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 cachex

+ 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
  • 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