Perioperative management - GIST - distal gastrectomy according to Roux-Y

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract. The number of so-called incidental GISTs (< 2cm) is increasing due to the growing use of modern endoscopic procedures. A complete surgical resection (R0) is a prerequisite for a curative treatment approach, despite all advances in medical treatment. Even small GISTs (< 2cm) must be completely resected. Only a complete resection (R0) offers a chance for cure.

Compared to other solid tumors of the gastrointestinal tract, there are some tumor biological peculiarities in GIST that must be considered:

• Due to the extremely rare lymphatic metastasis, a lymphadenectomy is not required; a safety margin of 2 cm is considered sufficient.
• Since these tumors originate within the muscle layer of the organ wall, a full-thickness resection is fundamentally necessary to avoid incomplete resection. This means that even in small, early GISTs, for example, an endoscopic mucosal resection can in no way lead to an R0 resection. This can only be ensured by a resection including the muscularis. The resection in the case of esophageal involvement must therefore extend into the periesophageal fat tissue, in the stomach into the free abdominal cavity, and in the rectum into the mesorectum.

If technically possible, the operation can be performed laparoscopically according to the guidelines of tumor surgery.

• laparoscopically, possibly endoscopy-assisted as atypical, local gastric wall resections (so-called wedge resection) in small tumors.
• laparoscopically hand-assisted in large gastric GISTs (> 5 cm) and in unfavorable locations, e.g., at the lesser curvature, the posterior gastric wall, or at the esophagogastric junction. The tactile control of the tumor increases the safety of complete resection.

Recommended location-dependent surgical procedures for GIST

• Esophagus→ surgical enucleation up to abdominothoracic esophageal resection
• Esophagogastric junction→ lap. transhiatal cardia resection (Merendino operation), extended gastrectomy
• Stomach→ local excision, laparoscopic wedge resection, partial gastric resections up to gastrectomy
• Duodenum→ local resection or partial pancreatoduodenectomy
• Small and large intestine → segmental resection
• Rectum→ local excision, e.g., as transanal endoscopic microsurgery, rectal resection (ant. rectal resection, abdominoperineal rectal extirpation)
• Complex multivisceral procedures in large or metastatic tumors

• Relevant comorbidities with inability for surgery or anesthesia.
• Lymphadenectomy and wide resection margins are not indicated; only visibly enlarged lymph nodes should be removed.
• The respective surgical procedure must be adapted to the tumor size and location to ensure that intraoperative tumor rupture is safely avoided.

• Abdominal sonography
• CT abdomen
• EGD possibly with tumor biopsy for tumor localization in the esophagus, stomach, duodenum. It should be noted that these tumors arise within the muscle layer of the organ wall and may evade detection by endoscopically obtained mucosal biopsies.
• Endosonography possibly with endosonographically guided fine needle aspiration (EUS-FNA)
• CT/MRI Sellink technique for small bowel manifestation
• Capsule endoscopy
• MRI for manifestation in the rectum
• Pre-therapeutic tumor biopsy only if it influences the treatment concept (differential diagnostic distinction of an adenocarcinoma, initiation of neoadjuvant systemic therapy) due to the risk of bleeding, tumor cell dissemination, or tumor rupture with an overall only about 50% reliability regarding tumor entity.
• FDG-PET for differential diagnostic distinction GIST-leiomyoma

• Neoadjuvant systemic therapy with tyrosine kinase inhibitors for primarily non-completely resectable tumors, especially of the gastroesophageal junction, duodenum, and rectum. Resection should occur at the time of optimal tumor regression, but not earlier than four to six months.
• Multimodal therapy concept for GIST metastases and recurrences.

General Surgical Risks:

• Thromboembolism
• Pneumonia
• Heparin intolerance, HIT
• Urinary tract infection

Specific Surgical Risks:

• Final decision on the resection procedure only intraoperatively
• Injury to internal vessels and organs, e.g., spleen, bile duct
• Anastomotic insufficiency
• Duodenal stump insufficiency
• Endoluminal/intra-abdominal bleeding
• Intra-abdominal abscess, peritonitis
• Pancreatitis or pancreatic fistulas
• Wound healing disorder
• Incisional hernia

Indications of:

• Temporary weight loss
• Changed eating habits
• Drains, gastric tube, urinary diversion
• Possibly blood transfusion