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

Intubation Anesthesia
Intra- and postoperative analgesia with Epidural Catheter

• Supine position
• Right arm positioned alongside
• Left arm extended

• Surgeon to the right of the patient
• 1st Assistant to the left of the patient
• 2nd Assistant to the right, towards the head from the surgeon
• Scrub nurse to the left, towards the feet from the 1st assistant

• Intraoperative endoscopy for tumor localization in laparoscopic procedures

Basic abdominal surgical and/or laparoscopic instruments, additional equipment depending on location as planned for the procedure.

In the film example (distal gastrectomy):

• Self-retaining abdominal wall retractor/spreader
• Linear cutter with various magazine lengths for closure of duodenal stump and proximal gastric stump
• Bipolar scissors

Postoperative Analgesia

• Continue epidural anesthesia postoperatively for 2 – 5 days

Follow the link here to PROSPECT (Procedure specific postoperative pain management) or to the current guideline Treatment of acute perioperative and post-traumatic pain.

Medical Follow-up Treatment

• Remove intra-abdominal target drains depending on the drainage volume
• Optionally, on the 5th-7th postoperative day, an X Ray UGI (upper gastrointestinal series) or an endoscopic check of the anastomotic conditions can be performed.
• Remove skin sutures between the 10th and 12th postoperative day

Pharmacological Follow-up Treatment with Tyrosine Kinase Inhibitors

• Imatinib is an orally administered phenylaminopyrimidine derivative that can block the ATP-binding site of specific tyrosine kinases such as KIT and PDGFRA. This results in the blockade of the signaling pathways through which the malignant growth behavior of GIST is mediated.
  Before starting adjuvant treatment, a determination of the mutation status should always be performed, as the efficacy of Imatinib correlates with the underlying mutation and is greatest with a mutation in exon 11, followed by exon 9. In the absence of mutation detection (wild type), the efficacy is significantly lower.
  The treatment should be continuous and ongoing. The standard therapy is a dosage of 400 mg Imatinib per day, with an increase to 800 mg per day for exon 9 mutations.
  The treatment of patients with advanced or metastatic GIST should be continued at full dosage until progression is detected. This also applies when complete remission is achieved or after complete resection of a residual tumor.
• Patients with a high risk of recurrence should receive adjuvant pharmacological therapy after potentially curative surgery. The clinical recommendation is for Imatinib 400 mg/day for 3 years. If there is an intermediate risk, the therapy decision must be made jointly with the patient due to insufficient data.
• Patients with tumor perforation should also be treated with Imatinib for at least 3 years, as the risk of progression is similar to that of metastasis.
• Patients with low and very low risk of recurrence do not require adjuvant therapy, even in the R1 situation.
• Therapy options for progression: Increase dose to 800 mg Imatinib per day. If further progression occurs, switch to the multikinase inhibitor Sunitinib.
• Regorafenib will be available as a third-line therapy after approval.
• For patients who received neoadjuvant therapy before resection, postoperative treatment should be conducted for a total duration of up to 3 years if indicated.
• In the case of post-adjuvant recurrence, resuming Imatinib therapy at the mutation status-appropriate dosage is recommended.

Tumor Follow-up
Recommendations for follow-up with limited data: CT/MRI examinations for intermediate- and high-risk tumors every 6 months in the first 3 years, then annual examinations up to the 5th year inclusive.

Thrombosis Prophylaxis
In the absence of contraindications, due to the moderate thromboembolic risk (surgical procedure > 30 minutes duration), in addition to physical measures, low molecular weight heparin should be administered in a prophylactic, possibly weight- or disposition risk-adapted dosage until full mobilization is achieved. Consider: renal function, HIT II (history, platelet control).
Follow the link here to the current guideline Prophylaxis of venous thromboembolism (VTE).

Mobilization

• rapid mobilization

Physiotherapy

• breathing exercises

Nutritional Build-up

• aim for enteral nutrition as quickly as possible; until then, parenteral nutrition and fluid substitution.

Bowel Regulation

• if necessary, laxatives from the 2nd postoperative day

Work Incapacity

• Work incapacity generally includes a minimum of 4 weeks.