Tumours of the stomach Flashcards
Aetiology of gastric tumours
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
Which dog breeds have a genetic predisposition to gastric carcinoma?
Belgian shepherd dog
Rough collie
Benign tumours that can occur in the stomach
Polyps
Leiomyoma
Malignant tumours that can occur in the stomach
Adenocarcinoma
Squamous cell carcinoma
Lymphoma
Leiomyosarcoma
Fibrosarcoma
Plasmacytoma
Mast cell tumour
Gastric adenocarcinoma
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
Metastasis of gastric adenocarcinoma
Local metastasis to gastroduodenal and splenic lymph nodes
Distant metastasis to abdominal organs is common
Lungs are rarely involved
Gastric leiomyosarcoma
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.
Gastric lymphoma
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.
Gastric plasmacytoma
often metastasises to local lymph nodes unlike cutaneous plasmacytoma which is benign
Feline lymphoma
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
Clinical signs of gastric neoplasia
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.
Haematological/biochemical signs of gastric neoplasia
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.
Gastric neoplasia on radiography
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
Gastric neoplasia on ultrasound
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.
Endoscopy of gastric neoplasia
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.
Gastrotomy of gastric neoplasia
should produce a more representative biopsy of the lesion which may have to be combined with surgical treatment.
Surgical exploration of the abdominal cavity for gastric neoplasia
permits clinical staging of the tumour through examination of primary tumour, regional (gastrosplenic) nodes and other possible metastatic sites.
Treatment options for gastric neoplasia
Surgery
Radiotherapy
Chemotherapy
Medical management of other signs
Anti-emetics
Ulcer soothing drugs
Surgery for gastric neoplasia
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.
Radiotherapy for gastric neoplasia
Not usually used
Chemotherapy for gastric neoplasia
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??
Prognosis of gastric tumours
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.
