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Cancer of the Esophagus and Stomach
Avenelle I. Turner, DVM, DACVIM (Oncology)

Veterinary Cancer Group, Culver City, CA, USA

Etiology/Pathophysiology component. The average age of patients affected with
carcinoma is 8 years with a 2.5:1 male‐to‐female ratio.
Esophageal sarcomas have been reported secondary to Other tumors affecting the stomach are lymphoma
infection with Spirocerca lupi, an esophageal worm (LSA), leiomyoma, leiomyosarcoma, gastrointestinal
found sporadically in the tropic warm temperate areas stromal cell tumor (GISTs), extramedullary plasmacy-
and throughout the United States. There is no known toma (EPC), mast cell tumor (MCT), and carcinoid.
cause for the more commonly seen esophageal carcino- Leiomyomas occur in older dogs (mean age >15) as a
mas. In cats, squamous cell carcinomas (SCC) are located discrete, often pedunculated lesion in the cardia or
in the middle third of the esophagus, just caudal to the gastroesophageal junction. Recent studies utilizing
thoracic inlet. These tumors are locally invasive and immunohistochemistry to detect CD117 (c‐kit protein),
metastasis to regional lymph nodes occurs early. a transmembrane receptor with a tyrosine kinase
No definitive etiology has been identified in the devel- component, have shown up to 50% of leiomyomas and lei-
opment of gastric cancer but experimentally, long‐term omyosarcomas are reclassified as GISTs. Leiomyosarcomas
administration of nitrosamines may induce carcinomas do not express the c‐kit protein.
in dogs. Lymphoma is the most common gastric tumor in cats
and males are more commonly affected. Gastric LSA is
covered in more detail in another section. Chronic
Epidemiology gastritis, Helicobacter, and common heritage have been
implicated in feline gastric cancer.
Cancer of the esophagus and stomach is rare and
accounts for less than 0.5% and 1% of all malignancies
respectively. Signalment
Esophageal tumors can be primary or metastatic.
Metastatic tumors are three times more common than Most animals with esophageal cancer are older and no
primary esophageal tumors and occur through local breed predilection is evident. The average age for dogs
invasion from the stomach, thymus, thyroid, and heart diagnosed with gastric carcinoma is 8 years. Males are
base as well as from mammary adenocarcinoma and diagnosed 2.5 times more often than females. Cats with
lymphoma. In dogs, the most common primary esopha- gastric carcinoma are typically older with mean ages
geal tumors are SCC, osteosarcoma (OSA), fibrosarcoma reported between 10.6 and 12.6 years.
(FSA), and leiomyosarcoma. Sarcomas are seen more
commonly in areas where Spirocerca lupi is endemic.
In cats, the most common primary esophageal tumor is History and Clinical Signs
SCC which is seen more commonly in females.
The most common gastric tumor in the dog is Clinical signs associated with esophageal cancer are gen-
adenocarcinoma. Belgian shepherds, chow chows, rough‐ erally noted late in the course of disease. Symptoms occur
coated collies, and Staffordshire bull terriers appear pre- when the tumor is large and has caused an obstruction or
disposed to gastric adenocarcinoma, implying a genetic motility dysfunction. This can result in dysphagia and

Clinical Small Animal Internal Medicine Volume II, First Edition. Edited by David S. Bruyette.
© 2020 John Wiley & Sons, Inc. Published 2020 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/bruyette/clinical