretical risk of seeding a ruptured tumor, but this risk has not been evaluated by well-designed clinical trials. While some clinical trials are still on-going, neoadjuvant imatinib is suggested when marginally unresectable or multiorgan resection is anticipated to reduce the extent of surgery and the chance of incomplete resection, rupture or bleeding.