Overview
Definition:
Wedge resection of a gastric gastrointestinal stromal tumor (GIST) is a surgical procedure involving the removal of a triangular or wedge-shaped portion of the stomach wall containing the tumor, along with a margin of healthy tissue
This is a local excision technique typically employed for smaller, non-invasive GISTs.
Epidemiology:
GISTs are the most common mesenchymal tumors of the gastrointestinal tract, accounting for 0.1-1% of all GI tumors
They can occur anywhere along the GI tract, with the stomach being the most common site (50-70%)
Incidence is estimated at 10-20 cases per million per year worldwide
They can affect any age group but are more common in middle-aged and older adults, with a slight predilection for males.
Clinical Significance:
Gastric GISTs can range from benign to malignant, with malignant potential determined by size, mitotic activity, and presence of metastasis
Wedge resection is a crucial surgical option for localized tumors, aiming for complete tumor removal (R0 resection) to prevent recurrence and metastasis
Understanding its indications, technique, and potential complications is vital for surgical residents preparing for DNB and NEET SS examinations.
Indications
Indications For Surgery:
Surgical resection is indicated for most symptomatic GISTs, asymptomatic GISTs >2 cm, GISTs with high mitotic index (>5/10 HPF), GISTs with suspicious imaging features (e.g., ulceration, necrosis), or any GIST with signs of invasion or metastasis.
Indications For Wedge Resection:
Wedge resection is generally preferred for smaller GISTs (<5 cm) located in the submucosa without significant transmural invasion or involvement of vital structures like the gastric cardia or pylorus
Lesions amenable to clean margins with minimal gastric sacrifice are ideal candidates
Lesions on the anterior or posterior wall, or fundus, are often good candidates.
Contraindications:
Absolute contraindications are rare but include unresectable disease due to extensive local invasion or distant metastasis
Relative contraindications may include very large tumors requiring extensive gastric resection, or tumors involving critical areas making margin achievement difficult with a wedge excision
Patients with poor surgical risk might be managed with imatinib (tyrosine kinase inhibitor) if surgery is not feasible.
Preoperative Preparation
Preoperative Evaluation:
Thorough medical history and physical examination
Baseline laboratory investigations including complete blood count, liver and renal function tests, and electrolytes
Assessment of comorbidities and nutritional status
Cardiopulmonary evaluation as indicated.
Imaging:
Endoscopy with biopsy for histological confirmation and assessment of submucosal involvement
Contrast-enhanced CT scan of the abdomen and pelvis is essential to assess tumor size, location, vascularity, presence of lymphadenopathy, and distant metastases
Endoscopic ultrasound (EUS) can provide detailed information about tumor depth and layer of origin.
Medical Management Considerations:
For high-risk GISTs, neoadjuvant imatinib therapy may be considered to downstage the tumor, reduce intraoperative bleeding, and facilitate complete resection
This decision is made in conjunction with an oncologist.
Informed Consent:
Detailed discussion with the patient regarding the procedure, potential risks, benefits, alternatives (e.g., imatinib therapy), and expected outcomes, including the possibility of conversion to a more extensive gastric resection.
Procedure Steps
Surgical Approach:
The approach can be laparoscopic or open, depending on tumor size, location, surgeon expertise, and patient factors
Laparoscopic resection is preferred for smaller, well-defined tumors due to less morbidity.
Tumor Identification And Margins:
Careful intraoperative palpation to confirm tumor location
Identification of appropriate margins of healthy gastric tissue around the tumor
The tumor is typically removed with a 1-2 cm margin of normal gastric wall.
Excision Technique:
The gastric wall containing the tumor is excised in a wedge or V-shape
For laparoscopic procedures, articulating graspers, endoscopic staplers (linear or circular), or harmonic scalpels can be used
Careful hemostasis is crucial due to the rich vascularity of the stomach.
Gastric Reconstruction:
After excision, the defect in the gastric wall is closed, usually with a running suture line using absorbable or non-absorbable sutures, or by using linear staplers
The closure aims to restore gastric integrity and prevent leakage.
Intraoperative Imaging And Pathology:
In some cases, intraoperative frozen section analysis may be performed to confirm margin status, though this is less common for GISTs than for other malignancies
Tumor specimen is sent for detailed histopathological examination.
Postoperative Care
Immediate Postoperative Care:
Patients are typically monitored in a post-anesthesia care unit (PACU)
Pain management with intravenous analgesics
Intravenous fluids for hydration
Monitoring of vital signs, urine output, and nasogastric tube drainage if placed.
Nasogastric Tube:
A nasogastric tube may be placed to decompress the stomach and monitor for signs of leaks or obstruction
It is usually removed once bowel sounds return and there is minimal drainage.
Dietary Advancement:
Gradual advancement of diet, starting with clear liquids and progressing to soft and regular diet as tolerated
This is guided by return of bowel function and absence of signs of complications.
Ambulation And Mobilization:
Early ambulation is encouraged to prevent deep vein thrombosis, pulmonary complications, and to promote bowel motility.
Monitoring For Complications:
Close monitoring for signs of gastric leak, bleeding, infection, ileus, and wound complications
Laboratory parameters (hemoglobin, white blood cell count) are monitored.
Complications
Early Complications:
Gastric leak from the suture line is the most serious early complication
Bleeding from the tumor bed or staple line
Infection of the wound or intra-abdominal abscess
Pancreatitis (if tumor is near pancreatic head)
Delayed gastric emptying or ileus.
Late Complications:
Stricture formation at the repair site leading to gastric outlet obstruction
Recurrence of GIST (local or distant).
Prevention Strategies:
Meticulous surgical technique with adequate margins and secure closure of the gastric defect
Careful hemostasis
Use of prophylactic antibiotics
Appropriate use of nasogastric tube and gradual dietary advancement
For high-risk GISTs, adjuvant imatinib therapy post-surgery is crucial to prevent recurrence.
Prognosis
Factors Affecting Prognosis:
The most critical prognostic factors are tumor size, mitotic count, and presence of metastasis
Risk stratification systems (e.g., Miettinen and Lasota criteria, National Comprehensive Cancer Network [NCCN] guidelines) are used to predict recurrence risk.
Outcomes:
For small, low-risk gastric GISTs treated with complete resection, the prognosis is generally excellent with a very low recurrence rate
Larger tumors, those with high mitotic activity, or those with evidence of metastasis have a poorer prognosis and higher risk of recurrence.
Follow Up:
Lifelong surveillance is recommended for all patients treated for GIST
This typically involves regular clinical examinations, laboratory tests (CEA may be monitored, though less reliable), and imaging studies (CT scans) at intervals determined by the risk stratification
Follow-up frequency decreases over time for low-risk patients.
Key Points
Exam Focus:
Wedge resection is for small, localized gastric GISTs
The key to success is R0 resection
Risk stratification is paramount for prognosis and adjuvant therapy decisions
Imatinib is the mainstay of treatment for unresectable, metastatic, or high-risk GISTs.
Clinical Pearls:
Always consider GIST in a submucosal gastric lesion on endoscopy
Differentiate from leiomyoma and adenocarcinoma
Laparoscopic approach is feasible for select cases
Thorough histopathological examination with KIT and DOG1 immunohistochemistry is diagnostic
Adjuvant imatinib is critical for high-risk patients post-resection.
Common Mistakes:
Inadequate surgical margins
Failure to adequately excise the submucosal component
Not performing complete workup for metastasis before surgery
Underestimating the risk of recurrence in GISTs
Discontinuing adjuvant therapy prematurely.