General Considerations

•gastric ADC is rare in cats but accounts for 42%-72% of all canine gastric tumors

•mean age 8 years, but 19% dogs are < 5 years

•sex predisposition: male with a male-to-female ratio of 2.5:1

•breed predisposition: Belgian Shepherd and Rough-Coated Collie

•location: pyloric antrum or lesser curvature

•3 anatomic descriptions:

•scirrhous due to firm and non-distensible texture = linitis plastica

•plaque-like mucosal lesion with large central ulcer

•raised polypoid lesions

•metastatic rate 74% in dogs with sites including gastric lymph node, peritoneum, liver, lungs, omentum, adrenal glands, duodenum, pancreas, spleen, esophagus, kidneys, diaphragm, myocardium, long bones, pituitary gland, bile duct, brain, and testes

Clinical Signs

•clinical signs are caused by gastric outflow obstruction, altered motility, or chronic blood loss secondary to tumor necrosis and ulceration

•progressive vomiting is common and may contain fresh or digested blood

•weight loss may be caused by poor digestion, protein malnutrition, or cancer cachexia

Laboratory Tests

•laboratory tests and survey radiographs are usually unrewarding

•leiomyoma and leiomyosarcoma have been associated with paraneoplastic hypoglycemia

•microcytic hypochromic anemia is common with chronic blood loss and occult blood may be detected in feces

•increased liver enzymes may be seen with hepatic metastasis or obstruction of the common bile duct

Imaging

Radiographs

•positive- or double-contrast radiographs: gastric tumors can appear as a mass effect, ulcer crater, delayed gastric emptying with poor motility, and delayed adherence of contrast material to an ulcerated tumor

Ultrasonography

•ultrasonographic findings include transmural thickening of the gastric wall with loss or altered layering (poor echogenic outer and inner lining with hyperechoic central zone)

•other findings include tumor location, ulceration, extension through gastric wall, and lymphadenopathy

•gastric ADC tend to appear as sessile mass located in the lesser curvature or antrum

Endoscopy

•gastroscopy allows direct visualization and guided biopsy

•several biopsies should be performed as superficial ulceration, necrosis, and inflammation is common

•submucosal masses are difficult to biopsy and false-negative results are common

Other Imaging Techniques

•CT and MRI

TREATMENT

Surgery

•surgery is recommended for gastric ADC, but complicated by advanced stage at presentation, frequent metastasis, difficult access, and debilitated animal

•lymph node metastasis is variable and all abdominal lymph node should be evaluated for staging purposes

•curative resection should be attempted if disease is localized to the stomach

•surgical techniques: Billroth I or II or palliative bypass procedures

•Billroth I or II provides immediate relief of gastric outflow obstruction and clinical improvement in early postoperative period

•Billroth II (partial gastrectomy and gastrojejunostomy) or complete gastrectomy (with biliary by-pass) are very extensive surgeries with high morbidity and minimal survival advantage

•partial gastrectomy preferred in humans due to better nutritional status and quality of life and radical gastrectomy does not improve survival time

•palliative gastrojejunostomy for inoperable or metastatic lesions but associated with significant morbidity including anastomotic ulcers

Chemotherapy

•no known effective chemotherapy agents for gastric ADC

Prognosis

•prognosis depends on surgical excision, tumor type and grade, and presence of metastatic lesions

•prognosis is poor for gastric ADC as majority are dead within 6 months due to either recurrent or metastatic disease