Pancreatic Cancer

Liaison: Jan Young

Tumors of the pancreas are of two types: exocrine (involving cells which produce digestive enzymes) and endocrine (involving cells which produce hormones). Tumors of either type can be benign (adenomas) or malignant/cancerous (adenocarcinomas). Benign tumors tend to grow slowly and often are amenable to surgical removal. Malignant tumors, particularly exocrine cancers, grow rapidly, metastasize early and carry a very poor prognosis. Pancreatic cancer is rare in dogs. Some breeds, including Samoyeds, are said to be more prone to pancreatic cancers than other breeds, although this has not been reported for Samoyeds in the scientific literature. Older dogs (of any breed) are more likely to develop pancreatic cancers. Malignant pancreatic tumors are more common than benign ones. Exocrine cancers are more common than endocrine. Exocrine cancers are the most common and have the poorest prognosis.

Signs and Symptoms

Exocrine tumors: Signs and symptoms of exocrine tumors are vague and generalized. Benign tumors are typically small and may not cause many symptoms. Malignant tumors, being fast growing, are larger and cause symptoms sooner, including pain, vomiting and weight loss. An abdominal mass may be palpable. Jaundice may be present because of blockage by the tumor of the bile ducts, and abdominal swelling may be present from accumulation of fluid (ascites). The tumor may also block the intestine. Leakage of digestive enzymes may cause the death of surrounding tissue which can be very painful. The course of malignant disease is rapid. Endocrine tumors: Endocrine tumors produce excessive hormones that affect other parts of the body. The most common are those that involve the cells that make insulin (insulinomas or beta cell tumors, usually malignant) which results in low blood sugar concentrations. This causes signs of weakness, confusion, collapse, possible convulsions and coma. There are other rare endocrine pancreatic tumors including gastrinomas (produce excess stomach acid causing ulcers and pain) and glucagonomas (induce high blood glucose levels and liver damage.)

Causes

Pancreatic cancers, since they are more common in some breeds than others, are thought to perhaps have a genetic component but the causes of cancer are certainly multifactorial and not well understood.

Risk Factors

No known specific risk factors

Diagnostic Tests

Malignant tumors may be large enough to be palpable. X-rays and ultrasound may show abnormalities of the pancreas but will not indicate whether the abnormality is cancer or not. Routine blood work is not helpful but blood tests for levels of specific endocrine hormones, such as insulin, may be useful in diagnosing endocrine tumors. There are no blood tests for exocrine tumors. Ultimate diagnosis requires abdominal operation and biopsy

Treatment Guidelines

Note: Treatment of animals should only be performed by a licensed veterinarian. Veterinarians should consult the current literature and current pharmacological formularies before initiating any treatment protocol.

Exocrine tumors: There is no adequate treatment for exocrine pancreatic tumors. They grow too rapidly and metastasize early; they are rarely if ever discovered early enough for treatment. Endocrine tumors: The signs and symptoms of endocrine tumors can be ameliorated by managing the excess of the specific hormone (insulin, gastrin, glucagon). Benign tumors can be removed or partially removed but tend to grow back. Life expectancy for dogs with endocrine pancreatic tumors is generally less than a year but may extend up to 16-18 months. Sometimes the pancreas is removed and the dog is managed with hormone replacement (endocrine) and typically fed intravenously since it is too complicated to replace the digestive enzymes of the exocrine pancreas. Again life expectancy is short, even with surgery, for malignant tumors because metastasis has almost always occurred by the time of diagnosis. For patients with endocrine tumors for whom surgical therapy is not an option, medical therapy may be tried. This includes dietary management and the use of sugar solutions rubbed on the dog’s gums during hypoglycemic episodes. Corticosteroids are used if dietary management is unsuccessful. Diazoxide, a medication which inhibits the secretion of insulin may also be helpful. As in humans, radiation therapy and chemotherapy are not helpful. Prognosis is guarded in any case.