Gastric adenocarcinoma is a stomach tumour that develops from the wall of the stomach. An adenocarcinomas is the most common gastric tumour (70-80%) and this tumour type forms a firm structure on the outside of the stomach. This tumour can put pressure on the stomach contents and / or grow into the wall.

Behaviour

Gastric adenocarcinoma is a stomach tumour that originates from stomach wall.

An adenocarcinoma will frequently spread to the nearby lymph nodes, followed by liver and lungs.

Other possible growths in the stomach:

• benign: leiomyomas (muscle wall growth) and other growths that only cause a nuisance if they become very large.
• malignant: in addition to gastric adenocarcinomas, it is possible to develop a tumour of the gastric muscle layer (leiomyosarcoma), fibrosarcoma, tumours consisting of immune cells such as lymphoma, mast cell tumour and extra-medullary plasmacytoma.

Prevalence

Stomach cancer is relatively rare, making up less than 1% of all malignancies. The average age at which this tumour occurs is 8 years and it is more common in males than females. Muscle wall tumours (leiomyomas) are more likely to occur in very old dogs (15 years on average).

Breed predisposition

A higher risk of developing this type of tumour has been reported for Belgian Shepherds (especially the Belgian Tervuren), Chow Chows, Collies and Norwegian Lundehunds compared to other dogs.

Symptoms

Usually, the dog gradually vomits more and more. Often there is a trace of blood in the vomit, or it looks like coffee grounds. The dog usually loses weight and / or does not want to eat anymore. These symptoms can vary in duration from weeks to many months.

In general, a blood test and normal radiography are not sufficient to make a diagnosis.

Blood analysis

Generally, the blood test does not show specific evidence for gastric adenocarcinoma. It may help to detect certain side effects or to distinguish them from other tumour types.

Radiography

By contrast radiography of the stomach, a growth that should not be present in the stomach can be discovered. It is also possible to find a stomach ulcer, which often occurs with gastric adenocarcinomas. Alternatively, the stomach may empty more slowly than usual (the contrast material moves more slowly than usual).

Ultrasound

Via an ultrasound the veterinarian can collect a sample from more difficult to reach places with a needle. The location of the tumour may be a possible indicator of the tumour type. Gastric adenocarcinomas tend to occur more at the level of the gastric outlet, while leiomyosarcomas are more common at the level of the stomach entrance.

Gastroscopy

By sliding a flexible tube into the stomach of the dog, the veterinarian can visualize growths and take extensive samples in a targeted manner. As the surface of a gastric tumour can be superficially necrotic, inflamed or ulcerated, it might be necessary to take several larger tissue samples. This is not always possible via the endoscopic tube and may require surgery.

Explorative surgery

This is the surest way to obtain a good sample of the tumour.

Histology

Thanks to these investigations, it can be determined whether the tumour is malignant or very aggressive. This information will help determine if additional treatments are needed.

If there is a suspicion of a GIST (gastrointestinal stromal tumour), a CD117 staining is done to confirm this. This is a rare tumour that arises from the support tissue of the gastrointestinal tract.

Surgery

If no metastases are present and the tumour is confined to the stomach, excising the tumour may be sufficient to heal the dog. The size, location and type of the tumour do play a role in how far one can go in surgically removing the tumour. After all, the more stomach tissue has to be removed, the greater the impact will be on the dog’s quality of life.

During the operation, the veterinarian checks whether the lymph nodes of the abdominal cavity are affected in order to properly estimate whether the tumour only occurs in the stomach. With benign tumours, the tumour can be removed without removing a lot of healthy stomach tissue.

Radiotherapy

This option is rarely used because the tissues near the stomach cannot tolerate radiation. If the tumour is a lymphoma, it can still be treated by radiation, because it requires lower doses of radiation than other tumour types. Lymphomas in the stomach generally do not respond well to standard chemotherapy.

Support

After surgery, a highly digestible diet can help the dog recover faster (causes less straining).

The prognosis is usually poor. Even after surgery, most dogs die from a relapse of the tumour or metastases within 6 months. However, if the tumour is benign, the dog can heal completely after surgical removal.