Tumours of the stomach

Question 1

Aetiology of gastric tumours

Answer 1

often involve the cardia, lesser curvature or pyloric antrum of the stomach

In the dog, two thirds of gastric tumours are adenocarcinomas

In the cat, the predominant tumour type is lymphoma

Long term ingestion of dietary carcinogens may play a role

Question 2

Which dog breeds have a genetic predisposition to gastric carcinoma?

Answer 2

Belgian shepherd dog

Rough collie

Question 3

Benign tumours that can occur in the stomach

Answer 3

Polyps

Leiomyoma

Question 4

Malignant tumours that can occur in the stomach

Answer 4

Adenocarcinoma

Squamous cell carcinoma

Lymphoma

Leiomyosarcoma

Fibrosarcoma

Plasmacytoma

Mast cell tumour

Question 5

Gastric adenocarcinoma

Answer 5

Usually occurs in the pyloric antrum

Ulcerated, plaque like thickening usually - can be up to 5cm

Mucosal ruggae around the crater are thickened

May progress to perforation of the stomach wall and peritonitis, or may obstruct the pylorus

Question 6

Metastasis of gastric adenocarcinoma

Answer 6

Local metastasis to gastroduodenal and splenic lymph nodes

Distant metastasis to abdominal organs is common

Lungs are rarely involved

Question 7

Gastric leiomyosarcoma

Answer 7

arises in the inner smooth muscle layer producing an extensive, plaque-like bulge into the lumen, usually without surface ulceration.

Metastasis is rare.

Leiomyoma has a similar appearance and is frequently multiple.

Question 8

Gastric lymphoma

Answer 8

produces diffuse non-ulcerated thickening similar to adenocarcinoma but not scirrhous in nature and with less ulceration and crater formation.

Multiple plaques may be noted on the gastric lumen and tumour may be present in the intestines and abdominal organs as well as the stomach.

Question 9

Gastric plasmacytoma

Answer 9

often metastasises to local lymph nodes unlike cutaneous plasmacytoma which is benign

Question 10

Feline lymphoma

Answer 10

Older cats

Few cases FeLV positive

Diffuse, often non-ulcerated thickening of stomach wall

Multiple plaques may be noted in lumen

Other parts of GIT may be affected

Question 11

Clinical signs of gastric neoplasia

Answer 11

usually present with persistent vomiting or haematemesis, with partially digested blood producing a ‘coffee grounds’ appearance.

Anorexia and weight loss are common and overt melaena or occult faecal blood may be present.

Some animals show anterior abdominal pain.

Question 12

Haematological/biochemical signs of gastric neoplasia

Answer 12

Regenerative anaemia may be detected on haematological analysis due to gastric haemorrhage.

Electrolyte imbalances may be obvious on biochemical assessment because of vomiting and renal parameters such as BUN and creatinine may be elevated due to dehydration.

Question 13

Gastric neoplasia on radiography

Answer 13

Plain radiographs rarely reveals gastric neoplasia and so positive contrast with barium or fluoroscopic examination is usually required.

Changes may include:
· gastric thickening or ulceration,
· filling defects
· loss of rugal folds
· delayed gastric emptying
· reduced or abnormal gastric motility in particular areas

Question 14

Gastric neoplasia on ultrasound

Answer 14

can be used to diagnose gastric neoplasia, detect enlarged lymph nodes and assess other abdominal organs for metastasis.

A thickened gastric wall with disruption of the wall layers is characteristic of neoplasia and ulceration may be recognised as a focal outpouching of the luminal surface that contains trapped gas bubbles.

Question 15

Endoscopy of gastric neoplasia

Answer 15

will usually allow visualisation of any gastric lesion and enable a grab biopsy to be taken.

Endoscopic biopsy is least invasive but can produce false-negative results.

Question 16

Gastrotomy of gastric neoplasia

Answer 16

should produce a more representative biopsy of the lesion which may have to be combined with surgical treatment.

Question 17

Surgical exploration of the abdominal cavity for gastric neoplasia

Answer 17

permits clinical staging of the tumour through examination of primary tumour, regional (gastrosplenic) nodes and other possible metastatic sites.

Question 18

Treatment options for gastric neoplasia

Answer 18

Surgery

Radiotherapy

Chemotherapy

Medical management of other signs

Anti-emetics

Ulcer soothing drugs

Question 19

Surgery for gastric neoplasia

Answer 19

Surgical resection is the treatment of choice for tumours which have not metastasised but wide local excision is often hard to achieve whilst allowing satisfactory reconstruction of the stomach and adequate post-operative function.

Tumours on the lesser curvature are generally considered unresectable, whereas those on the fundus or body can be resected successfully.

Postoperative complications are much higher with pyloric resections.

Pylorectomy and gastroduodenostomy or gastrojejunostomy have been described for wide local excision of antral tumours but these procedures are technically difficult and there is a significant risk of iatrogenic injury to the pancreas, extrahepatic biliary system and local blood supply.

Question 20

Radiotherapy for gastric neoplasia

Answer 20

Not usually used

Question 21

Chemotherapy for gastric neoplasia

Answer 21

Lymphoma is the only gastric tumour that may respond to systemic chemotherapy but if restricted to the stomach and easily resectable, surgery may remain the treatment of choice since chemotherapy carries a potential risk of gastric perforation.

For non-resectable or widespread disease, chemotherapy remains an option but prognosis is poor.

Metastatic deposits from adenocarcinomas or other tumours do not usually respond well to chemotherapy and so it is not recommended.

Palliative role for 5FU in carcinoma??

Question 22

Prognosis of gastric tumours

Answer 22

Highly variable survival times are reported for gastric neoplasms.

Even with surgical resection the prognosis for most malignant gastric tumours is poor with survival times of 6 months or less because of recurrent or metastatic disease.

Survival rates for gastric lymphoma are also low because it does not usually respond well to chemotherapy.

In contrast, benign gastric tumours have a good prognosis and are often cured by surgical resection.