Medical Oncology: Canine Hepatobiliary Tumors
What are Hepatobiliary Tumors?
These are rare tumors that arise from the liver, gall bladder, or bile ducts. They account for less than 2% of all cancers.
Hepatobiliary tumors occur most often in older dogs of any breed. The liver’s role in detoxifying the blood could make the hepatobiliary system more susceptible to forming tumors. Hepatobiliary tumors can be malignant or benign. Malignant tumors can spread around the body and are divided into one of four types:
- Hepatocellular tumors
- Bile duct tumors
- Neuroendocrine tumors (carcinoids)
- Primary hepatobiliary sarcomas
Benign liver tumors do not spread beyond the liver but can grow large enough to damage other organs or structures and rupture and bleed.
What Are The Clinical Signs?
Dogs can show signs related to liver disease, including decreased or absent appetite, increased thirst/urination, vomiting, and lethargy. They can also show abdominal distension from an enlarged liver or fluid buildup. Dogs may also show yellowing of their skin, eyes, or mucous membranes from jaundice. Neurological signs, including seizures, weakness, stumbling, and disorientation, can be seen when liver function is severely impaired. Many dogs with hepatocellular carcinoma show no clinical signs other than changes in blood work.
What Diagnostics Are Performed?
An abdominal ultrasound can confirm the presence of a hepatobiliary tumor. During this scan, a small needle can be inserted into a tumor to collect cells for cytology. This test aims to differentiate between different types of hepatobiliary tumors. A biopsy that removes a larger piece of the tumor is often necessary for a definitive diagnosis.
MRI/CT scans provide information regarding benign vs. malignant lesions. CT scans are also used to look for spread to the lungs and other areas in the abdomen and can help plan surgery. The chance of spread depends on the subtype (20-60% for hepatocellular tumors, 80% for bile duct tumors, and 90% for carcinoids).
Bloodwork is done to check liver enzyme values and to look for hypoglycemia (low blood glucose), a complication seen in up to 40% of dogs with hepatobiliary tumors. Further testing includes serum bile acids and serum ammonia levels and checking to ensure the dog’s blood can clot normally.
What Are The Treatment Options?
Surgery is recommended for most dogs with hepatobiliary tumors, depending on the size and extent of the disease. Large portions of the liver can be removed safely as this organ can regenerate itself if necessary.
For malignant tumors that are too large or too extensive to be removed surgically or those that have spread to or from other sites in the body, chemotherapy can be given to try and slow down tumor growth and palliate signs. Liver tumors are unlikely to respond to this form of treatment because the blood supply to the central part of large tumors is poor, preventing chemotherapy from reaching all the cancerous cells. Additionally, the liver can detoxify the chemotherapy drug before it reaches its target. Options to evade these limitations include transarterial chemo/embolization (TAE/TACE) and metronomic chemotherapy.
In TAE/TACE, a catheter is threaded directly into the blood vessel(s) that supply the tumor and used to deposit a blocking agent or chemotherapy.
Metronomic chemotherapy entails administering low doses of oral chemotherapy daily or every other day at home. For a tumor to grow and spread, it must acquire new blood vessels. Metronomic chemotherapy prevents new blood vessels from forming. It also helps the dog’s immune system fight off tumor cells.
What Is The Prognosis?
The prognosis varies with the subtype of the tumor and the extent of the disease.
Dogs with hepatocellular carcinoma can be cured with surgery. Bile duct tumors are most often biliary carcinomas. Unfortunately, the invasive nature of this tumor makes surgery difficult, if not impossible. Chemotherapy is usually not helpful, and the overall prognosis is poor (weeks/months.)
Carcinoids are almost always diffuse and highly metastatic. Like biliary carcinomas, chemotherapy is not successful in treatment. Palladia, an oral tyrosine kinase inhibitor drug, has shown promising results in anecdotal reports; however, the prognosis remains guarded.
The most common primary hepatic sarcomas are hemangiosarcoma or leiomyosarcoma. Hemangiosarcoma is an aggressive cancer originating from blood vessels. For both tumor types, metastasis (to the lungs or other intra-abdominal sites) is present in most cases at the time of diagnosis. Surgical resection of the primary tumor (when possible) and systemic treatment with doxorubicin chemotherapy are recommended. The prognosis is considered poor.
Getting Started
Once you have determined the best option, we will work with you to develop an appointment plan. Appointments for patients undergoing treatments and rechecks must be scheduled in advance. All appointments are drop-off appointments.
Drop-offs are between 7:30 am-8:30 am.
Pick-ups occur by 6:00 pm.
No discharges occur between 2:30-3:30 pm as our oncology team is in rounds.
*Costs are estimates. The overall cost depends on patient response. Estimates do not include supportive care or hospitalization.