Liver Cancer

Tumors in the liver (also known as hepatic neoplasia) may be malignant (cancer) or benign. Cancer found in the liver can originate there (primary) or spread (metastasize) to the liver from malignant tumors elsewhere in the body (secondary - more common in dogs).

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Tumors are classified based on the embryonic origin of the cancerous cells they contain, determined by microscopic analysis of the tumor biopsy. The prefix "-hepato" (liver) may be added to give the formal name of the cancer, e.g., hepatocarcinoma.

Benign liver tumors:

Adenoma

Malignant liver tumors:

Carcinoma
Lymphoma
Hemangiosarcoma

Primary liver cancer is not common in dogs, accounting for only 1-3% of canine tumors. Most primary liver cancer seen in dogs is hepatocellular carcinoma or biliary carcinoma (carcinoma of the bile tract, which moves bile from the liver to the small intestine).

Primary liver cancer can spread to other organs, such as the lungs. Secondary cancers in the liver may have metastasized from cancers in a number of different organs including the pancreas, mammary glands, adrenal glands, intestine or thyroid.

Signs and Symptoms

Signs are similar to those of other liver diseases where there is loss of liver function. Because the liver has a lot of reserve capacity, signs are often only seen after a large part of the liver is damaged. Signs may include:

Pale gums
Decreased appetite
Vomiting
Weakness
Swelling of the abdomen (ascites)
Jaundice Weight loss

If the cancer in the liver started in another organ, there may also be signs from the original cancer.

Causes

Primary liver cancer is thought to be caused by toxins. Because one of the liver's functions is detoxification of substances filtered from blood, it is exposed to anything ingested and absorbed into the bloodstream.

Secondary liver cancer is due to metastases (spread) of cancer from another area of the body.

Risk Factors

Exposure to toxins (primary liver cancer).

Cancer in another area of the body (secondary liver cancer).

Diagnostic Tests

A differential diagnosis must differentiate liver cancer from other liver diseases, such as infection or parasites. Diagnosis must also differentiate between benign and malignant tumors, and primary or secondary cancer.

Tests include:

Physical examination with palpation of abdomen to feel for masses (can detect enlarged liver)
Blood tests to evaluate liver function and "liver enzymes" (AP or ALP and ALT)
Blood count - this can show unusual cells in some types of liver cancer
X-rays and ultrasound can detect masses but cannot tell definitively whether they are malignant or benign.
Ultrasound guided fine needle aspirate - however, pre-surgery fine needle aspirates differ from surgical biopsy results approximately 20% of the time
Most definitive test is an ultrasound guided core biopsy (large bore needle) or a biopsy taken at the time of tumor removal.

Decreased liver function may lead to prolonged bleeding times. Prior to a core biopsy or liver surgery, a veterinarian may recommend that a coagulation profile be performed.

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.

If the cancer is primary and just in one lobe it can often be treated by surgical removal of the lobe. A dog can survive after removal of more than half the liver since the liver has a large reserve capacity. Unfortunately, this same reserve makes it possible for liver cancer to exist and grow for a long time before signs are seen.

The location of the tumor within the liver must be considered prior to surgery; if tumor is near the major blood vessels there is more risk of bleeding/death from the surgery itself.

Chemotherapy is not very effective for treatment of primary liver cancer.

Management

Prognosis - if the cancer is also in other organs, prognosis is poor, and management may be limited to easing discomfort. Transfusions may be used if there is anemia.

Some recommend SAM-e (S-adenosylmethionine), an amino acid, to "support" the liver. Preliminary research shows some positive effects.