+ General Considerations

  • Gastric tumors are uncommon and account for < 1% of all cancers
  • Etiology unknown although chronic nitrosamines administration may cause gastric carcinoma in dogs

+ Gastric Carcinoma

  • 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

+ Lymphosarcoma

  • LSA is the most common gastric tumor in cats (solitary or multicentric) and most are FeLV negative
  • Sex predisposition: males
  • Gross appearance: discrete mass or diffuse gastric wall diffusion

+ Leiomyoma

  • Leiomyoma is common in very old dogs and is the 2nd most common gastric tumor in dogs
  • Mean age 15 years with 82% prevalence in 17-18-year-old Beagles
  • Discrete solitary lesions (usually pedunculated) in the cardia or gastroesophageal junction causing mass effect
  • Ulceration is uncommon

+ Carcinoids

  • Gastric carcinoids are tumors of the enterochromaffin system and are referred to as amine precursor uptake and decarboxylation tumors or APUDomas
  • Gastric carcinoids are functional and, in humans, are diagnosed by clinical presentation, measurement of urinary serotonin metabolites, provocative pentagastric testing, radionucleide scans, and CT
  • Carcinoids are locally invasive, and metastasize to regional lymph nodes, lungs, pleura, and peritoneum
  • Carcinoids usually occur in geriatric animals and gastric carcinoid has been reported in a 15-year-old cat

+ Other Tumors

  • Other malignant gastric tumors include FSA, leiomyosarcoma, plasmacytoma, and carcinoid
  • Metastasis to the liver and duodenum reported in both cases of leiomyosarcoma
  • Benign gastric tumors include adenoma, leiomyoma, or hypertrophic gastropathy
  • Adenomatous polyps are usually an incidental finding but they may cause pyloric obstruction

+ 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


+ 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 tumo

+ 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
  • Benign lesions tend to be either pedunculated or well circumscribed with gastric leiomyoma commonly located in the cardia

+ 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


+ Surgery

  • Surgery is recommended for gastric ADC and possibly solitary feline gastric LSA 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

+ Leiomyoma

  • Gastrotomy via exploratory ventral midline or lateral intercostal thoracotomy approach
  • Gastrotomy and submucosal resection recommended with minimal risk of contamination, hemorrhage, or stricture, and good tumor control

+ Chemotherapy

  • No known effective chemotherapy agents for gastric ADC
  • Gastric LSA does not respond well to conventional chemotherapy protocols and chemotherapy may not be required following surgical resection of solitary gastric LSA in cats

+ 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
  • Gastric leiomyosarcoma: MST 12.0-21.3 months, with 1-year survival rate 75% and 2-year survival rate 66%
  • 54% metastatic rate, but metastasis is not a poor prognostic factor with a MST 21.7 months
  • Gastric LSA: MST 40 weeks with Madison-Wisconsin protocol and 15.5 months with prednisolone-chlorambucil
  • Benign lesions and extramedullary plasmacytoma have an excellent prognosis following surgical resection