CHAPTER 8 Gastrectomy
Case Study
Repeat endoscopy shows a nonhealing ulcer. Biopsy of the rim of the ulcer reveals adenocarcinoma.
BACKGROUND
The stomach may be divided into four anatomic regions: the cardia, fundus, body, and antrum. The stomach derives its blood supply from four main arterial trunks: the right and left gastric arteries along the lesser curvature and the right and left gastroepiploic arteries along the greater curvature. Additional blood supply is provided by the short gastric arteries (Fig. 8-1). Given this extensive collateral vascular network, the stomach may remain viable after ligation of multiple main feeding vessels. Venous and lymphatic drainage, in general, follows the arterial supply.
INDICATIONS FOR GASTRECTOMY
I. Adenocarcinoma: Adenocarcinoma accounts for 95% of gastric malignancies and is the 14th most common cancer and the 8th leading cause of cancer-related death in the United States.
A. Gastric adenocarcinoma typically presents with nonspecific symptoms, and the diagnosis may be delayed until the disease is relatively advanced. In the absence of metastatic disease, surgical resection is indicated. Gastric adenocarcinoma frequently spreads intramurally, and the extent of disease may be masked by normal-appearing gastric mucosa; thus, resection should include 6-cm margins. Because of the high morbidity rate associated with proximal partial gastric resections, proximal tumors and midbody tumors are usually treated with total or near-total gastrectomy. In patients with distal lesions, subtotal gastrectomy is an acceptable alternative approach if appropriate margins can be obtained; otherwise, total gastrectomy is required.
B. The role of extended lymphadenectomy for gastric adenocarcinoma is controversial. A D1 dissection includes removal of perigastric nodes only; a D2 dissection includes removal of regional lymph nodes along the celiac axis (left gastric, common hepatic, and splenic arteries). A D3 dissection includes removal of additional regional nodes within the porta hepatis and next to the aorta. Numerous prospective randomized clinical trials have failed to demonstrate an improvement in 5-year survival rates with more extensive dissections. In the United States, most surgeons advocate a limited (D1 or D2) nodal dissection, harvesting at least 15 nodes for pathologic evaluation. Although once routinely performed during resection for gastric cancer, splenectomy is associated with higher perioperative morbidity and mortality rates and is no longer recommended unless there is direct invasion of the spleen or splenic hilum.
II. Other Gastric Malignancies
A. Gastric lymphoma is the second most common malignancy of the stomach. Treatment regimens vary; however, most gastric lymphomas are initially treated with chemoradiation therapy. Mucosal-associated lymphatic tissue tumors are low-grade lymphomas and are associated with Helicobacter pylori infection. Treatment aimed at eradication of the bacteria often results in tumor regression. Surgical resection of lymphomas is reserved for tumors refractory to other therapies and cases with complications, including perforation and bleeding. If indicated, the goal of resection is to obtain circumferential negative margins.
B. Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors. GISTs may arise throughout the gastrointestinal (GI) tract, although the stomach is the most common site. Surgical resection with wide negative margins remains the primary treatment modality; however, encouraging results have been achieved with imatinib (Gleevec), a tyrosine kinase inhibitor, for the treatment of metastases and as an adjuvant to resection for high-risk tumors (as defined by necrosis, mitosis, and size).
C. Gastric carcinoids are rare and account for only 0.5% of all gastric tumors. Multiple gastric carcinoid tumors may be associated with enterochromaffin-like cell hyperplasia, chronic atrophic gastritis, and pernicious anemia, and have a low risk of malignancy. Solitary gastric carcinoid tumors have higher malignant potential. Resection is the mainstay of treatment.
III. Peptic Ulcer Disease: PUD results from an imbalance between physiologic acid secretion and mucosal defense mechanisms and causes erosion of either the gastric or the duodenal wall. Advances in our understanding of the pathophysiology of PUD (specifically, the implications of H. pylori infection of the gastric mucosa) as well as the development of proton pump inhibitors for the management of acid hypersecretion have made elective surgery for the treatment of PUD uncommon. Initial treatment of PUD includes lifestyle modification (e.g., avoidance of tobacco, alcohol, and nonsteroidal anti-inflammatory drugs) and a pharmacologic regimen that includes an H2 receptor antagonist or proton pump inhibitor and antibiotic therapy for H. pylori infection.
A. Indications for surgery include emergent complications of PUD (e.g., obstruction and perforation) and bleeding refractory to endoscopic intervention. Rarely, failure of medical therapy and concern about malignancy constitute additional indications. The location of the ulcer dictates the surgical approach. The modified Johnson classification categorizes gastric ulcers according to their location. Acid hypersecretion is believed to play a role in types II and III ulcers only (Table 8-1 and Fig. 8-2). Surgical therapy for these types of ulcers is therefore aimed not only at resection of the ulcer, but also at acid reduction. Treatment of types I and IV gastric ulcers, on the other hand, involves resection of the ulcer only (Fig. 8-3).
B. Patients with free perforation or hemorrhage are often systemically ill and hemodynamically unstable. A focused surgical approach is appropriate in such settings; perforated ulcers are typically patched with omentum (i.e., Graham patch) and bleeding vessels are oversewn. In the stable patient, optimal treatment for a bleeding or perforated gastric ulcer includes resection (distal gastrectomy or antrectomy). Proximal ulcers are treated with wedge resection.
| Johnson Classification | Location | Acid Hypersecretion |
|---|---|---|
| Type I | Lesser curve | No |
| Type II | Lesser curve and duodenum | Yes |
| Type III | Prepyloric | Yes |
| Type IV | Proximal lesser curve near gastroesophageal junction | No |
